Roger Penrose and Brian Cox discuss 'remarkable new evidence' about the origins of the universe

0:00I think this is too often in physics.

0:02People who think a certain area is very

0:05beautiful mathematics and therefore it's

0:07got to be true of the physical world.

0:09And there is a big branch and perhaps I

0:11shouldn't be rude enough to mention what

0:13this main branch is in that area, but

0:16there is string theory.

0:18>> [laughter]

0:19>> I do mean string theory.

0:21There is a lot of feeling that this must

0:23be the basis of physics because it's

0:25such beautiful mathematics.

0:27And I say that's not a good guide at

0:29all. Just because you think the

0:31mathematics is beautiful in certain

0:32respects, sure.

0:34But that's not a good guide in itself.

0:43>> [applause]

0:49>> Well, thank you very much and so it's

0:52it's a huge honor to be here talking to

0:54to Roger. I thought I'd begin by saying

0:57that when when I was an undergraduate,

0:59so I started doing physics at Manchester

1:01in 1992,

1:02I think it was.

1:04And one of the first books I read to

1:06prepare me for my undergraduate physics

1:09was The Emperor's New Mind. And I think

1:12we might talk about consciousness later

1:14on, but the two things that really stuck

1:16with me was that book gave me my

1:19picture, my default picture of quantum

1:21mechanics, which I've always carried

1:23with me.

1:24But also it for the first time

1:27I think made me think about mathematical

1:30beauty. And I remember so vividly

1:32reading about how you describe complex

1:34numbers and the fact that mathematics is

1:37beautiful. So, could you talk a bit

1:40about that idea that mathematics is a

1:43beautiful thing and also mathematicians

1:44have a have an aesthetic sense?

1:47Well, I think that

1:49what drives people to do mathematics is

1:51certainly

1:53I mean, beauty. But it's a particular

1:56kind of beauty which I suppose which has

1:58a purity

2:00which you don't find

2:01in other areas. I mean, lots of things

2:04are beautiful, but they're sort of

2:05complicated and arbitrary in a way. But,

2:08what's so special about mathematics is

2:10it has this

2:11a very

2:13I don't know quite the right word to

2:14describe it, but it's pristine, I

2:16suppose word that one might use.

2:18It's uh it's a very kind of pure kind of

2:21beauty.

2:23And some people just don't feel it. I

2:25think it's true. I don't think one

2:28should be rude about people who don't

2:29see the beauty in mathematics.

2:31I find that sometimes it's rather the

2:33opposite to find people who do see the

2:36beauty in mathematics, which maybe is a

2:38little strange in a way. So, I find

2:41myself to be a little strange in that

2:42way, too. So, I'm not sure I can answer

2:45your question.

2:46I mean, there certainly is a beauty in

2:48the subject, and that is what drives

2:49mathematicians to do mathematics.

2:52Or it drives physicists often to do

2:55mathematics.

2:56And then it's certainly a subject which

2:59You see, when I was at school,

3:02well, I should say this was when I was

3:04in Canada because during the war years,

3:07we we the family went and lived in

3:09Canada, sort of getting out of the way

3:11of

3:14the war, which

3:15good in other ways. But, anyway, no, it

3:17was a lovely time in Canada, and I

3:19remember I didn't do very well in my

3:22mathematics tests.

3:24And I just No, I didn't get very high

3:26marks at all. I got low marks. But, one

3:28of the teachers was very insightful, and

3:31he realized, looking at my papers, that

3:33it was not that I was very stupid, but

3:36that I was very slow.

3:38And I it took me a long time. I think I

3:41just didn't know my tables very well. I

3:43had to work them out each time, you see.

3:45But, I knew how to work them out, so I

3:47thought it was good enough. And so, I

3:49didn't know instantly how to do it.

3:51And I think he was a very good teacher

3:53and he realized that if I was allowed to

3:56take as long as I like and I remember

3:58sitting in the class and then there was

4:00a play period afterwards and I looked

4:02out of the window and I could see all

4:03these people having fun out of the

4:04window and here I was slugging away

4:08still working at this test. And maybe

4:11even the tip of the

4:12they

4:13the

4:14whatever came after the play period

4:16occasionally I leaked into that one. But

4:19then I would do very well. I get into

4:21the high 90s, you see. Whereas before it

4:23was I would, you know,

4:2430% or something. Fail. So he realized I

4:27was just slow.

4:29But I think it was slow in a curious way

4:31because I

4:33I knew the ideas

4:35but I couldn't sort of even even then

4:38maybe not what 7 * 7 was or

4:40probably that one was fairly easy

4:42because it's

4:44a bit more distinctive than some of the

4:45others. But um no, I was not very good

4:48at even doing the arithmetic. And we

4:51were talking just before we came on

4:53about Dirac. So you you knew Dirac very

4:56well and um I remember Dirac saying that

5:00um the beautiful mathematics is often

5:04used by nature. But I I

5:07remember reading The Road to Reality you

5:09disagree with that to some extent that

5:11nature doesn't necessarily select the

5:12most beautiful mathematics.

5:14>> I think it's hard to know, you see.

5:16I mean you find it's beautiful when it

5:17works afterwards but you may not see why

5:20because sometimes the beauty doesn't

5:22come in till much later.

5:24And you actually see how these things

5:26fit together in a way that you've never

5:27seen before. So you can't sort of judge

5:29it early on to see whether that I don't

5:32what mathematics applies to physics.

5:35We don't know yet. I mean we know some

5:37of the things that I

5:39certainly what attracts me in how

5:41mathematics applies to physics

5:43is in something which is a very

5:45beautiful area of mathematics and I

5:47think that's true.

5:48But then other people work on things

5:50which you don't look particularly

5:51beautiful to me at all. Maybe this is

5:53important in other ways.

5:55It can be just complicated.

5:57I don't know. There's no straight answer

5:59to your question, I think. So, you don't

6:00think that beauty is necessarily a guide

6:03to

6:04the laws of nature don't have to be

6:06beautiful mathematics? I think it's a

6:07misleading guide, you see. You're

6:09attracted and think I think this is too

6:11often in physics. People who think a

6:14certain area is very beautiful

6:16mathematics and therefore it's got to be

6:18true of the physical world. And there is

6:20a big branch Perhaps I shouldn't be rude

6:22enough to mention what this main branch

6:25is in that area. But there is String

6:27theory.

6:29>> [laughter]

6:30>> I do mean string

6:32There is a lot of feeling that this must

6:34be the basis of physics because it's

6:36such beautiful mathematics.

6:38And I say that's not a good guide at

6:39all. Just because you think the

6:41mathematics it is beautiful in certain

6:43respects, sure.

6:45But that's not a good guide in itself.

6:48How

6:48>> So, I think that's the trouble there.

6:50How did you get interested in physics?

6:54Well, I got interested in physics in a

6:55rather strange kind of way, I think.

6:58You see, I was doing mathematics

7:00at university in London, at University

7:03College in London.

7:04And

7:06I remember going up to visit my brother

7:09who was doing physics research at that

7:12time in Cambridge.

7:15And I went up to visit him for some

7:16reason. I've forgotten exactly why. And

7:19I had been hearing these talks on the

7:21radio by given by Fred Hoyle. Where he

7:23was talking The first thing was about

7:25the solar system or something. Got

7:27broader and broader. And then he talked

7:29about cosmology in the last one. And he

7:31said something which I didn't quite

7:32believe, you see. And I said to my

7:35brother, I said, "Look, I didn't quite

7:36believe what Fred was saying here."

7:38And he said, "Well, I don't know either.

7:39I'm going Sitting at the table over

7:41there is the person who will give you

7:43the answer.

7:44And this was Dennis Sciama. He was

7:47sitting by himself, un unusually, by

7:49himself at this table. And I sat down

7:52and explained my little problem to me to

7:54him. And he said, "Well, I'm not sure

7:55about that. I'll go and ask Fred."

7:57Fred Hoyle, that was.

7:59And [snorts] so

8:00Um but the thing was, apparently, I made

8:02an impression on on Dennis.

8:05And he thought this was a really quite

8:06an interesting question that I'd raised.

8:09Why did the galaxies disappear one by

8:11one when they went faster than light?

8:13So, I thought, "No, they didn't

8:14disappear. You will always see them, but

8:15they would fade gradually, you see."

8:17And it was quite a simple argument to

8:19see why they did that. But apparently,

8:21Fred had got that little bit wrong. And

8:23he said, "No, that's wrong." Because he

8:24was He was a steady state theory at the

8:27time that Fred was talking.

8:28>> Well, you see, Dennis was a great steady

8:29state

8:30No. You see, I had one of my great

8:33admirations of Dennis

8:36was when the microwave background was

8:39discovered. This is the radiation which

8:40is permeating

8:42the whole of the universe at a certain

8:44stage. And this microwave background was

8:46discovered. And this showed, really,

8:48that the steady state model must be

8:50wrong.

8:52And Dennis, when he You see, he used to

8:54give lectures about steady state model.

8:55He had big screens and saying how

8:57wonderful it was.

8:59And when it was turned out to be wrong,

9:00he gave these lectures. And in first

9:02slide would say, "I was wrong."

9:06I was very proud of Dennis. Since

9:09I mean, I was I followed him very much

9:11in the steady state. I was a follower of

9:12that. And then when he changed his mind,

9:15I thought that was showing a real

9:18the right attitude to science.

9:21When you see you're wrong, you admit

9:22you're wrong. Absolutely. And I thought

9:24that was really impressive. So, we You

9:27mentioned We mentioned string theory

9:28before. And everybody laughed at that.

9:31But in in terms of trying to look for a

9:35deeper theory, so let's say quantum

9:37gravity. Then of

9:40what do you think of that

9:42attempt? Well, you trying to lose to

9:43think that. I thought well, it might

9:45it's got to be quantum gravity.

9:48But since you got to have something

9:50extremely asymmetrical in time.

9:53So, maybe quantum gravity is a very

9:55peculiar theory which is asymmetrical in

9:58time. And I went through several years

9:59of my life thinking that.

10:01And then I changed my mind. That's not

10:03the answer.

10:04>> [laughter]

10:05>> But I did that was my sort of solution.

10:08The quantum gravity had to be very

10:09peculiar time asymmetrical theory.

10:13And Big Bang was a quantum gravity which

10:15had this funny

10:17I says had to be time asymmetrical

10:19because the Big Bang was so very

10:21special. And all the singularities in

10:24black holes and all that are very very

10:26general.

10:27They're completely different. The ones

10:29in black holes are very very complicated

10:31with this conformal curvature going to

10:33infinity.

10:35Get going completely wild and

10:38these Russians have worked out what they

10:40might be looked looked at applying and

10:42so on.

10:43No, I I accepted all that.

10:46Nothing like what the Big Bang was like.

10:48So, there's something very peculiar

10:50about the Big Bang. It's not like any

10:51other singularity.

10:53Oh, that's right. Because because

10:55probably the most fashionable approaches

10:57at the moment are to

10:59So, approaches like so-called emergent

11:02space-time where you essentially picture

11:04quantum mechanics as the base framework

11:06and you attempt to

11:08see how space-time would emerge from

11:11some underlying theory. It could be a

11:13network of qubits or whatever it is.

11:15>> Eventually, I lived out of that phase.

11:17Did you? Because because that's

11:19what most not not most maybe but many

11:22physicists would would say today.

11:24Certainly with work on black holes and

11:26the black hole information paradox and

11:28so on. So, why did you why did you

11:31what do you say? Grow out of it?

11:35I think the thing was to realize it was

11:36not a quantum gravity problem.

11:39That's the thing, you see.

11:41Because it doesn't I mean it If it were,

11:43you wouldn't get this huge asymmetry.

11:45And it's in your right in your face.

11:47It's not a subtlety.

11:49It couldn't be there in your face.

11:52But my sort of solution is to think that

11:54quantum gravity is a very strange

11:56theory, which is time asymmetrical.

11:58Well, I eventually lived out of that

12:00phase, my God,

12:02and thinking, "No, no,

12:04that's not the answer."

12:06So, my my answer is something which

12:08people still have trouble believing in,

12:10I have to say.

12:11Even though

12:13there is some remarkable new evidence.

12:16You know about this.

12:18This is the

12:21The the new evidence is this young lady

12:25who

12:27in uh University of Yorkshire or

12:29something There was she.

12:31And she made a remarkable discovery.

12:34Very recently, the last couple of years

12:36ago.

12:37Of this huge ring in the sky. A very,

12:41very distant galaxies, which form this

12:44beautiful circular ring.

12:46And another one, which is a big arc, and

12:49that she showed me is probably really a

12:51circle, too. Not quite the same center.

12:54This ring and this arc And now she's

12:56found a third one.

12:58So, what are these huge rings doing?

13:01Where do they come from? They're so big

13:05that there's no time for anything within

13:07the standard model of cosmology.

13:10They'd have to be right in

13:12well, before the Big Bang.

13:15And that is not what people think. There

13:17shouldn't be a before the Big Bang.

13:19But then I said, "Haha, that's nice,

13:22because my theory says there was a big

13:23before the Big Bang."

13:25>> [laughter]

13:27>> So, I'm very keen on her ideas.

13:30>> [laughter]

13:33>> We've had good chats after that. No.

13:35No. So, essentially is there a way of

13:38explaining in a a couple of minutes so

13:41the idea how does So, our universe is

13:44expanding, dark energy is

13:47is driving that expansion and dominating

13:50it. So, the standard cosmological model

13:51is that goes on forever and you have a

13:53heat death at some point. So, how does

13:56that map on to

13:58a new

14:00uh eon, let's say? Absolutely amazing

14:02galaxies. The key point

14:05has to do with mass.

14:09How do I put this now?

14:11>> [snorts]

14:12>> You see, the space-time metric

14:15is a thing which has 10 components. At

14:17any point

14:19there is 10 numbers which define what

14:22the metric is like. Space

14:24the curved space geometry of Einstein

14:26needs this thing which is called the

14:27metric.

14:28And the metric has 10 components.

14:31Now, nine of these 10 components

14:35I should really say that the nine

14:37independent ratios of the 10 components

14:40are describing

14:42what the light cone is doing. The light

14:44cone tells you what light does.

14:47So, you see you follow a point flash of

14:49light here, as time evolves, it becomes

14:52a sphere which goes out and that's the

14:54light cone.

14:55Now, that is 9/10 9/10 of the geometry

14:58of space-time.

15:00What is the remaining 10th?

15:02The remaining 10th

15:04is one number. That number

15:07is thing that you get by combining the

15:09two most famous formulae of 20th century

15:12physics.

15:13One of them, of course, Einstein's E =

15:15mc squared, energy and mass are

15:18equivalent.

15:20The other one is Max Planck's E equals H

15:23new or HF. Energy is frequency. So, that

15:27tells you that mass and frequency are

15:29equivalent.

15:30So, that if you want a clock, that's a

15:33frequency. In other words, to have a

15:34scale of time or a scale of space, which

15:36is the same thing basically,

15:38you have to have a mass.

15:41If you don't have mass, you don't have

15:43scale.

15:44So, that's the key point. Where don't

15:47you have mass?

15:49Well, one place you probably don't have

15:51mass is in the remote future.

15:53Pretty well photons.

15:55It's more complicated than that, but

15:57that's the main story. What is there?

15:59Well, there are gravitational waves,

16:00too. They don't have mass, either.

16:03Photons. They just go out. They don't

16:05have any mass.

16:07So, in the remote future, there is no

16:09mass.

16:11So, it forgets how big it is

16:13in a certain sense.

16:15How about the Big Bang? That's the other

16:17place where you forget mass, because the

16:20energy is so

16:21enormous. The closer and you go back

16:25into the Big Bang, the

16:27less important the mass of particles

16:29become. They're effectively massless for

16:32a completely different reason.

16:34And so, they're massless at the Big

16:35Bang, they're massless in the remote

16:38future.

16:39So, the key idea is that those both ends

16:42you don't have any mass. And so,

16:44therefore, the geometry is the geometry

16:47of conformal

16:49physic conformal geometry, which is a

16:50very beautiful geometry. I used to play

16:52with it when I was before I went to

16:54university. Geometry of circles and

16:56things like this. Now, it's a really

16:58lovely kind of geometry. You don't have

16:59scale, but big and small

17:02are equivalent. Uh but angles are

17:04important and those sorts of things. So,

17:06velocities are important, I suppose, but

17:08you don't actually have the scale.

17:10And then, if you don't have a scale,

17:12where don't you have a scale? At the Big

17:14Bang, in the remote future.

17:16So, what I'm saying is the Big Bang is

17:18really somebody else's remote future.

17:21It's an eon, I call it an eon, a cosmic

17:24eon. Our cosmic eon started with the Big

17:27Bang.

17:28It ends, in a certain sense, with the

17:30remote future. And then you draw a

17:32picture which stretches out the Big

17:34Bang, squashes down the remote future,

17:36and you have a nice picture of the

17:38entire history of the universe.

17:40And then you can stick that on to

17:42another picture.

17:43It's generally the same as the previous

17:46eon. And in the previous eon, there were

17:48galaxies, galactic clusters, and all

17:50this stuff.

17:51And every now and again, in the remote

17:53future of the previous eon, there will

17:55be the galactic clusters whopping into

17:58the black There are these enormous black

18:00holes. These enormous black holes will

18:02whoop into each other. Huge burst of

18:05gravitational energy comes through.

18:08That's one of the things which get

18:09through, gravitational waves. They come

18:11through

18:12and maybe produce these wonderful rings

18:14that

18:15Alexia Lopez, that's the name of this

18:18young lady who's made this wonderful

18:19discovery, produced the rings. I never

18:22thought of it before, but when I heard

18:23about her rings, I went, "My god, that's

18:25I should have thought of that. This is

18:27something a nice effect that this theory

18:31should I should have thought that's a

18:32nice prediction." I never made the

18:34prediction, but that's sort of

18:36retrodiction, you see,

18:39coming from her, her discovery of these

18:41wonderful rings.

18:43And so, you you don't In that picture,

18:46you don't require some kind of

18:48unification between quantum mechanics

18:50and and gravity. So, do do you picture

18:52space-time as fundamental?

18:56>> It's not You see, it's not really

18:57quantum at all. It's a very different

18:59perspective. I'm not saying

19:02In fact, quantum mechanics is is a

19:05perturbation in this picture. It's a

19:07very classical. And I think people don't

19:09like that. They think, "Oh, it's got to

19:10be quantum mechanical." I thought that,

19:11too.

19:12But, this is a

19:13divergence from that view. It's saying

19:16the Big Bang is not quantum mechanical.

19:19It's It comes from the fact that it's

19:21conformal.

19:23Because the mass has got lost.

19:26Once you've lost the mass, you have a

19:28conformal picture. And then the Big Bang

19:30is very like the remote future.

19:33That's In fact, it's so much like it

19:35that our Big Bang is the continuation of

19:38the remote future of this previous eon.

19:41So, there there is no theory in that

19:44picture from

19:45which underlies general relativity,

19:47let's say this. General relativity is a

19:50is a

19:51a base theory, let's call it.

19:53>> you would say it is a result of a result

19:54of a generalization of it. But, it's not

19:57saying it's quantized. No.

19:59So, it's not quantum general relativity.

20:02See, that's the difference. I think

20:03people were saying, "Oh, well, you've

20:04got to quantize GR before you can

20:07explain the Big Bang." This a very

20:09different picture. It is a

20:10generalization in the sense you're

20:13looking at space-time within the broader

20:15spectrum of conformal space-time.

20:18And you say, "Well, conformal geometry

20:20is a bit of a deeper picture." And that

20:23the mass gives you a scale, but the mass

20:25is only important later on or earlier

20:28on.

20:29Before the Big Bang when you're going

20:31back to the remote future of the

20:32previous eon or after the Big Bang like

20:35us now.

20:36But, there was this stage a crossover

20:38from one to the other where the mass was

20:40not important. It more or less

20:43disappeared.

20:45To continue watching this video, click

20:47the link in the top left or in the

20:49description below. With a free trial,

20:51you can enjoy the full talk and

20:53thousands more. Thank you for being part

20:55of the conversation.