1995-02-26 Channel 4 Reality on the Rocks - Part 3 - Beyond Our Ken
Duration: 00:51:12
Transcript
Ken Campbell
And the last reality on the rocks of the series, reality itself meets quantum, and it’s all beyond our ken. I wanted to find out how the universe really is. To discover the secret plans and hidden schemes behind creation. Why is the whole show the way it is? I wanted to see how much about everything you could cram into one head. This one. Quarks, mesons, bosons, gluons, leptons, taus. Now, not a lot of people know this, but we live in a quantum universe. I’d come to this notion through months of research, grappling first with the theory of the entire universe.
Previous episode expert
Well, no, because you can never get right to the edge. No. The edge in relativity has no real meaning.
Ken Campbell
I’d had to check out the cosmos for myself from telescopes in the world’s highest places. So I’m looking right into the beginning of time. Here I was shown proof that the universe began, and that it’s still expanding from the bang. A ball of space-time shaped by gravity. Gravity that made the stars and galaxies. Gravity that formed our universe out of the matter that emerged from the Big Bang. Then I’d been to where they recreate the Big Bang here on Earth to discover what the universe is made out of. Subatomic particles. Higgs boson. These tiny chaps follow weird rules of probability. They don’t know where or what they are. See, in the micro world, the only certainty is uncertainty. We’re not talking about one thing being in three places at once or anything, are we?
Previous episode expert
Oh, yes, we are. Oh, yes, we are.
Ken Campbell
But then I found these laws say cats can be dead and alive at the same time. This is because all matter is just a form of energy. This blurring of energy and matter leads to the startling conclusion that things can be in several places at once. Physicists call this quantum theory. The leap I had to make was to square the quantum with the universe. You see, there’s another theory of the universe, a theory of gravity, known in the trade as Einstein’s theory of relativity. And these two theories just don’t fit together. So the search is on for a theory that incorporates them both. A theory of quantum gravity. Recently I’d heard about a particle called the Higgs boson, and it works behind the scenes of the whole show. It gives mass to the stuff in the universe. But who is Higgs? Oh, really, he’s still alive, is he? To be honest, I thought he was a guy years ago. This is the right one, is it? Yeah, Higgs of the… Higgs of Higgs bosons. Higgs’s field and everything. Is he? What are you… He’s coming here to Oxford. Where… What’s he doing? Higgs was giving a lecture on the search for the theory of everything, this quantum gravity business. So perhaps I’d find out what it is. I was about to discover how to rebuild the entire universe out of its tiniest constituent parts, so I knew it wasn’t going to be easy.
Peter Higgs
The standard model of particle physics, particularly the Glashow-Weinberg-Salam electroweak theory, has its origin in superconductivity theory back in the late 50s. The one which tells you how the magnetic field is generated…
Ken Campbell
Limey. This was the ultimate answer. I couldn’t understand the first thing.
Peter Higgs
Glashow, Salam, Weinberg, the Higgs boson is a pair of these things. Then its mass should probably be…
Ken Campbell
Needless to say, I came out none the wiser.
Peter Higgs
… these are all the different… apparently different kinds of physics is a rather fruitful one.
Ken Campbell
But I’ve come too far to let a bit of maths get in the way. So I thought Higgs would get a grilling Campbell style. What is quantum gravity?
Peter Higgs
Well, quantum gravity is… It appears that if you quantise anything, you have to quantise everything. In other words, you can’t pick and choose. So if there are various kinds of forces and fields around, including gravity, which interact with what you’ve already described in quantum physics, then you must bring in gravity too. Otherwise, you haven’t got a final consistent theory.
Ken Campbell
The thing is, what they’ve done is they’ve found all the different forces, the things that hold the bits and pieces of atoms together. The strong force, the weak force, all that electromagnetic force. And there’s a quantum particle for each of these forces. Now, they haven’t yet found any particle which holds us to the earth. In fact, the thing that Newton found out, you know, boing, things drop and things go round and all that, the gravity, this is the big bugger. Because nobody can find, you know, what it is. We can’t find the graviton. And apparently when we do find the graviton, bang! That’ll be the thing. Not that we’ll understand everything, but maybe we’ll… What happened with it? G-U-T, what’s that called? A grand unified theory will be ours. So if you can get gravity happily into the quantum world, the quantum picture… does that mean that you’ll then have the equation that’ll explain everything? In one sense, the answer is yes. I mean, that’s what people would be aiming for. Then that might be, as Stephen Hawking once put it, …
Stephen Hawking
The end of theoretical physics. Our goal is a complete understanding of the events around us and of our own existence.
Ken Campbell
So if gravity does come into the quantum picture and everything follows quantum rules, does that mean everything is in many places at once? Is Campbell a quantum being in a quantum universe? Am I somewhere else as well? Reality on the rocks. Well, as far as I’m concerned, reality’s fine, you know. I’d no particular bother with any of this. And then came the meeting with David Deutsch. Right. He said, you know at a choice point in your life, you don’t like, you think, I’ll go see me auntie. No, I’ll go to the pub. See? Well, at that moment, at that moment, another universe is born. There is a universe when you go to your auntie, and there is a universe where you went to the pub.
David Deutsch
It sounds very startling when you hear it at first, but I think I might be able to persuade you…
Ken Campbell
Sounds unbelievable.
David Deutsch
Well, yes, but I might be able to persuade you that you already believe in this theory in another way.
Ken Campbell
David Deutsch?
David Deutsch
Yeah. Ken Campbell. Come in.
Ken Campbell
Thank you.
David Deutsch
You believe that the past happened. You believe that when you came in a few minutes ago, you actually did pass through that doorway and did begin talking. Those are perfectly real physical events, we think. We’re used to there being a parallelism of different times. That is, we have the present of which we are directly aware, and we have the past and the future of which we’re only indirectly aware. Well, all that quantum theory is saying is that there are a whole lot more of those of which we’re even less directly aware. But we can infer their existence through a combination of theory and experiment.
Ken Campbell
Is there a name for all these universes?
David Deutsch
Some people call it the multiverse.
Ken Campbell
The multiverse. And the multiverse means all of them.
David Deutsch
That’s right. All of them considered as an interacting whole. And they all exist at once, both the parallel ones and the past and future ones. The theory of parallel universes is usually used to describe the interaction of very similar universes, ones which differ in perhaps the position of one photon or one electron. And it’s those ones that we’re really very sure exist. The classic experiment is an interference experiment, where one shines a beam of light through some slits or something and sees a pattern.
Ken Campbell
I had this funny feeling I’d been here before. The proof of this, or what’s led scientists to get on top of this concept, is what’s called the twin slit experiment. Now what happens with the twin slit experiment? Let’s imagine one slit first, alright. We’ll fire light at the one slit, right? The light will go through that one slit, okay? And we’ll narrow it down to just one, what do you call it, package of light, a photon. Like one photon, doink, goes through that slit. One photon. Okay, now we’re going to have two slits, yeah? And we fire our one photon, doink, and it’s gone through both. I said, David, are you sure it was only one photon anyway? Yes, we’re certain. And I said, no chance it sort of bounced back at all, I said, no.
David Deutsch
No, it didn’t.
Ken Campbell
So what happened there?
David Deutsch
It’s your little chaps, your little tiny chaps, your quarks, and such, inhabit all the universes of the multiverse. And that is where you have had interference with another universe.
Ken Campbell
Are you saying they’re physical?
David Deutsch
Absolutely, as physical as the centre of the sun.
Ken Campbell
And it’s sort of identical, so that one is identical to this one, except there’s one little thing there and sort of there.
David Deutsch
That’s right.
Ken Campbell
And where are they physically located?
David Deutsch
There you’re really asking, where are they in our universe? But they aren’t in our universe.
Ken Campbell
Well, I never said they were in it, no, they must be, well, they’re either in it or next to it or somewhere away.
David Deutsch
Yes, they don’t, when you ask where something is located… you mean what is its spatial position? Where is it in space? But if you ask where is the universe, well, that isn’t in space, it isn’t anywhere in that sense. It just exists. And similarly, the parallel universes also just exist. Ask yourself…
Ken Campbell
Well, it just seems to be a bit lacking in the middle of what you’re saying there to me. It’s no… I have no difficulty with saying, well, the universe is that, I mean, it apparently is…
David Deutsch
But you do have that difficulty. If you think about the past, where is the past?
Ken Campbell
Well, wherever that is… Well, I had thought that it had gone, but I mean, with what you’re saying, maybe it hasn’t…
David Deutsch
That’s certainly not the picture that modern physics gives us, because all the universes, the past, the present and the future, and the parallel ones, are all part of a unified whole. And there is no one of those which is distinguished as objectively the one which exists, while the other…
Ken Campbell
You know these guys who lived before, under hypnosis and sometimes without it, it turns out that they were a 14th century nun and all that.
David Deutsch
There’s no basis for that in physics.
Ken Campbell
Pardon?
David Deutsch
There’s no basis for that in physics.
Ken Campbell
It seems to be what you’re saying, though. I mean, why not? I mean, maybe I wasn’t a nun then, but maybe I am now, inasmuch as I’ve managed to…
David Deutsch
Well, let’s keep our feet on the ground. I mean, just because quantum theory is weird doesn’t mean that everything that’s weird is true. It’s only the few weird things that quantum theory says are true which are true.
Ken Campbell
Let’s understand it as a universe for every decision point. You know, like if I’m coming along a road, and I either go right or left, there’s another universe for when I go right, another universe for when I go left.
David Deutsch
That’s right, yes.
Ken Campbell
So that’s going to start another universe.
David Deutsch
It’s not just the things that you do, it’s the things that every atom or subatomic particle does as well.
Ken Campbell
Right, I see. So there’s a separate universe to the number of every atom or subatomic particle.
David Deutsch
Perhaps it’s better to say one for every possible history of the universe.
Ken Campbell
It all sounded quite unlikely to me, except when… I never said this, but on the other hand, I had a little thought which might have been something similar. I don’t know if it happened to anyone else here, but sometimes I’d have thought, yeah, well, I think I’ll go down the pub, but I’ll just have a couple of pints. I just thought, I’ll just have a little thought, go down there, have a couple of pints, and that’s all I’ve had. Right? And I come back, and I’ve got mystery bruises. Right? I don’t know, I mean, two pints. I come back, I’ve got mystery bruises. Right? I think, oh, see what’s happened. In another universe, I went down there and fell into bad company at eight or nine. I fell over, you see. I had… Yeah, multiverse interference. I just like to… If this quantum theory of everything is right, then there’s more of everything than I’d ever bargained for. The whole multiverse of parallel realities. I was going to say, I was… I was… I was trying to say, I mean, I was doing my best to follow this stuff. I found it unhandable, really. But anyway, what I knew was that I would be meeting the great Roger Penrose next. Now, Roger Penrose had been tutor to David Deutsch, and… But then, because there had come a point, I think at multiverse time, when they split, split paths… Deutsch had gone his way, and I would have pen-rose with somewhere else. Anyway, Deutsch, who knew I was going to see his old tutor, Penrose, he said, do it. But he said, just ask him this. He said, if we take on board the observations of quantum mechanics, we cannot avoid the multiverse. Just ask him that. I don’t understand it. With quantum mechanics, quantum gravity and so forth, insist that there is… that there are many universes, a phenomenal amount of universes.
Roger Penrose
I think what you have to understand is that in quantum mechanics, quantum mechanics is usually concerned with very small things, atoms, molecules, that sort of thing, and the rules which apply there do insist that all alternative possibilities must in some sense coexist. Now, the trouble comes when you extrapolate that up to the level of people or what have you. And the thing is that…
Ken Campbell
Is there any reason why things can’t work one way at such a tiny level and a different way up and out?
Roger Penrose
Well, I think, you see, that’s exactly what I think.
Ken Campbell
Do you?
Roger Penrose
Yes, that’s right.
Ken Campbell
Why?
Roger Penrose
But you see, if you really take quantum mechanics seriously, if you really think it through, you are really driven to a many-worlds view, so that all these alternative universes do have to coexist, and you’re driven that way. But there’s no good evidence that the theory does hold right up to that level.
Ken Campbell
Really?
Roger Penrose
No. No good evidence. Well, you see, in my own view, there’s something missing in the theory. What is the state of dither? It would mean you’d have to bring something else in, and that’s kind of disturbing because it needs a new theory. But I think you do need a new theory.
Ken Campbell
Now, this was refreshing. When it comes to the multiverse, even the big boys can’t agree. Penrose reckons our only hope for common sense lies with good old-fashioned gravity. He’s not at all convinced that gravity will play by the quantum rules.
Roger Penrose
OK, if you want a unified picture of the world as a whole, then you’d expect quantum mechanics and gravity to come together. Now, there are many people who work on these ideas, and there’s no theory yet. I mean, there’s no successful theory of quantum gravity. But there are many good ideas that people have. But, see, one thing I think is important here is that there’s no good reason to believe that the quantum gravity theory, whatever it is that unifies those two, will be quantum theory as we understand quantum theory. I think it will change quantum theory. You see, you were asking me before about at what level do things become classical, and that’s where things…
Ken Campbell
Well, so your view is that if they find the quantum theory of gravity, then we probably won’t need all the many worlds.
Roger Penrose
Exactly. No, exactly. That’s right. I certainly think that.
Ken Campbell
David, hello. Sorry, it’s me again. Listen, this, er… Campbell’s cosmic consciousness was full of enough barmy ideas. The last thing I needed was someone adding to the problem unnecessarily. It was time for David Deutsch to explain himself. David, isn’t it easier to believe in one universe that’s got some weird rules than all these other universes that have comprehensible rules?
David Deutsch
I think it rather depends on what you want from science, what you want it to tell you about reality. After all, in a way, the multiverse is one universe with weird rules. The rules say that there are many copies of us, but the weirdness in the conventional way of looking at quantum mechanics is not so much weirdness, it’s just that something that doesn’t make sense. So, if the question is, isn’t it better to believe in one universe that doesn’t make sense, or lots of universes that do make sense, well, then the answer is more obvious.
Ken Campbell
To convince me of this, David demonstrated how the old view of quantum mechanics, the one that’s been around since the 30s, tells us things that are actually weirder than a multiverse.
David Deutsch
According to the usual view, it talks about indeterminacy.
Ken Campbell
So the same as uncertainty?
David Deutsch
Uncertainty, the uncertainty principle. What that top card is, is uncertain until we look at it. That’s the usual view. There is nothing on the back.
Ken Campbell
Can I just check, you are saying that the card is uncertain, it’s not that we’re uncertain.
David Deutsch
Yes, according to that interpretation, it’s both we and the card who are uncertain. There is nothing on that top card, definite, until we look at it. When we turn it over, it then becomes definite.
Ken Campbell
David, how does the thing make up its mind? Just as you turn it, the card’s still dithering, look, it’s still dithering, David, it’s still dithering, it’s made up its mind.
David Deutsch
But don’t blame me for that interpretation. In fact, one of the pioneers of quantum theory used to say, it’s not permitted to ask what that top card is.
Ken Campbell
Did you used to think that?
David Deutsch
Yeah, I did. When I was a student, that’s what we learned. In fact, that’s what most…
Ken Campbell
You found it easy to take it on board?
David Deutsch
Not at all. I think when you learn these things, you learn, like Niels Bohr said, you learn not to ask certain questions.
Ken Campbell
Albert Einstein and Niels Bohr, the founders of quantum theory, argued for years over what quantum uncertainty could mean. Bohr thought it meant that reality is just the sum of our observations. Einstein said, but the universe really is out there. Quantum theory must be wrong. God does not play dice. Don’t tell God what to do. Einstein could never accept his own quantum theory. Two years after his death, the new explanation of uncertainty came along. And it wasn’t that reality wasn’t real. It was that every reality is real. I wondered what Herr Albert would have made of parallel worlds.
David Deutsch
Now, in many worlds’ view, it may be hard to believe, but at least it makes sense. The many worlds interpretation is normal physics applied to a very unfamiliar universe.
Ken Campbell
So really, if we were looking at this pack from a God’s eye view, we’d see lots of different packs. And when I take the card off the top, there’s a copy of me doing that in each universe. Yeah, but listen, what worries me about this idea is it seems to me that you’ve thrown away free will. You’ve thrown away freedom of choice. And all you’ve left us with is ignorance. You’ve left us merely with an ignorance as to which universe we’re in. I mean, if I do a really good deed in this one, and it makes everyone really happy, that’s very nice, but it’s a bit selfish really because it’s condemning my clone or sister, brother being in the… I suppose I’m a girl in one of the universes, it’s condemning them to unhappiness.
David Deutsch
I think that’s the wrong way of thinking about it.
Ken Campbell
I mean, also because I think I’ll be the lazy one, you know? I’ll be the one who stays in bed.
David Deutsch
You see, if we were having this discussion and we thought that classical physics was true, then you could say free will doesn’t make sense.
Ken Campbell
David told me I was still holding out for a classical universe where everything ran like clockwork, where the fate of the world was predetermined from the very first tick. In this universe I wouldn’t have any choice at all. I’d be a prisoner of the clockwork. Only by leaping into the quantum world could I rediscover my freedom of choice, but the choice was ridiculous. Either there was no reality or every reality, a multiverse. Presumably in one of these other universes there was a Campbell lookalike who didn’t think this multiverse idea was a Looneyverse. Anyway, I’ve ferreted out another quantum gravity chap, Julian Barbour, and he reckoned he could break down my monoversal insistence.
Julian Barbour
The world of possibilities is just vast. I don’t think you’d comprehend how many possibilities there are. And I suppose the most amazing thing about quantum mechanics is that it says in principle everything is possible. Everything in principle could be experienced.
Ken Campbell
So am I right, Julian, that with this excellent multiverse concept that every particle, every quark, lepton, slepton, muon, tau, each one branches off and has its own universe, but also every instant of time is yet another universe?
Julian Barbour
Well, yes. The way I would like to get you to think about this is to ask what do you mean by an instant of time?
Ken Campbell
Well, I would say that an instant of time is if you could freeze the world and take a snapshot of it, and it would show all the objects in the universe in some particular position. Yes.
Julian Barbour
You would have a complete snapshot of the entire universe. Now think about, as you look about this room here, in fact if you stop and look at everything, the portraits on the wall, the family photographs, me, and even here, look, I’ve even got my progress book, which I’ve fished out here. Look, you see, even here. Here’s what seems to me. This is the progress of you. Now, you’re looking at this progress book of mine, and you’re looking at me at the same time. Now imagine a snapshot is taken.
Ken Campbell
Yes, it’s sweet, isn’t it?
Julian Barbour
Imagine a snapshot is taken of this and me and the whole room all at once, and it’s frozen there, and you’ve got that all frozen in one snapshot. Now, doesn’t that tell a fantastic story? That snapshot is completely static, but it reeks of time. If you sat and looked at that snapshot long enough, you would start saying, this is a record of a history of a young chap who grew up and became this crazy fellow, Julian Barbour, sitting here telling you about the many worlds. And there seem to be lots of records, and it all sort of matches, and it matches with your memory when we first met. Even the atoms of our brain are, so to speak, representing all that structure there, so that you can get your notion of time, I believe, from the fact that we are in such a structured configuration whenever we experience anything. So I don’t think there is any time at all. All that it is is we’re constantly experiencing things which seem to tell a very rich story, and one of the challenges of quantum gravity will be to explain why it should be that we do experience that.
Ken Campbell
I really just fall out of this at a point, because you say, well, there isn’t time. There’s just these snaps, but that is time. I don’t see where the discovery is. This is a way of saying what time is, not saying how there isn’t it.
Julian Barbour
Yes, that’s true. I mean, let me remind you what St Augustine said. If nobody asks me what time is, I know perfectly well what it is. But if they ask me, then I’m at a loss. I can’t actually put my finger on time. So what I’ve been trying to do is try and get a clear idea of what do you mean by time. You see, Newton thought that time existed externally. There was a time flowing. As we’re talking here, in addition, time is flowing. In fact, let me read you what Newton said. Here’s his famous Principia. Absolute, true, and mathematical time of itself and from its own nature flows equably without relation to anything external. So in Newton’s view, there is sort of some God’s clock which is ticking away, if you like, outside this room where we can’t see. And each of the instants that we experience here is embedded in this external time, occurs at a definite place in external time. Absolute time, as he called it. Now, I think that’s quite wrong because I’m saying that time must be something concrete, something that we experience in this world and deduced from what we can see in this world. So I say the instant is not in time. Time is in the instant.
Ken Campbell
Time is in the instant.
Julian Barbour
Yeah, well look, you can see it here. How could you say there was time if you didn’t see the evidence all around you? There’s the appearance of time here. Look, you see it everywhere you look. The gravestones, the church. This seems to tell a story. As you’re here, you see it in this instant now. It’s here. Time is in the instant.
Ken Campbell
So there isn’t ever going to be time travel then?
Julian Barbour
Well, not in the sense perhaps that you mean it because the instant of time is defined by what you find around you. That’s what it is. So you can’t go back and bring in some new material. So if you go back, it isn’t the same instant of time as it were. It’s going to be a different one.
Ken Campbell
The way Julian explained it, it all seems so reasonable. In the multiverse, time is not an issue because time is not real. Just a pile of snapshots. A world without time. Shame about the time travel though. The more I thought about it, the more I got concerned about this time travel business. You see, a few years back I’d run a science fiction theatre in Liverpool and I’d built a life around time travel, believing that it would be a fact one day. Had I been selling my audience duff scripts? Wait a minute. Wait a minute. You! You!
Mac MacDonald
Me?
Ken Campbell
Yeah, you. Now suppose you go back in time, you meet your grandfather and you kill your grandfather. Well, then there’ll be no you to go back in time.
Mac MacDonald
It’s just a film.
Ken Campbell
Just a film? It’s as real to me as yours is to you. What do you mean?
Mac MacDonald
Right. Now, your time is a series of instants, right? Okay. Think of those instants as a frame. The first frame is the big bang. The last frame is where you are now.
Ken Campbell
Yeah, but film time only happens when you’re watching it.
Mac MacDonald
Au contraire. Film time is in the film all the time, whether you’re watching it or not. The time is contained within the images on the unprojected frames. Your time is in frames too, only you call your frames instants. And you believe your future and past exist, don’t you?
Ken Campbell
Yeah.
Mac MacDonald
Well, they do.
Ken Campbell
Hold on. Your future is fixed. Mine is uncertain.
Mac MacDonald
That’s another way of saying in your universal movie, there’s a number of possible endings. Now, in my movie, I don’t know what’s going to come next. In the director’s cut, there could be a totally different ending. In the movie version, it might be really exciting. In the TV version, not so good. In yours, there’s a number of ways the film can be cut, like in mine.
Ken Campbell
But if we say that this is a film in a multiverse, who’s the director?
Mac MacDonald
You got me, buddy. Let’s hope it ain’t Michael Winner.
Ken Campbell
You all right? It was then I found this article in the Scientific American, and guess who it was by? David Deutsch. Time travel, he said, was possible, but only with the multiverse. That way, you see, you avoid the grandfather paradox because you travel to a parallel universe. Another possible past. I don’t think it was anyone. Who was anyone?
Stage manager
Mr Campbell, this is your ten minute call. Mr Campbell, your ten minute call. Thank you.
Ken Campbell
I mean, actually, every instant that there actually was, and every instant that there actually will be. It’s like you who’s bringing in these probable ones to confound me.
Julian Barbour
The difficulty is, well, I agree, and I’m very sorry that I have to do it, and I do incline, like David Deutsch, to think that they’ve got to be all there, although it’s very hard to imagine.
Ken Campbell
So Julian, you don’t think in any terms of beginning and end, then, do you? There’s… Do you subscribe to this Big Bang concept?
Julian Barbour
Let me take this model here. I would say that the Big Bang did not occur in the past. It is just somewhere else in this structure here, which I call the relative configuration space of the world. This is the space of all possible configurations. If you take each possible configuration of the universe, which is one of these points here, that could be, so to speak, a possible world, or a possible instant. Now think what ordinary classical physics was like. It’s very odd. Here’s this great huge sea of possibilities, but according to classical physics, only a tiny, miserable little part of it is explored. The actual universe is just this one unique curve running through it. But then it’s very strange that all this other huge sea of possibilities, and they’re vast, all these possibilities, are completely unused. Now quantum mechanics in a way seems to be much more reassuring, because quantum mechanics is, as it were, picking up all of these possibilities, and in some senses it’s seeing which of them it likes best, which one it’s going to give the biggest probability to. It’s like a sort of a competition in eternity. Each possible instant here is sort of competing with all the other ones to see which is the most probable.
Ken Campbell
I mean, to me the probability is in the future.
Julian Barbour
But you see, there’s no time in this picture. It turns out that time disappears completely. It’s a timeless world. You just have probabilities for these configurations. And somehow or other there isn’t quite anything like it.
Ken Campbell
Does physics destroy the history of the world?
Julian Barbour
It does. Yes.
Ken Campbell
I didn’t realise this. You seem to be saying that this probability thing is on history too. You’re saying, well, probably the Romans came. We’ve found out on it.
Julian Barbour
Well, for a start, yes. I mean, in the most extreme form, the quantum theory, you have to ask yourself, did I even come into this room? Was that experienced? Or is it just your memory? Remember, you really have to practice Cartesian doubt. Descartes said, the only thing of which I’m absolutely sure is that I think, cogito ergo sum, I’m aware now. So in fact, quantum mechanics really confronts you with this Cartesian problem because all we know for certain is that the present instant exists.
Ken Campbell
My brain was crammed with quantum uncertainty. If I was to catch this time connection, I had to hold on tight to another train of thought. Einstein’s train, where each instant of time is not a when but a where. We do not move through space and time, but just exist in a greater scheme called space-time. Einstein proved this from the single fact that the speed of light is always the same, no matter where you are or what you’re doing. He realized that if someone struck a match in the middle of a carriage, they would see the light from it hit the front and back of the carriage at the same time. But if you were on a platform watching the match being struck by the time the light moves from the match to the ends of the carriage, the train has moved. So you would see that light hit the back before the front. You disagree over when things happen. So even time is only meaningful relative to your position in space. Einstein said what happens when you move is that your time must slow down. And if it were possible to travel at the speed of light, time would grind to a complete halt. Now, in the universe there are objects of such huge mass that they do strange things with light. This is the clue to the secret of everything. These are black holes, objects of such concentrated mass even light cannot escape them. So inside a black hole, light must come to a halt. And this could only happen if time stops. A black hole is the place in the universe where the end of time exists, where reality gets crushed out of existence by gravitational energy. It’s the mirror image of creation! So I’d actually made it from Big Bang to black holes, apparently in no time at all. This history of time was even briefer than I thought. But surely time can’t be an illusion, can it? Is time real? Or is it an illusion? It’s real, isn’t it? Surely time is as real as you are, Professor.
Stephen Hawking
Well, you’re talking about our experience of time, the flow of time. That if you think about the universe having originated at a certain moment in the sense, then you might ask what happened before or what was time like at the Big Bang and so on. Well, that is a situation where you really do have to worry about how quantum theory and space-time structure relate to each other. And it’s a big unsolved problem. Nobody knows how to do that. I mean, there are various different ideas people have. And, for example, Stephen Hawking has an approach to this where he talks about imaginary time. He has a scheme in which imaginary time, in this sense, is brought in and space and time look the same as each other. But it’s a particular approach to looking at quantum gravity which gives a picture of what the Big Bang might be like.
Ken Campbell
I haven’t got what this imaginary time is. So imaginary time isn’t the time before time began.
Stephen Hawking
No, no, no. It’s off at a right angle, so to speak. Time before time began would be minus time. Whereas this is not negative time. It’s square root of minus one times time. It’s square root of negative time.
Ken Campbell
That doesn’t make any sense. The square root of negative time.
Stephen Hawking
Well, no. In quantum mechanics, you see, you have to do this.
Ken Campbell
They’d have to have given him that job.
Stephen Hawking
See, in quantum mechanics, the deeper you look into the way the world works, the more mathematical you find that it is. And things like these imaginary numbers, in a sense, they’re just sitting there in the world. You can’t see them in the ordinary way. But they underlie the very precise way in which the world behaves. So yes, the world is governed by incredibly precise mathematics. And mathematics is not always the most obvious kind. It’s subtle mathematics. But that seems to be the case, yes.
Ken Campbell
So God worked it out mathematically first.
Stephen Hawking
Well, that’s a way of putting it, if you like. I certainly have the view that the mathematics is there, in a sense. It’s out there, and the world conforms to it. So it’s not that we come up with these funny ideas. We come across the funny ideas. They’re there. They’re, if you like, God’s ideas already. They’re out there in the world. So yes, that is the way I would agree with that way of putting it.
Ken Campbell
I suppose God didn’t say, let there be light. He said, time, gentlemen, please. Time’s an illusion. Blimey, it’s up our six. It was then I got the letter. Stephen Hawking had agreed to see me. But only if I could make it on a Wednesday. I’d got together questions as ultimate as the Campbell brain could muster. I must ask him about that. It was for me very difficult to know that in a very few minutes I’d be meeting Stephen Hawking, the greatest brain possibly in the world. Certainly in Britain one would think Stephen Hawking. The first of the big questions. Is quantum physics just maths, or is it the way the world really is?
Stephen Hawking
I don’t think it has any meaning to ask what the universe really is. Reality is not something you can test with litmus paper. All you can ask for is a model of the universe that predicts the results of observation. Quantum theory does that very successfully. It is a picture of the universe that is often at odds with common sense. But so much the worse for common sense. Common sense tells us that the sun goes round the earth. But Newton’s theory of gravity, which says that the earth goes round the sun, allows us to put satellites in orbit and send men to the moon.
Ken Campbell
So for the big man of everything, common sense doesn’t matter. I next asked him, could quantum gravity explain everything?
Stephen Hawking
Gravity interacts with everything in the universe. So a theory of quantum gravity would be a theory of everything.
Ken Campbell
Gravity would be everything. Hey, hold on. Just because gravity interacts with everything, it doesn’t mean gravity would actually be everything. Or does it?
Stephen Hawking
At the beginning, the universe contained nothing. However, as it expanded, it borrowed energy from the gravitational field to create matter. As any economist would have predicted, the result of this borrowing was inflation. The universe expanded and borrowed at an ever-increasing rate. Fortunately, the debt of gravitational energy will not have to be repaid until the end of the universe. So gravity is everything. Strange. It is said that there is no such thing as a free lunch, but the universe is pretty close.
Ken Campbell
So if you found the theory of everything, is that going to be all up then for physics?
Stephen Hawking
If we found the theory of everything, it would be an end of the first chapter. But there would still be a long way to go before we understand the consequences and the reasons behind the theory.
Ken Campbell
I see. All right. Because I have to say, I had a notion actually that that was secret that you’d found it, but we’re sitting on it because you weren’t really trained for anything else.
Stephen Hawking
No.
Ken Campbell
Would the theory of everything tell us why we’re here?
Stephen Hawking
A theory of everything by itself would not tell us why we are here or why the universe bothers to exist. But it might give us a clue. Finding a theory of everything won’t help us to feed more people. It won’t even enable us to make a better washing powder. But man does not live by bread alone, nor does he exist to wash his clothes whiter than white. Surely the quest to understand the universe and the laws that govern it is worth a bit of effort and expense.
Ken Campbell
Yeah. I’ve got a theory that they put dirt into washing powder because I was washing some, I mean they weren’t really dirty these trousers at all, but I was washing them by hand. And it was incredible the dirt that came out of them. I think they put dirt in them.
Stephen Hawking
Maybe.
Ken Campbell
I said to him afterwards, it’s alright, that voice they’ve given you. I called him Stephen. It’s funny isn’t it, calling him the greatest brain in the universe, Stephen. Anyway, that’s how it was. I said, it’s quite nice that voice they’ve given you, it’s alright. I said, because it’s got a sense of humour in it. You see? And he went, yes!
Stephen Hawking
Yes!
Ken Campbell
I said, except when you say yes. I said, I think you should get them to give you an ironic yes.
Stephen Hawking
Maybe!
Ken Campbell
Anyway, in any event, what was I doing there? I said, listen, all these trillions of universes of the multiverse, are they as real as this one seems to be to me?
Stephen Hawking
Yes. According to Feynman’s idea, every possible history of Ken is equally real. It is just that some histories are more probable.
Ken Campbell
My past was catching up with me. Did it ever happen at all? What was I to believe? Nothing? Or everything? You see, in science, there is no final truth… There’s no final truth. We know things at the given level. The only reality left to suppose was the multiverse. And that is the story of how Ken Campbell came to be a many-universes man. This is the penultimate answer to what question I can’t recall. This is a tape of the answers only.
Stephen Hawking
He said, the human race is just a chemical scum on a moderate sized planet, orbiting around a very average star. In the outer suburb of one among a hundred billion galaxies. We are so insignificant that I can’t believe the whole universe exists for our benefit. That would be like saying that you would disappear if I closed my eyes.
Ken Campbell
Close my eyes.
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