Humans will never get to deep space – Nobel Prize physicist (2/2)

SS: So when you're saying that – I've heard in one of your interviews, you're saying that there is a level of reality, of physics that is even deeper than quantum mechanics? Is this what you mean? Are you talking about the language?

GH: That’s exactly what I mean, that there is a language where you don't need fairly familiar quantum concepts. Because according to quantum mechanics, it looks as if our universe is actually only one of many universes, it looks as if there's a universe of universes, that's the way the equations are constructed. But it's wrong. I don't believe there are many universes, I think there's only one, all those others are universes that didn't materialise because of probability - it was just too improbable. so they happened  not to happen. Only one universe came out – it’s the universe that we are in and we can calculate the probability. If we would be able to do the calculation with infinite precision, that probability will be one or the probability will be zero, but we can't calculate with infinite precision – it’s hopeless, you shouldn't even try. So we find this universe is the most likely universe, from our perspective, it doesn't mean that any other universe exists or so, or that no other universe could exist. But there is only one.

SS: But do you know how most people believe that universe is endless? And a lot of professors actually claim and believe that, too. And I was reading the Nature Astronomy magazine article, and they were saying, they had this supposition that actually universe might not be endless. For instance, if you were to start walking in one direction, eventually you would come back home. Could that be true? I mean, what do you make of it? And if our reality has borders, suppose that it has borders, what is beyond them?

GH: So I sympathise a lot with a theory that says the universe is bounded in the sense that the surface of the Earth is bounded. In ancient times, people thought if you travel in one direction, you'll always end up in new countries, you'll never return. But now we know  thatthe earth is a sphere. If you go far enough, you end up at the other side of where you came from and you're back home. So I would like to envision that also the universe that we live in is just like that, you go in one direction, you will return from the other side. 

SS: And what's beyond it? 

GH: There is nothing beyond it because there's no other dimensions than the dimensions that you are looking at. On planet Earth in two dimensions, it's rounded, and it's a sphere. But there's a third dimension, which is height – elevation above the ground. And that still seems to be an infinite dimension. But that's only because we don't know about the universe being returned back to itself. The equations we have for the cosmos, certainly allow the situation in principle. So they allow the notion that the universe is like a really big sphere but in one dimension higher than the planet Earth, so that also the concept of height is included in this picture. So all three dimensions will return when you go faster far enough. That's in principle possible. But I would find that more satisfactory as a theory of the universe but I can't tell God what to do. So maybe the reality is something different. But for me, it would be very pleasing to see a theory where the universe itself is also completely finite in that sense, then you don't need any boundary, just like there's no boundary anywhere on the planet Earth to say, you can go to here but any further, well, some places are so difficult to walk into, like Antarctica, but that doesn't mean that Antarctica is different from the rest of the universe.

SS: I don't know if you've heard… Your Korean colleagues, scientists, they have recently suggested that dark energy, the thing that actually expands our universe, may not really exist?

GH: Dark energy is one of the deep puzzles of today's cosmology, the science of the cosmos. Einstein, when he introduced general relativity, he already noticed, there's one term that you could add to this equation, and that term would modify the shape of the universe. And in the beginning, he needed that term, then he realised he could do without that term. So he said, ‘That was an error, I should have never introduced that term.’ But it isn’t Einstein who's got to tell whether that term was there, — his experiments, experimental observations. And then for some decades, there were astronomical observations that accumulated saying that there is a very small constant in Einstein's equations, that tells you that there's something that is now called dark energy. And the equations work much better with dark energy than without, but now recently, cosmologists have been saying that they have overestimated the accuracy of their previous observations, there could be some effect that wasn't taken properly into account in the beginning. And so the conclusion that we had drawn previously, that there is such a term as Einstein predicted, might be wrong and actually that term might be zero. I would find a theory much more understandable if that term was zero.

SS: So there is no such thing?

GH: But even if the term is zero, that would still be a problem. Because the next question will be, why is it zero? Why did nature forbid such a term? And it's just because of my lack of fantasy. I can't imagine any other value than zero for that term because if there’s the value that the cosmology said, I would have a big difficulty understanding where that value comes from because it doesn't fit with all the other numbers in the universe. It doesn't fit with the forces that particles have on each other. It doesn't fit with our theory of gravity very well. It's just there annoying us. So it doesn't look right. But I can't come up with more valid objections than that. And my only objection is, I don't like that term, I wish it was zero. That's not good enough for any scientist. So they all look at me and they just say, ‘Okay, you said that, now we just continue.’ And so I think it would be more satisfactory as a starting point that the universe has no such term. But eventually, I don't know. Even if there's no term, I would need more understanding as to why there is no such term. And this also we don't understand today.

SS: When I was a kid, it was still the Soviet Union and cosmos was like a huge thing, we had cosmonauts, Americans had astronauts, they were national heroes. And I think like every other Soviet kid, including myself, I wanted to be a ballerina or a cosmonaut. It was this complete, not even a dream, it seemed like it was our future. It seemed like everything that was up there, cosmos is where we're gonna end up. All the literature that we read, that we loved so much, it was about that. And then the quantum physics comes in, and with it we're thinking this is it, you know, we understand everything. So the next step is up there. 40 years later, the only thing I understand is that we're definitely not going into the cosmos. We know nothing about it. We still don't know so much about the quantum physics, the only future that actually turned out to be my present is a smartphone and virtual reality. Do you think that my generation – I mean, how long am I going live? another 40 years maybe with luck – I'm just bound to the virtual reality? Oh, there's still a chance of me stepping on some planet out there?

GH: That's a good question. I don't know. I also thought that the space technology will develop faster. I was also a kid and I thought, “2020 is so far away! By that time we'll be walking around on Mars or Venus or wherever. And you'd be running around in spaceships all the time.” That hasn't indeed materialised, it's a lot more difficult than people thought in the early days. And the same for nuclear energy, by the way. I thought all energy would be nuclear, and they wouldn't need to pollute our atmosphere with carbon dioxide because we wouldn't burn fossil fuels, we would just use nuclear energy, So why don't we do that? And it all means that the questions are more difficult than originally realised. I'm also surprised that artificial intelligence didn't develop faster than it actually is doing. I thought that by this time, all computers would be at least as intelligent as human beings themselves. And that also did not materialise. I think some of these things will come. I think that the cosmos, well, not literally the cosmos that you talked about…

SS: But our extension to deep space, do you still think it's possible?

GH: What do you call ‘deep space’? The Solar system can be reached by human beings–

SS: Some beautiful planet in the Orion constellation?

GH: Well, wait a minute. Don't go too fast.

SS: Okay, Mars.

GH: Our Solar system has a bunch of objects, which are suitable for human life in principle, and they will be probably very uncomfortable unless technology improves a lot. You have to be able to make very expensive homes in those places. And I think in principle, technically, it's possible. We've already sent our robots to Mars and many other places in the universe. So all they have to do is make a decent house to live in, and all the comforts that we need as humans, and then we will travel there and will inhabit the entire Solar system eventually. These things are possible in the time span of 50 or 100 years or something like that. But there's another thing you mentioned – a planet somewhere in Orion. That's not our story. You know, these are really far away. Those stars are tremendously far away. And it takes probably thousands if not millions of years for a spaceship, manmade spaceship, to reach those other planets. You can't put a human on them because they’ll not survive for millions of years. Even if they are asleep they won’t survive that because it's too much radiation and all that sort of thing. So it's going to be very, very difficult for humans to travel that far. I don't think that will ever happen. But robots eventually will go there. The first thing robots will do is they colonize our planets. They're doing that already with Mars and the Moon, things landing there all the time. And they do investigations still in the way that’s very primitive. In eyes of someone say over a few hundreds or thousands of years from now, they'll say, now we really know how to send robots anywhere. And these robots will be smart enough to build houses for humans to live in and then the humans will come after those robots. This is the way I see it, those robots might, in millions of years of time, be able to reach those other planets. But I'm talking about millions of years, so that's a long time for any human standard, but it's short in terms of the universe, in terms of evolution. A million years ago we were monkeys, but that is nothing in evolutionary terms. Life was a thousand times earlier than that and has developed all the time. So in the face of evolution, a million years is not much. So if that's the timescale you have to use, and that will be the timescale at which even humanity eventually will reach the other planets, but not before that. 

SS: Okay, two more questions left. First of all, where's the quantum computer that everyone is claiming is going to be here if not tomorrow, then the next week, for sure?

GH: Well, I have a slight problem with the quantum computer because it is claimed to be able to solve problems that no other classical computer can. But I'm saying at the same time, that eventually, the laws of nature should be just like the classical laws. So logic should be classical logic. And I believe in that, which means that something must go wrong with a quantum computer. But in practice, the quantum computer can still work very well because when things go wrong they go wrong at a very, very tiny distance scale and timescale, so tiny that for all practical purposes the quantum computer will function. We will need quantum mechanics to describe it and it will do miracles compared to ordinary computers.

SS: Like what?

GH: Like solving difficult problems, difficult combinatorial problems, search problems, finding things that are impossible to find. Codebreaking is a very interesting application for computers, they can fracture very large numbers into their prime components much better than any classical computer can. These things will happen –

SS: When?

GH: That I don't know. I'm not really an expert in the quantum computing business.

SS: In your view, approximately?

GH: In my view, a couple of decades or so that quantum computers will be able to do very specialised tasks better than other computers. But most tasks, I don't believe, will be done better by quantum computers. So I think we should continue constructing old-fashioned computers because, in practice, they will be much better.

SS: And also, you know, we, humans, are talented, we invent beautiful things. But then somehow we'll manage to make horrible things out of those beautiful things. Do you think that quantum mechanics could also be weaponised?

GH: I think practically anything can be weaponised. So that's an awful side effect of science that our enemies can also use it. Our criminal enemies can do crimes with science, dictators in other countries can dictate the people using science. Yes, that can happen. There's nothing we can do about it. But we want to use science to better human life if possible, to enable humans to do things that would otherwise be impossible. You just asked about the colonisation of outer space – without science it’s unthinkable. So yes, that's the way we want to use science. But we can't prevent that some will use science in the way that we don't like. We're not under control. We can't just tell a dictator not to use science to suppress his own people or things like this.

SS: Professor ‘t Hooft, thank you so much for this amazing in-depth talk about the universe and how it works. I wish you all the best of luck with your future inventions and openings and looking forward.

GH: Thank you very much.

SS: Thank you.