Higgs Particle (Harry Cliff) | AI Podcast Clips

00:00:00.000 | - I mean, wasn't the Higgs called the God particle

00:00:04.520 | at some point?

00:00:05.360 | - It was by a guy trying to sell popular science books, yeah.

00:00:08.320 | - Yeah, but I mean, I remember 'cause when I was hearing it,

00:00:12.520 | I thought it would, I mean, that would solve a lot of,

00:00:16.680 | that unify a lot of our ideas of physics, was my notion.

00:00:20.960 | But maybe you can speak to that.

00:00:23.680 | Is it as big of a leap?

00:00:25.420 | Is it a God particle, or is it a Jesus particle?

00:00:28.760 | (laughing)

00:00:30.920 | Which, you know, what's the big contribution of Higgs

00:00:33.640 | in terms of this unification power?

00:00:35.440 | - Yeah, I mean, to understand that,

00:00:37.240 | it maybe helps to know the history a little bit.

00:00:39.720 | So when the, what we call electro weak theory

00:00:42.360 | was put together, which is where you unify electromagnetism

00:00:45.240 | with the weak force, and the Higgs is involved

00:00:47.020 | in all of that.

00:00:47.920 | So that theory, which was written in the mid '70s,

00:00:50.080 | predicted the existence of four new particles,

00:00:54.000 | the W plus boson, the W minus boson, the Z boson,

00:00:57.160 | and the Higgs boson.

00:00:58.100 | So there were these four particles

00:00:59.400 | that came with the theory,

00:01:00.620 | that were predicted by the theory.

00:01:02.080 | In 1983, '84, the W's and the Z particles

00:01:06.220 | were discovered at an accelerator at CERN,

00:01:08.920 | called the super proton synchrotron,

00:01:10.600 | which was a seven kilometer particle collider.

00:01:13.840 | So three of the bits of this theory had already been found.

00:01:17.400 | So people were pretty confident from the '80s

00:01:20.160 | that the Higgs must exist,

00:01:21.640 | because it was a part of this family of particles

00:01:25.400 | that this theoretical structure only works

00:01:27.640 | if the Higgs is there.

00:01:29.080 | So what then happens,

00:01:31.200 | so this question about why is the LHC the size it is?

00:01:34.040 | Well, actually the tunnel that the LHC is in

00:01:36.140 | was not built for the LHC.

00:01:37.440 | It was built for a previous accelerator

00:01:39.760 | called the large electron positron collider.

00:01:43.360 | So that began operation in the late '80s, early '90s.

00:01:48.360 | They basically, that's when they dug

00:01:49.880 | the 27 kilometer tunnel.

00:01:51.080 | They put this accelerator into it,

00:01:52.640 | the collider that fires electrons and anti electrons

00:01:55.360 | at each other, electrons and positrons.

00:01:57.280 | So the purpose of that machine was,

00:01:59.800 | well, it was actually to look for the Higgs.

00:02:01.320 | That was one of the things it was trying to do,

00:02:03.320 | but it didn't have enough energy to do it in the end.

00:02:06.040 | But the main thing it achieved was it studied

00:02:08.440 | the W and the Z particles at very high precision.

00:02:12.160 | So it made loads of these things.

00:02:13.920 | Previously you can only make a few of them

00:02:15.180 | at the previous accelerator.

00:02:16.080 | So you could study these really, really precisely.

00:02:19.120 | And by studying their properties,

00:02:20.320 | you could really test this electroweak theory

00:02:22.840 | that had been invented in the '70s

00:02:24.440 | and really make sure that it worked.

00:02:25.900 | So actually by 1999, when this machine turned off,

00:02:30.900 | people knew, well, okay, you never know

00:02:34.120 | until you find the thing.

00:02:36.040 | But people were really confident

00:02:37.640 | this electroweak theory was right.

00:02:39.440 | And that the Higgs almost,

00:02:41.440 | the Higgs or something very like the Higgs had to exist

00:02:44.480 | because otherwise the whole thing doesn't work.

00:02:46.860 | It'd be really weird if you could discover

00:02:48.640 | and these particles, they all behave exactly

00:02:50.520 | as your theory tells you they should.

00:02:51.960 | But somehow this key piece of the picture is not there.

00:02:55.520 | So in a way, it depends how you look at it.

00:02:58.560 | The discovery of the Higgs on its own

00:03:00.440 | is obviously a huge achievement in many,

00:03:04.640 | both experimentally and theoretically.

00:03:06.960 | On the other hand, it's like having a jigsaw puzzle

00:03:09.880 | where every piece has been filled in.

00:03:11.720 | You have this beautiful image, there's one gap

00:03:13.640 | and you kind of know that that piece

00:03:16.000 | must be there somewhere, right?

00:03:17.520 | So the discovery in itself, although it's important,

00:03:22.520 | is not so interesting.

00:03:25.080 | - It's like a confirmation of the obvious at that point.

00:03:29.000 | - But what makes it interesting

00:03:30.680 | is not that it just completes the standard model,

00:03:32.720 | which is a theory that we've known,

00:03:34.600 | had the basic layout of for 40 years or more now.

00:03:39.400 | It's that the Higgs actually is a unique particle.

00:03:43.040 | It's very different to any of the other particles

00:03:45.200 | in the standard model.

00:03:46.520 | And it's a theoretically very troublesome particle.

00:03:49.900 | There are a lot of nasty things to do with the Higgs,

00:03:53.880 | but also opportunities.

00:03:55.480 | So we don't really understand how such an object

00:03:58.840 | can exist in the form that it does.

00:04:00.880 | So there are lots of reasons for thinking

00:04:03.120 | that the Higgs must come with a bunch of other particles

00:04:07.200 | or that it's perhaps made of other things.

00:04:09.680 | So it's not a fundamental particle,

00:04:11.080 | that it's made of smaller things.

00:04:12.560 | I can talk about that if you like a bit.

00:04:14.200 | - That's still a notion.

00:04:15.600 | So the Higgs might not be a fundamental particle,

00:04:19.440 | that there might be some, oh man.

00:04:21.840 | So that is an idea.

00:04:23.040 | It's not been demonstrated to be true.

00:04:25.720 | But I mean, all of these ideas basically come

00:04:28.480 | from the fact that this is a problem

00:04:32.600 | that motivated a lot of development in physics

00:04:34.760 | in the last 30 years or so.

00:04:37.040 | And it's this basic fact that the Higgs field,

00:04:39.440 | which is this field that's everywhere in the universe,

00:04:41.960 | this is the thing that gives mass to the particles.

00:04:43.720 | And the Higgs field is different

00:04:44.880 | from all the other fields in that,

00:04:46.800 | let's say you take the electromagnetic field,

00:04:49.080 | which is, if we actually were to measure

00:04:50.760 | the electromagnetic field in this room,

00:04:52.080 | we would measure all kinds of stuff going on

00:04:53.560 | 'cause there's light, there's gonna be microwaves

00:04:55.640 | and radio waves and stuff.

00:04:56.800 | But let's say we could go to a really, really remote part

00:04:59.600 | of empty space and shield it and put a big box around it

00:05:02.320 | and then measure the electromagnetic field in that box.

00:05:04.720 | The field would be almost zero,

00:05:06.880 | apart from some little quantum fluctuations.

00:05:09.440 | But basically it goes to naught.

00:05:11.640 | The Higgs field has a value everywhere.

00:05:13.800 | So it's a bit like the whole,

00:05:15.360 | it's like the entire space has got this energy

00:05:18.120 | stored in the Higgs field, which is not zero.

00:05:20.080 | It's finite.

00:05:21.120 | It's a bit like having the temperature of space

00:05:24.000 | raised to some background temperature.

00:05:27.000 | And it's that energy that gives mass to the particles.

00:05:31.520 | So the reason that electrons and quarks have mass

00:05:35.080 | is through the interaction with this energy

00:05:37.080 | that's stored in the Higgs field.

00:05:39.440 | Now, it turns out that the precise value this energy has

00:05:45.240 | has to be very carefully tuned if you want a universe

00:05:50.240 | where interesting stuff can happen.

00:05:52.780 | So if you push the Higgs field down,

00:05:55.300 | it has a tendency to collapse to,

00:05:57.720 | well, there's a tendency,

00:05:58.640 | if you do your sort of naive calculations,

00:06:00.280 | there are basically two possible likely configurations

00:06:02.920 | for the Higgs field, which is either it's zero everywhere,

00:06:05.960 | in which case you have a universe

00:06:07.120 | which is just particles with no mass that can't form atoms

00:06:10.480 | and just fly about at the speed of light,

00:06:12.680 | or it explodes to an enormous value,

00:06:15.360 | what we call the Planck scale,

00:06:16.440 | which is the scale of quantum gravity.

00:06:18.800 | And at that point, if the Higgs field was that strong,

00:06:21.700 | even an electron would become so massive

00:06:23.540 | that it would collapse into a black hole.

00:06:25.840 | And then you have a universe made of black holes

00:06:27.720 | and nothing like us.

00:06:29.580 | So it seems that the strength of the Higgs field

00:06:32.280 | is to achieve the value that we see

00:06:34.800 | requires what we call fine tuning of the laws of physics.

00:06:37.560 | You have to fiddle around with the other fields

00:06:39.980 | in the standard model and their properties

00:06:41.960 | to just get it to this right sort of Goldilocks value

00:06:45.400 | that allows atoms to exist.

00:06:47.760 | This is deeply fishy.

00:06:49.200 | People really dislike this.

00:06:52.040 | - Well, yeah, I guess, so what would be,

00:06:54.040 | so two explanations.

00:06:55.480 | One, there's a God that designed this perfectly,

00:06:57.680 | and two is there's an infinite number

00:07:00.200 | of alternate universes, and we just happen to be in the one

00:07:03.960 | in which life is possible.

00:07:05.760 | - Yeah, yeah. - Complexity.

00:07:07.000 | So when you say, I mean, life, any kind of complexity,

00:07:10.180 | that's not either complete chaos or black holes.

00:07:14.560 | - Yeah, yeah.

00:07:16.160 | - I mean, how does that make you feel?

00:07:17.400 | What do you make of that?

00:07:18.240 | That's such a fascinating notion

00:07:19.920 | that this perfectly tuned field

00:07:23.000 | that's the same everywhere is there.

00:07:25.760 | What do you make of that?

00:07:27.800 | Yeah, what do you make of that?

00:07:28.840 | - I mean, yeah, so you laid out

00:07:29.920 | two of the possible explanations.

00:07:31.320 | - Really? - Somewhat.

00:07:32.520 | Yeah, I mean, well, someone,

00:07:34.160 | some cosmic creator went, yeah, let's fix that

00:07:36.800 | to be at the right level.

00:07:37.780 | That's one possibility, I guess.

00:07:39.040 | It's not a scientifically testable one,

00:07:40.520 | but theoretically, I guess, it's possible.

00:07:43.360 | - Sorry to interrupt, but there could also be,

00:07:45.520 | not a designer, but couldn't there be just,

00:07:48.120 | I guess, I'm not sure what that would be,

00:07:50.600 | but some kind of force that,

00:07:52.860 | some kind of mechanism by which this kind of field

00:08:01.840 | is enforced in order to create complexity.

00:08:05.840 | Basically, forces that pull the universe

00:08:10.840 | towards an interesting complexity.

00:08:14.440 | - I mean, yeah, I mean, there are people

00:08:16.040 | that have those ideas.

00:08:16.960 | I don't really subscribe to them.

00:08:18.280 | - As I'm saying, it sounds really stupid.

00:08:20.200 | - No, I mean, there are definitely people

00:08:21.760 | that make those kind of arguments.

00:08:24.080 | There's ideas that, I think it's Lee Smolin's idea,

00:08:27.680 | one, I think, that universes are born inside black holes.

00:08:32.680 | And so universes, they basically have

00:08:34.920 | like Darwinian evolution of the universe,

00:08:37.160 | where universes give birth to other universes.

00:08:39.480 | And if universes where black holes can form

00:08:41.400 | are more likely to give birth to more universes,

00:08:43.440 | so you end up with universes which have similar laws.

00:08:45.920 | I mean, I don't know, whatever.

00:08:47.160 | - Well, I talked to Lee recently on this podcast,

00:08:51.720 | and he's a reminder to me that the physics community

00:08:56.720 | has so many interesting characters in it.

00:09:00.240 | It's fascinating.

00:09:01.600 | Anyway, sorry, so.

00:09:02.440 | - I mean, as an experimentalist, I tend to sort of think,

00:09:04.720 | these are interesting ideas,

00:09:05.840 | but they're not really testable,

00:09:07.400 | so I tend not to think about them very much.

00:09:09.360 | So, I mean, going back to the science of this,

00:09:12.200 | there is an explanation.

00:09:13.760 | There is a possible solution to this problem of the Higgs,

00:09:15.880 | which doesn't involve multiverses

00:09:17.800 | or creators fiddling about with the laws of physics.

00:09:21.200 | If the most popular solution

00:09:23.040 | was something called supersymmetry,

00:09:25.080 | which is a theory which involves

00:09:28.400 | a new type of symmetry of the universe.

00:09:30.360 | In fact, it's one of the last types of symmetries

00:09:32.320 | that is possible to have

00:09:33.200 | that we haven't already seen in nature,

00:09:35.040 | which is a symmetry between force particles

00:09:38.240 | and matter particles, so what we call fermions,

00:09:41.080 | which are the matter particles,

00:09:42.520 | and bosons, which are force particles.

00:09:44.560 | And if you have supersymmetry,

00:09:45.760 | then there is a super partner for every particle

00:09:49.160 | in the standard model.

00:09:50.560 | And without going into the details,

00:09:52.160 | the effect of this basically is that

00:09:53.640 | you have a whole bunch of other fields,

00:09:55.960 | and these fields cancel out

00:09:58.400 | the effect of the standard model fields,

00:10:00.320 | and they stabilize the Higgs field

00:10:02.480 | at a nice, sensible value.

00:10:03.680 | So in supersymmetry, you naturally,

00:10:06.040 | without any tinkering about

00:10:07.560 | with the constants of nature or anything,

00:10:09.820 | you get a Higgs field with a nice value,

00:10:12.040 | which is the one we see.

00:10:13.600 | So this is one of the reasons,

00:10:14.840 | and supersymmetry's also got

00:10:16.120 | lots of other things going for it.

00:10:17.280 | It predicts the existence of a dark matter particle,

00:10:20.000 | which would be great.

00:10:21.680 | It potentially suggests that the strong force

00:10:24.800 | and the electroweak force unify at high energy.

00:10:27.400 | So lots of reasons people thought

00:10:28.440 | this was a productive idea.

00:10:30.000 | And when the LHC was, just before it was turned on,

00:10:32.440 | there was a lot of hype, I guess,

00:10:34.240 | a lot of an expectation that we would discover

00:10:37.080 | these super partners, because,

00:10:38.920 | and particularly the main reason was

00:10:40.720 | that if supersymmetry stabilizes the Higgs field

00:10:44.840 | at this nice Goldilocks value,

00:10:47.600 | these super particles should have a mass

00:10:50.400 | around the energy that we're probing at the LHC,

00:10:53.160 | around the energy of the Higgs.

00:10:54.560 | So it was kind of thought, you discover the Higgs,

00:10:56.160 | you probably discover super partners as well.

00:10:58.240 | - So once you start creating ripples in this Higgs field,

00:11:00.800 | you should be able to see these kinds of,

00:11:03.280 | you should be, yeah.

00:11:04.120 | - So these super fields would be there.

00:11:05.600 | When at the very beginning I said,

00:11:06.920 | we're probing the vacuum, what I mean is really that,

00:11:09.560 | you know, okay, let's say these super fields exist.

00:11:11.280 | The vacuum contains super fields, they're there,

00:11:13.320 | these supersymmetric fields.

00:11:14.760 | If we hit them hard enough, we can make them vibrate.

00:11:17.240 | We see super particles come flying out.

00:11:19.400 | That's the sort of, that's the idea.

00:11:20.920 | - That's the hope, okay.

00:11:21.760 | - That's the whole point.

00:11:22.600 | - But we haven't.

00:11:25.240 | - But we haven't.

00:11:26.120 | So, so far at least, I mean, we've had now a decade

00:11:30.520 | of data taking at the LHC.

00:11:32.560 | No signs of super partners have,

00:11:36.360 | supersymmetric particles have been found.

00:11:37.960 | In fact, no signs of any physics,

00:11:39.760 | any new particles beyond the standard model have been found.

00:11:42.120 | So supersymmetry is not the only thing that can do this.

00:11:44.120 | There are other theories that involve

00:11:46.040 | additional dimensions of space

00:11:47.760 | or potentially involve the Higgs boson

00:11:50.280 | being made of smaller things, being made of other particles.

00:11:53.000 | - Yeah, that's an interesting, you know,

00:11:54.080 | I haven't heard that before.

00:11:55.160 | That's really, that's an interesting point.

00:11:57.080 | Could you maybe linger on that?

00:11:58.200 | Like what, what could be,

00:12:01.000 | what could the Higgs particle be made of?

00:12:03.480 | - Well, so the oldest, I think the original ideas

00:12:05.800 | about this was these theories called technicolor,

00:12:08.640 | which were basically like an analogy with the strong force.

00:12:11.920 | So the idea was the Higgs boson was a bound state

00:12:16.040 | of two very strongly interacting particles

00:12:19.080 | that were a bit like quarks.

00:12:20.160 | So like quarks, but I guess higher energy things

00:12:23.800 | with a super strong force.

00:12:25.000 | So not the strong force,

00:12:25.840 | but a new force that was very strong.

00:12:27.640 | And the Higgs was a bound state of these objects.

00:12:31.120 | And the Higgs would in principle, if that was right,

00:12:33.080 | would be the first in a series of technicolor particles.

00:12:37.040 | Technicolor, I think, not being a theorist,

00:12:40.200 | but it's not, it's basically not done very well,

00:12:42.560 | particularly since the LHC found the Higgs,

00:12:44.240 | that kind of, it rules out, you know,

00:12:47.000 | a lot of these technicolor theories.

00:12:48.120 | But there are other things that are a bit like technicolor.

00:12:50.080 | So there's a theory called partial compositeness,

00:12:55.080 | which is an idea that some of my colleagues

00:12:57.160 | at Cambridge have worked on,

00:12:58.960 | which is a similar sort of idea

00:13:01.000 | that the Higgs is a bound state

00:13:02.800 | of some strongly interacting particles,

00:13:05.040 | and that the standard model particles themselves,

00:13:07.600 | the more exotic ones like the top quark,

00:13:09.800 | are also sort of mixtures of these composite particles.

00:13:15.080 | So it's a kind of an extension to the standard model,

00:13:17.920 | which explains this problem with the Higgs bosons,

00:13:21.640 | Goldilocks value, but also helps us understand,

00:13:25.360 | we're in a situation now, again,

00:13:27.440 | a bit like the periodic table,

00:13:29.080 | where we have six quarks, six leptons,

00:13:32.560 | in this kind of, you can arrange in this nice table,

00:13:34.600 | and you can see these columns where the patterns repeat,

00:13:37.080 | and you go, "Hmm, okay,

00:13:39.320 | "maybe there's something deeper going on here."

00:13:42.280 | And so this would potentially be something,

00:13:44.240 | this partial compositeness theory,

00:13:46.080 | could explain, sort of enlarge this picture

00:13:48.960 | that allows us to see the whole symmetrical pattern,

00:13:51.040 | and understand what the ingredients,

00:13:52.800 | why do we have, so one of the big questions

00:13:54.520 | in particle physics is,

00:13:55.720 | why are there three copies of the matter particles?

00:14:00.800 | So in what we call the first generation,

00:14:02.520 | which is what we're made of,

00:14:03.480 | there's the electron, the electron neutrino,

00:14:06.360 | the up quark and the down quark,

00:14:07.760 | they're the most common matter particles in the universe,

00:14:10.240 | but then there are copies of these four particles

00:14:13.360 | in the second and the third generations,

00:14:14.960 | so things like muons and top quarks and other stuff.

00:14:17.720 | We don't know why.

00:14:18.960 | We see these patterns, we have no idea where it comes from,

00:14:21.040 | so that's another big question,

00:14:23.480 | can we find out the deeper order

00:14:26.600 | that explains this particular periodic table

00:14:29.840 | of particles that we see?

00:14:31.000 | - Is it possible that the deeper order

00:14:33.920 | includes almost a single entity?

00:14:37.000 | So like something that I guess like string theory

00:14:39.560 | dreams about, is this essentially the dream?

00:14:44.840 | Is to discover something simple, beautiful and unifying?

00:14:48.720 | - Yeah, I mean, that is the dream.

00:14:50.440 | And I think for some people, for a lot of people,

00:14:54.120 | it still is the dream.

00:14:55.040 | So there's a great book by Steven Weinberg,

00:14:58.440 | who is one of the theoretical physicists

00:15:00.400 | who was instrumental in building the standard model.

00:15:03.000 | So he came up with some others with the electroweak theory,

00:15:06.640 | the theory that unified electromagnetism

00:15:08.560 | and the weak force.

00:15:09.400 | And he wrote this book,

00:15:10.320 | I think it was towards the end of the '80s, early '90s,

00:15:12.720 | called "Dreams of a Final Theory,"

00:15:14.640 | which is a very lovely, quite short book

00:15:17.520 | about this idea of a final unifying theory

00:15:20.800 | that brings everything together.

00:15:22.160 | And I think you get a sense reading his book

00:15:24.040 | written at the end of the '80s, early '90s,

00:15:26.360 | that there was this feeling that such a theory was coming.

00:15:30.200 | And that was the time when string theory

00:15:33.760 | had been, was very exciting.

00:15:35.800 | So string theory, there's been this thing

00:15:37.280 | called the super string revolution

00:15:38.680 | and theoretical physics getting very excited.

00:15:40.680 | They discovered these theoretical objects,

00:15:42.560 | these little vibrating loops of string

00:15:44.040 | that in principle,

00:15:45.080 | not only was a quantum theory of gravity,

00:15:47.040 | but could explain all the particles in the standard model

00:15:49.440 | and bring it all together.

00:15:50.320 | And as you say, you have one object, the string,

00:15:54.120 | and you can pluck it.

00:15:55.720 | And the way it vibrates gives you these different notes,

00:15:58.440 | each of which is a different particle.

00:16:00.560 | So it's a very lovely idea.

00:16:02.720 | But the problem is that,

00:16:05.240 | well, there's a few people discover

00:16:07.120 | that mathematics is very difficult.

00:16:09.280 | So people have spent three decades or more

00:16:12.240 | trying to understand string theory.

00:16:13.680 | And I think, you know,

00:16:14.960 | if you spoke to most string theorists,

00:16:16.120 | they would probably freely admit

00:16:17.240 | that no one really knows what string theory is yet.

00:16:19.520 | I mean, there's been a lot of work,

00:16:20.560 | but it's not really understood.

00:16:21.920 | And the other problem is that string theory

00:16:25.840 | mostly makes predictions about physics

00:16:28.640 | that occurs energies far beyond

00:16:31.160 | what we will ever be able to probe in the laboratory.

00:16:35.200 | Yeah, probably ever.

00:16:36.800 | - By the way, so sorry,

00:16:38.240 | take a million tangents,

00:16:39.440 | but is there room for complete innovation

00:16:42.680 | of how to build a particle collider

00:16:44.800 | that could give us an order of magnitude increase

00:16:47.320 | in the kind of energies,

00:16:49.800 | or do we need to keep just increasing the size of things?

00:16:53.120 | - I mean, maybe, yeah.

00:16:54.040 | I mean, there are ideas,

00:16:55.520 | to give you a sense of the gulf that has to be bridged.

00:16:58.520 | So the LHC collides particles at an energy

00:17:03.520 | of what we call 14 tera electron volts.

00:17:08.040 | So that's basically the equivalent

00:17:09.640 | of you've accelerated a proton through 14 trillion volts.

00:17:13.800 | That gets us to the energies where the Higgs

00:17:15.800 | and these weak particles live.

00:17:17.840 | They're very massive.

00:17:19.080 | The scale where strings become manifest

00:17:22.400 | is something called the Planck scale,

00:17:23.920 | which I think is of the order 10 to the,

00:17:26.600 | hang on, get this right,

00:17:28.320 | it's 10 to the 18 giga electron volts.

00:17:30.440 | So about 10 to the 15 tera electron volts.

00:17:35.440 | So you're talking, you know,

00:17:37.000 | trillions of times more energy,

00:17:39.400 | more than- - Yeah, 10 to the 15,

00:17:41.480 | or 10 to the 14th larger.

00:17:43.400 | - I may be wrong, but it's of that order.

00:17:45.480 | It's a very big number.

00:17:47.320 | So, you know, we're not talking just an order

00:17:49.040 | of magnitude increase in energy.

00:17:50.240 | We're talking 14 orders of magnitude energy increase.

00:17:53.240 | So to give you a sense of what that would look like,

00:17:55.840 | were you to build a particle accelerator

00:17:57.640 | with today's technology-

00:17:59.400 | - Bigger or smaller than our solar system?

00:18:02.120 | - As the size of the galaxy.

00:18:03.800 | - The galaxy.

00:18:04.680 | - So you'd need to put a particle accelerator

00:18:06.120 | that circled the Milky Way

00:18:07.920 | to get to the energies where you would see strings

00:18:11.040 | if they exist.

00:18:12.280 | So that is a fundamental problem,

00:18:15.040 | which is that most of the predictions

00:18:17.280 | of these unified theories,

00:18:19.080 | quantum theories of gravity,

00:18:20.720 | only make statements that are testable

00:18:23.320 | at energies that we will not be able to probe.

00:18:25.840 | And barring some unbelievable, you know,

00:18:29.880 | completely unexpected technological

00:18:31.840 | or scientific breakthrough,

00:18:32.760 | which is almost impossible to imagine.

00:18:34.640 | You never say never, but it seems very unlikely.

00:18:37.480 | - Yeah, I can just see the news story.

00:18:39.760 | Elon Musk decides to build a particle collider

00:18:43.520 | the size of our-

00:18:45.240 | - It would have to be,

00:18:46.080 | we'd have to get together with all our galactic neighbors

00:18:47.840 | to pay for it, I think.

00:18:50.080 | It'd be like CERN on mega steroids.

00:18:52.520 | (static)

00:18:54.600 | (silence)

00:18:56.760 | (silence)

00:18:58.920 | (silence)

00:19:01.080 | (silence)

00:19:03.240 | (silence)

00:19:05.400 | (silence)

00:19:07.560 | (silence)

00:19:09.720 | you

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