Avi Loeb: Aliens, Black Holes, and the Mystery of the Oumuamua

00:00:00.000 | "The following is a conversation with Avi Loeb,

00:00:02.360 | "an astrophysicist, astronomer, and cosmologist at Harvard.

00:00:06.120 | "He has authored over 800 papers and written eight books,

00:00:10.700 | "including his latest called 'Extraterrestrial,

00:00:13.880 | "The First Sign of Intelligent Life Beyond Earth.'

00:00:16.920 | "It'll be released in a couple of weeks,

00:00:18.820 | "so go pre-order it now to show support

00:00:21.200 | "for what I think is truly an important book

00:00:23.520 | "in that it serves as a strong example of a scientist

00:00:26.460 | "being both rigorous and open-minded

00:00:29.040 | "about the question of intelligent alien civilizations

00:00:32.760 | "in our universe."

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00:01:02.420 | As a side note, let me say a bit more

00:01:04.020 | about why Avi's work is so exciting to me

00:01:07.820 | and I think to a lot of people.

00:01:09.580 | In 2017, a strange interstellar object,

00:01:13.460 | now named a muamua, it's fun to say,

00:01:17.200 | was detected traveling through our solar system.

00:01:19.780 | Based on the evidence we have,

00:01:21.140 | it has strange characteristics

00:01:22.540 | which made it not like any asteroid or comet

00:01:25.240 | that we've seen before.

00:01:26.820 | Avi was one of the only world-class scientists

00:01:29.580 | who fearlessly suggested that we should be open-minded

00:01:32.660 | about whether it is naturally made

00:01:35.340 | or in fact is an artifact

00:01:37.400 | of an intelligent alien civilization.

00:01:39.940 | In fact, he suggested that the more likely explanation,

00:01:43.080 | given the evidence, is the latter hypothesis.

00:01:46.120 | We also talk about a lot of fascinating mysteries

00:01:48.700 | in our universe, including black holes,

00:01:51.100 | dark matter, the Big Bang,

00:01:53.180 | and close to speed of light space travel.

00:01:55.900 | The theme throughout is that in scientific pursuits,

00:01:59.220 | the weird things, the anomalies,

00:02:01.740 | the ideas that right now are considered taboo

00:02:04.180 | should not be ignored if we're to have a chance

00:02:06.940 | at finding the next big breakthrough,

00:02:09.060 | the next big paradigm shift,

00:02:11.300 | and also if we are to inspire the world

00:02:14.340 | with the power and beauty of science.

00:02:17.300 | If you enjoy this thing, subscribe on YouTube,

00:02:19.760 | review on Apple Podcasts, follow on Spotify,

00:02:22.820 | support on Patreon, or connect with me

00:02:24.780 | on Twitter @LexFriedman.

00:02:26.940 | And now, here's my conversation with Avi Loeb.

00:02:30.480 | In the introduction to your new book, "Extraterrestrial,"

00:02:34.500 | you write, "This book confronts

00:02:36.460 | "one of the universe's most profound questions,

00:02:39.020 | "are we alone?

00:02:41.180 | "Over time, this question has been framed in different ways.

00:02:44.500 | "Is life here on Earth the only life in the universe?

00:02:47.520 | "Are humans the only sentient intelligence

00:02:50.020 | "in the vastness of space and time?"

00:02:52.520 | A better, more precise framing of this question

00:02:55.220 | would be this, "Throughout the expanse of space

00:02:58.780 | "and over the lifetime of the universe,

00:03:00.740 | "are there now or have ever been

00:03:03.200 | "other sentient civilizations that, like ours,

00:03:06.980 | "explored the stars and left evidence of their efforts?"

00:03:10.580 | So let me ask, are we alone?

00:03:13.420 | - That's an excellent question.

00:03:15.020 | For me, the answer is sort of clear

00:03:18.440 | because I start from the principle of modesty.

00:03:22.000 | (Sherlock laughs)

00:03:23.320 | If we believe that we are alone and special and unique,

00:03:26.960 | that shows arrogance.

00:03:28.680 | My daughters, when they were infants,

00:03:30.360 | they tended to think that they are special, unique,

00:03:33.260 | and then they went out to the street

00:03:35.560 | and realized that other kids are very much like them,

00:03:38.800 | and then they developed a sense of a better perspective

00:03:42.480 | about themselves.

00:03:44.100 | And I think the only reason that we are still thinking

00:03:46.920 | that we are special is because we haven't searched

00:03:49.960 | well enough to find others

00:03:51.920 | that might even be better than us.

00:03:54.700 | And I say that because I look at the newspaper every morning

00:03:58.360 | and I see that we do foolish things.

00:04:00.600 | We are not necessarily the most intelligent ones.

00:04:03.000 | And if you think about it, if you open a recipe book,

00:04:05.920 | you see that out of the same ingredients,

00:04:08.720 | you can make very different cakes,

00:04:11.040 | depending on how you put them together

00:04:13.280 | and how you heat them up.

00:04:14.980 | And what is the chance that by taking the soup of chemicals

00:04:19.400 | that existed on Earth and cooking it one way

00:04:22.440 | to get our life, that you got the best cake possible?

00:04:26.960 | I mean, we are probably not the sharpest cookie in the jar.

00:04:30.680 | And my question is, I mean, it's pretty obvious to me

00:04:34.020 | that we are probably not alone

00:04:35.320 | because half of all the sun-like stars,

00:04:38.320 | we know now as astronomers,

00:04:39.800 | half of the sun-like stars from the Kepler satellite data

00:04:43.760 | have a planet the size of the Earth,

00:04:47.400 | roughly at the same distance that the Earth is from the sun.

00:04:51.160 | And that means that they can have liquid water

00:04:54.060 | on their surface and the chemistry of life as we know it.

00:04:57.160 | So if you roll the dice billions of times

00:05:00.260 | just within the Milky Way galaxy,

00:05:02.960 | and then you have tens of billions of galaxies like it

00:05:07.160 | within the observable volume of the universe,

00:05:09.280 | it would be extremely arrogant

00:05:10.720 | to think that we are special.

00:05:11.680 | I would think that we are sort of middle of the road,

00:05:14.520 | typical forms of life.

00:05:16.400 | And that's why nobody pays attention to us.

00:05:19.160 | If you go down the street on a sidewalk

00:05:21.680 | and you see an ant, you don't pay attention

00:05:24.520 | or a special respect to that ant,

00:05:26.520 | you just continue to walk.

00:05:27.680 | And so I think that we are sort of average,

00:05:30.960 | not very interesting, not exciting,

00:05:32.800 | so nobody cares about us.

00:05:34.760 | We tend to think that we are special,

00:05:36.560 | but that's a sign of immaturity.

00:05:38.480 | - And we're very early on in our development.

00:05:40.480 | - Yes, that's another thing,

00:05:41.680 | that we have our technology only for 100 years

00:05:44.800 | and it's evolving exponentially right now

00:05:47.520 | on a three-year timescale.

00:05:49.200 | So imagine what would happen in 100 years,

00:05:51.600 | in 1,000 years, in a million years or in a billion years.

00:05:54.880 | Now the sun is actually relatively late

00:05:58.800 | in the star formation history of the universe.

00:06:01.160 | Most of the sun-like stars formed earlier

00:06:03.880 | and some of them already died, became white dwarfs.

00:06:08.120 | So if you imagine that a civilization like ours

00:06:12.120 | existed around a typical sun-like star,

00:06:15.120 | by now, if they survived,

00:06:17.040 | they could be a billion years old.

00:06:19.480 | And then imagine a billion-year technology.

00:06:22.360 | It would look like magic to us,

00:06:24.840 | an approximation to God.

00:06:26.520 | We wouldn't be able to understand it.

00:06:28.800 | And so in my view, we should be humble.

00:06:32.480 | And by the way, we should probably just listen

00:06:34.880 | and not speak because there is a risk, right?

00:06:38.680 | If you are inferior, there is a risk.

00:06:42.080 | If you speak too loudly,

00:06:43.600 | something bad may happen to you.

00:06:46.760 | - You mentioned we should be humble also in the sense

00:06:50.440 | with the analogy to ants,

00:06:52.160 | that they might be better than us.

00:06:55.000 | So there's a kind of scale that we're talking about.

00:06:58.960 | And in the question, you mentioned the word sentient.

00:07:03.080 | So sentience, or maybe the more basic formulation of that

00:07:07.600 | is consciousness.

00:07:09.000 | Do you think that this thing within us humans

00:07:14.000 | in terms of the typical life form of consciousness

00:07:19.440 | is the essential element that permeates

00:07:22.240 | if there's other alien civilizations out there

00:07:25.360 | that they have something like consciousness as well?

00:07:28.120 | Or is this, I guess I'm asking,

00:07:30.360 | can you try to untangle the word sentient?

00:07:33.400 | - Yeah, so that's a good question.

00:07:36.280 | I think what is most abundant,

00:07:38.040 | depending on how long it survives.

00:07:40.200 | So if you look at us as an example,

00:07:42.800 | we are now, we do have conscious and we do have technology,

00:07:48.280 | but the technologies that we are developing

00:07:51.040 | are also means for our own destruction, as we can tell.

00:07:56.040 | We can change the climate if we are not careful enough.

00:07:59.800 | We can go into nuclear wars.

00:08:02.120 | So we are developing means for our own destruction

00:08:06.280 | through self-inflicted wounds.

00:08:08.280 | And it might well be that creatures like us

00:08:11.840 | are not long-lived, that the crocodiles on other planets

00:08:16.840 | live for billions of years.

00:08:19.400 | They don't destroy themselves, they live naturally.

00:08:21.960 | And so if you look around, the most common thing

00:08:24.560 | would be dumb animals that live for long times,

00:08:27.920 | not those that have conscious.

00:08:30.000 | But in terms of changing the environment,

00:08:33.440 | I think since, I mean, humans develop tools,

00:08:37.400 | they develop the ability to construct technologies

00:08:42.400 | that would lift us from this planet that we were born in.

00:08:47.280 | And that's something animals without a consciousness

00:08:51.120 | cannot really do.

00:08:52.600 | And so I, in terms of looking for things

00:08:57.600 | that went beyond the circumstances they were born into,

00:09:04.000 | I would think that even if they're short-lived,

00:09:06.640 | these are the creatures that made the biggest difference

00:09:09.580 | to their environment, and we can search for them.

00:09:12.600 | Even if they're short-lived,

00:09:14.080 | and most of the civilizations are dead by now.

00:09:17.280 | Even if that's the case--

00:09:18.120 | - That's sad to think about, by the way.

00:09:19.920 | - Well, but if you look on Earth,

00:09:21.680 | that there are lots of cultures that existed throughout time

00:09:24.880 | and they're dead by now.

00:09:26.120 | The Mayan culture was very sophisticated, died,

00:09:29.820 | but we can find evidence for it and learn about it

00:09:32.420 | just by archeology, digging into the ground, looking.

00:09:35.780 | And so we can do the same thing in space.

00:09:38.060 | Look for dead civilizations,

00:09:40.100 | and perhaps we can learn a lesson why they died

00:09:44.440 | and behave better so that we will not share the same fate.

00:09:48.340 | So I think there is a lesson to be learned from the sky.

00:09:52.500 | And by the way, I should also say,

00:09:54.160 | if we find a technology that we have not dreamed of,

00:09:58.060 | that we can import to Earth,

00:10:00.500 | that may be a better strategy for making a fortune

00:10:03.900 | than going to Silicon Valley or going to Wall Street.

00:10:06.820 | (Lex laughs)

00:10:07.660 | Because you make a jump start into something of the future.

00:10:12.180 | - So that's one way to do the leap is actually to find,

00:10:15.460 | to literally discover versus come up with the idea

00:10:18.860 | in our own limited human capacity,

00:10:21.420 | like a cognitive capacity.

00:10:23.300 | - It would feel like cheating in an exam

00:10:26.060 | where you look over the shoulder of a student next to you.

00:10:29.100 | But it's not good on an exam,

00:10:31.140 | but it is good when you're coming up with technology

00:10:33.600 | that could change the fabric of human civilization.

00:10:36.580 | But there is, in my neck of the woods

00:10:40.660 | of artificial intelligence,

00:10:42.340 | there's a lot of trajectories one can imagine

00:10:44.940 | of creating very powerful beings,

00:10:49.940 | the technology that's essentially,

00:10:52.540 | you can call superintelligence,

00:10:55.420 | that could achieve space exploration,

00:10:58.060 | all those kinds of things without consciousness,

00:11:00.780 | without something that to us humans

00:11:03.220 | looks like consciousness.

00:11:04.620 | And there is a sad feeling I have that consciousness too,

00:11:09.620 | in terms of us being humble,

00:11:12.580 | is a thing we humans take too seriously,

00:11:16.620 | that we think it's special just because we have it.

00:11:19.640 | But it could be a thing that's actually holding us back

00:11:21.580 | in some kind of way.

00:11:22.420 | - May well be, may well be.

00:11:24.260 | I should say something about AI

00:11:26.220 | because I do think it offers a very important

00:11:29.300 | step into the future.

00:11:31.880 | If you look at the Old Testament, the Bible,

00:11:35.360 | there is this story about Noah's Ark

00:11:38.060 | that you might know about.

00:11:39.940 | Noah knew about a great flood

00:11:43.240 | that is about to endanger all life on earth.

00:11:46.860 | So he decided to build an ark.

00:11:49.760 | And the Bible actually talks about specifically

00:11:52.540 | what the size of this ark was,

00:11:54.700 | what the dimensions were.

00:11:56.180 | Turns out it was quite similar to Umuamua

00:11:59.460 | that we will discuss in a few minutes.

00:12:01.380 | But at any event, he built this ark

00:12:04.020 | and he put animals on it

00:12:06.220 | so that they were saved from the great flood.

00:12:09.060 | Now you can think about doing the same on earth

00:12:11.820 | because there are risks for future catastrophes.

00:12:16.620 | We could have the self-inflicted wounds

00:12:18.600 | that we were talking about,

00:12:19.900 | like nuclear war, changing the climate,

00:12:22.140 | or there could be an asteroid impacting us,

00:12:25.620 | just like the dinosaurs died.

00:12:27.940 | The dinosaurs didn't have science, astronomy,

00:12:30.100 | they couldn't have a warning system,

00:12:32.600 | but there was this big stone, big rock that approached them.

00:12:36.380 | It must've been a beautiful sight.

00:12:38.560 | Just when it was approaching,

00:12:39.780 | got very big and then smashed them, okay, and killed them.

00:12:43.220 | So you could have a catastrophe like that,

00:12:45.740 | or in a billion years,

00:12:46.940 | the sun will basically boil off all the oceans on earth.

00:12:50.860 | And currently all our eggs are in one basket,

00:12:55.420 | but we can spread them.

00:12:57.220 | It's sort of like the printing press,

00:12:59.340 | if you think about it.

00:13:00.420 | The revolution that Gutenberg brought

00:13:02.940 | is there were very few copies of the Bible at the time,

00:13:06.460 | and each of them was precious because it was handwritten.

00:13:09.140 | But once the printing press produced multiple copies,

00:13:13.180 | if something bad happened to one of the copies,

00:13:15.500 | it wasn't a catastrophe, it wasn't disaster

00:13:18.340 | 'cause you had many more copies.

00:13:20.180 | And so if we have copies of life here on earth elsewhere,

00:13:25.580 | then we avoid the risk of it being eliminated

00:13:29.220 | by a single point breakdown, catastrophe.

00:13:33.000 | So the question is, can we build NOAAX spaceship

00:13:37.380 | that will carry life as we know it?

00:13:39.460 | Now, you might think we have to put elephants

00:13:42.060 | and whales and birds on a big spaceship,

00:13:45.660 | but that's not true because all you need to know

00:13:48.060 | is the DNA making, the genetic making of these animals,

00:13:52.780 | put it on a computer system that has AI plus a 3D printer

00:13:57.780 | so that this CubeSat, which is rather small,

00:14:03.820 | can go with this information to another planet

00:14:06.860 | and use the raw materials there to produce synthetic life.

00:14:11.160 | And that would be a way of producing copies,

00:14:13.800 | just like the Gutenberg printing press.

00:14:16.500 | - Yeah, and it doesn't have to be exact copies

00:14:18.580 | of the humans, it could just contain

00:14:20.460 | some basic elements of life and then have enough life

00:14:24.740 | on board that it could reproduce the process of evolution

00:14:29.740 | on another place.

00:14:31.380 | So I mean, that also makes you sad, of course,

00:14:33.380 | because you confront the mortality

00:14:35.580 | of your own little precious consciousness

00:14:37.460 | and all your own memories and knowledge

00:14:38.900 | and all that stuff. - That's right,

00:14:39.740 | but who cares?

00:14:41.380 | I mean, we are not--

00:14:42.220 | - I care about mine, right, and you care about yours.

00:14:44.460 | - No, no, I actually don't.

00:14:46.060 | You know, if you look at the big,

00:14:47.340 | if you're an astronomer, one thing that you learn

00:14:49.380 | from the universe is to be modest,

00:14:51.220 | 'cause you're not so significant.

00:14:53.100 | - Oh, boy, yeah. - I mean, think about it.

00:14:54.980 | All these emperors and kings that conquered a piece of land

00:14:57.900 | on Earth and were extremely proud.

00:14:59.860 | You know, you see these images of kings and emperors

00:15:03.860 | that usually are alpha males, and they stand strong,

00:15:08.860 | and they're very proud of themselves.

00:15:11.980 | But if you think about it, there are 10 to the power 20

00:15:15.380 | planets like the Earth in the observable volume

00:15:17.880 | of the universe, and this view of conquering a piece

00:15:22.580 | of land and even conquering all of Earth

00:15:24.900 | is just like an ant hugging a single grain of sand

00:15:28.940 | on the landscape of a huge beach.

00:15:30.860 | That's not very impressive.

00:15:32.400 | So you can't be arrogant.

00:15:34.500 | If you see the big picture, you have to be humble.

00:15:37.500 | You know, also, we are short-lived.

00:15:39.380 | You know, within 100 years, that's it, right?

00:15:43.180 | So what does it teach you?

00:15:45.060 | First, to be humble, modest.

00:15:47.100 | You never have significant powers relative

00:15:49.660 | to the big scheme of things.

00:15:51.420 | And second, you should appreciate every day that you live.

00:15:54.660 | - Yes. - And learn about the world.

00:15:56.880 | - Humble and still grateful.

00:15:59.780 | - Yes, exactly.

00:16:01.500 | - Well, let's talk about probably the most interesting

00:16:06.500 | object I've heard about and also the most fun to pronounce.

00:16:10.460 | - Oumuamua, yes. - Oumuamua.

00:16:12.380 | Can you tell me the story of this object

00:16:15.500 | and why it may be an important event in human history?

00:16:19.060 | And is it possibly a piece of alien technology?

00:16:23.040 | - Right, so this is the first object

00:16:26.260 | that was spotted close to Earth

00:16:29.140 | from outside the solar system.

00:16:31.780 | And it was found on October 19th, 2017.

00:16:36.780 | And at that time, it was receding away from us.

00:16:39.920 | And at first, astronomers thought it must be a piece

00:16:44.320 | of rock, just like all the asteroids and comets

00:16:47.560 | that we have seen from within the solar system.

00:16:50.420 | And it just came from another star.

00:16:52.900 | I should say that the actual discovery of this object

00:16:55.460 | was surprising to me because a decade earlier,

00:16:58.260 | I wrote the first paper together with Ed Turner

00:17:00.780 | and Amaya Moro-Martin that tried to predict

00:17:04.740 | whether the same telescope that was surveying the sky,

00:17:08.060 | Pan-STARRS, from Hawaii, would find anything

00:17:11.140 | from interstellar space, given what we know

00:17:14.100 | about the solar system.

00:17:15.000 | So if you assume that other planetary systems

00:17:17.600 | have similar abundance of rocks and you just calculate

00:17:21.420 | how many should be ejected into interstellar space,

00:17:24.760 | the conclusion is no, we shouldn't find anything

00:17:28.700 | with Pan-STARRS.

00:17:29.960 | - To me, I apologize, probably revealing my stupidity,

00:17:32.700 | but it was surprising to me that so few interstellar objects

00:17:36.800 | from outside this whole system have ever been detected.

00:17:40.160 | - No, none. - None.

00:17:41.000 | - Nothing. - None has been.

00:17:42.560 | - You do, well, maybe talk about it,

00:17:45.120 | that there has been one or two rocks since then.

00:17:48.760 | - Well, since then, there was one called the Borisov.

00:17:52.120 | It was discovered by an amateur Russian astronomer,

00:17:56.000 | Gennady Borisov, and that one looked like a comet.

00:18:01.000 | And just like a comet from within the solar system.

00:18:05.480 | - But this is a really important point,

00:18:06.880 | and sorry to interrupt it.

00:18:08.600 | You showed that it's unlikely that a rock

00:18:10.800 | from another solar system would arrive to ours.

00:18:14.480 | - Right, and so the actual detection of this one

00:18:16.900 | was surprising by itself, to me.

00:18:19.000 | - Yes, yes.

00:18:19.840 | - But then, so at first they thought maybe it's a comet

00:18:24.560 | or an asteroid, but then it didn't look like anything

00:18:27.600 | we've seen before.

00:18:29.120 | Borisov did look like a comet, so people asked me afterwards

00:18:33.440 | and said, you know, doesn't it convince you

00:18:36.840 | if Borisov looks like a comet, doesn't it convince you

00:18:40.400 | that Oumuamua is also natural?

00:18:43.040 | And I said, you know, when I went on the first date

00:18:45.840 | with my wife, she looked special to me,

00:18:49.280 | and since then I met many women,

00:18:51.280 | that didn't change my opinion of my wife.

00:18:53.400 | So, you know, that's not an argument.

00:18:55.360 | Anyway, so why did Oumuamua look weird?

00:19:00.360 | Let me explain.

00:19:02.520 | So first of all, astronomers monitored the amount of light,

00:19:06.280 | sunlight, that it reflects.

00:19:08.360 | And it was tumbling, spinning, every eight hours.

00:19:12.840 | And as it was spinning, the brightness that we saw

00:19:16.040 | from that direction, we couldn't resolve it

00:19:17.800 | 'cause it's tiny, it's about 100 meters, a few hundred feet,

00:19:21.160 | size of a football field, and we cannot, from Earth,

00:19:25.280 | with existing telescopes, we cannot resolve it.

00:19:28.160 | The only way to actually get a photograph of it

00:19:30.760 | is to send a camera close to it,

00:19:33.860 | and that was not possible at the time

00:19:37.000 | that Oumuamua was discovered

00:19:39.120 | because it was already moving away from us

00:19:41.240 | faster than any rocket we can send.

00:19:43.480 | It's sort of like a guest that appeared for dinner,

00:19:46.800 | and then by the time we realized that it's weird,

00:19:49.840 | the guest is already out the front door

00:19:51.600 | into the dark street.

00:19:53.520 | What we would like to find is an object like it

00:19:57.040 | approaching us, because then you can send the camera,

00:19:59.440 | irrespective of how fast it moves.

00:20:01.680 | And if we were to find it in July 2017,

00:20:06.000 | that would have been possible

00:20:07.360 | because it was approaching us at that time.

00:20:09.560 | Actually, I was visiting Mount Haleakala in Maui, Hawaii,

00:20:14.120 | with my family for vacation at that time, in July 2017,

00:20:17.760 | but nobody knew at the observatory

00:20:22.200 | that Oumuamua is very close.

00:20:25.520 | - That's sad to think about,

00:20:26.480 | that we had the opportunity at that time

00:20:28.880 | to send up a camera.

00:20:29.960 | - But don't worry, I mean, there will be more.

00:20:32.160 | There will be more because, you know,

00:20:34.480 | I operate by the Copernican principle,

00:20:37.360 | which says we don't live at a special place,

00:20:40.400 | and we don't live at a special time.

00:20:42.920 | And that means, you know,

00:20:44.360 | if we surveyed the sky for a few years,

00:20:47.400 | and we had sensitivity to this region

00:20:49.680 | between us and the sun,

00:20:51.320 | and we found this object with pan-stars,

00:20:54.720 | you know, there should be many more

00:20:56.080 | that we will find in the future

00:20:58.240 | with surveys that might be even better.

00:21:01.280 | And actually, in three years' timescale,

00:21:03.520 | there would be the so-called LSST,

00:21:06.400 | that's a survey of the Vera Rubin Observatory,

00:21:09.240 | that would be much more sensitive

00:21:11.280 | and could potentially find an Oumuamua-like object

00:21:15.560 | every month, okay? - Yes, wow.

00:21:16.840 | - So I'm just waiting for that.

00:21:18.840 | And the main reason for me to alert everyone

00:21:21.480 | to the unusual properties of Oumuamua

00:21:24.720 | is with the hope that next time around,

00:21:27.360 | when we see something as unusual,

00:21:29.480 | we would take a photograph,

00:21:30.760 | or we would get as much evidence as possible,

00:21:32.800 | 'cause science is based on evidence, not on prejudice.

00:21:36.080 | And we will get back to that theme.

00:21:38.080 | So anyway, let me point out what is--

00:21:39.920 | - Some of the properties, actually.

00:21:41.000 | - Yes. - Yeah, the elongated nature,

00:21:42.760 | all those kinds of things. - Right.

00:21:43.880 | So the light curve, the amount of light,

00:21:46.840 | sunlight that was reflected from it,

00:21:49.320 | was changing over eight hours by a factor of 10,

00:21:53.480 | meaning that the area of this object,

00:21:56.440 | even though we can't resolve it,

00:21:58.440 | the area on the sky that reflects sunlight

00:22:02.400 | was bigger by a factor of 10 in some phases

00:22:07.120 | as it was tumbling around than in other phases.

00:22:09.400 | So even if you take a piece of paper that is razor thin,

00:22:13.760 | there is a very small likelihood that it's exactly edge-on.

00:22:16.720 | And getting a factor of 10 change in the area

00:22:20.360 | that you see on the sky is huge.

00:22:22.520 | It's much more than any other.

00:22:23.920 | It means that the object has an unusual geometry.

00:22:27.760 | It's at least a factor of a few more

00:22:29.640 | than any of the comets or asteroids

00:22:31.560 | that we have seen before.

00:22:32.760 | - You mentioned reflectivity,

00:22:34.320 | so it's not just the geometry,

00:22:35.700 | but the properties of the surface of that thing.

00:22:39.440 | - Well-- - Or no.

00:22:41.000 | - If you assume the reflectivity is the same,

00:22:43.760 | then it's just geometry.

00:22:45.080 | If you assume the reflectivity may change,

00:22:47.720 | then it could be a combination of the area that you see

00:22:50.960 | and the reflectivity,

00:22:51.840 | because different directions may reflect differently.

00:22:55.040 | But the point is that it's very extreme.

00:22:57.400 | - Yes.

00:22:58.280 | - And actually the best fit to the light curve that we saw

00:23:02.720 | was of a flat object,

00:23:04.360 | unlike all the cartoons that you have seen of a cigar shape.

00:23:08.880 | A flat object at the 90% confidence

00:23:11.920 | gives a better model for the way that the light varied.

00:23:15.800 | And it's also-- - So like flat,

00:23:17.520 | meaning like a pancake.

00:23:18.480 | - Like a pancake, exactly. - Yeah, got it.

00:23:20.960 | - And so that's the very first unusual property.

00:23:25.120 | But to me, it was not unusual enough

00:23:28.240 | to think that it might be artificial.

00:23:30.640 | It was not significant enough.

00:23:32.640 | Then there was no cometary tail,

00:23:35.440 | no dust, no gas around this object.

00:23:39.100 | And the Spitzer Space Telescope really searched very deeply

00:23:42.840 | for carbon-based molecules.

00:23:44.960 | There was nothing.

00:23:46.320 | So it's definitely not a comet

00:23:48.200 | the way people expected it to be.

00:23:50.200 | - Can you maybe briefly mention what properties a comet

00:23:54.060 | that you're referring to usually has?

00:23:55.900 | - Right, so a comet is a rock

00:23:58.680 | that has some water ice on the surface.

00:24:01.700 | So you can think of it as an icy rock.

00:24:05.040 | Actually, comets were discovered a long time ago,

00:24:07.440 | but the first model that was developed for them

00:24:12.440 | was by Fred Wippel, who was at Harvard.

00:24:17.320 | And I think the legend goes that he got the idea

00:24:20.440 | from walking through Harvard Square

00:24:22.460 | and seeing, during a winter day,

00:24:25.260 | and seeing these icy rocks.

00:24:27.720 | - So a comet is icy, and an asteroid is not.

00:24:31.640 | - It's just a rock. - It's just a rock.

00:24:33.120 | - Yeah, so when you have ice on the surface,

00:24:36.280 | when the rock gets close to the sun,

00:24:39.120 | the sunlight warms it up,

00:24:41.160 | and the ice sublimates, evaporates.

00:24:44.560 | 'Cause the one thing about ice, water ice,

00:24:47.800 | is it doesn't become liquid if you warm it up in vacuum,

00:24:52.400 | without an external pressure.

00:24:55.180 | It just goes straight into gas.

00:24:57.520 | And that's what you see as the tail of a comet.

00:25:00.440 | - Wow.

00:25:01.320 | - The only way to get liquid water

00:25:03.620 | is to have an atmosphere, like on Earth,

00:25:06.200 | that has an external pressure.

00:25:08.020 | Only then you get liquid.

00:25:09.680 | And that's why it's essential to have an atmosphere

00:25:12.520 | to a planet in order to have liquid water

00:25:15.160 | and the chemistry of life.

00:25:16.640 | So if you look at Mars, Mars lost its atmosphere,

00:25:20.480 | and therefore, no liquid water on the surface anymore.

00:25:23.680 | I mean, there may have been early,

00:25:25.220 | and that's what the Perseverance survey,

00:25:29.380 | the Perseverance mission will try to find out,

00:25:31.760 | whether it had liquid water,

00:25:33.260 | whether there was life, perhaps, on it at the time.

00:25:36.740 | But at some point, it lost its atmosphere,

00:25:39.420 | and then the liquid water was gone.

00:25:41.260 | So the only reason that we can live on Earth

00:25:44.820 | is because of the atmosphere.

00:25:46.700 | But a comet is in vacuum, pretty much,

00:25:49.580 | and when it gets warmed up on the surface,

00:25:53.500 | the water becomes, the water ice becomes gas,

00:25:57.360 | and then you see this cometary tail behind it.

00:25:59.960 | In addition to water, there are all kinds

00:26:04.000 | of carbon-based molecules, or dust,

00:26:06.320 | that comes off the surface.

00:26:08.000 | - And those are detectable.

00:26:09.420 | - Yeah, it's easy to detect.

00:26:10.800 | It's very prominent.

00:26:12.320 | You see these cometary tails that look very prominent

00:26:14.720 | because they reflect sunlight, and you can see them.

00:26:17.440 | In fact, it's sometimes difficult

00:26:18.680 | to see the nucleus of the comet

00:26:20.760 | because it's surrounded and shrouded with,

00:26:23.460 | and in this case, there was no trace of anything.

00:26:26.860 | - That's fascinating. - Now, you might say,

00:26:28.180 | "Okay, it's not a comet."

00:26:29.220 | So that's what the community said.

00:26:30.540 | "Okay, it's not a, no problem, it's still a rock.

00:26:32.840 | "It's not a comet, but it's just a rock, bare rock.

00:26:36.960 | "Okay, no problem."

00:26:38.300 | Then, and that's the thing that convinced me

00:26:41.060 | to write about it, and then in June 2018,

00:26:45.180 | significantly later, there was a report

00:26:48.160 | that in fact the object exhibited an excess push

00:26:53.160 | in addition to the force of gravity.

00:26:56.120 | So the sun acts on it by gravity,

00:26:58.300 | but then there was an extra push on this object

00:27:01.000 | that was figured out from the orbit that you can trace.

00:27:05.040 | And the question was, what is this excess push?

00:27:08.160 | So for comets, you get the rocket effect.

00:27:10.360 | When you evaporate gas, just like a jet engine

00:27:14.040 | on an airplane, a jet engine is very simple.

00:27:17.560 | You throw the gas back, and it pushes the airplane forward.

00:27:21.180 | That's all, that's how it's done.

00:27:22.760 | So in a case of a comet, you throw gas

00:27:25.840 | in the direction of the sun, and then you get a push.

00:27:29.920 | So in the case of comets, you can get a push,

00:27:32.480 | but there was no cometary tail.

00:27:34.560 | So then people said, "Oh, wait a second.

00:27:36.840 | "Is it an asteroid?"

00:27:38.000 | No, but it behaves like a comet,

00:27:39.560 | but it doesn't look like a comet.

00:27:41.340 | So what, well, forget about it, business as usual.

00:27:44.820 | - So that's what they mean by non-gravitation,

00:27:46.960 | non-gravitational acceleration.

00:27:48.440 | So that's interesting.

00:27:49.800 | So the primary force acting on something

00:27:52.680 | like just a rock, like an asteroid,

00:27:55.080 | would be, you can predict the trajectory based on--

00:27:58.360 | - Gravity.

00:27:59.200 | - Based on gravity.

00:28:00.200 | And so here, there's detected movement

00:28:02.120 | that cannot be accounted purely by the gravity of the sun.

00:28:05.320 | - And if it was a comet, you would need about a 10th

00:28:08.660 | of the mass of this comet, the weight of this comet,

00:28:12.240 | to be evaporated in order to give it--

00:28:14.240 | - And there was no sign of that.

00:28:15.440 | - No sign, 10% of the mass evaporating, it's huge.

00:28:19.320 | Think about it, a 100-meter-sized object

00:28:21.760 | losing 10% of its mass.

00:28:23.760 | You can't miss that.

00:28:25.560 | And--

00:28:26.400 | - So that's super weird.

00:28:27.720 | - It's super weird.

00:28:28.560 | - Is there a good, is there in your mind

00:28:31.040 | a possible explanation for this?

00:28:31.880 | - You know, so I operated just like Sherlock Holmes

00:28:34.280 | in a way. (Lex laughs)

00:28:35.400 | I said, "Okay, what are the possibilities?"

00:28:37.280 | And the only thing I could think,

00:28:38.760 | so I ruled out everything else,

00:28:40.700 | and I said, "It must be the sunlight reflected off it."

00:28:44.840 | Okay, so the sunlight reflects off the surface

00:28:48.840 | and gives it a push, just like you get a push on a sail

00:28:52.880 | on a boat, you know, from the wind reflecting off it.

00:28:56.160 | Now, in order for this to be effective,

00:28:59.160 | it turns out the object needs to be extremely thin.

00:29:02.020 | It turns out it needs to be less than a millimeter thick.

00:29:07.040 | Nature does not produce such things.

00:29:09.840 | So, but we produce it because it's called

00:29:13.280 | the technology of a light sail.

00:29:15.400 | So we are, for space exploration,

00:29:17.200 | we are exploring this technology

00:29:19.100 | because it has the benefit of not needing

00:29:22.320 | to carry the fuel with the spacecraft.

00:29:24.600 | So you don't have the fuel, you just have a sail,

00:29:29.360 | and it's being pushed either by sunlight

00:29:32.400 | or by a laser beam or whatever.

00:29:34.900 | So perhaps this is a light sail.

00:29:38.600 | - So this is actually the same technology

00:29:40.480 | with the Starshot project.

00:29:42.160 | - Yes, so people afterwards say,

00:29:45.760 | "Okay, you work on this project, you imagine."

00:29:48.280 | - No, that's a pretty good explanation, right?

00:29:50.640 | - Obviously my imagination is limited by what I know.

00:29:53.840 | So I would not deny that working on light sails

00:29:58.400 | expanded my ability to imagine this possibility.

00:30:01.960 | But let me offer another interesting anecdote.

00:30:05.160 | In September this year, 2020,

00:30:10.960 | there was another object found,

00:30:13.960 | and it was given the name 2020SO

00:30:17.320 | by the Minor Planet Center.

00:30:20.800 | This is an organization actually in Cambridge, Massachusetts

00:30:24.480 | that gives names to objects, astronomical objects

00:30:27.880 | found in the solar system.

00:30:28.920 | And they gave it that name, 2020SO,

00:30:31.240 | because it looked like an object in the solar system,

00:30:35.560 | and it moved in an orbit that is similar

00:30:38.960 | to the orbit of the Earth,

00:30:40.600 | but not the same exactly.

00:30:42.560 | And therefore it was bound to the sun,

00:30:45.480 | but it also exhibited a deviation

00:30:48.740 | from what you expect based on gravity.

00:30:51.200 | So astronomers that found it extrapolated back in time

00:30:54.960 | and found that in 1966, it intercepted the Earth.

00:30:59.960 | And then they realized, they went to the history books,

00:31:02.880 | and they realized, oh, there was a mission

00:31:05.080 | called Lunar Surveyor, Lunar Lander, Surveyor 2,

00:31:09.920 | that had a rocket booster.

00:31:11.840 | It was a failed mission, but there was a rocket booster

00:31:15.320 | that was kicked into space.

00:31:17.540 | And presumably this is the rocket booster

00:31:19.280 | that we are seeing.

00:31:20.320 | Now, this rocket booster was sufficiently hollow and thin

00:31:24.440 | for us to recognize that it's pushed by sunlight.

00:31:27.740 | So here is my point.

00:31:29.240 | We can tell from the orbit of an object,

00:31:31.640 | obviously this object didn't have any cometary tail,

00:31:34.960 | it was artificially made.

00:31:36.920 | We know that it was made by us.

00:31:39.560 | And it did deviate from an orbit of a rock.

00:31:43.400 | So just by seeing something that doesn't have cometary tail

00:31:47.640 | and deviates from an orbit shaped by gravity,

00:31:50.600 | we can tell that it's artificial.

00:31:52.560 | In the case of Oumuamua,

00:31:54.280 | it couldn't have been sent by humans

00:31:56.000 | because it just passed near us for a few months.

00:31:59.200 | We know exactly what we were doing at that time.

00:32:02.160 | And also it was moving faster than any object

00:32:04.600 | that we can launch.

00:32:06.040 | And so obviously it came from outside the solar system.

00:32:09.680 | And the question is who produced it?

00:32:11.880 | Now, I should say that when I walk on vacation on the beach,

00:32:16.440 | I often see natural objects like seashells

00:32:20.440 | that are beautiful and I look at them.

00:32:22.360 | And every now and then I stumble on a plastic bottle

00:32:26.640 | and that was artificially produced.

00:32:30.620 | And my point is that maybe Oumuamua

00:32:33.160 | was a message in a bottle.

00:32:34.600 | And this is simply another window into searching

00:32:39.520 | for artifacts from other civilizations.

00:32:42.220 | - Where do you think it could have come from?

00:32:45.320 | And if it's, so, okay.

00:32:48.640 | From a scientific perspective,

00:32:51.560 | the narrow-minded view,

00:32:53.600 | as we'll probably talk about throughout,

00:32:56.640 | is you kinda wanna stick to the things

00:33:00.840 | to naturally originating objects like asteroids and comets.

00:33:05.360 | Okay, that's the space of possible hypotheses.

00:33:07.480 | And then if we expand beyond that,

00:33:10.080 | you start to think, okay,

00:33:11.440 | these are artificially constructed.

00:33:12.920 | Like you just said, it could be by humans.

00:33:15.120 | It could be by whatever that means

00:33:19.480 | by some kind of extraterrestrial alien civilizations.

00:33:23.240 | If it's the alien civilization variety,

00:33:28.300 | what is this object then that we're looking at?

00:33:31.960 | - An excellent question.

00:33:32.800 | And let me lay out,

00:33:34.640 | I mean, we don't have enough evidence to tell.

00:33:36.760 | If we had a photograph,

00:33:37.840 | perhaps we would have more information.

00:33:39.760 | But there is one other peculiar fact about Oumuamua.

00:33:44.420 | Well, other than it was very shiny,

00:33:48.440 | that I didn't mention,

00:33:50.200 | we didn't detect any heat from it.

00:33:52.000 | And that implies that it's rather small and shiny.

00:33:56.400 | But the other peculiar fact is that

00:33:59.020 | it came from a very special frame of reference.

00:34:02.140 | So it's sort of like finding a car in a parking lot,

00:34:05.780 | in a public parking lot,

00:34:07.980 | that you can't really tell where it came from.

00:34:11.540 | So there is this frame of reference

00:34:13.100 | where you average over the motions of all the stars

00:34:16.620 | in the neighborhood of the sun.

00:34:18.500 | So you find the so-called local standard of rest

00:34:23.220 | of the galaxy.

00:34:24.660 | And that's a frame of reference

00:34:27.680 | that is obtained by averaging the random motions

00:34:30.800 | of all the stars.

00:34:31.640 | And the sun is moving relative to that frame at some speed.

00:34:35.020 | But this object was at rest in that frame.

00:34:38.840 | And only one in 500 stars is so much at rest in that frame.

00:34:43.400 | And that's why I was saying it's like a parking lot.

00:34:45.200 | It was parked there and we bumped into it.

00:34:48.160 | So the relative speed between the solar system

00:34:51.320 | and this object is just because we are moving.

00:34:55.480 | It was sitting still.

00:34:56.720 | Now you ask yourself,

00:34:57.560 | why is it so unusual in that context?

00:35:00.640 | You know why?

00:35:01.560 | Because if it was expelled from another planetary system,

00:35:05.000 | most likely it will carry the speed of the host star

00:35:09.160 | that it came from.

00:35:10.520 | Because the most loosely bound objects

00:35:13.500 | are in the periphery of the planetary system

00:35:16.620 | and they move very slowly relative to the star.

00:35:20.240 | And so they carry, when they are ripped apart

00:35:23.000 | from the planetary system,

00:35:24.200 | most of the objects will have the residual motion

00:35:27.560 | of the star, roughly, relative to the local star.

00:35:29.960 | But this one was at rest in the local.

00:35:31.800 | Now, one thing I can think of,

00:35:33.960 | if there is a grid of road posts,

00:35:38.080 | you know, like for navigation system,

00:35:40.440 | so that you can find your way in the local frame,

00:35:43.760 | then that would be one possibility.

00:35:45.480 | - These are like little sensors of,

00:35:47.600 | that's fascinating to think about.

00:35:48.640 | So there could be, I mean, not necessarily,

00:35:51.000 | literally a grid, but just evenly,

00:35:54.360 | in some definition of evenly spread out

00:35:56.760 | set of objects like these that are just out there.

00:35:59.840 | - A lot of them.

00:36:01.000 | Another possibility is that these are relay stations,

00:36:04.040 | you know, for communication.

00:36:05.620 | You might think in order to communicate,

00:36:07.400 | you need a huge beacon, a very powerful beacon,

00:36:11.480 | but it's not true.

00:36:12.680 | Even on Earth, you know, we have these relay stations.

00:36:15.200 | So you have a not so powerful beacon,

00:36:17.600 | so it can be heard only out to a limited distance,

00:36:20.720 | but then you relay the message.

00:36:23.040 | And it could be one of those.

00:36:24.800 | Now, after it collided with the solar system,

00:36:27.920 | of course, it got a kick.

00:36:29.000 | So it's just like a billiard ball, you know,

00:36:31.240 | we gave it a kick by colliding with,

00:36:33.980 | but most of them are not colliding with stars.

00:36:36.280 | So that's one possibility, okay?

00:36:38.440 | And there should be lots of them, if that's the case.

00:36:41.400 | The other possibility is that it's a probe, you know,

00:36:46.940 | that was sent in the direction of the

00:36:51.200 | habitable region around the sun

00:36:54.520 | to find out if there is life.

00:36:56.080 | Now, it takes tens of thousands of years

00:36:58.680 | for such a probe to traverse the solar system

00:37:00.960 | from the outer edge of the Oort cloud

00:37:03.240 | all the way to where we are.

00:37:05.620 | And, you know, it's a long journey.

00:37:07.120 | So when it started the journey

00:37:08.320 | from the edge of the solar system to get to us now,

00:37:11.120 | you know, we were rather primitive back then, you know,

00:37:13.680 | we still didn't have any technology.

00:37:15.880 | There was no reason to visit, you know,

00:37:17.620 | there was grass around and so forth.

00:37:19.620 | But, you know, maybe it is a probe.

00:37:21.800 | - So you said 10,000 years, that's fastest.

00:37:24.740 | So it takes that long.

00:37:25.660 | - Tens of thousands, yes.

00:37:26.860 | - Tens of thousands of years.

00:37:28.900 | - Yeah, and the other thing I should say is,

00:37:31.500 | you know, it could be just an outer layer of something else,

00:37:36.500 | like, you know, something that was ripped apart,

00:37:39.540 | like a surface of an instrument that was,

00:37:43.300 | and you can have lots of these pieces, you know,

00:37:45.460 | something breaks, lots of these pieces spread out,

00:37:48.060 | like space junk.

00:37:49.620 | And, you know, that--

00:37:51.220 | - It could be just space junk

00:37:53.700 | from an alien civilization.

00:37:56.900 | - Yes.

00:37:57.980 | - So it's--

00:37:58.820 | - I should tell you about space junk.

00:38:01.060 | Let me--

00:38:01.900 | - Yes, what do you mean by space junk?

00:38:03.740 | - So I think, you know, you might ask,

00:38:07.220 | why aren't they looking for us?

00:38:09.260 | One possibility is that we are not interesting,

00:38:11.060 | like we were talking about--

00:38:11.900 | - Yeah, the ants hypothesis.

00:38:13.140 | - Another possibility, you know,

00:38:15.020 | if they are millions or billions of years

00:38:18.300 | into their technological development,

00:38:21.880 | they created their own habitat, their own cocoon,

00:38:26.880 | where they feel comfortable, they have everything they need,

00:38:30.100 | and it's risky for them to establish communication

00:38:33.420 | with other, so they have their own cocoon,

00:38:37.020 | and they close off.

00:38:38.420 | They don't care about anything else.

00:38:40.020 | Now, in that case, you might say,

00:38:42.020 | oh, so how can we find about them if they are closed off?

00:38:45.820 | The answer is, they still have to deposit trash, right?

00:38:49.460 | That is something from the law of thermodynamics.

00:38:52.500 | There must be some production of trash.

00:38:55.020 | And, you know, we can still find about them

00:38:57.700 | just like investigative journalists

00:39:00.300 | going through the trash cans of celebrities in Hollywood.

00:39:04.060 | You know, you can learn about the private lives

00:39:06.780 | of those celebrities by looking at the trash.

00:39:09.180 | - It's fascinating to think, you know,

00:39:11.100 | if we are the ants in this picture,

00:39:13.500 | if this thing is a water bottle,

00:39:16.420 | or if it's like a smartphone,

00:39:18.100 | like where on the spectrum of possible objects of space,

00:39:23.100 | 'cause there's a lot of interesting trash.

00:39:25.340 | - Right. (laughs)

00:39:26.500 | - So like, how interesting is this trash possible?

00:39:29.140 | - But imagine a caveman seeing a cell phone.

00:39:32.380 | The caveman would think,

00:39:33.660 | since the caveman played with rocks all of his life,

00:39:36.340 | he would say, it's a rock,

00:39:37.700 | just like my fellow astronomers said.

00:39:39.820 | - Yes. - Right?

00:39:40.820 | - Yes, exactly.

00:39:41.660 | That's brilliantly put.

00:39:43.100 | Actually, as a scientist,

00:39:44.220 | do you hope it's a water bottle or a smartphone?

00:39:46.420 | Because--

00:39:47.260 | - I hope it's even more than a smartphone.

00:39:49.220 | I hope that it's something that is really sophisticated.

00:39:52.460 | - That's funny.

00:39:53.300 | - Yeah. - See, I'm the opposite.

00:39:54.460 | I feel like I hope it's a water bottle

00:39:56.740 | because at least we have a hope

00:39:59.060 | with our current set of skills to understand it.

00:40:01.900 | - Yeah, but-- - A caveman has no way

00:40:03.300 | of understanding the smartphone.

00:40:04.700 | It's like, it will be,

00:40:06.020 | like, I feel like a caveman has more to learn

00:40:08.500 | from the plastic water bottle

00:40:09.940 | than it'll do from the smartphone.

00:40:11.580 | - But suppose we figure it out,

00:40:13.100 | if we, for example, come close to it

00:40:15.700 | and learn what it's made of.

00:40:17.980 | - And I guess a smartphone is full of, like,

00:40:20.380 | thousands of different technologies

00:40:22.100 | that we could probably pick at.

00:40:23.860 | Do you have a sense of where,

00:40:27.220 | a hypothesis of where is the cocoon

00:40:32.700 | that it might have come from?

00:40:34.820 | - No, because, okay, so first of all,

00:40:38.620 | you know, the solar system,

00:40:40.100 | the outermost edge of the solar system

00:40:42.140 | is called the Oort cloud.

00:40:43.780 | It's a cloud of icy rocks

00:40:46.980 | of different sizes that were left over

00:40:52.020 | from the formation of the solar system.

00:40:54.020 | - Yes. - And it's thought to be

00:40:56.340 | roughly a ball or a sphere.

00:40:59.940 | And it's halfway, the extent of it

00:41:01.900 | is roughly halfway to the nearest star, okay?

00:41:05.460 | So you can imagine each planetary system

00:41:09.100 | basically touching the Oort clouds of those stars

00:41:14.100 | that are near us are touching each other.

00:41:17.580 | Space is full of these billiard balls

00:41:21.820 | that are very densely packed.

00:41:24.380 | And what that means is any object that you see,

00:41:28.140 | irrespective of whether it came from the local standard,

00:41:30.420 | so we said that this object is special

00:41:32.340 | because it came from a local standard of rest,

00:41:34.140 | but even if it didn't,

00:41:35.580 | you would never be able to trace where it came from

00:41:37.820 | because all these Oort clouds overlap.

00:41:41.820 | So if you take some direction in the sky,

00:41:44.540 | you will cross as many stars as you have

00:41:48.220 | in that direction.

00:41:49.180 | Like there is no way to tell which Oort cloud it came from.

00:41:52.420 | - So yes, I didn't realize how densely packed everything was

00:41:56.180 | from the perspective of the Oort cloud.

00:41:58.140 | And that's really interesting.

00:41:59.140 | So yeah, it could be nearby, it could be very far away.

00:42:02.020 | - Yeah, we have no clue.

00:42:03.860 | You said cocoon and you kind of paint,

00:42:08.260 | I think in the book,

00:42:11.580 | I've read a lot of your articles too

00:42:13.340 | on the Scientific American, which are brilliant.

00:42:15.300 | So I'm kind of mixing things up in my head a little bit.

00:42:17.660 | But there's, what does that cocoon look like?

00:42:22.100 | What does a civilization that's able to harness

00:42:24.620 | the power of multiple suns, for example, look like?

00:42:29.020 | When you imagine possible civilizations

00:42:31.100 | that are a million years more advanced than us,

00:42:34.140 | what do you think that actually looks like?

00:42:36.980 | - I think it's very different than we can imagine.

00:42:40.300 | By the way, I should start from the point

00:42:42.460 | that even biological life,

00:42:45.220 | just without technology getting into the game,

00:42:48.980 | could look like something we have never seen before.

00:42:52.180 | Take, for example, the nearest star,

00:42:54.260 | which is Proxima Centauri.

00:42:55.980 | It's four and a quarter light years away.

00:42:58.460 | So they will know about the results of the 2016 elections

00:43:03.100 | only next month in February, 2021.

00:43:06.140 | It's very far away.

00:43:08.500 | But if you think about it,

00:43:11.660 | this star is a dwarf star,

00:43:17.340 | and it's much cooler than,

00:43:19.260 | it's twice as cold as the sun, okay?

00:43:23.060 | And it emits mostly infrared radiation.

00:43:26.020 | So if there are any creatures on the planet close to it

00:43:30.980 | that is habitable, which is called Proxima b,

00:43:34.300 | there is a planet in the habitable zone,

00:43:36.100 | in the zone just at the right distance

00:43:38.140 | where in principle liquid water can be on the surface.

00:43:41.260 | If there are any animals there,

00:43:43.020 | they have infrared eyes because our eyes

00:43:45.860 | was designed to be sensitive

00:43:48.580 | to where most of the sunlight is in the visible range.

00:43:52.140 | But Proxima Centauri emits mostly infrared.

00:43:54.940 | So, you know, the nearest- - Who's not able

00:43:56.500 | to see each other? (laughs)

00:43:57.660 | - In the nearest star system,

00:43:59.380 | these animals would be quite strange.

00:44:02.260 | They would have eyes that are detectors of infrared,

00:44:05.700 | very different from ours.

00:44:07.180 | Moreover, this planet, Proxima b,

00:44:09.500 | faces the star always with the same side.

00:44:12.540 | So it has a permanent day side and a permanent night side.

00:44:16.180 | And obviously the creatures that would evolve

00:44:19.060 | on the permanent day side, which is much warmer,

00:44:21.620 | would be quite different than those

00:44:23.260 | on the permanent night side.

00:44:24.740 | Between them, there would be a permanent sunset strip.

00:44:28.820 | And my daughters said that that's the best opportunity

00:44:32.060 | for high-value real estate

00:44:34.220 | 'cause you will see the sunset throughout your life, right?

00:44:38.860 | The sun never sets on this strip.

00:44:42.660 | So, you know, these worlds are out of our imagination.

00:44:46.180 | - Just even the individual creatures,

00:44:48.220 | the sensor suite that they're operating with

00:44:50.380 | might be very different.

00:44:51.220 | - Very different.

00:44:52.060 | So I think when we see something like that,

00:44:53.820 | we would be shocked.

00:44:55.220 | Not to speak about seeing technology.

00:44:57.100 | Now, so I don't even dare to imagine, you know?

00:45:00.540 | And I think, you know,

00:45:02.900 | obviously we can bury our head in the sand

00:45:05.540 | and say it's never aliens, like many of my colleagues say.

00:45:10.340 | And it's a self-fulfilling prophecy.

00:45:12.020 | If you never look, you will never find.

00:45:14.300 | If you are not ready to find wonderful things,

00:45:17.780 | you will never discover them.

00:45:19.460 | And the other thing I would like to say is

00:45:22.020 | reality doesn't care whether you ignore it or not.

00:45:25.500 | You can ignore reality, but it's still there.

00:45:27.980 | So we can all agree based on Twitter

00:45:32.500 | that aliens don't exist, that Oumuamua was a rock.

00:45:37.060 | We can all agree.

00:45:38.060 | And you will get a lot of likes.

00:45:40.100 | We will have a big crowd of supporters

00:45:42.260 | and everyone will be happy and give each other awards

00:45:45.100 | and honors and so forth.

00:45:46.980 | But Oumuamua might still be an alien artifact.

00:45:50.980 | Who cares what humans agree on?

00:45:53.460 | - Yeah, exactly.

00:45:54.300 | - There is a reality out there.

00:45:55.540 | And we have to be modest enough to recognize

00:45:59.700 | that we should make our statements based on evidence.

00:46:03.820 | Science is not about ourself.

00:46:06.420 | It's not about glorifying our image.

00:46:09.020 | It's not about getting honors, prizes, you know?

00:46:11.620 | A lot of the scientific, a lot of the academic activity

00:46:14.900 | is geared towards creating your echo chamber

00:46:18.420 | where you have students, postdocs

00:46:19.820 | repeating your mantras so that your voice is heard loudly

00:46:23.860 | so that you can get more honors, prizes, recognition.

00:46:27.420 | That's not the purpose of science.

00:46:29.220 | The purpose is to figure out what nature is, right?

00:46:32.940 | And in the process of doing that,

00:46:34.620 | it's a learning experience.

00:46:35.820 | You make mistakes.

00:46:37.420 | Einstein made three mistakes at the end of his career.

00:46:40.620 | He argued that in the 1930s,

00:46:43.220 | he argued that black holes don't exist,

00:46:45.740 | gravitational waves don't exist,

00:46:48.100 | and quantum mechanics doesn't have spooky action

00:46:52.580 | at a distance.

00:46:53.780 | And all three turned out to be wrong, okay?

00:46:56.540 | So the point is that if you work at the frontier,

00:46:59.860 | then you make mistakes.

00:47:00.940 | It's inevitable because you can't tell what is true or not.

00:47:04.140 | And avoiding making mistakes in order to preserve your image

00:47:08.180 | makes you extremely boring, okay?

00:47:10.380 | You will get a prize, but you will be a boring scientist

00:47:14.220 | because you will keep repeating things we already know.

00:47:17.300 | If you want to make progress, if you want to innovate,

00:47:20.180 | you have to take risks,

00:47:21.660 | and you have to look at the evidence.

00:47:23.940 | It's a dialogue with nature.

00:47:25.940 | You don't know the truth in advance.

00:47:28.340 | You let nature tell you, educate you,

00:47:31.100 | and then you realize that what you thought before

00:47:34.300 | is incorrect.

00:47:35.560 | And a lot of my colleagues prefer to be in a state

00:47:39.580 | where they have a monologue.

00:47:40.940 | You know, if you look at these people

00:47:42.020 | that work on string theory, they have a monologue.

00:47:45.460 | They know what, and in fact,

00:47:47.180 | their monologue is centered on anti-de Sitter space,

00:47:50.340 | which we don't live in now.

00:47:53.140 | You know, to me, it's just like the Olympics.

00:47:55.060 | You know, you define 100 meters,

00:47:57.460 | and you say, "Whoever runs this 100 meters

00:47:59.940 | "is the best athlete, the fastest," you know?

00:48:02.660 | And it's completely arbitrary.

00:48:04.580 | You could have decided it would be 50 meters or 20 meters.

00:48:08.140 | Who cares?

00:48:08.980 | You just measure the ability of people this way.

00:48:11.300 | So you define anti-de Sitter space

00:48:13.300 | as a space where you do your mathematical gymnastics,

00:48:16.620 | and then you find who can do it the best,

00:48:18.500 | and you give jobs based on that, you give prizes based.

00:48:21.540 | But as we said before, you know,

00:48:23.420 | nature doesn't care about, you know,

00:48:25.500 | the prizes that you give to each other.

00:48:28.360 | It cares, you know, it has its own reality,

00:48:31.540 | and we should figure it out, and it's not about us.

00:48:34.660 | The scientific activity is about figuring out nature.

00:48:37.700 | And sometimes we may be wrong.

00:48:39.340 | Our image will not be preserved,

00:48:42.060 | but that's the fun, you know?

00:48:45.920 | Kids explore the world out of curiosity,

00:48:49.020 | and I always want to maintain my childhood curiosity,

00:48:52.700 | and I don't care about the labels that I have.

00:48:55.300 | In fact, having tenure is exactly the opportunity

00:48:59.140 | to behave like a child because you can make mistakes.

00:49:02.420 | And I was asked by the Harvard Gazette,

00:49:05.220 | you know, the Pravda of Harvard,

00:49:08.120 | (Sami laughs)

00:49:09.500 | what is the one thing that you would like

00:49:12.880 | to change about the world?

00:49:14.980 | And I said, I would like my colleagues

00:49:17.760 | to behave more like kids.

00:49:20.060 | That's the one thing I would like them to do

00:49:22.080 | because something bad happens to these kids

00:49:25.860 | when they become tenured professors.

00:49:27.700 | They start to worry about their ego

00:49:29.940 | and about themselves more than about the purpose of science,

00:49:33.620 | which is, you know, curiosity-driven,

00:49:35.820 | figuring out from evidence.

00:49:37.300 | Evidence is the key.

00:49:38.780 | So when an object shows anomalies, like Oumuamua,

00:49:41.820 | what's the problem discussing, you know,

00:49:44.460 | whether it's artificial or not?

00:49:46.100 | You know, so there was, I should tell you,

00:49:47.540 | there was a mainstream paper in Nature

00:49:50.940 | published saying it must be natural.

00:49:53.740 | That's it.

00:49:55.060 | It's unusual, but it must be natural, period.

00:49:58.460 | And then at the same time,

00:49:59.980 | some other mainstream scientists

00:50:04.260 | tried to explain the properties.

00:50:06.160 | And they came up with interpretations like,

00:50:08.660 | it's a dust bunny, you know,

00:50:10.380 | the kind that you find in a household,

00:50:11.900 | a collection of dust particles pushed by sunlight.

00:50:15.040 | Something we have never seen before.

00:50:18.380 | Or it's a hydrogen iceberg.

00:50:20.580 | It actually evaporates like a comet,

00:50:22.740 | but hydrogen is transparent, you don't see it,

00:50:25.260 | and that's why we don't see the cometary tail.

00:50:27.260 | Again, we have never seen something like that.

00:50:29.340 | In both cases, the objects would not survive

00:50:32.500 | the long journey.

00:50:33.900 | We discussed it in a paper that I wrote afterwards.

00:50:36.820 | But my point is, those that tried to explain

00:50:39.500 | the unusual properties went into great length

00:50:42.980 | at discussing things that we have never seen before.

00:50:47.020 | So even when you think about the natural origin,

00:50:49.840 | you have to come up with scenarios

00:50:52.180 | of things that were never seen before.

00:50:54.120 | And by the way, they look less plausible to me, personally.

00:50:58.920 | But my point is, if we discuss things

00:51:00.980 | that were never seen before,

00:51:02.540 | why not discuss, why not contemplate an artificial origin?

00:51:06.940 | What's the problem?

00:51:07.920 | Why do people have this pushback?

00:51:11.940 | I worked on dark matter,

00:51:14.800 | and we don't know what most of the matter in the universe is.

00:51:18.500 | It's called dark matter.

00:51:19.640 | It's just an acronym because we have no clue.

00:51:23.000 | We simply don't know.

00:51:23.940 | So it could be all kinds of particles.

00:51:25.800 | And over the years, people suggested

00:51:27.480 | weakly interacting massive particles,

00:51:29.320 | axions, all kinds of particles.

00:51:31.440 | And experiments were made.

00:51:33.620 | They cost hundreds of millions of dollars.

00:51:36.480 | They put upper limits, constraints,

00:51:39.040 | that ruled out many of the possibilities

00:51:41.040 | that were proposed as natural initially.

00:51:43.960 | The mainstream community regarded it

00:51:45.960 | as a mainstream activity

00:51:47.480 | to search the nature of the dark matter.

00:51:49.640 | And nobody complained that it's speculative

00:51:53.320 | to consider weakly interacting massive particles.

00:51:56.280 | Now, I ask you, why is it speculative

00:51:59.000 | to consider extraterrestrial technologies?

00:52:02.920 | We have a proof that it exists here on Earth.

00:52:06.400 | We also know that the conditions of Earth

00:52:09.960 | are reproduced in billions of systems

00:52:13.140 | throughout the Milky Way galaxy.

00:52:14.920 | So what's more conservative than to say

00:52:17.400 | if you arrange for similar conditions,

00:52:20.000 | you get the same outcome?

00:52:21.440 | How can you imagine this to be speculative?

00:52:23.480 | It's not speculative at all.

00:52:24.840 | And nevertheless, it's regarded the periphery.

00:52:27.400 | And at the same time, you have physicists,

00:52:29.320 | theoretical physicists, working on extra dimensions,

00:52:32.440 | supersymmetry, superstring theory,

00:52:36.040 | the multiverse, maybe we live in a simulation,

00:52:39.080 | all of these ideas that have no grounding in reality,

00:52:43.480 | some of which sound to me like, you know,

00:52:46.400 | just like what someone would say--

00:52:49.000 | - Science fiction, basically.

00:52:50.760 | - Because you have no way to test it, you know,

00:52:54.880 | through experiments, and experiments really are key.

00:52:57.440 | It's not just the nuance.

00:52:58.880 | You say, okay, forget about the experiment.

00:53:00.680 | As some philosophers try to say,

00:53:02.440 | you know, if there is a consensus, what's the problem?

00:53:04.880 | The point is, it's key, and that's what Galileo found.

00:53:08.040 | It's key to have feedback from reality.

00:53:10.520 | You know, you can think that you have a billion dollar,

00:53:12.960 | or that you are more rich than, you know, Elon Musk.

00:53:17.600 | That's fine, you can feel very happy about it.

00:53:20.800 | You can talk about it with your friends,

00:53:22.640 | and all of you will be happy,

00:53:23.800 | and think about what you can do with the money.

00:53:25.960 | Then you go to an ATM machine, and you make an experiment.

00:53:28.820 | You check how much money you have in your checking account.

00:53:32.320 | And if it turns out that, you know, you don't have much,

00:53:35.640 | you can't materialize your dreams.

00:53:39.400 | Okay, so you realize, you have a reality check.

00:53:42.080 | And my point is, without experiments,

00:53:44.200 | giving you a reality check, without the ATM machine

00:53:46.560 | showing you whether your ideas are bankrupt or not,

00:53:49.720 | without putting skin in the game,

00:53:52.280 | and by skin in the game, I mean,

00:53:54.400 | don't just talk about theoretical ideas.

00:53:56.960 | Make them testable.

00:53:58.560 | If you don't make them testable, they're worthless.

00:54:01.680 | They're just like theology that is not testable.

00:54:05.000 | By the way, theology has some tests.

00:54:07.840 | Let me give you--

00:54:08.680 | - (laughs) That's interesting.

00:54:09.880 | - Three examples.

00:54:10.720 | - Yes.

00:54:11.540 | - It turns out that my book already inspired

00:54:15.760 | a PhD student at Harvard in the English department

00:54:19.240 | to pursue a PhD in that direction.

00:54:22.000 | And she invited me to the PhD exam a couple of months ago.

00:54:26.580 | And in the exam, one of the examiners, a professor,

00:54:31.560 | asked her, "Do you know why Giordano Bruno

00:54:35.760 | "was burnt at the stake?"

00:54:37.640 | And she said, "I think it's because he was an obnoxious guy

00:54:42.620 | "and irritated a lot of people."

00:54:45.520 | Which is true.

00:54:46.400 | But the professor said, "No, it's because Giordano Bruno

00:54:51.940 | "said that other stars are just like the sun,

00:54:55.520 | "and they could have a planet like the Earth around them

00:55:00.720 | "that could host life."

00:55:03.400 | And that was offensive to the church.

00:55:05.720 | Why was it offensive?

00:55:07.320 | Because there is the possibility that this life sinned.

00:55:11.040 | And if that life sinned on planets around other stars,

00:55:16.720 | it should have been saved by Christ.

00:55:19.380 | And then you need multiple copies of Christ,

00:55:22.400 | and that's unacceptable.

00:55:23.980 | How can you have duplicates of Christ?

00:55:27.320 | And so they burned the guy.

00:55:30.640 | - It was about, okay, I'm just loading this all in

00:55:34.240 | 'cause that's kind of brilliant.

00:55:35.720 | So he was actually already, it's not just about the stars,

00:55:38.640 | it's anticipating that there could be other life forms.

00:55:41.300 | Like why, if there's other stars,

00:55:44.640 | why would our star be special?

00:55:47.920 | - He was making the right argument.

00:55:49.240 | - And he would just follow that all along to say

00:55:52.280 | there should be other Earth-like places,

00:55:55.160 | there should be other life forms.

00:55:56.320 | And then there needs to be copies of Christ.

00:55:58.720 | - Yeah, so that was offensive.

00:56:00.120 | So I said to that professor, I said, "Great."

00:56:05.120 | I wanted to introduce some scientific tone

00:56:07.720 | to the discussion.

00:56:09.400 | And I said, "This is great because now you basically

00:56:12.480 | "laid the foundation for an experimental test

00:56:14.920 | "of this theology.

00:56:16.300 | "What is the test?

00:56:17.900 | "We now know that other stars are like the sun,

00:56:20.760 | "and we know they have planets like the Earth around them.

00:56:23.300 | "So suppose we find life there,

00:56:25.560 | "and we figure out that they sinned.

00:56:28.700 | "Then we ask them, did you witness Christ?

00:56:32.440 | "And if they say no, it means that this theology

00:56:36.540 | "is ruled out."

00:56:38.160 | So there is an experimental test.

00:56:39.500 | So this is experimental test number one.

00:56:41.360 | Another experimental test.

00:56:42.900 | In the Bible, in the Old Testament, Abraham

00:56:49.000 | was heard the voice, the voice of God,

00:56:54.540 | to sacrifice his son, right?

00:56:58.160 | Only son.

00:56:59.120 | And that's what the story says.

00:57:01.720 | Now suppose Abraham, my name, by the way,

00:57:05.600 | had a voice memo up on his cell phone.

00:57:10.020 | He could have pressed this up and recorded the voice of God,

00:57:13.440 | and that would have been experimental evidence

00:57:16.160 | that God exists, right?

00:57:18.800 | Fortunately, he didn't.

00:57:20.220 | But it's an experimental test, right?

00:57:23.280 | There is a third example I should tell,

00:57:25.560 | and that is Elie Wiesel attributed this story

00:57:28.940 | to Martin Buber, but it's not clear whether it's true or not.

00:57:32.080 | At any event, the story goes that Martin Buber,

00:57:36.280 | he was a philosopher, and he said,

00:57:39.040 | "The Christians argue that the Messiah arrived already,

00:57:44.040 | "and will come back again in the future.

00:57:48.140 | "The Jews argue the Messiah never came,

00:57:52.380 | "and will arrive in the future."

00:57:54.640 | So he said, "Why argue?

00:57:56.940 | "Both sides agree that the Messiah will arrive

00:58:00.860 | "in the future.

00:58:02.240 | "When the Messiah arrives, we can ask whether he or she

00:58:06.620 | "came before," you know, like visited us,

00:58:10.380 | and then figure it out, and one side.

00:58:12.400 | So again, experimental test of a theology.

00:58:15.040 | So even theology, if it puts a skin in the game,

00:58:20.040 | if it makes a prediction, could be tested, right?

00:58:23.240 | So why can't string theories test themselves?

00:58:25.960 | Or why can't, you know, even cosmic inflation,

00:58:28.400 | that's another model that, you know,

00:58:30.200 | one of the inventors from MIT, Alan Guth,

00:58:32.500 | argues that it's not falsifiable.

00:58:34.420 | My point is a theory that cannot be falsified

00:58:39.400 | is not helpful, because it means

00:58:41.580 | that you can't make progress.

00:58:42.820 | You cannot improve your understanding of nature.

00:58:45.360 | The only way for us to learn about nature

00:58:48.040 | is by making hypotheses that are testable,

00:58:51.960 | doing the experiments, and learning

00:58:53.600 | whether we are correct or not.

00:58:55.120 | - So be, and couple that with a curiosity

00:58:58.480 | and open-mindedness that allows us to explore

00:59:00.600 | all kinds of possible hypotheses,

00:59:03.240 | but always the pursuit of those,

00:59:06.840 | the scientific rigor around those hypotheses

00:59:09.240 | is ultimately get evidence.

00:59:12.720 | - Knowledge is, of what nature is,

00:59:16.160 | should be a dialogue with nature,

00:59:18.440 | rather than a monologue.

00:59:19.360 | - Monologue, beautifully put.

00:59:21.480 | Can we talk a little bit about the Drake equation?

00:59:24.160 | Another framework from which to have

00:59:26.460 | this kind of discussion about

00:59:28.280 | possible civilizations out there.

00:59:30.560 | So let me ask, within the context of the Drake equation,

00:59:33.320 | or maybe bigger, how many alien civilizations

00:59:36.680 | do you think are out there?

00:59:38.400 | - Well, it's hard to tell, 'cause the Drake equation

00:59:40.360 | is, again, quantifying our ignorance.

00:59:42.320 | It's just a set of factors.

00:59:45.280 | The only one that we know, or actually two

00:59:48.880 | that we know quite well is the rate of star formation

00:59:52.000 | in the Milky Way galaxy, which we measured by now,

00:59:55.280 | and the frequency of planets like the Earth around stars,

01:00:00.200 | and at the right distance to have life.

01:00:03.080 | But other than that, there are lots of implicit assumptions

01:00:07.280 | about all the other factors that will enable us

01:00:09.320 | to detect a signal.

01:00:10.960 | Now, I should say the Drake equation

01:00:13.160 | has a very limited validity just for signals

01:00:16.640 | from civilizations that are transmitting

01:00:19.440 | at the time that you're observing them.

01:00:21.560 | However, we can do much better than that.

01:00:25.040 | We can look for artifacts that they left behind.

01:00:28.720 | Even if they are dead, you can look for

01:00:31.680 | industrial pollution in the atmosphere of planets.

01:00:34.240 | Why do I bring this up?

01:00:37.040 | Again, to show you the conservatism

01:00:38.840 | of the mainstream in astronomy.

01:00:40.920 | By the way, I have leadership positions.

01:00:43.440 | I was chair of the astronomy department for nine years,

01:00:45.760 | the longest serving chair at Harvard.

01:00:48.240 | I'm the chair of the board on physics and astronomy

01:00:51.600 | of the National Academies.

01:00:53.000 | It's a primary board.

01:00:55.680 | I'm director of two centers at Harvard and so forth.

01:01:00.240 | So I do represent the community in various ways,

01:01:04.760 | but at the same time, I'm a little bit disappointed

01:01:07.600 | by the conservatism that people have.

01:01:10.120 | Let me give you an illustration of that.

01:01:12.120 | So the astronomy community actually is going right now

01:01:15.960 | through the process of defining its goals

01:01:18.280 | for the next decade.

01:01:19.800 | And there are proposals for telescopes

01:01:23.080 | that would cost billions of dollars

01:01:25.680 | and whose goal is to find evidence for oxygen

01:01:31.520 | in the atmosphere of planets around other stars

01:01:34.560 | with the idea that this would be a marker,

01:01:37.680 | a signature of life.

01:01:40.000 | Now, the problem with that is Earth didn't have much oxygen

01:01:44.680 | in its atmosphere for the first two billion years.

01:01:47.000 | Roughly half of its life, it didn't have much oxygen,

01:01:51.240 | but it had life.

01:01:52.160 | It had microbial life.

01:01:53.960 | It's not clear yet, as of yet, what the origin is

01:01:58.880 | for the rise in the oxygen level after two billion years,

01:02:02.640 | about 2.4 billion years ago.

01:02:06.260 | But we know that a planet can have life

01:02:09.760 | without oxygen in the atmosphere because Earth did it.

01:02:12.760 | The second problem with this approach

01:02:14.840 | is that you can have oxygen from natural processes.

01:02:19.280 | You can break water molecules and make oxygen.

01:02:22.400 | So even if you find it, it will never tell you

01:02:24.600 | that for sure life exists there.

01:02:27.840 | And so even with these billions of dollars,

01:02:30.300 | the mainstream community will never be confident

01:02:33.480 | whether there is life there.

01:02:36.240 | Now, how can it be confident?

01:02:37.920 | There is actually a way.

01:02:39.480 | If instead of looking with the same instruments,

01:02:41.840 | if you look for molecules that indicate industrial pollution,

01:02:46.120 | for example, CFCs that are produced

01:02:49.200 | by refrigerating systems or industries here on Earth,

01:02:52.600 | that they do the ozone layer, you can search for that.

01:02:55.640 | And I wrote a paper five years ago suggesting that.

01:02:58.520 | Now, what's the problem?

01:03:00.160 | You can just tell NASA, I want to build this telescope

01:03:04.060 | to search for oxygen, but also for industrial pollution.

01:03:08.420 | Nobody would say that because it sounds like

01:03:11.840 | on the periphery of the field.

01:03:15.820 | And I ask you, why would--

01:03:17.520 | - That's hilarious 'cause that's exactly, I mean--

01:03:20.440 | - Even just you saying it's quite brilliant.

01:03:22.320 | I mean, 'cause it's a really strong signal.

01:03:25.720 | And if there's alien civilizations out there,

01:03:29.760 | then there are probably going to be many of them,

01:03:32.720 | and they're probably going to be more advanced than us,

01:03:35.360 | and they're probably going to have something

01:03:36.760 | like industrial pollution, which would be

01:03:38.140 | a much stronger signal than some basic gas,

01:03:42.100 | which could have a lot of different explanations.

01:03:44.340 | So like, somebody like oxygen, or, I mean, I don't,

01:03:47.100 | I mean, we could talk about signs of life on Venus

01:03:51.860 | and so on, but if you want a strong signal,

01:03:55.100 | it would be pollution.

01:03:56.460 | I love how garbage is--

01:03:58.620 | - No, but the pollution, you have to understand,

01:04:00.480 | we think of pollution as a problem,

01:04:02.660 | but on a planet that was too cold, for example,

01:04:06.260 | to have a comfortable life on it,

01:04:09.000 | you can imagine terraforming it and putting a blanket

01:04:12.920 | of polluting gases such that it will be warmer,

01:04:16.560 | and that would be a positive change.

01:04:18.960 | So if an industrial or a technological civilization

01:04:23.840 | wants to terraform a planet that otherwise

01:04:27.440 | is too cold for them, they would do it.

01:04:29.760 | So what's the problem of defining it as a search goal,

01:04:34.700 | using the same technologies?

01:04:37.200 | The problem is that there is a taboo.

01:04:40.200 | We are not supposed to discuss extraterrestrial intelligence.

01:04:43.120 | There is no funding for this subject, not much, very little,

01:04:47.240 | and young people, because of the bullying on Twitter,

01:04:51.240 | you know, all the social media and elsewhere,

01:04:54.080 | young people with talent that are curious

01:04:56.080 | about these questions do not enter this field of study,

01:05:00.880 | and obviously, if you step on the grass,

01:05:04.480 | it will never grow, right?

01:05:05.740 | So if you don't give funding, obviously, you know,

01:05:09.320 | the mainstream community says,

01:05:10.240 | "Look, nothing was discovered so far."

01:05:12.180 | Obviously, nothing would be discovered.

01:05:13.900 | If talented people go to other disciplines,

01:05:17.100 | you never search for it well enough,

01:05:19.500 | you will never find anything.

01:05:20.940 | I mean, look at gravitational wave astrophysics.

01:05:23.660 | It's a completely new window into the universe,

01:05:25.620 | pioneered by Ray Weiss at MIT,

01:05:28.180 | and at first, it was ridiculed,

01:05:31.180 | and thanks to some administrators

01:05:33.900 | at the National Science Foundation,

01:05:36.060 | it received funding, despite the fact

01:05:38.220 | that the mainstream of the astronomy community

01:05:40.660 | was very resistant to it,

01:05:43.700 | and now it's considered a frontier.

01:05:46.340 | So all these people that I remember as a postdoc,

01:05:48.740 | a young postdoc, these people that bashed this field

01:05:50.940 | and said bad things about people,

01:05:52.740 | said nothing will come out of it,

01:05:54.380 | now they say, "Oh, yeah, of course."

01:05:57.180 | You know, the Nobel Prize was given

01:05:59.500 | to the LIGO collaboration.

01:06:03.860 | Of course, now they are supportive of it,

01:06:07.220 | but my point is, if you suppress innovation early on,

01:06:12.220 | there are lots of missed opportunities.

01:06:15.100 | The discovery of exoplanets is one example.

01:06:18.960 | You know, in 1952, there was an astronomer

01:06:21.460 | called Otto Struve, and he wrote a paper saying,

01:06:26.460 | "Why don't we search for Jupiter-like planets

01:06:31.460 | "close to their host star?"

01:06:33.460 | Because if they're close enough,

01:06:35.300 | they would move the star back and forth

01:06:37.140 | and we can detect the signal, okay?

01:06:39.660 | And so astronomers on time allocation committees

01:06:43.460 | of telescopes for 40 years argued,

01:06:47.300 | "This is not possible because we know

01:06:49.780 | "why Jupiter resides so far from the sun.

01:06:53.560 | "You cannot have Jupiter so close

01:06:55.060 | "because there is this region where ice forms

01:06:57.860 | "far from the sun, and beyond that region

01:07:00.360 | "is where Jupiter-like planets can form."

01:07:02.420 | There was a theory behind it,

01:07:03.900 | which ended up being wrong by today's standards.

01:07:06.580 | But anyway, they did not give time on telescopes

01:07:10.660 | to search for such systems until the first system

01:07:13.940 | was discovered four decades after Otto Struve's paper.

01:07:17.580 | And the Nobel Prize was awarded to that

01:07:20.100 | just a couple of years ago.

01:07:22.180 | And you ask yourself, "Okay, so science still

01:07:25.420 | "made progress, what's the problem?"

01:07:27.500 | The problem is that this baby came out barely,

01:07:31.500 | and there was a delay of four decades,

01:07:34.500 | so the progress was delayed, and I wonder

01:07:37.100 | how many babies were not born because of this resistance.

01:07:40.180 | So there must be ideas that are as good as this one

01:07:43.060 | that were suppressed because they were bullied,

01:07:45.140 | because people ridiculed them,

01:07:48.100 | that were actually good ideas.

01:07:50.620 | And these are missed opportunities,

01:07:52.660 | babies that were never born.

01:07:54.580 | And I'm willing to push this frontier

01:07:58.020 | of the search for technologies

01:07:59.840 | or technological signatures for other civilization.

01:08:02.660 | Because when I was young, I was in the military in Israel,

01:08:06.820 | it's obligatory to serve.

01:08:08.660 | And there was this saying that one of the soldiers

01:08:12.020 | sometimes has to put his body on the barbed wire

01:08:15.780 | so that others can go through.

01:08:18.700 | And I'm willing to suffer the pain

01:08:21.060 | so that younger people in the future

01:08:24.260 | will be able to speak freely about the possibility

01:08:26.980 | that some of the anomalies we find in the sky

01:08:29.540 | are due to technological signatures.

01:08:31.720 | - And it's quite obvious, this is why I like folks

01:08:34.460 | in the artificial intelligence space,

01:08:36.020 | Elon Musk and a few others speak about this,

01:08:39.260 | and they look at the long arc.

01:08:41.000 | They say like, what, you know, this kind of,

01:08:44.220 | you can call it like first principles thinking,

01:08:46.540 | or you can call it anything really,

01:08:48.580 | is like if we just zoom off from our current bickering

01:08:52.860 | and our current discussions in what science is doing,

01:08:57.380 | look at the long arc of the trajectory

01:08:59.420 | we're headed at, which questions

01:09:01.940 | are obviously fundamental to science?

01:09:06.700 | And it should be asked.

01:09:07.780 | And which is the space of hypotheses

01:09:09.540 | we should be exploring?

01:09:10.700 | And like exoplanets is a really good example

01:09:12.860 | of one that was like an obvious one.

01:09:15.900 | I recently talked to Sarah Seager,

01:09:17.740 | and it was very taboo when she was starting out

01:09:19.940 | to work on an exoplanet, and that was even in the '90s.

01:09:22.660 | - Yeah.

01:09:23.500 | - And like it's obvious should not be a taboo subject.

01:09:27.580 | And to me, I mean, I'm probably ignorant,

01:09:29.780 | but to me exoplanets seems like it's ridiculous

01:09:32.900 | that that would ever be a taboo subject.

01:09:35.220 | - Right.

01:09:36.060 | - To not fund, to not explore.

01:09:37.900 | That's very, but even for her,

01:09:40.700 | it's now taboo to say like what, you know,

01:09:45.700 | to look for industrial pollution, right?

01:09:47.900 | - Right.

01:09:48.740 | And I find that ridiculous.

01:09:50.500 | I'll tell you why.

01:09:51.340 | - Even if she can't take the next step.

01:09:52.160 | - It's ridiculous for another reason.

01:09:53.900 | - Yes.

01:09:54.740 | - Not because of just the scientific benefits

01:09:56.860 | that we might have by exploring it,

01:09:58.780 | but because the public cares about these questions.

01:10:01.900 | - Yes, a lot.

01:10:02.740 | - And the public funds science.

01:10:04.940 | So how dare the scientists shy away

01:10:07.780 | from addressing these questions

01:10:09.460 | if they have the technology to do it?

01:10:12.940 | It's like saying,

01:10:14.180 | I don't want to look through Galileo's telescope.

01:10:16.100 | It's exactly the same.

01:10:17.200 | You have the technology to explore this question,

01:10:19.740 | to find evidence, and you shy away from it.

01:10:22.940 | You might ask, why do people shy away from it?

01:10:25.500 | - Yes.

01:10:26.340 | - Perhaps it's because of the fact

01:10:27.860 | that there is science fiction.

01:10:28.900 | I'm not a fan of science fiction

01:10:30.900 | because it has an element to it

01:10:33.240 | that violates the laws of physics

01:10:34.820 | in many of the books and the films.

01:10:36.780 | - Magic.

01:10:37.620 | - And I cannot enjoy these things

01:10:39.900 | when I see the laws of physics violated.

01:10:42.140 | But who cares that, you know,

01:10:44.180 | the fact that there is science fiction?

01:10:45.740 | I mean, if you have the scientific methodology

01:10:48.620 | to address the same subject,

01:10:50.740 | I don't care that other people, you know,

01:10:53.160 | spoke nonsense about this subject

01:10:55.140 | or said things that make no sense.

01:10:56.860 | Who cares?

01:10:57.680 | You do your scientific work

01:10:59.300 | just like you explore the dark matter.

01:11:02.020 | You explore the possibility that Oumuamua is an artifact.

01:11:06.060 | You just look for evidence

01:11:08.020 | and try to deduce what it means.

01:11:12.420 | And I have no problem with doing that.

01:11:14.940 | To me, it sounds like any other scientific question

01:11:17.060 | that we have, and given the public's interest,

01:11:19.420 | we have an obligation to do that.

01:11:21.540 | By the way, science to me

01:11:23.660 | is not an occupation of the elite.

01:11:25.580 | It doesn't allow me to feel superior to other humans

01:11:28.500 | that are unable to understand the math.

01:11:31.180 | To me, it's a way of life.

01:11:33.060 | You know, if there is a problem in the faucet

01:11:35.180 | or in the pipe at home,

01:11:37.660 | I try to figure out what the problem is.

01:11:39.580 | And with a plumber, we figure it out.

01:11:41.660 | And, you know, we look at the clues.

01:11:43.340 | And the same thing in science.

01:11:45.380 | You know, you look at the evidence,

01:11:46.820 | you try to figure out what it means.

01:11:48.820 | It's common sense in a way.

01:11:51.140 | And it shouldn't be regarded

01:11:54.020 | as something removed from the public.

01:11:56.460 | It should be a reflection of the public's interest.

01:11:59.140 | And I think it's actually a crime

01:12:00.980 | to resist the public interest.

01:12:02.780 | If the public says, "I care about this,"

01:12:05.340 | and you say, "No, no, no,

01:12:06.180 | "that's not sophisticated enough for me.

01:12:08.020 | "I want to do intellectual gymnastics

01:12:09.860 | "on anti-de Sitter space,"

01:12:11.500 | to me, that's a crime.

01:12:12.620 | - Yes, I 100% agree.

01:12:14.980 | So it's hilarious that the very,

01:12:17.780 | not hilarious, it's sad,

01:12:20.380 | that people who are trained in the scientific community

01:12:25.380 | to have the tools to explore this world,

01:12:28.180 | to be children, to be the most effective at being children,

01:12:31.620 | are the ones that resist being children the most.

01:12:34.900 | But there is a large number of people

01:12:38.540 | that embrace the childlike wonder about the world,

01:12:43.540 | and may not necessarily have the tools to do it.

01:12:46.100 | That's the more general public.

01:12:47.940 | And so I wonder if I could ask you

01:12:51.780 | and talk to you a little bit about UFO sightings.

01:12:56.180 | That there's people, quote-unquote believers,

01:13:01.060 | there's hundreds of thousands of UFO sightings.

01:13:03.940 | And I've consumed some of the things

01:13:08.940 | that people have said about it.

01:13:11.620 | And one thing I really like about it

01:13:15.340 | is how excited they are by the possibility,

01:13:20.340 | by, it's almost like this childlike wonder

01:13:23.700 | about the world out there.

01:13:24.940 | They're not, it's not a fear, it's an excitement.

01:13:28.540 | Do you think, 'cause we're talking about

01:13:30.940 | this possibly extraterrestrial object

01:13:35.540 | that visited, that flew by Earth,

01:13:37.820 | do you think it's possible that

01:13:39.940 | out of those hundreds of thousands of UFO sightings,

01:13:44.500 | one is an actual, one or some number

01:13:48.820 | is an actual sighting of a non-human,

01:13:51.900 | some alien technology?

01:13:53.540 | And that we're not,

01:13:54.840 | we did not, we're too close-minded

01:14:00.060 | to look and to see?

01:14:04.260 | - I think to answer this question,

01:14:06.380 | we need better evidence.

01:14:08.220 | My starting point, as I said, out of modesty,

01:14:12.540 | is that we are not particularly interesting.

01:14:15.500 | - Yes, I agree with you. - And therefore,

01:14:17.020 | I would be hard-pressed to imagine

01:14:19.020 | that someone wants to really spy on us.

01:14:21.100 | So I would think, as a starting point,

01:14:25.240 | that we don't deserve attention

01:14:27.180 | and we shouldn't expect someone, but who knows?

01:14:30.640 | Now, the problem that I have with UFO sighting reports

01:14:34.480 | is that 50 years ago, there were some reports

01:14:37.860 | of fuzzy images, saucer-like things.

01:14:42.320 | By now, our technologies are much better,

01:14:44.900 | our cameras are much more sensitive.

01:14:48.020 | These fuzzy images should have turned

01:14:50.100 | into crisp, clear images of things

01:14:53.620 | that we are confident about.

01:14:55.380 | And they haven't turned that way.

01:14:57.420 | It's always on the borderline of believability.

01:15:00.340 | And because of that, I believe that it might be,

01:15:02.540 | most likely, artifacts of our instruments

01:15:05.260 | or some natural phenomena that we are unable to understand.

01:15:09.220 | Now, of course, the reason you need,

01:15:10.820 | you must examine those, if, for example,

01:15:14.420 | pilots report about them or the military

01:15:18.220 | finds evidence for them, is because it may pose

01:15:21.420 | a national security threat.

01:15:22.740 | If another country has technologies

01:15:24.780 | that we don't know about and they're spying on us,

01:15:27.640 | we need to know about it.

01:15:28.940 | And therefore, we should examine everything

01:15:30.700 | that looks unusual.

01:15:32.140 | But to associate it with an alien life

01:15:36.260 | is a little too far for me

01:15:38.980 | until we have evidence that stands up

01:15:42.540 | to the level of scientific credence,

01:15:45.620 | that we are 100% sure that,

01:15:49.260 | from multiple detectors and through a scientific process.

01:15:54.140 | Now, again, if the scientific community

01:15:55.820 | shies away from these reports, we will never have that.

01:15:59.340 | It's like saying, I don't want to take photographs

01:16:02.780 | of something because I know what it is,

01:16:05.140 | then you will never know what it is.

01:16:07.180 | But I think if some science, if grants,

01:16:10.120 | let's put it this way, if funding will be given to scientists

01:16:13.860 | to follow on some of these reports

01:16:16.820 | and use scientific instruments that are capable

01:16:19.620 | of detecting those sightings with much better resolution,

01:16:23.940 | with much better information, that would be great

01:16:26.420 | because it will clarify the matter.

01:16:28.180 | You know, these are not, as you said,

01:16:30.420 | you know, hundreds of thousands,

01:16:31.460 | these are not once in a lifetime events.

01:16:34.260 | So it's possible to take scientific instrumentation

01:16:37.580 | and explore, go to the ocean where the, you know,

01:16:41.220 | someone reported that there are frequent events

01:16:43.980 | that are unusual and check it out.

01:16:47.220 | Do a scientific experiment, what's the problem?

01:16:48.900 | Why not, why only do experiments deep into the ocean

01:16:51.960 | and look at the oceanography or do other things?

01:16:56.380 | You know, we can do scientific investigation

01:16:58.300 | of these sightings and figure out what they mean.

01:17:02.620 | I'm very much in favor of that,

01:17:04.740 | but until we have the evidence,

01:17:06.300 | I would be doubtful as to what they actually mean.

01:17:09.540 | - Yeah, we'll have to be humble

01:17:10.700 | and acknowledge that we're not that interesting.

01:17:14.380 | It's kind of, you're making me realize

01:17:16.060 | that because it's so taboo,

01:17:17.540 | that the people that have the equipment,

01:17:20.300 | meaning, and we're not just talking,

01:17:22.260 | everybody has cameras now,

01:17:24.380 | but to have a large-scale, like, sensor network

01:17:30.180 | that collects data, that regularly collects,

01:17:32.500 | just like we look at the weather,

01:17:33.820 | we're collecting information,

01:17:35.420 | and then we can then access that information

01:17:37.220 | when there is reports and, like,

01:17:39.080 | have it not be a taboo thing where there's, like,

01:17:41.500 | millions or billions of dollars funding this effort

01:17:44.660 | that, by the way, inspires millions of people.

01:17:49.660 | This is exactly what you're talking about.

01:17:51.260 | It's like, the scientific community is afraid of a topic

01:17:55.900 | that inspires millions of people.

01:17:57.540 | - Exactly. - It's absurd.

01:17:58.740 | But if you put blinders on your eyes, you don't see it.

01:18:02.140 | - Yeah. - Right.

01:18:03.620 | I should say that we do have meteors that we see.

01:18:06.900 | These are rocks that, by chance,

01:18:09.340 | happen to collide with the Earth.

01:18:11.620 | And if they're small, they burn up in the atmosphere,

01:18:14.980 | but if they're big enough,

01:18:17.500 | tens of meters or more, hundreds of meters,

01:18:20.780 | the outer layer burns up,

01:18:22.780 | but then the core of the object makes it through.

01:18:26.940 | And this is our chance of putting our hands

01:18:29.780 | around an object if this meteor came from interstellar space.

01:18:34.380 | So one path of discovery

01:18:37.460 | is to search for interstellar meteors.

01:18:40.380 | And with a student of mine,

01:18:42.380 | we actually looked through the record

01:18:44.060 | and we thought that we found one example

01:18:46.540 | of a meteor that was reported

01:18:48.480 | that might have come from interstellar space.

01:18:51.700 | - That's fantastic. - And another approach

01:18:54.400 | is, for example, to look at the moon.

01:18:56.500 | The moon is different from the Earth

01:18:58.300 | in the sense that it doesn't have an atmosphere.

01:19:00.580 | So objects do not burn up on their way to it.

01:19:04.420 | It's sort of like a museum.

01:19:05.660 | It collects everything that comes--

01:19:06.980 | - Of rocks from out there in deep space, yeah.

01:19:09.300 | - And there is no geological activity on the moon.

01:19:11.900 | So on Earth, every 100 million years,

01:19:14.660 | we could have had computer terminals on Earth

01:19:17.300 | that could have been a civilization like ours

01:19:20.060 | with electronic equipment more than 100 million years ago,

01:19:24.300 | and it's completely lost.

01:19:25.820 | You cannot excavate and find evidence for it

01:19:28.740 | because in archeological digs,

01:19:30.700 | because the Earth is being mixed on these timescales,

01:19:34.660 | and everything that was on the surface

01:19:36.420 | more than 100 million years ago

01:19:37.980 | is buried deep inside the Earth right now

01:19:40.100 | because of geological activity.

01:19:41.220 | - Fascinating to think about, by the way, yeah.

01:19:42.900 | - But on the moon, this doesn't happen.

01:19:45.460 | The only thing that happens on the moon

01:19:46.800 | is you have objects impacting the moon

01:19:49.780 | and they go 10 meters deep, so they produce some dust.

01:19:53.540 | But the moon keeps everything.

01:19:55.020 | It's like a museum, it keeps everything on the surface.

01:19:57.260 | So if we go to the moon, I would highly recommend

01:20:01.540 | regarding it as an archeological site

01:20:04.780 | and looking for objects that are strange.

01:20:07.580 | Maybe it collected some trash from interstellar space.

01:20:11.380 | - If we could just linger on the Drake equation

01:20:13.900 | for a little bit, we kind of talked about

01:20:16.340 | there's a lot of uncertainty in the parameters,

01:20:18.860 | and the Drake equation itself is very limited,

01:20:24.140 | but I think the parameters are interesting in themselves,

01:20:27.300 | even if it's limited, because I think each one

01:20:29.820 | is within the reach of science, right,

01:20:32.060 | to get the evidence for.

01:20:33.260 | A few I find really interesting,

01:20:36.540 | could be interesting to get your comment on.

01:20:40.100 | So the one with the most variance,

01:20:42.580 | I would say, from my perspective,

01:20:44.540 | is the length that civilizations last,

01:20:47.580 | however you define it.

01:20:48.420 | In the Drake equation, it's the length

01:20:50.420 | of how long you're communicating.

01:20:52.020 | - Yeah, transmitting.

01:20:53.060 | - Transmitting, just like you said,

01:20:54.980 | that's a wrong way to think about it,

01:20:57.780 | because we could be detecting some other outputs

01:21:00.140 | of the civilizations, et cetera.

01:21:01.660 | But if we just define broadly

01:21:03.780 | how long those civilizations last,

01:21:06.140 | do you have a sense of how long that might last?

01:21:10.260 | Like what are the great filters

01:21:12.980 | that might destroy civilizations

01:21:14.740 | that we should be thinking about?

01:21:16.380 | How can science give us more hints on this topic?

01:21:21.900 | - So I, as I mentioned before,

01:21:24.140 | operate by the Copernican principle,

01:21:26.460 | meaning that we are not special.

01:21:28.860 | We don't live in a special place,

01:21:31.340 | and not in a special time.

01:21:33.440 | And by the way, it's just modesty

01:21:36.340 | encapsulated in scientific terms, right?

01:21:39.220 | You're saying, I'm not special,

01:21:41.020 | I find conditions here, they exist everywhere.

01:21:44.260 | So if you adopt the Copernican principle,

01:21:46.720 | you basically say, our civilization

01:21:50.860 | transmitted radio signals for 100 years, roughly.

01:21:55.080 | So probably it would last another 100 or a few hundred,

01:21:59.020 | and that's it.

01:22:00.620 | Because we don't live at a special time.

01:22:02.620 | So that's, you know, well, of course,

01:22:06.260 | if we get our act together,

01:22:09.020 | and we somehow start to cooperate,

01:22:11.400 | rather than fighting each other,

01:22:13.540 | killing each other, wasting a lot of resources

01:22:17.620 | on things that would destroy our planet,

01:22:20.920 | maybe we can lengthen that period, if we get smarter.

01:22:25.040 | But the most natural assumption is to say

01:22:29.360 | that we will live into the future

01:22:31.120 | as much as we lived from the time

01:22:33.440 | that we start to develop the means for our own destruction,

01:22:36.040 | the technologies we have.

01:22:37.400 | Which is quite pessimistic, I must say.

01:22:39.760 | So several centuries, that's what I would give,

01:22:42.400 | not unless we get our act,

01:22:44.120 | unless we become more intelligent

01:22:45.840 | than the newspapers report every day, okay?

01:22:49.280 | Point number one.

01:22:50.320 | Second, and by the way, this is relevant, I should say,

01:22:53.400 | because there was a report about

01:22:55.160 | perhaps a radio signal detected from Proxima Centauri.

01:23:00.640 | - What do you make of that signal?

01:23:01.760 | - Oh, I think it's some Australian guy

01:23:03.520 | with a cell phone next to the observatory

01:23:05.120 | or something like that.

01:23:06.440 | Because it was the Parkes Telescope in Australia.

01:23:09.840 | - Okay, I was like, why an Australian guy?

01:23:11.800 | Yeah, okay.

01:23:12.640 | So it's human-created noise.

01:23:14.200 | - Yeah, which is always the worry,

01:23:16.600 | because actually the same observatory,

01:23:18.320 | the Parkes Observatory, detected a couple of years ago

01:23:22.000 | some signal, and then they realized

01:23:24.680 | that it comes back at lunchtime.

01:23:27.480 | And they said, okay, what could it be?

01:23:30.560 | And then they figured out that it must be

01:23:32.320 | the microwave oven in the observatory

01:23:34.040 | because someone was opening it before it finished,

01:23:37.820 | and it was creating this radio signal

01:23:39.920 | that they detected with a telescope every lunchtime.

01:23:42.800 | So just a cautionary remark. - That's fascinating.

01:23:46.160 | - But the reason I think it's human-made,

01:23:49.320 | without getting to the technical details,

01:23:51.600 | is because of this very short window

01:23:54.660 | by which we were transmitting radio signals

01:23:56.800 | out of the lifetime of the Earth.

01:23:58.720 | As I said, 100 years out of 4 1/2 billion years

01:24:02.660 | that the Earth existed.

01:24:03.800 | So what's the chance that another civilization,

01:24:06.120 | a twin civilization of ours,

01:24:08.400 | is transmitting radio signals exactly at the time

01:24:11.200 | that we are looking with our radio telescopes?

01:24:14.480 | - Yeah.

01:24:15.320 | - 10 to the minus seven.

01:24:17.000 | You know, so, and the other argument I have

01:24:20.160 | that is that they detected it

01:24:22.680 | in a very narrow band of frequencies,

01:24:25.960 | and that makes it, you know,

01:24:28.240 | it cannot be through natural processes,

01:24:30.600 | a very narrow band,

01:24:31.920 | just like some radio transmissions that we produce.

01:24:35.680 | But if it were to come from the habitable zone,

01:24:40.720 | from a transmitter on the surface of Proxima b,

01:24:43.560 | this is the planet that orbits Proxima Centauri,

01:24:47.000 | then I calculated that the frequency would drift

01:24:49.720 | through the Doppler effect.

01:24:51.760 | You know, just like when you hear a siren on the street,

01:24:55.820 | you know, when the car approaches you,

01:24:58.080 | it has a different pitch than when it goes,

01:25:00.400 | recedes away from you, that's the Doppler effect.

01:25:03.080 | And when the planet orbits the star, Proxima Centauri,

01:25:07.200 | you would see or detect a different frequency

01:25:11.180 | when the planet approaches us

01:25:12.760 | as compared to when it recedes.

01:25:14.040 | So there should be a frequency drift

01:25:16.720 | just because of the motion of the planet.

01:25:20.280 | And I calculated that it must be much bigger than observed.

01:25:24.880 | So it cannot just be a transmitter sitting on the planet

01:25:29.280 | and sending in our direction a radio signal,

01:25:31.520 | unless they want to cancel the Doppler effect,

01:25:35.960 | but then they need to know about us,

01:25:37.740 | because in a different direction, it will not be canceled.

01:25:40.000 | Only in our direction, they can cancel it perfectly.

01:25:43.040 | So there is this direction of Proxima Centauri,

01:25:47.400 | but I have a problem imagining a transmitter

01:25:50.480 | on the surface of a planet in the habitable zone,

01:25:53.360 | emitting it.

01:25:54.180 | But my main issue is really with the likelihood,

01:25:59.640 | given what we know about ourself.

01:26:01.800 | - Right, in terms of the duration of the civilization.

01:26:04.080 | - The Copernican principle, yeah.

01:26:05.720 | - So nevertheless, this particular signal

01:26:08.840 | is likely to be a human interference perhaps,

01:26:11.560 | but do you find Proxima be interesting,

01:26:15.960 | or the more general question is,

01:26:18.640 | do you think we humans will venture out

01:26:22.640 | outside our solar system

01:26:26.920 | and potentially colonize other habitable planets?

01:26:30.320 | - Actually, I am involved in a project

01:26:32.800 | whose goal is to develop the technology

01:26:34.880 | that would allow us to leave the solar system

01:26:36.920 | and visit the nearest stars,

01:26:39.160 | and that is called the Starshot.

01:26:42.240 | In 2015, in May 2015,

01:26:45.320 | an entrepreneur from Silicon Valley, Uri Milner,

01:26:48.240 | came to my office at Harvard and said,

01:26:50.960 | would you be interested in leading a project

01:26:55.600 | that would do that in our lifetime?

01:26:57.880 | Because as we discussed before,

01:26:59.480 | to traverse those distances with existing rockets

01:27:03.360 | would take tens of thousands of years.

01:27:06.120 | And that's too long.

01:27:09.640 | For example, to get to Proxima Centauri

01:27:11.840 | with the kind of spacecrafts that we already sent,

01:27:15.920 | like New Horizons or Voyager 1, Voyager 2,

01:27:19.920 | you needed to send them when the first humans left Africa,

01:27:26.280 | so that they would arrive there now.

01:27:28.520 | And that's a long time to wait.

01:27:31.400 | So Uri wanted to do it within our lifetime,

01:27:34.240 | 10, 20 years, meaning it has to move

01:27:36.880 | at a fraction of the speed of light.

01:27:38.800 | So can we send a spacecraft that would be moving

01:27:41.960 | at the fraction of the speed of light?

01:27:43.240 | And I said, let me look into that for six months.

01:27:47.000 | And with my students and postdocs,

01:27:49.040 | we arrived to the conclusion that the only technology

01:27:51.440 | that can do that is the light sail technology, where--

01:27:54.920 | - Can you explain?

01:27:56.080 | - You basically produce a very powerful laser beam on Earth,

01:28:01.160 | so you can collect sunlight with photovoltaic cells

01:28:06.160 | or whatever, and then convert it into stored energy,

01:28:11.280 | and then produce a very powerful laser beam

01:28:15.600 | that is 100 gigawatt, and focus it on a sail in space

01:28:20.600 | that is roughly the size of a person,

01:28:26.560 | a couple of meters or a few meters,

01:28:29.200 | that weighs only a gram or a few grams, very thin.

01:28:34.200 | And through the math, you can show that you can propel

01:28:38.560 | such a sail, if you shine on it for a few minutes,

01:28:41.460 | it will traverse a distance that is five times

01:28:43.680 | the distance to the moon, and it will get

01:28:45.580 | to a fifth of the speed of light.

01:28:47.480 | - Sounds crazy, but I've talked to a bunch of people,

01:28:50.840 | and they're like, I know it sounds crazy,

01:28:52.640 | but it's actually, it will work.

01:28:56.080 | This is one of those, it's just beautiful.

01:28:58.360 | I mean, this is science.

01:28:59.960 | - And the point is, people didn't get excited about space

01:29:04.800 | since the Apollo era, and it's about time

01:29:09.400 | for us to go into space.

01:29:12.120 | Couple of months ago, I was asked to participate

01:29:14.280 | in a debate organized by IBM and Bloomberg News,

01:29:19.240 | and the discussion centered on the question,

01:29:22.240 | is the space race between the US and China

01:29:25.280 | good for humanity?

01:29:26.640 | - Oh, interesting.

01:29:27.480 | - And all the other debaters were worried

01:29:31.160 | about the military threats.

01:29:33.000 | And I just couldn't understand what they're talking about,

01:29:36.080 | 'cause military threats come from hovering

01:29:39.640 | above the surface of the Earth, right?

01:29:41.880 | And we live on a two-dimensional surface.

01:29:45.200 | We live on the surface of the Earth.

01:29:46.600 | But space is all about the third dimension,

01:29:48.600 | getting far from Earth.

01:29:50.120 | So if you go to Mars, or you go to a star, another star,

01:29:54.080 | there is no military threat.

01:29:55.720 | What are we talking about?

01:29:56.960 | Space is all about feeling that we are one civilization,

01:30:01.960 | in fact, not fighting each other, just going far,

01:30:06.200 | and having aspirations for something

01:30:08.200 | that goes beyond military threats.

01:30:10.240 | So why would we be worried that the space race will lead?

01:30:14.680 | - That's actually brilliant.

01:30:16.080 | In our discourse about it, the space race

01:30:20.480 | is sometimes made synonymous with the Cold War,

01:30:23.120 | or something like that, or with wars.

01:30:25.000 | But really, yeah, there was a lot of ego tied up in that.

01:30:28.440 | I remember, I mean, it's still, to this day,

01:30:30.920 | there's a lot of pride that Russians,

01:30:33.000 | the Soviet Union was the first to space,

01:30:34.680 | and there's a lot of pride on the American side

01:30:36.360 | that it was the first on the moon.

01:30:38.160 | But yeah, you're exactly right.

01:30:39.880 | There's no aggression, there's no wars.

01:30:42.320 | - And beyond that, if you think about the global economy

01:30:45.280 | right now, there is a commercial interest.

01:30:47.920 | That's why Jeff Bezos and Elon Musk

01:30:50.080 | are interested about Mars and so forth.

01:30:52.840 | There is a commercial interest which is international.

01:30:55.000 | It's driven by money, not by pride.

01:30:59.280 | And nations can sign treaties.

01:31:02.360 | First of all, there are lots of treaties that were signed

01:31:05.200 | even before the First World War and the Second World War,

01:31:07.760 | and the World War took place.

01:31:08.920 | So who cares?

01:31:11.200 | Humans, treaties do not safeguard anything.

01:31:15.440 | But beyond that, even if nations sign treaties

01:31:18.040 | about space exploration, you might still find

01:31:21.600 | commercial entities that will find a way

01:31:24.280 | to get their launches.

01:31:25.760 | And so I think we should rethink space.

01:31:29.680 | It has nothing to do with national pride.

01:31:32.040 | Once again, nothing to do with our egos.

01:31:34.760 | It's about exploration.

01:31:36.320 | And the biggest problem I think in human history

01:31:40.400 | is that humans tend to think about egos

01:31:45.120 | and about their own personal image

01:31:50.360 | rather than look at the big picture.

01:31:54.720 | We will not be around for long.

01:31:56.680 | We are just occupying a small space right now.

01:31:59.320 | Let's move out of this.

01:32:01.920 | The way that Oscar Wilde said, I think is the best.

01:32:04.880 | He said, "All of us are in the gutters,

01:32:07.720 | "but some of us are looking at the stars."

01:32:11.640 | - Yeah, and the more of us are looking at the stars,

01:32:14.240 | the likelier we are to, for this little experiment

01:32:19.320 | we have going on to last a while

01:32:22.440 | as opposed to end too quickly.

01:32:24.480 | I mean, it's not just about science of being humble.

01:32:27.200 | It's about the survival of the human species

01:32:30.000 | is being humble.

01:32:31.460 | To me, it's incredibly inspiring,

01:32:34.240 | the Starshot Project of, I mean,

01:32:36.840 | there's something magical about being able to go

01:32:39.320 | to another habitable planet and take a picture even.

01:32:43.240 | I mean, within our lifetime, I mean,

01:32:46.000 | that with crazy technology too,

01:32:48.600 | which is, it's exciting.

01:32:50.240 | - I should tell you how it was conceived.

01:32:51.440 | So I was at the time, so after six months passed,

01:32:56.440 | after the visit of Yuri Miller,

01:32:58.240 | I was, usually I go in December during the winter break,

01:33:03.040 | I go to Israel.

01:33:04.920 | I used to go to see my family and I get a phone call

01:33:09.000 | just before the weekend started.

01:33:11.840 | They get a phone call,

01:33:13.920 | Yuri would like you to present your concept

01:33:16.480 | in two weeks at his home.

01:33:19.560 | And I said, well, thank you for letting me know

01:33:22.360 | because I'm actually out of the door of the hotel

01:33:25.400 | to go to a goat farm in the Negev,

01:33:29.120 | in the Southern part of Israel,

01:33:30.600 | because my wife wanted to have sort of,

01:33:32.640 | to go to a place that is removed from civilization,

01:33:37.520 | so to speak.

01:33:39.160 | So we went to that goat farm

01:33:42.240 | and I need to make the presentation.

01:33:45.080 | And there was no internet connectivity

01:33:48.160 | except in the office of the goat farm.

01:33:50.280 | So the following morning at 6 a.m.,

01:33:53.320 | I sit with my back to the office of that goat farm,

01:33:56.640 | looking at goats that were newly born

01:33:58.960 | and typing into my laptop the presentation,

01:34:03.200 | the PowerPoint presentation about our ambitions

01:34:06.360 | for visiting the nearest star.

01:34:08.760 | And that was very surreal to me that,

01:34:11.960 | you know, look.

01:34:12.800 | (laughing)

01:34:14.720 | - Like our origins in many ways,

01:34:16.760 | this very primitive origins

01:34:18.400 | and our dreams of looking out there.

01:34:21.960 | It's brilliant.

01:34:22.840 | So that is incredibly inspiring to me,

01:34:25.160 | but it's also inspiring of putting humans

01:34:30.160 | onto other moons or planets.

01:34:34.220 | I still find going to the moon really exciting.

01:34:37.320 | I don't know, maybe I'm just a sucker for it,

01:34:39.000 | but it's really exciting.

01:34:41.080 | And Mars, which is a new place, a new planet,

01:34:43.800 | another planet that might have life.

01:34:46.400 | I mean, there's something magical to that

01:34:48.080 | or some traces of previous life.

01:34:49.960 | - You might think that humans cannot really survive

01:34:52.880 | and there are risks by going there.

01:34:55.120 | But my point is, you know, we started from Africa

01:35:00.000 | and we got to apartment buildings in Manhattan, right?

01:35:03.440 | It's a very different environment

01:35:04.880 | from the jungles to live in an apartment building

01:35:07.800 | in, you know, a small cubicle.

01:35:10.880 | And, you know, it took tens of thousands of years,

01:35:13.560 | but humans adapted, right?

01:35:16.000 | So why couldn't humans also make the leap

01:35:18.920 | and adapt to a habitat in space?

01:35:20.760 | You know that?

01:35:21.680 | Now you can build a platform

01:35:23.560 | that would look like an apartment building

01:35:25.920 | in the Bronx or somewhere,

01:35:28.480 | but have inside of it everything that humans need.

01:35:32.440 | And just like the space station, but bigger,

01:35:35.280 | and it will be a platform in space.

01:35:37.360 | And the advantage of that

01:35:39.280 | is if something bad happens on Earth,

01:35:42.220 | you have that complex where humans live

01:35:45.400 | and you can also move it back and forth

01:35:47.760 | depending on how bright the sun gets.

01:35:50.260 | Because, you know, within a billion years,

01:35:53.040 | within a billion years, the sun would be too hot

01:35:57.160 | and it will boil off all the oceans on Earth.

01:35:59.960 | So we cannot stay here for more than a billion years.

01:36:02.200 | That's for sure.

01:36:03.040 | - Yes.

01:36:03.960 | So that's a billion years from now.

01:36:06.320 | I prefer like shorter term deadlines.

01:36:08.840 | And so, and that's, I mean,

01:36:10.760 | there's a lot of threats that we're facing currently.

01:36:12.760 | Do you find it exciting, the possibility of,

01:36:15.560 | you know, landing on Mars and starting little like

01:36:20.920 | building a Manhattan style apartment building on Mars

01:36:24.040 | and humans occupying it?

01:36:26.120 | Do you think from a scientific

01:36:27.320 | or an engineering perspective, that's a worthy pursuit?

01:36:31.380 | - I think it's worthy, but the real issue

01:36:33.880 | that is often underplayed is the risk

01:36:38.660 | to the human body from cosmic rays.

01:36:41.400 | These are energetic particles

01:36:43.600 | and we are protected from them

01:36:46.280 | by the magnetic field around the Earth that blocks them.

01:36:50.760 | But if you go to Mars,

01:36:52.680 | where there is no such magnetic field to block them,

01:36:55.760 | then, you know, a significant fraction of the brain cells

01:36:59.000 | in your head will be damaged within a year.

01:37:03.040 | And the consequences of that are not clear.

01:37:05.280 | I mean, it's quite possible

01:37:08.940 | that humans cannot really survive on the surface.

01:37:12.740 | Now it may mean that we need to dig tunnels,

01:37:15.840 | go underground or create some protection.

01:37:18.660 | This is something that can be engineered.

01:37:21.660 | - Yes.

01:37:22.540 | - And, you know, we can start from the moon

01:37:24.220 | and then move to Mars.

01:37:25.680 | That would be a natural progression.

01:37:27.540 | But it's a big issue that needs to be dealt with.

01:37:31.180 | I don't think, you know, it's a showstopper.

01:37:34.160 | I think we can overcome it.

01:37:35.700 | But, you know, just like anything in science and technology,

01:37:38.860 | you have to work on it for a while, figure out solutions.

01:37:42.500 | But it's not as rosy as Elon Musk talks about.

01:37:45.500 | I mean, Elon Musk can obviously be optimistic.

01:37:49.100 | I think eventually it will boil down to figuring out

01:37:51.700 | how to cope with this risk, the health risk.

01:37:55.140 | - Yeah, I mean, in defense of optimism,

01:37:57.580 | I find that there's at least a correlation,

01:38:01.220 | if not their best friends,

01:38:02.620 | is optimism and open-mindedness.

01:38:04.600 | It's a necessary, it's a precondition to try crazy things.

01:38:14.180 | And in that sense, the sense I have about going to Mars,

01:38:19.060 | if we use today's logic of what kind of benefits

01:38:24.060 | we'll get from that, we're never going to go.

01:38:27.460 | Like most decisions we make in life,

01:38:31.600 | most decisions we've made as a human species,

01:38:34.420 | are irrational if you look at just today.

01:38:39.220 | But if you look at the long arc

01:38:41.540 | and the possibilities that it might bring,

01:38:44.080 | just like humans--

01:38:46.180 | - Left Europe and went--

01:38:47.500 | - Yeah, Europe and--

01:38:49.340 | - And by the way, it was for--

01:38:50.180 | - And destroyed everybody on the--

01:38:51.300 | - But it was a commercial interest that drove that

01:38:54.420 | for trade.

01:38:56.700 | And, you know, it might happen again in this context.

01:38:59.020 | You have people like Jeff Bezos and Elon Musk

01:39:01.380 | that are commercially driven to go to space.

01:39:03.780 | But it doesn't mean that what we will ultimately find

01:39:07.980 | is not new worlds that have nothing,

01:39:11.020 | have much more to offer than just commercial interests.

01:39:15.380 | - As a side effect almost, right?

01:39:17.900 | - Yeah, yeah, and that's why I think

01:39:21.060 | we should be open-minded and explore.

01:39:23.100 | However, at the same time,

01:39:25.460 | because of the reasons you pointed out,

01:39:28.060 | I'm not optimistic that we will survive

01:39:30.020 | more than a few centuries into the future.

01:39:32.220 | Because people do not think long-term,

01:39:34.460 | and that means that we will only survive for the short term.

01:39:38.140 | - I don't know if you have thoughts about this,

01:39:40.240 | but what are the things that worry you the most about,

01:39:43.320 | from the great perspective of the universe,

01:39:46.100 | which is the great filters

01:39:47.500 | that destroys intelligent civilizations,

01:39:50.060 | but for our own species here,

01:39:52.080 | like what are the things that worry you the most?

01:39:55.580 | - Yeah, the thing that worries me the most

01:39:57.420 | is that people pay attention

01:39:58.780 | to how many likes they have on Twitter.

01:40:00.780 | And rather than, you know,

01:40:05.180 | basketball coaches tell the team players,

01:40:08.460 | keep your eyes on the ball, not on the audience.

01:40:12.900 | The problem is we keep our eyes on the audience

01:40:15.460 | most of the time.

01:40:16.380 | Let's keep our eyes on the ball.

01:40:18.660 | And what does that mean?

01:40:19.740 | First of all, in context of science,

01:40:21.780 | it means pay attention to the evidence.

01:40:24.080 | When the evidence looks strange,

01:40:27.740 | then we should figure it out.

01:40:29.380 | You know, I went to a seminar about Umuamua at Harvard,

01:40:33.980 | and a colleague of mine that is mainstream, conservative,

01:40:38.980 | would never say anything that would deviate

01:40:43.540 | from what everyone else is thinking.

01:40:46.500 | Said to me after the seminar,

01:40:48.700 | "I wish this object never existed."

01:40:51.740 | Now, to me, I mean, I just couldn't hear that.

01:40:55.300 | What do you mean?

01:40:56.140 | Nature is whatever it is, you have to pay attention to it.

01:40:59.700 | You cannot say, you know, you cannot bury your head in this.

01:41:03.340 | I mean, you should bless nature for giving you clues

01:41:06.180 | about things that you haven't expected.

01:41:08.300 | And I think that's the biggest fault,

01:41:10.620 | that we are looking for confirmations

01:41:13.660 | of things we already know,

01:41:15.460 | so that we can maintain our pride that we already knew it,

01:41:20.460 | and maintain our image, not make mistakes,

01:41:23.580 | because we already knew it,

01:41:24.860 | therefore we expected the right thing.

01:41:27.300 | But science is a learning experience,

01:41:29.900 | and sometimes you're wrong.

01:41:31.420 | And let's learn from those mistakes.

01:41:33.300 | And what's the problem about that?

01:41:34.820 | Why do we have to get prizes,

01:41:38.340 | and why do we get to be honored and maintain our image,

01:41:42.140 | when the actual objective of science

01:41:43.860 | is learning about nature?

01:41:45.460 | - And like you've talked about,

01:41:47.620 | anomalies in this case are actually,

01:41:50.060 | are not things that are unfortunate and to be ignored,

01:41:53.460 | are in fact gifts, and should be the focus of science.

01:41:56.620 | - Exactly, because that's the way for us

01:41:58.420 | to improve our understanding.

01:42:00.020 | If you look at quantum mechanics, nobody dreamed about it,

01:42:03.340 | and it was revolutionary,

01:42:05.500 | and we still don't fully understand it.

01:42:07.340 | It's a pain for us to figure out.

01:42:09.260 | - So why do you, so I understand from the perspective

01:42:12.420 | that's holding our science back,

01:42:14.240 | well, why do you have a sense that that's also something

01:42:17.980 | that might be a problem for us,

01:42:21.120 | in terms of the survival of human civilization?

01:42:23.800 | - Because when you look at society,

01:42:25.680 | it operates by the same principles.

01:42:28.380 | There is, people look for affirmation by groups,

01:42:34.500 | and they, you know, people segregate into herds

01:42:39.380 | that think like them, especially these days,

01:42:41.380 | when social media is so strong,

01:42:43.220 | you can find your support group.

01:42:45.140 | And if you don't look for evidence for what you're saying,

01:42:48.940 | you can say crazy things,

01:42:50.180 | as long as there are enough people supporting what you say,

01:42:53.500 | you can even have your newspapers,

01:42:55.700 | you can have everything to support your view,

01:42:58.500 | and then bad things will happen to society.

01:43:01.380 | - Because we're detaching ourselves from reality,

01:43:03.820 | and if we detach ourselves from reality,

01:43:06.380 | all the destructive things that naturally can occur

01:43:08.980 | in the real world, whether from nuclear weapons,

01:43:11.460 | all the kinds of threats that we're facing,

01:43:13.760 | even we're living through a pandemic,

01:43:16.100 | the supposed, you know, a much, much worse pandemic

01:43:19.980 | could happen, and then we could, sadly,

01:43:23.300 | like we did this one, politicize it in some kind of way

01:43:25.740 | and have bickering in the space of Twitter and politics,

01:43:29.580 | as opposed to there's an actual thing

01:43:31.660 | that could destroy the human species.

01:43:32.900 | - Exactly, so the only way for us to maintain,

01:43:35.220 | to stay modest and learn about what really happens

01:43:39.060 | is by looking for evidence.

01:43:40.740 | Again, I'm saying, it's not about ourself, you know?

01:43:45.580 | It's about figuring out what's around us,

01:43:47.820 | and if you close yourself by surrounding yourself

01:43:50.500 | with people that are like-minded,

01:43:53.140 | that refuse to look at the evidence,

01:43:55.860 | you can do bad things, and throughout human history,

01:43:59.860 | that's the origin of all the bad things that happen.

01:44:03.620 | - Yes.

01:44:04.460 | - And I think it's a key.

01:44:05.740 | It's a key to be modest and to look at evidence,

01:44:08.580 | and it's not a nuance.

01:44:10.120 | Now, you might say, oh, okay, the uneducated person

01:44:15.020 | might operate, no, it's the scientific community

01:44:17.700 | operates this way.

01:44:18.700 | My problem is not with people that don't have

01:44:22.540 | an academic pedigree, it's include everywhere in society.

01:44:25.900 | - On the topic of the discovery of evidence

01:44:30.420 | of alien civilizations, which is something

01:44:32.120 | you touch on in your book, what that idea

01:44:36.020 | would do to societies, to the human psyche,

01:44:40.220 | and in general, do you think,

01:44:43.020 | and you talk about the, I still have trouble pronouncing,

01:44:47.500 | but-- - Oumuamua.

01:44:48.860 | - Oumuamua wager, right?

01:44:51.060 | What do you think is, can you explain it,

01:44:54.580 | and what do you think in general is the effect

01:44:56.780 | that such knowledge might have on human civilization?

01:44:59.860 | - Right, so Pascal had this wager about God,

01:45:03.580 | and by the way, there are interesting connections

01:45:05.500 | between theology and the search for extraterrestrial life.

01:45:08.940 | You know, it's possible that, you know,

01:45:10.740 | we were planted on this planet by another civilization.

01:45:14.820 | - Yes. - You know, we attribute

01:45:16.900 | to God powers that belong really

01:45:19.420 | to the technological civilization.

01:45:21.780 | But putting that aside, Pascal basically said,

01:45:25.900 | you know, let's, there are two possibilities,

01:45:28.000 | either God exists or not, right?

01:45:30.540 | And if God exists, you know, the consequences

01:45:34.720 | are quite significant, and therefore, you know,

01:45:38.220 | we should consider that possibility differently

01:45:42.340 | than equal weight to both possibilities.

01:45:45.140 | And I suggest that we do the same with Oumuamua

01:45:50.140 | or other technological signatures,

01:45:53.460 | that we keep in mind the consequences,

01:45:58.380 | and therefore, pay more attention to that possibility.

01:46:01.220 | Now, some people say extraordinary claims

01:46:05.160 | require extraordinary evidence.

01:46:07.420 | My point is that the term extraordinary

01:46:10.220 | is really subjective, you know.

01:46:12.940 | For one person, a black hole is extraordinary.

01:46:16.360 | For another, you know, it's just a consequence

01:46:18.980 | of Einstein's theory of gravity.

01:46:20.980 | Yeah, it's nothing extraordinary.

01:46:22.620 | The same about the type of dark matter, anything.

01:46:26.660 | So we should leave the extraordinary part of that sentence.

01:46:31.320 | Just keep evidence, okay?

01:46:33.920 | So let's be guided by evidence,

01:46:36.260 | and even if we have extraordinary claims,

01:46:39.220 | you know, let's not dismiss them

01:46:41.220 | because the evidence is not extraordinary enough,

01:46:43.660 | because if we have an image of something

01:46:46.340 | and it looks really strange, and we say,

01:46:48.260 | oh, the image is not sufficiently sharp,

01:46:50.800 | therefore, we should not even pay attention to this image

01:46:53.100 | or not even consider, I think that's a mistake.

01:46:56.180 | What we should do is say, look,

01:46:57.980 | there is some evidence for something unusual.

01:47:00.480 | Let's try and build instruments

01:47:02.420 | that will give us a better image.

01:47:04.780 | And if you just dismiss extraordinary claims

01:47:07.940 | because you consider them extraordinary,

01:47:10.860 | you avoid discovering things that you haven't expected.

01:47:14.340 | And so I believe that along the history of astronomy,

01:47:19.340 | there are many missed opportunities.

01:47:21.100 | And I speak about astronomy,

01:47:22.340 | but I'm sure in other fields, it's also true.

01:47:24.260 | I mean, this is my expertise.

01:47:26.740 | For example, you know, the Astrophysical Journal,

01:47:28.900 | which is the main primary publication in astrophysics,

01:47:33.940 | if you go before the 1980s,

01:47:36.860 | there are images that were posted in the Astrophysical Journal

01:47:40.100 | of giant arcs, you know, arcs of light

01:47:43.860 | surrounding clusters of galaxies.

01:47:46.940 | And you know, you can find it in printed versions

01:47:50.800 | of the Astrophysical Journal.

01:47:51.720 | People just ignore, they put the image, they see the arc,

01:47:55.060 | they say, oh, who knows what it is, and just ignore it.

01:47:58.620 | And then in the 1980s,

01:48:00.780 | the subject of gravitational lensing became popular.

01:48:04.540 | And the idea is that you can deflect light

01:48:09.200 | by the force of gravity.

01:48:11.060 | And then you can put the source

01:48:13.980 | behind the cluster of galaxies,

01:48:15.600 | and then you will get these arcs.

01:48:17.220 | And actually Einstein predicted it in 1940.

01:48:20.660 | And you know, so these things were expected,

01:48:24.620 | but people just had them in the images,

01:48:27.080 | didn't pay attention.

01:48:27.980 | So I'm sure there are lost opportunities sometimes.

01:48:30.340 | Even in existing data,

01:48:31.860 | you have things that are unusual and exceptional,

01:48:35.760 | and are not being addressed.

01:48:38.380 | - Yeah, you actually, I think you have an article,

01:48:41.540 | the data's not enough from quite a few years ago,

01:48:44.540 | where you talk, you know, we can go back to the '70s and '80s

01:48:48.420 | but we can go also to the Mayan civilization.

01:48:50.860 | - Right, the Mayan civilization

01:48:52.220 | basically believed in astrology

01:48:53.780 | that you can forecast the outcome of a war

01:48:56.980 | based on the position of the planets.

01:48:59.380 | And they had, you know, astronomers in their culture

01:49:03.660 | had the highest social status.

01:49:06.660 | They were priests, they were elevated.

01:49:09.380 | And the reason was that they helped politicians

01:49:11.860 | decide when to go to war,

01:49:13.940 | because they would tell the politicians, you know,

01:49:16.460 | the planets would be in this configuration,

01:49:18.380 | it's a better chance for you to win the war, go to war.

01:49:21.900 | And in retrospect, they collected wonderful data,

01:49:26.460 | but misinterpreted it.

01:49:28.220 | Because we now know that the position of Venus,

01:49:30.940 | or Jupiter, or whatever, has nothing to do

01:49:34.300 | with the outcome of World War I, World War II,

01:49:36.580 | you know, it has nothing to do.

01:49:38.380 | And so we can have a prejudice and collect data

01:49:42.980 | without actually doing the right thing with it.

01:49:46.380 | - That's such a Pisces thing to say,

01:49:48.100 | I looked up what your astrological sign is, so.

01:49:50.500 | (both laughing)

01:49:53.780 | Well, so you mentioned Einstein predicted

01:49:55.980 | that black holes don't exist,

01:49:57.580 | or just didn't, or--

01:49:59.140 | - Don't exist in nature.

01:50:00.300 | - Don't exist in nature.

01:50:01.620 | - When Einstein came up with his theory of gravity

01:50:03.740 | in 1915, November 1915, a few months later,

01:50:08.220 | another physicist, Karl Schwarzschild,

01:50:11.100 | he was the director of the Potsdam Observatory,

01:50:13.820 | but he was a patriot, a German patriot.

01:50:16.060 | So he went into the First World War fighting for Germany.

01:50:18.980 | But while he was at the front,

01:50:21.620 | he sent a postcard to Einstein saying,

01:50:23.580 | you know, a few months after the theory was developed,

01:50:25.740 | saying, actually, I found a solution to your equations.

01:50:29.140 | And that was a black hole solution.

01:50:30.860 | And then he died a few months later.

01:50:33.700 | And Einstein was a pacifist, and he survived.

01:50:36.940 | So the lesson from this story is that

01:50:38.940 | if you want to work out the consequences of a theory,

01:50:42.340 | you better be a pacifist.

01:50:43.860 | (both laughing)

01:50:45.540 | But the point is that this solution was known

01:50:48.780 | shortly after Einstein came up with his theory.

01:50:51.380 | But in 1939, Einstein wrote a paper

01:50:56.020 | in the "Analysis of Mathematics" saying,

01:50:58.380 | even though the solution exists,

01:51:00.140 | I don't think it's realized in nature.

01:51:02.500 | And his argument was, if you imagine a star collapsing,

01:51:06.100 | stars often spin, and the spin will prevent them

01:51:10.140 | from making a black hole, collapsing to a point.

01:51:12.900 | - So, I mean, can you maybe,

01:51:14.940 | one of the many things you have work on,

01:51:19.220 | you're an expert in, is black holes.

01:51:22.060 | Can you first say what are black holes?

01:51:24.160 | And second, how do we know that they exist?

01:51:27.780 | - Right, so black holes are the ultimate prison.

01:51:30.620 | You know, you can check in, but you can never check out.

01:51:33.260 | - You're such a romantic.

01:51:34.460 | (both laughing)

01:51:35.620 | - Even light cannot escape from them.

01:51:38.300 | So there are extreme structures of space and time.

01:51:41.180 | And there is this so-called Schwarzschild radius,

01:51:46.660 | or the event horizon of a black hole.

01:51:49.580 | Once you enter into it with a spaceship,

01:51:52.620 | you would never be able to tweet back to your friends

01:51:55.620 | and tell them, by the way, I asked the students in my class,

01:51:58.780 | freshman seminar at Harvard, I said,

01:52:01.340 | "Let me give you two possible journeys that you can take."

01:52:05.020 | I said, "Suppose aliens come to Earth

01:52:08.380 | "and suggest that you would board their spaceship.

01:52:12.420 | "Would you do it?"

01:52:14.900 | And the second is, suppose you could board a spaceship

01:52:17.460 | that will take you into a black hole, would you do it?

01:52:20.140 | So all of them said to the first question,

01:52:24.300 | "Yes, under one condition,

01:52:26.380 | "that I'll be able to maintain my social media contacts

01:52:29.900 | "and report back, share the experience with them."

01:52:33.220 | I couldn't, personally, I have no footprint on social media.

01:52:36.460 | - Yeah, which is as a matter of principle.

01:52:39.100 | - Yeah, my wife asked me when we got married,

01:52:42.180 | and I honor that.

01:52:44.780 | - And I told you offline,

01:52:45.820 | I need to get married to such a woman.

01:52:48.300 | She truly is a special agent.

01:52:49.500 | - Well, she was wise enough to recognize the risk,

01:52:52.780 | but it saves me time,

01:52:55.220 | and it also keeps me away from crowds.

01:52:57.740 | I don't have the notion of what a lot of other people think,

01:53:02.740 | so I can think independently.

01:53:03.860 | - So crowd think, exactly.

01:53:04.860 | - Yeah, exactly.

01:53:05.700 | So I was surprised to hear that for students,

01:53:10.500 | it's extremely important to share experiences.

01:53:12.740 | Even if they go on a spaceship with aliens,

01:53:14.900 | they still want to brag about it,

01:53:17.420 | rather than look around and see what's going on.

01:53:19.820 | - This is not an option when you go to the black hole,

01:53:21.860 | is exactly the point.

01:53:22.980 | - So for the black hole, they said no,

01:53:24.980 | because obviously you can find your death

01:53:27.780 | after you get into it,

01:53:30.220 | and you crash into singularity.

01:53:32.780 | There is this singularity in the center.

01:53:34.260 | So inside the event horizon,

01:53:36.900 | we know that all the matter collects at a point.

01:53:41.420 | Now, we can't really predict what happens at the singularity

01:53:45.700 | because Einstein's theory breaks down,

01:53:48.460 | and we know why it breaks down,

01:53:49.780 | because he doesn't have quantum mechanics

01:53:51.820 | that talks about small distances.

01:53:54.260 | We don't have a theory that unifies quantum mechanics

01:53:57.340 | and gravity so that it will predict what happens

01:54:01.780 | in near a singularity.

01:54:03.380 | And in fact, a couple of years ago,

01:54:06.180 | I had a flood in my basement.

01:54:09.140 | And I invited a plumber to come over and figure out,

01:54:15.100 | and we found that the sewer was clogged

01:54:19.420 | because of tree roots that got into it.

01:54:23.020 | And we solved the problem.

01:54:24.740 | But then I thought to myself,

01:54:28.260 | well, isn't that what happens

01:54:30.020 | at the singularity of a black hole?

01:54:31.460 | Because the question is, where does the matter go?

01:54:35.420 | If, in the case of a home, I never thought about it,

01:54:38.900 | but the water, all the water that we use

01:54:41.260 | goes in through the sewer to some reservoir somewhere.

01:54:45.660 | And the question is, what happens inside a black hole?

01:54:48.580 | And one possibility is that there is an object

01:54:51.420 | in the middle, just like a star,

01:54:53.060 | and everything collects there.

01:54:54.580 | And the object has the maximum density

01:54:56.840 | that we can imagine, like Planck densities.

01:54:59.460 | It's the ultimate density that you can have,

01:55:02.900 | where gravity is as strong as all the other forces.

01:55:06.440 | So you can imagine this object,

01:55:09.920 | very dense object at the center

01:55:11.580 | that collects all the matter.

01:55:13.300 | Another possibility is that there is some tunnel,

01:55:15.900 | just like the sewer, it takes the matter into another place.

01:55:19.900 | And we don't know the answer,

01:55:21.780 | but I wrote a Scientific American essay about it,

01:55:24.460 | admitting our ignorance.

01:55:26.940 | So it's a fascinating question.

01:55:28.100 | What happens to the matter that goes into a black hole?

01:55:30.500 | I actually recommended to some of my colleagues

01:55:32.620 | that work on string theory,

01:55:34.100 | at the closing of a conference,

01:55:36.580 | I'm the founding director of the Black Hole Initiative

01:55:39.380 | at Harvard, which brings together astronomers,

01:55:41.740 | physicists, philosophers, and mathematicians.

01:55:44.460 | And we have a conference once a year.

01:55:46.940 | And at the end of one of them,

01:55:48.660 | since I'm the director, I had to summarize,

01:55:50.740 | and I said that I wish we could go on a field trip

01:55:55.740 | to a black hole nearby.

01:55:57.900 | And I highly recommend to my colleagues

01:56:00.660 | that work on string theory to enter into that black hole,

01:56:03.780 | because then they can test their theory

01:56:05.780 | when they get inside.

01:56:07.400 | But one of the string theorists in the audience,

01:56:10.460 | Nimar Kani Hamid, immediately raised his voice and said,

01:56:14.060 | "You have an ulterior motive

01:56:15.820 | "for sending us into a black hole."

01:56:17.700 | (Lex laughing)

01:56:19.140 | Which I didn't deny, but at any event.

01:56:21.540 | (Lex laughing)

01:56:23.780 | - Yeah, that's true, that's true.

01:56:26.160 | Can you say why we know that black holes exist?

01:56:31.160 | - Right, so it's an interesting question,

01:56:36.440 | because black holes were considered a theoretical construct.

01:56:39.860 | And Einstein even denied their existence in 1939.

01:56:44.920 | But then in the mid 1960s, quasars were discovered.

01:56:53.060 | These are very bright sources of light,

01:56:55.820 | 100 times brighter than their host galaxy,

01:56:59.940 | which are point-like at the center of galaxies.

01:57:03.580 | And it was immediately suggested by Ed Salpeter in the West,

01:57:08.580 | and by Yakov Zeldovich in the East,

01:57:13.140 | that these are black holes that accrete gas,

01:57:18.340 | collect gas from their host galaxy

01:57:20.420 | that are being fed with gas.

01:57:22.280 | And they shine very brightly,

01:57:23.700 | because as the gas falls towards the black holes,

01:57:28.540 | just like water running down the sink,

01:57:32.600 | the gas swirls and then rubs against itself,

01:57:39.260 | and heats up and shines very brightly,

01:57:42.660 | because it's very hot close to the black hole,

01:57:45.340 | by viscosity, it heats up.

01:57:49.700 | And in the case of black holes, it's the turbulence,

01:57:52.440 | the turbulent viscosity that causes it to heat up.

01:57:55.720 | So we get these very bright sources of light

01:57:58.920 | just from black holes that are supposed to be dark.

01:58:02.000 | Nothing escapes from them,

01:58:03.120 | but they create a violent environment

01:58:06.960 | where gas moves close to the speed of light,

01:58:09.540 | and therefore shines very brightly,

01:58:11.400 | much more than any other source in the sky.

01:58:13.840 | And we can see these quasars

01:58:15.840 | all the way to the edge of the universe.

01:58:17.720 | So we have evidence now that when the universe was

01:58:21.180 | about 7% of its present age, infant,

01:58:25.940 | already back then you had black holes

01:58:28.180 | of a billion times the mass of the sun,

01:58:31.060 | which is quite remarkable.

01:58:32.620 | It's like finding giant babies in a nursery.

01:58:36.860 | How can these black holes grow so fast?

01:58:40.620 | Less than a billion years after the Big Bang,

01:58:42.980 | you already have a billion times the mass of the sun

01:58:45.740 | in these black holes.

01:58:46.780 | And the answer is presumably there are very quick processes

01:58:51.780 | that build them up.

01:58:54.160 | - They build quickly.

01:58:56.100 | - Very quickly.

01:58:57.120 | And so we see those black holes,

01:58:59.880 | and that was found in the mid 1960s,

01:59:01.960 | but in 19, sorry, in 2015,

01:59:05.920 | exactly 100 years after Einstein came up

01:59:09.200 | with his theory of gravity,

01:59:11.880 | the LIGO observatory detected gravitational waves.

01:59:15.920 | And these are just ripples in space and time.

01:59:18.500 | So according to Einstein's theory,

01:59:20.060 | the ingenuity of Einstein's theory of gravity

01:59:24.340 | that was formulated in November, 1915,

01:59:27.980 | was to say that space and time are not rigid.

01:59:32.020 | They respond to matter.

01:59:36.820 | So for example, if you have two black holes

01:59:40.200 | and they collide, it's just like a stone being thrown

01:59:45.100 | on the surface of a pond.

01:59:47.340 | They generate waves, disturbances in space and time

01:59:51.820 | that propagate out at the speed of light.

01:59:53.780 | These are gravitational waves.

01:59:55.460 | They create a space-time storm around them,

01:59:58.380 | and then the waves go all the way through the universe

02:00:02.260 | and reach us.

02:00:03.220 | And if you have a sensitive enough detector like LIGO,

02:00:07.140 | you can detect these waves.

02:00:08.380 | And so it was not just the message that we received

02:00:12.000 | for the first time, gravitational waves,

02:00:14.060 | but it was the messenger.

02:00:16.100 | So there are two aspects to it.

02:00:17.500 | One is the messenger, which is gravitational wave

02:00:19.500 | for the first time were detected directly.

02:00:21.900 | And the second was the message,

02:00:23.300 | which was a collision of two black holes,

02:00:26.160 | because we could see the pattern

02:00:27.900 | of the ripples in space and time.

02:00:30.180 | And it was fully consistent with the prediction

02:00:33.700 | that Schwarzschild made for how the space-time

02:00:37.180 | around the black hole is,

02:00:38.140 | because when two black holes collide,

02:00:40.420 | you can sort of map from the message that you get,

02:00:43.960 | you can reconstruct what really happened,

02:00:46.820 | and it's fully consistent.

02:00:48.420 | - And in 2017 and 2020, there's two Nobel Prizes.

02:00:53.420 | - That's right.

02:00:55.740 | - That had to do with the black holes.

02:00:59.860 | Can you maybe describe in the same masterful way

02:01:03.220 | that you already been doing,

02:01:05.140 | what those Nobel Prizes were given for?

02:01:06.900 | - Yeah, so the 2017 was given for the LIGO collaboration

02:01:10.640 | for discovering gravitational waves

02:01:13.060 | from collisions of black holes.

02:01:14.840 | And the 2020 Nobel Prize in physics

02:01:20.540 | was given for two things.

02:01:23.480 | One was theoretical work that was done by Roger Penrose

02:01:27.960 | in the 1960s, demonstrating that black holes

02:01:31.680 | are inevitable when stars collapse.

02:01:35.820 | And it was mostly mathematical work.

02:01:38.720 | And actually Stephen Hawking also contributed significantly

02:01:43.720 | to that frontier, and unfortunately he is not alive,

02:01:47.660 | so he could not be honored.

02:01:49.440 | So Penrose received it on his own.

02:01:51.980 | And then two other astronomers received it as well,

02:01:57.740 | Andrea Ghez and Reinhard Genzel,

02:02:00.040 | and they provided conclusive evidence

02:02:02.620 | that there is a black hole

02:02:03.920 | at the center of the Milky Way galaxy

02:02:06.780 | that weighs about four million times the mass of the sun.

02:02:11.280 | And they found the evidence from the motion of stars

02:02:13.880 | very close to the black hole.

02:02:15.700 | Just like we see the planets moving around the sun,

02:02:18.640 | there are stars close to the center of the galaxy,

02:02:21.400 | and they are orbiting at very high speeds

02:02:24.120 | of order of thousands of kilometers per second

02:02:26.680 | or thousands of miles per second.

02:02:29.260 | Think about it.

02:02:31.180 | Which can only be induced at those distances

02:02:36.380 | if there is a four million solar mass object

02:02:41.380 | that is extremely compact.

02:02:44.880 | And the only thing that is compatible with the constraints

02:02:48.000 | is a black hole.

02:02:49.520 | And they actually made a movie of the motion of these stars

02:02:54.520 | around the center.

02:02:56.200 | One of them moves around the center over a decade,

02:02:59.160 | over timescales that we can monitor.

02:03:02.520 | And it was a breakthrough in a way.

02:03:05.780 | So combining LIGO with the detection of a black hole

02:03:11.980 | at the center of the Milky Way

02:03:13.220 | and in many other galaxies like quasars,

02:03:16.280 | now I would say black hole research is vogue.

02:03:22.660 | It's very much in fashion.

02:03:25.380 | We saw it back in 2016

02:03:27.380 | when we established the Black Hole Initiative.

02:03:31.180 | You kind of saw that there's this excitement

02:03:34.040 | about in breakthroughs and discoveries around black holes,

02:03:39.040 | which are probably one of the most fascinating objects

02:03:42.120 | in the universe.

02:03:43.680 | It's up there.

02:03:44.700 | They're both terrifying and beautiful,

02:03:48.440 | and they capture the entirety of the physics

02:03:50.640 | that we know about this universe.

02:03:51.680 | - I should say, the question is,

02:03:53.600 | where is the nearest black hole?

02:03:54.840 | Can we visit it?

02:03:56.480 | And I wrote a paper with my undergraduate student,

02:04:01.220 | Amir Siraj, suggesting that perhaps there could be,

02:04:05.140 | if there is one in the solar system, we can detect it.

02:04:08.260 | Because I don't know if you heard,

02:04:10.900 | but there is a claim that maybe there is a planet nine

02:04:15.100 | in the solar system,

02:04:16.320 | because we see some anomalies

02:04:19.740 | at the outer parts of the solar system.

02:04:21.420 | So some people suggested maybe there is a planet out there

02:04:24.060 | that was not yet detected.

02:04:26.220 | So people searched for it, didn't find it.

02:04:29.540 | It weighs roughly five times the mass of the Earth.

02:04:32.120 | And we said, okay, maybe you can't find it

02:04:34.620 | because it's a black hole

02:04:36.580 | that was formed early in the universe.

02:04:38.260 | - Is that part, so where do you stand on that?

02:04:40.820 | - It could be that the dark matter

02:04:42.180 | is made of black holes of this mass.

02:04:44.140 | We don't know what the dark matter is made of.

02:04:46.340 | It could be black holes.

02:04:48.140 | So we said, but there is an experimental way to test it.

02:04:51.900 | And the way to do it is because

02:04:54.380 | there is the Oort cloud of icy rocks

02:04:59.220 | in the outer solar system.

02:05:01.220 | And if you imagine a black hole there,

02:05:03.420 | every now and then a rock will pass close enough

02:05:06.820 | to the black hole to be disrupted

02:05:09.340 | by the very strong gravity close to the black hole.

02:05:12.420 | And that would produce a flare that you can observe.

02:05:15.500 | And we calculated how frequently these flares should occur.

02:05:19.020 | And with LSST on the Vera Rubin Observatory,

02:05:21.620 | we found that you can actually test this hypothesis.

02:05:24.700 | - That's brilliant.

02:05:25.540 | - And if you don't see flares,

02:05:27.220 | then you can put limits on the existence of a black hole

02:05:30.060 | in the solar system.

02:05:31.380 | It would be extremely exciting if there was a black hole,

02:05:34.060 | if planet nine was a black hole,

02:05:35.660 | because we could visit it, and we can examine it.

02:05:39.340 | And it will not be a matter of an object

02:05:44.100 | that is very removed from us.

02:05:46.220 | Another thing I should say is it's possible

02:05:48.460 | that the black hole affected life on Earth.

02:05:51.580 | The black hole at the center of the Milky Way.

02:05:54.540 | How?

02:05:56.540 | That black hole right now is dormant.

02:05:59.580 | It's very faint.

02:06:01.180 | But we know that it flares.

02:06:04.180 | When a star like the sun comes close to it,

02:06:07.640 | the star will be spaghettified,

02:06:09.460 | basically become a stream of gas, like a spaghetti.

02:06:13.760 | And then the gas would fall into the black hole,

02:06:16.300 | and there would be a flare.

02:06:17.700 | And this process happens once every 10,000 years or so.

02:06:21.020 | So we expect that these flares to occur every 10,000 years.

02:06:25.340 | But we also see evidence for the possibility

02:06:28.860 | that gas clouds were disrupted by the black hole,

02:06:32.100 | because the stars that are close to the black hole

02:06:35.140 | are residing in a single or two planes.

02:06:38.400 | And the only way you can get that

02:06:39.940 | is if they formed out of a disk of gas,

02:06:42.260 | just like the planets in the solar system formed.

02:06:44.760 | So there is evidence that gas fell into the black hole

02:06:48.740 | and powered possibly a flare.

02:06:51.140 | And these flares produce X-rays and ultraviolet radiation

02:06:56.140 | that could damage life if the Earth was close enough

02:07:01.380 | to the center of the galaxy.

02:07:03.620 | Where we are right now, it's not very risky for us.

02:07:07.160 | But there is a theoretical argument

02:07:11.540 | that says the solar system, the sun,

02:07:13.940 | was closer to the galactic center early on,

02:07:16.960 | and then it migrated outwards.

02:07:19.460 | So maybe in the early stage of the solar system,

02:07:24.460 | the conditions were affected, shaped by these flares

02:07:30.020 | of the black hole at the center of the galaxy.

02:07:31.740 | And that's why for the first two billion years,

02:07:34.020 | there wasn't any oxygen in the atmosphere.

02:07:36.340 | Who knows?

02:07:37.180 | But it's just interesting to think that

02:07:40.780 | from a theoretical concept that Einstein resisted in 1939,

02:07:45.580 | it may well be that black holes have influence on our life.

02:07:50.060 | And that it's just like discovering that some stranger

02:07:53.460 | affected your family and in a way your life.

02:08:01.380 | And if that happens to be the case,

02:08:05.580 | a second Nobel Prize should be given,

02:08:07.360 | not for just the discovery of this black hole

02:08:11.220 | at the center of the galaxy,

02:08:12.060 | but perhaps for the Nobel Prize in chemistry,

02:08:14.820 | for the effect that it had on life.

02:08:16.380 | - For the effect, for the interplay that resulted

02:08:18.700 | in some kind of, yeah, so yeah, the chemical effect,

02:08:23.700 | biology, I mean, all those kinds of things

02:08:25.940 | in terms of the emergence of life

02:08:29.900 | and the creation of a habitable environment.

02:08:32.260 | That's so fascinating.

02:08:33.460 | And of course, like you said, dark matter,

02:08:35.220 | like black holes have some--

02:08:36.860 | - They could be the dark matter in principle, yes.

02:08:40.060 | We don't know what the dark matter is at the moment.

02:08:43.320 | - Does it make you sad?

02:08:44.620 | So you've had an interaction

02:08:46.340 | and perhaps a bit of a friendship with Stephen Hawking.

02:08:49.780 | Does it make you sad that he didn't win the Nobel?

02:08:51.940 | - Well, altogether, I don't assign great importance

02:08:56.500 | to prizes because--

02:08:58.100 | - As you said.

02:08:58.940 | - You know, Jean-Paul Sartre,

02:09:00.540 | who I admired as a teenager

02:09:03.140 | because I was interested in philosophy.

02:09:04.740 | When I grew up on a farm in Israel,

02:09:06.740 | I used to collect eggs every afternoon

02:09:09.500 | and I would drive the tractor to the hills of our village.

02:09:13.180 | And just think about philosophy, read philosophy books.

02:09:15.740 | And Jean-Paul Sartre was one of my favorite.

02:09:18.220 | And he was honored with a Nobel Prize in literature.

02:09:21.900 | He was a philosopher primarily, existentialist.

02:09:25.180 | And he said, "The hell with it.

02:09:26.860 | "Why should I give special attention to this committee

02:09:31.860 | "of people that get their self-importance

02:09:34.760 | "from awarding me the prize?

02:09:37.020 | "Like what's, you know,

02:09:39.700 | "why does that merit my attention?"

02:09:41.860 | So he gave up on the Nobel Prize.

02:09:43.900 | And you know, there are two benefits to that.

02:09:46.900 | One, that you're not working your entire life

02:09:51.900 | in the direction that would satisfy the will

02:09:54.100 | of other people.

02:09:54.940 | You know, you work independently,

02:09:57.140 | you're not after these honors.

02:09:59.040 | Just for the same reason that if you're not living your life

02:10:03.940 | for making a profit or money,

02:10:06.220 | you can live a more fulfilling life

02:10:08.300 | because you're not being swayed by the wind, you know,

02:10:11.020 | of how to make money and so forth.

02:10:12.820 | The second aspect of it is, you know,

02:10:17.100 | that very often, you know, these prizes,

02:10:21.980 | they distort the way we do science

02:10:26.820 | because instead of people willing to take risks

02:10:31.380 | and instead of having announcements

02:10:35.020 | only after a group of people converges

02:10:37.300 | with a definite result, you know,

02:10:41.480 | the natural progression of science

02:10:44.000 | is based on trial and error.

02:10:45.640 | You know, it's reporting some results

02:10:47.600 | and perhaps they're wrong,

02:10:49.040 | but then other people find perhaps better evidence

02:10:51.800 | and then you figure out what's going on.

02:10:53.720 | And that's the natural way that science is,

02:10:55.640 | you know, it's a learning experience.

02:10:57.220 | So if you give the public an image

02:10:59.960 | by which scientists are always right, you know,

02:11:03.280 | and you know, some of my colleagues say,

02:11:05.020 | "We must do that because otherwise the public

02:11:07.260 | "will never believe us that global warming

02:11:09.100 | "is really taking place."

02:11:10.640 | But that's not true because the public

02:11:12.120 | would really believe you if you show the evidence.

02:11:15.160 | So the point is you should be sincere

02:11:16.960 | when the evidence is not absolutely clear

02:11:19.560 | or where there are disputes about the interpretation

02:11:21.640 | of the evidence, we should show ourselves.

02:11:23.360 | You know, the king is naked, okay?

02:11:26.400 | There is no point in pretending that the king is dressed,

02:11:30.240 | saying that scientists are always right.

02:11:32.240 | Scientists are wrong frequently.

02:11:35.000 | And the only way to make progress is by evidence,

02:11:38.500 | giving us the support that we need

02:11:40.880 | to make airtight arguments.

02:11:43.360 | So when you say global warming is taking place,

02:11:46.140 | if the evidence is fully supportive,

02:11:48.920 | if there are no holes in the argument,

02:11:51.440 | then people will be convinced

02:11:53.240 | because you're not trying to fool them.

02:11:55.280 | When the evidence was not complete,

02:11:56.680 | you also show them that the evidence is not complete.

02:11:58.600 | - Yeah, and when there's holes,

02:11:59.680 | you show that there's holes

02:12:00.920 | and here's the methodology we're using

02:12:02.480 | to try to close those holes.

02:12:03.680 | - Exactly, let's be sincere, why pretend?

02:12:06.000 | So if there were no, in a world

02:12:07.640 | where there were no prizes, no honors,

02:12:10.700 | we would act like kids, as I said before.

02:12:13.720 | We would really be focusing on the ball

02:12:16.320 | and not on the audience.

02:12:17.480 | - Yeah, the prizes get in the way,

02:12:19.280 | and that's so powerful.

02:12:21.960 | Do you think, in some sense,

02:12:23.960 | the few people that have turned down the prize

02:12:26.440 | made a much more powerful statement?

02:12:28.520 | I don't know if you're familiar

02:12:29.640 | in the space of mathematics with the Fields Medal

02:12:33.460 | and Grigori Perelman who turned down the prize.

02:12:37.760 | So he, I've committed,

02:12:40.040 | one of the reasons I started this podcast

02:12:41.880 | is I'm going to definitely talk to Putin,

02:12:44.320 | I'm definitely talking to Perelman,

02:12:46.200 | and people keep telling me it's impossible.

02:12:48.240 | I love hearing that because I'll talk to both.

02:12:52.360 | Anyway, but do you have a sense

02:12:56.920 | of why he turned down the prize?

02:13:00.680 | And is that a powerful statement to you?

02:13:03.580 | - Well, what I read is that,

02:13:05.720 | you're talking about the mathematician, right?

02:13:06.960 | - The mathematician turned down the prize.

02:13:07.800 | - What I read is that he was disappointed

02:13:10.920 | by the response of the community,

02:13:12.600 | the mainstream community, the mathematicians,

02:13:15.440 | to his earlier work where they dismissed it,

02:13:19.440 | they didn't attend to the details

02:13:22.320 | and didn't treat him with proper respect

02:13:25.120 | because he was not considered one of them.

02:13:28.840 | And I think that speaks volumes

02:13:32.480 | about the current scientific culture,

02:13:34.200 | which is based on groupthink

02:13:38.120 | and on social interaction,

02:13:41.940 | rather than on the merit of the argument

02:13:44.600 | and on the evidence in the context of physics.

02:13:46.560 | So in mathematics, there is no empirical basis,

02:13:49.320 | you're exploring ideas that are logically consistent,

02:13:53.480 | but nevertheless, there is this groupthink.

02:13:57.080 | And I think he was so frustrated with his past experience

02:14:01.640 | that he didn't even bother to publish his papers,

02:14:04.360 | he just posted them on the archive.

02:14:06.760 | And in a way, it's saying,

02:14:09.880 | I know what the answer is, go look at it.

02:14:12.560 | (both laugh)

02:14:13.720 | - And then again, in the long arc of history,

02:14:17.200 | his work on archive will be remembered

02:14:19.920 | and all the prizes, most of the prizes will be forgotten.

02:14:23.400 | This is what people don't kind of think about.

02:14:26.720 | When you look at Roger Penrose, for example,

02:14:29.600 | he's another fascinating figure.

02:14:31.300 | It's possible, and forgive me if I'm showing my ignorance,

02:14:36.080 | but he's also did some work on consciousness.

02:14:39.520 | He's been one of the only people

02:14:40.800 | who spoke about consciousness,

02:14:42.560 | which for the longest time,

02:14:44.000 | and is still arguably outside of the realm of the sciences.

02:14:49.000 | It's still seen as a taboo subject.

02:14:51.600 | And he was brave enough to explore it

02:14:57.040 | from a physics perspective,

02:14:58.320 | from just a philosophical perspective,

02:15:00.480 | but with the rigor,

02:15:02.200 | proposing different kind of hypotheses

02:15:04.480 | of how consciousness might be able to emerge in the brain.

02:15:07.760 | And it's possible that that is the thing he's remembered for

02:15:10.260 | if you look 100 years from now, right?

02:15:12.520 | As opposed to the work in the black holes,

02:15:15.440 | which fits into the kind of,

02:15:17.600 | fits into what the current scientific community

02:15:24.520 | allows to be the space of what is and isn't science.

02:15:29.080 | - Yeah, it's really interesting to look at people

02:15:30.880 | that are innovators,

02:15:32.480 | where in some phases of their career,

02:15:35.800 | their ideas fit into the social structure

02:15:40.280 | that is around them,

02:15:41.160 | but in other phases, it doesn't.

02:15:43.160 | And when you look at them,

02:15:45.360 | they just operated the same way throughout.

02:15:48.080 | And it says more about their environment than about them.

02:15:52.920 | - Well, yeah, I don't know if you know who Max Tegmark is.

02:15:55.440 | I just recently talked to him.

02:15:56.680 | - He's a friend of mine.

02:15:58.200 | - I just recently talked to him again.

02:15:59.560 | And he was a little bit more explicit about saying,

02:16:03.920 | being aware, which is something I also recommend,

02:16:06.320 | is being aware where the scientific community stands

02:16:09.000 | and doing enough to move along in your career.

02:16:13.520 | And it's the necessary evil, I suppose.

02:16:16.160 | If you are one of those out-of-the-box thinkers

02:16:19.120 | that just naturally have this childlike curiosity,

02:16:21.440 | which Max definitely is one of them,

02:16:23.720 | is sometimes you have to do some stuff that fits in.

02:16:26.480 | You publish and you get tenure and all those kinds of things.

02:16:28.920 | - But the tenure is a great privilege

02:16:30.600 | 'cause it allows you to, in principle,

02:16:32.600 | explore things that are not accepted by others.

02:16:35.840 | And unfortunately, it's not being taken advantage of

02:16:40.320 | by most people,

02:16:41.440 | and it's a waste of a very precious resource.

02:16:45.360 | - Yeah, absolutely.

02:16:46.960 | The space that you kind of touched on

02:16:49.360 | that's full of theories

02:16:52.240 | and is perhaps detached from

02:16:55.200 | appreciation of empirical evidence

02:16:59.200 | or longing for empirical evidence

02:17:00.960 | or grounding in empirical evidence

02:17:02.560 | is the theoretical physics community

02:17:05.200 | and the interest in unifying the laws of physics

02:17:09.760 | and with the theory of everything.

02:17:11.800 | I'm not sure from which direction

02:17:15.960 | to approach this question,

02:17:17.160 | but how far away are we from arriving

02:17:20.600 | at a theory of everything, do you think?

02:17:23.120 | And how important is it to try to arrive at it,

02:17:28.120 | at this kind of goal of this beautiful, simple theory

02:17:34.200 | that unlocks the very fundamental basis

02:17:38.760 | of our nature as we know it?

02:17:45.400 | And what are the kinds of approaches

02:17:48.200 | we need to take to get there?

02:17:50.240 | - Yeah, so in physics,

02:17:52.160 | the biggest challenge is to unify quantum mechanics

02:17:54.820 | with gravity.

02:17:56.320 | And I believe that once we have experimental evidence

02:18:01.000 | for how this happens in nature,

02:18:02.980 | in systems that have quantum mechanical effects,

02:18:07.560 | but also gravity is important,

02:18:09.940 | then the theory will fall into our lap, okay?

02:18:14.120 | But the mistake that is made by the community right now

02:18:17.660 | is to come up with the right theory from scratch.

02:18:22.660 | And Einstein gave the illusion

02:18:25.840 | that you can just sit in your office

02:18:27.940 | and understand nature when he came up

02:18:30.640 | with his general theory of relativity.

02:18:33.280 | But first of all, perhaps he was lucky,

02:18:36.680 | but it's not a rule.

02:18:39.480 | The rule is that you need evidence to guide you,

02:18:41.680 | especially when dealing with quantum mechanics,

02:18:43.500 | which is really not intuitive.

02:18:46.680 | And so there are two places where the two theories meet.

02:18:51.680 | One is black holes, and there is a puzzle there.

02:18:55.880 | It's called the information paradox.

02:18:58.640 | In principle, you can throw the Encyclopedia Britannica

02:19:01.520 | into a black hole.

02:19:02.360 | It's a lot of information.

02:19:03.580 | And then it will be gone

02:19:06.660 | because a black hole carries only three properties

02:19:12.680 | or qualities, the mass, the charge, and the spin,

02:19:16.380 | according to Einstein.

02:19:17.500 | But then when Hawking tried to bring in quantum mechanics

02:19:22.340 | to the game, he realized that black holes

02:19:25.340 | have a temperature and they radiate.

02:19:27.900 | This is called Hawking radiation.

02:19:30.100 | It was sort of anticipated by Jacob Bekenstein before him,

02:19:35.100 | and Hawking wanted to prove Bekenstein wrong

02:19:40.200 | and then figure this out.

02:19:42.300 | And so what it means is black holes eventually evaporate,

02:19:45.740 | and they evaporate into radiation

02:19:48.720 | that doesn't carry this information,

02:19:50.520 | according to Hawking's calculation.

02:19:52.660 | And then the question is, according to quantum mechanics,

02:19:55.320 | information must be preserved.

02:19:57.120 | So where did the information go if a black hole is gone?

02:20:02.120 | And where is the information that was encoded

02:20:05.400 | in the Encyclopedia when it went into the black hole?

02:20:08.960 | And to that question, we don't have an answer yet.

02:20:12.380 | It's one of those puzzles about black holes,

02:20:14.960 | and it touches on the interplay

02:20:16.540 | between quantum mechanics and gravity.

02:20:19.340 | Another important question is what happened

02:20:22.440 | at the beginning of the universe?

02:20:24.640 | What happened before the Big Bang?

02:20:26.380 | And by the way, on that, I should say,

02:20:29.620 | there are some conjectures.

02:20:32.440 | In principle, if we figure it out,

02:20:36.000 | if we have a theory of quantum gravity,

02:20:37.900 | it's possible to imagine that we will figure out

02:20:41.140 | how to create a universe in the laboratory.

02:20:44.220 | By irritating the vacuum, you might create a baby universe.

02:20:48.940 | And if we do that, it will offer a solution

02:20:52.140 | to what happened before the Big Bang.

02:20:53.840 | Perhaps the Big Bang emerged from the laboratory

02:20:56.840 | of another civilization.

02:20:57.980 | So it's like baby universes are being born

02:21:01.540 | out of laboratories, and inside the baby universe,

02:21:05.100 | you have a civilization that brings to existence

02:21:07.580 | a new baby universe.

02:21:09.060 | Just like humans, right?

02:21:10.260 | We have babies, and they make babies.

02:21:12.220 | So in principle, that would solve the problem

02:21:14.500 | of why there was a Big Bang,

02:21:17.360 | and also what happened before the Big Bang.

02:21:20.460 | So we came, our umbilical cord is connected

02:21:24.540 | to a laboratory of a civilization

02:21:26.540 | that produced our universe once it figured out

02:21:28.680 | quantum gravity.

02:21:29.680 | - It's baby Big Bangs all the way down.

02:21:33.660 | It's just Big Bangs all the way down.

02:21:36.300 | - So if we collect data about how the universe started,

02:21:38.780 | we could potentially test theories of,

02:21:41.220 | or it can educate us about how to unify

02:21:44.460 | quantum mechanics and gravity.

02:21:45.660 | If we get any information about what happens

02:21:48.180 | near the singularity of a black hole,

02:21:50.020 | if we get a sense of, somehow we learn

02:21:55.860 | what happens at the singularity, that would educate.

02:21:57.980 | So there are places where we can search for evidence,

02:22:01.700 | but it's very challenging, I should say.

02:22:03.780 | And my point is, the string theorists,

02:22:06.780 | they decided that they know how to approach the problem,

02:22:10.060 | but they don't have a single theory.

02:22:13.980 | There is a multitude of theories,

02:22:15.580 | and it's not tightly constrained,

02:22:17.700 | and they cannot make predictions about black holes

02:22:20.740 | or about the beginning of the universe.

02:22:22.580 | So at the moment, I say we are at a loss.

02:22:24.700 | And the way I feel about this concept

02:22:27.740 | of the theory of everything,

02:22:29.060 | we should wait until we get enough evidence to guide us.

02:22:33.060 | And until then, there are many important problems

02:22:35.460 | that we can address.

02:22:37.020 | Why bang our head against the wall

02:22:40.780 | on a problem for which we have no guidance?

02:22:43.380 | - Right, we don't have a good dance partner

02:22:45.260 | in terms of evidence.

02:22:46.260 | - Exactly.

02:22:47.100 | - I mean, it'd be interesting, Jessica said,

02:22:49.980 | the lab is one place to create universes or black holes,

02:22:54.980 | but it'd be fascinating if there is indeed a black hole

02:22:58.180 | in our solar system that you can interact with.

02:23:01.060 | So the problem with the origin of the universe

02:23:03.580 | is all you can do is collect data about it, right?

02:23:06.060 | You can't interact with it.

02:23:07.780 | - Well, you can, for example, detect gravitational waves

02:23:10.540 | that emerged from that.

02:23:12.460 | And there is an effort to do that,

02:23:14.580 | and that could potentially tell us something.

02:23:17.060 | But yeah, it's a challenge, and that's why we're stuck.

02:23:21.860 | So I should say, despite what physicists portray,

02:23:25.980 | that we live through an exceptional growth

02:23:29.620 | in our understanding of the universe,

02:23:31.540 | we're actually pretty much stuck, I would say,

02:23:33.900 | because we don't know the nature of the dark matter,

02:23:36.700 | most of the matter in the universe.

02:23:38.020 | We don't know what it is,

02:23:40.100 | and we don't know how the universe started.

02:23:42.240 | We don't know what happens in the interior of a black hole.

02:23:45.900 | - Because you've thought quite a bit

02:23:47.220 | about dark matter as well.

02:23:48.900 | Do you have any kind of interesting hypothesis?

02:23:51.300 | We already mentioned a few about what is dark matter

02:23:55.140 | and what are the possible paths that we could take

02:23:59.700 | to unlock the mystery of dark, what is dark matter?

02:24:02.540 | - Yeah, so what we need is some anomalies

02:24:04.940 | that would hint what the nature of the dark matter is,

02:24:08.300 | or to detect it in the laboratory.

02:24:09.940 | There are lots of laboratory experiments searching,

02:24:12.320 | but it's like searching for a needle in a haystack,

02:24:14.900 | 'cause there are so many possibilities

02:24:16.280 | for the type of particle that it may be.

02:24:18.880 | But maybe at some point, we'll find either a particle

02:24:23.540 | or black holes as dark matter or something else.

02:24:26.500 | But at the moment-- - Can you also maybe,

02:24:28.420 | sorry to interrupt, comment about what is dark matter?

02:24:31.460 | Like what, it's just a name we're assigned to what?

02:24:34.740 | - So most of the community believes that it's a particle

02:24:38.220 | that we haven't yet detected.

02:24:41.540 | It doesn't interact with light, so it's dark.

02:24:44.540 | But the question is, what does it interact with,

02:24:47.260 | and how can we find it?

02:24:48.860 | And for many years, physicists were guided by the idea

02:24:53.020 | that it's some extension of the standard model

02:24:55.820 | of particle physics, but then they said,

02:24:58.540 | oh, we will find some clues from the Large Hadron Collider

02:25:02.000 | about its nature, or maybe it's related to supersymmetry,

02:25:05.540 | which is a new symmetry

02:25:06.700 | that we haven't found any evidence for.

02:25:08.820 | In both cases, the Large Hadron Collider

02:25:10.860 | did not give us any clues.

02:25:12.620 | And other people searched for specific types of particles

02:25:16.500 | in the laboratory and didn't find any.

02:25:18.400 | A couple of years ago, actually,

02:25:21.980 | around the time that I worked on Oumuamua,

02:25:24.620 | I also worked on the possibility

02:25:26.680 | that the dark matter particles

02:25:28.620 | may have a small electric charge, which is a speculation.

02:25:32.900 | But nobody complained about it, and it was published,

02:25:37.460 | and I regarded more of a speculation

02:25:40.740 | than the artificial origin of Oumuamua.

02:25:43.500 | And to me, as far as I'm concerned,

02:25:47.500 | I applied the same scientific tools in both cases.

02:25:49.940 | There is an anomaly that led me to that discussion,

02:25:53.420 | which has to do with the hydrogen being cold

02:25:56.140 | in the early universe more than we expected,

02:25:58.020 | so we suggested maybe the dark matter particles

02:26:00.420 | have some small charge.

02:26:02.260 | But you deal with anomalies by exploring possibilities.

02:26:06.100 | That's the only way to do it,

02:26:07.220 | and then collecting more data to check those.

02:26:09.820 | And searching for technological signatures

02:26:16.620 | is the same as any other part of our scientific endeavor.

02:26:21.620 | We make hypotheses, and we collect data,

02:26:25.120 | and I don't see any reason for having a taboo

02:26:27.940 | on this subject.

02:26:28.860 | - In your childlike, open-minded excitement

02:26:32.380 | and approach to science, I think,

02:26:35.220 | to anyone listening to this, truly inspiring.

02:26:37.620 | I mean, the question I think is useful to ask

02:26:40.860 | is by way of advice for young people.

02:26:43.340 | A lot of young people listen to this,

02:26:45.780 | whether from all over the world,

02:26:47.740 | and teenagers, undergraduate students,

02:26:51.280 | even graduate students, even young faculty,

02:26:56.220 | even older faculty, they're all young at heart.

02:26:58.340 | Like, there's many of us young at heart.

02:26:59.900 | Do you have advice for, let's focus on

02:27:02.660 | the traditionally defined sort of young folks,

02:27:05.220 | like undergraduate, do you have advice

02:27:07.320 | to give to young people like that today

02:27:10.220 | about life, maybe in general,

02:27:12.780 | maybe a life of curiosity in the sciences?

02:27:16.260 | - Definitely.

02:27:17.480 | Well, first I should confess that I enjoy

02:27:19.640 | working with young people much more than with senior people.

02:27:23.420 | And the reason is they don't carry a baggage of prejudice.

02:27:27.500 | They're not so self-centered.

02:27:29.460 | They're open to exploration.

02:27:31.260 | My advice, I mean, one of the lessons

02:27:34.860 | that took me a while to learn,

02:27:37.260 | and I should say I lost important opportunities

02:27:40.920 | as a result of that,

02:27:41.760 | so I would regard it as a mistake on my behalf,

02:27:45.460 | was to believe experts, so quote unquote.

02:27:49.860 | So on a number of occasions,

02:27:52.860 | I would come up with an original idea

02:27:55.500 | and then suggest it to an expert,

02:27:57.900 | someone that works in the same field for a while,

02:28:01.060 | and the expert would dismiss it,

02:28:03.940 | most of the time because it's new

02:28:06.580 | and was not explored, not because of the merit.

02:28:09.760 | And then what happened to me,

02:28:11.460 | several times, is that someone else

02:28:14.120 | would listen to the conversation

02:28:15.560 | or would hear me suggesting it,

02:28:18.180 | and I would give up because the expert said no,

02:28:21.560 | and then that someone else would develop it

02:28:25.720 | so that it becomes the hottest thing in this field.

02:28:28.700 | And once it happened to me multiple times,

02:28:31.900 | I then realized, the hell with the experts.

02:28:34.820 | (Sami laughs)

02:28:35.740 | They don't know what they're talking,

02:28:36.840 | they're just repeating the,

02:28:38.880 | they don't think creatively,

02:28:40.500 | they are being threatened by innovation, okay?

02:28:44.220 | And it's the natural reaction of someone

02:28:47.180 | that cares about their ego more than about the matter

02:28:52.180 | that we are discussing.

02:28:53.140 | And so I said, I don't care how many likes I have on Twitter,

02:28:57.500 | I don't care whether the experts say one thing or another,

02:29:00.260 | I will basically exercise my judgment

02:29:02.900 | and do the best I can.

02:29:04.780 | Turns out that I'm wrong, I made a mistake.

02:29:07.900 | That's part of the scientific endeavor.

02:29:11.380 | And it took me a while to recognize that,

02:29:14.220 | and it was a lot of wasted opportunities.

02:29:16.300 | So to the young people, I would recommend,

02:29:18.580 | don't listen to experts, carve your own path.

02:29:23.580 | Now, of course, you will be wrong,

02:29:25.740 | you should learn from experience, just like kids do,

02:29:29.060 | but do it yourself.

02:29:32.940 | - Your father died in 2017, your mother died in 2019.

02:29:37.940 | Do you miss them?

02:29:43.100 | - Very much so.

02:29:43.940 | - Is there a memory, that fond memory that stands out,

02:29:50.500 | or maybe what have you learned from them?

02:29:53.820 | - From my mother, I mean, she was very much my inspiration

02:29:59.420 | for pursuing intellectual work,

02:30:01.180 | because she studied at the university,

02:30:05.380 | and then because of the Second World War,

02:30:08.980 | after the Second World War, she was born in Bulgaria,

02:30:12.060 | they immigrated to Israel.

02:30:14.380 | And she left university to work on a farm.

02:30:19.380 | And later in life, when all the kids left home,

02:30:24.620 | she went back to the university and finished the PhD.

02:30:27.740 | But she planted in me the intellectual curiosity

02:30:31.660 | and valuing learning, or acquiring knowledge

02:30:36.660 | as a very important element in life.

02:30:41.060 | And my love with philosophy came from attending classes

02:30:46.060 | that she took at the university.

02:30:49.900 | When I was a teenager, I was fortunate to go to some of these

02:30:55.260 | and they inspired me later on.

02:30:57.740 | And I'm very different than my colleagues, as you can tell,

02:31:01.660 | because my upbringing was quite different.

02:31:03.980 | And the only reason I'm doing physics or astrophysics

02:31:07.100 | is because of circumstances.

02:31:08.580 | At age 18, I was asked to serve in the military.

02:31:12.740 | And the only way for me to pursue intellectual work

02:31:17.740 | was to work on physics,

02:31:21.540 | because that was the closest to philosophy.

02:31:24.220 | And I was good at physics,

02:31:26.060 | so they admitted me to an elite program called Alpiot

02:31:28.860 | that allowed me to finish my PhD at age 24

02:31:33.020 | and to actually propose the first international project

02:31:37.900 | that was funded by the Star Wars initiative

02:31:40.540 | of Ronald Reagan.

02:31:42.140 | And that brought me to the US to visit Washington, DC,

02:31:45.660 | where we were funded from.

02:31:47.140 | And then on one of the visits,

02:31:49.100 | I went to the Institute for Advanced Study at Princeton.

02:31:53.660 | And met John Bacall

02:31:56.220 | that later offered me a five-year fellowship there

02:31:59.260 | under the condition that I'll switch to astrophysics.

02:32:02.220 | At which point, I said,

02:32:03.980 | "Okay, I cannot give up on this opportunity.

02:32:05.780 | "I'll do it, switch to astrophysics."

02:32:08.260 | It felt like a forced marriage, kind of arranged marriage.

02:32:12.300 | And then I was offered the position at Harvard

02:32:15.740 | because nobody wanted that.

02:32:17.180 | They first selected someone else.

02:32:20.460 | And that someone said,

02:32:21.380 | "I don't want to become a junior faculty

02:32:24.340 | "at the Harvard Astronomy Department

02:32:25.900 | "because the chance for being promoted are very small."

02:32:29.180 | So he took another job.

02:32:30.540 | And then I was second in line.

02:32:32.180 | They gave it to me.

02:32:33.020 | I didn't care much

02:32:33.860 | 'cause I could go back to the farm any day.

02:32:35.820 | (Sherlock laughs)

02:32:37.340 | And after three years, I was tenured.

02:32:40.220 | And eventually, a decade later,

02:32:42.940 | became the chair of this department

02:32:44.860 | and served for nine years

02:32:46.260 | as the chair of the astronomy department at Harvard.

02:32:49.060 | But at that point, it became clear to me

02:32:51.700 | that I'm actually married to the love of my life.

02:32:54.660 | Even though it was an arranged marriage,

02:32:56.620 | there are many philosophical questions in astrophysics

02:32:59.340 | that we can address.

02:33:00.460 | But I'm still very different than my colleagues

02:33:03.500 | that were focusing on technical skills

02:33:06.700 | in getting to this job.

02:33:09.540 | So my mother was really extremely instrumental

02:33:14.860 | in planting the seeds of thinking about the big picture.

02:33:19.420 | In me.

02:33:20.420 | Then my father, he was working in the farm

02:33:25.060 | and we didn't speak much

02:33:26.820 | because we sort of understood each other without speaking.

02:33:29.380 | (Sherlock laughs)

02:33:31.380 | But what he gave me is a sense of,

02:33:36.380 | that it's more important to do things

02:33:40.340 | than to talk about them.

02:33:41.740 | - I love the, I mean, my apologies,

02:33:45.260 | but MIT mind and hand.

02:33:47.340 | I love that there's the root of philosophy

02:33:50.820 | that you gained from your mom

02:33:53.020 | and the hand that action is all that ultimately

02:33:56.700 | in the end matters from your dad.

02:33:58.780 | That's really powerful.

02:34:01.100 | If we could take a small detour into philosophy,

02:34:05.620 | is there by chance any books, authors,

02:34:10.320 | whether philosophical or not,

02:34:11.780 | you mentioned Sartre, that stand out to you

02:34:13.700 | that were formative in some small or big way

02:34:16.780 | that perhaps you would recommend to others,

02:34:18.520 | maybe when you were very young or maybe later on in life?

02:34:22.260 | - Well, actually, yeah, I read the number of existentialists

02:34:27.260 | that appealed to me because they were authentic.

02:34:31.740 | Sartre, he declined the Nobel prizes we discussed,

02:34:35.480 | but he also was mocking people

02:34:39.900 | that pretend to be something better than they are.

02:34:42.340 | He was living an authentic life that is sincere

02:34:45.940 | and that's what appealed to me.

02:34:47.340 | And Albert Camus was another French philosopher

02:34:51.380 | that advocated existentialism.

02:34:53.580 | That really appealed to me.

02:34:56.020 | - That's probably my favorite existentialist Camus, yeah.

02:34:58.860 | - Yeah, and he died at a young age

02:35:01.060 | in an accident, unfortunately.

02:35:02.800 | And then people like Nietzsche that broke conventions.

02:35:11.740 | And I noticed that Nietzsche is still extremely popular.

02:35:16.740 | That's quite surprising.

02:35:18.620 | He appeals to the young people of today.

02:35:22.260 | - People that, it's the childlike wonder about the world

02:35:26.340 | and he was unapologetic.

02:35:28.620 | You know, it's like most philosophers

02:35:30.020 | have a very strict adherence to terminology

02:35:32.660 | and to the practices, academic philosophers.

02:35:35.180 | And Nietzsche was full of contradictions

02:35:37.140 | and he just, I mean, he was just this big kid with opinions

02:35:42.140 | and thought deeply about this world

02:35:45.580 | and people are really attracted to that.

02:35:47.020 | And surprisingly, there's not enough people like that

02:35:50.620 | throughout history of philosophy.

02:35:53.080 | And that's why I think he's still drawn to him.

02:35:55.780 | - Yeah, to me what stands out is his statement

02:35:59.580 | that the best way to corrupt the mind of young people

02:36:03.960 | is to tell them that they should agree with the common view.

02:36:08.960 | And it goes back to the thread

02:36:13.360 | that went throughout discussion.

02:36:14.860 | - Yes, you've kind of suggested that we ought to be humble

02:36:19.600 | about our very own existence

02:36:21.340 | and that our existence lasts only a short time.

02:36:25.680 | We talked about you losing your father and your mother.

02:36:30.680 | Do you think about your own mortality?

02:36:33.480 | Are you afraid of death?

02:36:35.480 | - I'm not afraid.

02:36:36.480 | You know what Epicurus,

02:36:37.760 | actually Epicurus was a very wise person.

02:36:40.120 | According to Lucretius,

02:36:43.240 | Epicurus didn't leave anything in writing,

02:36:45.400 | but he said that he's never afraid of death

02:36:49.040 | because as long as he's around, death is not around.

02:36:53.680 | And when death will be around, he will not be around.

02:36:57.140 | So he will never meet death.

02:36:59.320 | So why should you be worried

02:37:01.240 | about something you will never meet?

02:37:03.240 | And it's an interesting philosophy of life.

02:37:06.160 | You shouldn't be afraid of something

02:37:07.720 | that you will never encounter.

02:37:09.560 | - But there's a finiteness to this experience.

02:37:12.080 | - Oh yeah.

02:37:12.920 | - We live every day.

02:37:14.440 | I mean, I think if we're being honest,

02:37:18.000 | we live every day as if it's gonna last forever.

02:37:21.040 | We often kind of don't contemplate the fact that it ends.

02:37:24.840 | You kind of have plans and goals

02:37:26.240 | and you have these possibilities.

02:37:28.960 | You have a kind of lingering thought,

02:37:30.920 | especially as you get older and older and older,

02:37:33.120 | that this is, especially when you lose friends,

02:37:36.400 | and then you start to realize it doesn't.

02:37:40.680 | But I don't know if you really are cognizant of that.

02:37:43.400 | I mean, because--

02:37:44.560 | - But you have to be careful not to be depressed by it

02:37:47.060 | because otherwise you lose the vitality, right?

02:37:50.320 | So I think the most important thing to draw

02:37:53.080 | from knowing that you are short-lived

02:37:56.160 | is a sense of appreciation that you're alive.

02:37:59.880 | That's the first thing.

02:38:01.060 | But more importantly, a sense of modesty

02:38:03.760 | because how can anyone be arrogant

02:38:06.960 | if they kept at the same time this notion

02:38:10.280 | that they are short-lived?

02:38:11.120 | I mean, you cannot be arrogant

02:38:12.600 | because anything that you advocate for,

02:38:15.240 | you will not be around to do that in a hundred years.

02:38:18.840 | So people will just forget and move on.

02:38:21.920 | And if you keep that in mind,

02:38:25.080 | the Caesars in ancient Rome,

02:38:27.400 | they had a person next to them telling them,

02:38:30.680 | "Don't forget that you're immortal."

02:38:32.820 | You know, there was a person with that duty

02:38:35.080 | because the Caesars thought that they are all powerful.

02:38:37.880 | And they had, for a good reason,

02:38:43.160 | someone they hired to whisper in their ear,

02:38:47.080 | "Don't forget that you're immortal."

02:38:48.720 | - Yeah.

02:38:49.760 | Well, you're somebody, one of the most respected,

02:38:54.760 | famous scientists in the world,

02:38:56.940 | sitting on a farm, gazing up at the stars.

02:38:59.600 | So you seem like an appropriate person

02:39:01.280 | to ask the completely inappropriate question

02:39:04.200 | of what do you think is the meaning of it all?

02:39:06.600 | What's the meaning of life?

02:39:07.960 | - That's an excellent question.

02:39:10.280 | And if we ever find an alien that we can converse with,

02:39:13.920 | I would like to answer this.

02:39:15.240 | I would like to ask for an answer to this question

02:39:17.640 | 'cause--

02:39:19.240 | - Would they have a different opinion, you think?

02:39:21.080 | - Well, they might be wiser

02:39:22.260 | because they lived around for a while,

02:39:24.400 | but I'm afraid they will be silent.

02:39:27.120 | I'm afraid they will not have a good answer.

02:39:29.160 | And I think it's the process

02:39:34.160 | that you should get satisfied by,

02:39:38.120 | the process of learning you should enjoy.

02:39:41.560 | Okay, so it's not so much that there is a meaning.

02:39:45.400 | In fact, there is, as far as I can tell,

02:39:49.400 | things just exist.

02:39:50.700 | And I think it's inappropriate for us

02:39:55.520 | to assign a meaning for our existence

02:39:58.220 | because as a civilization, we will eventually perish

02:40:02.560 | and nothing will be, just another planet

02:40:06.000 | on which life died.

02:40:07.560 | And if you look at the big scheme of things,

02:40:12.080 | who cares?

02:40:13.160 | Who cares?

02:40:14.260 | And how can we assign significance to what we are doing?

02:40:17.680 | So if you said the meaning of life is this,

02:40:20.880 | well, it will not be around in a billion years.

02:40:23.560 | It cannot be the meaning of life

02:40:26.720 | because nothing will be around.

02:40:29.100 | So I think we should just enjoy the process.

02:40:32.260 | And it's like many other things in life.

02:40:35.740 | You enjoy good food, okay?

02:40:38.660 | And you can enjoy learning.

02:40:41.160 | Why?

02:40:42.000 | Because it makes you appreciate better

02:40:46.300 | the environment that you live in.

02:40:47.780 | And sometimes people think religion, for example,

02:40:50.780 | is in conflict with science, spirituality.

02:40:55.980 | That's not true.

02:40:57.000 | If you see a watch and you look at it from the outside,

02:41:02.560 | you might say, oh, that's interesting.

02:41:05.620 | But then if you start to open it up

02:41:07.300 | and learn about how it works, you appreciate it more.

02:41:10.320 | So science is the way to learn about how the world works.

02:41:14.240 | And it's not in conflict to the meaning

02:41:18.180 | that you assign to all of this,

02:41:19.440 | but it helps you appreciate the world better.

02:41:23.380 | So in fact, I would think that a religious person

02:41:25.660 | should promote science because it gives you

02:41:28.900 | a better appreciation of what's around you.

02:41:31.900 | It's like if you buy in a grocery,

02:41:35.340 | you buy something, a bunch of fruits

02:41:39.940 | that are packed together,

02:41:41.380 | and you can't see from the outside

02:41:43.180 | exactly what kind of fruits are inside.

02:41:45.200 | But if you open it up and study,

02:41:47.220 | you appreciate better the merchandise that you get, right?

02:41:49.700 | So you pay the same amount of money,

02:41:51.340 | but at least you know what's inside.

02:41:53.340 | So why don't we figure out what the world is about,

02:41:56.300 | what the universe contains, what is the dark matter?

02:41:58.700 | It will help us appreciate the bigger picture,

02:42:02.100 | and then you can assign your own flavor

02:42:05.740 | to what it means.

02:42:06.840 | - I think I'm truly grateful that a person like you exists

02:42:13.260 | at the center of the scientific community

02:42:15.420 | gives me faith and hope about this big journey

02:42:20.420 | that we call science.

02:42:21.660 | So thank you for writing the book you wrote recently.

02:42:25.700 | You have many other books and articles

02:42:28.980 | that I think people should definitely read.

02:42:31.140 | And thank you for wasting all this time with me.

02:42:33.780 | It's truly an honor.

02:42:35.020 | Thank you so much. - It was not a waste at all,

02:42:36.380 | and thank you for having me.

02:42:37.460 | I learned a lot from your questions and your remarks.

02:42:40.300 | Thank you. - Thank you.

02:42:42.340 | Thanks for listening to this conversation with Avi Loeb,

02:42:44.700 | and thank you to our sponsors,

02:42:46.300 | Zero Fasting App for intermittent fasting,

02:42:49.500 | Element Electrolyte Drink,

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02:42:54.260 | and Pessimist Archive History Podcast.

02:42:57.160 | So the choice is a fasting app, fasting fuel,

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02:43:08.560 | Choose wisely, my friends.

02:43:09.980 | And if you wish, click the sponsor links below

02:43:12.840 | to get a discount and to support this podcast.

02:43:16.100 | And now let me leave you with some words

02:43:17.700 | from Albert Einstein.

02:43:19.460 | "The important thing is not to stop questioning.

02:43:22.100 | Curiosity has its own reason for existence.

02:43:25.060 | One cannot help but be in awe

02:43:27.220 | when he contemplates the mysteries of eternity,

02:43:29.860 | of life, of the marvelous structure of reality.

02:43:33.540 | It is enough if one tries merely to comprehend

02:43:36.580 | a little of this mystery every day."

02:43:39.740 | Thank you for listening, and hope to see you next time.

02:43:42.500 | (upbeat music)

02:43:45.080 | (upbeat music)

02:43:47.660 | [BLANK_AUDIO]

Avi Loeb: Aliens, Black Holes, and the Mystery of the Oumuamua | Lex Fridman Podcast #154

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