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WALTER ISAACSON: Brian, welcome to the show.
BRIAN GREENE, THEORETICAL PHYSICIST: Thank you.
ISAACSON: If you could solve three scientific problems, tell me what they’d be.
GREENE: Very clear what they would be. So I want to know the origin of the universe — I want to know the origin …
ISAACSON: Origin of the universe and we’ve gotten a little bit closer.
GREENE: We’re closer — we’re closer but if you were to say to me so why did it start at all? We still don’t have an answer to what happened at time zero. It’s an origin of the university, origin of life. How did these particles coalesce and come together to yield living, breathing things like us. Again, we’re getting closer but certainly we can’t create life in the laboratory yet. When we can do that, then I would say that we’ve really cracked that problem. And the third is the origin of mind, the origin of consciousness. As we were talking about, how is that particles that don’t seem to think on their own; electrons and corks. Do they cry, do they have emotions? I don’t think so but somehow they all swirl together and here we are having an inner life that somehow lights up. What turns on the lights in there? I don’t know.
ISAACSON: Explain to me how quantum computing works.
GREENE: There actually are small quantum computers in existence now. So this is not just pie in the sky. If classical computer, the ones that typically use, it goes step and step and step and step. Everything is sequential and everything is definite. In the quantum world you can do all of these fuzzy calculations at the same time and have them coalesce into the answer that you’re seeking, which means you can do the calculations far more quickly. You can do the analysis far more quickly. You can tackle problems that a classical computer couldn’t touch. What would that mean for our lives? To me that the real — the real possibilities of quantum computing are to undertake problems of today we simply couldn’t even approach using classical ideas or which we will take to a spectacularly new level. I mean one that comes to mind is machine learning. So machine learning has the capacity to transform everything. And we are used to having devices be it a bulldozer or a jackhammer that extends the power of the human form to do things that otherwise would be impossible. But that’s just sort of a stronger, faster, leaner version of ourselves if you would. It doesn’t really replace creativity in the human intellect. Machine learning, many people suspect, may be able to do that. When a machine can actually look at large data sets and not me told how to analyze them but learn by seeing the patterns that’s what we do, we are pattern recognition machines and when a computer can do that, then we’re in a completely different arena. And that we see starting to happen and quantum computing is a very powerful means for recognizing patterns to dealing with large data sets. So this is at least — you know its decades off but this could be a place where we begin to really see computers doing the things that for the most part, for all of human history, we have viewed as intrinsically us.
ISAACSON: And that includes creativity, you said.
GREENE: I think so.
ISAACSON: But it seems to me creativity means something a computer couldn’t do, which is thinking outside of a rule. Tell me why that’s
GREENE: Well, we like to say that because we like to think that we’re special and I don’t mind the human species being a special entity in reality but the fact of the matter is, creativity may well be seeing unusual and hidden patterns within data, manipulating those patterns to a powerful effect. And that happens inside this thing inside our head, this grey gloppy thing and I think it just operates by the rules of physics. And if it operates by the rules of physics and doesn’t have any other kind of inspiration, why can’t a device outside of a grey gloppy thing inside of our heads also undertake those very same kinds of calculations, computations, and analyses (ph). So I think it’s very possible that one day they’ll be somebody in that chair who is able to carry out this kind of interview that we’re interview that we’re having and certainly somebody will do a better job than I am right here. And that is when we cross a threshold into a brave new world
ISSACSON: That gray gloppy thing you referred to, it has consciousness. Is consciousness explainable by physics?
GREENE: I think so. I don’t have any proof of that. Now we’re just in the territory of gut feel at the moment. But again, I don’t think there’s anything going on inside our heads that isn’t ultimately the motion of particles and the oscillation of fields (ph) and we have equations that describe those processes, they may not be the finale equations. One day perhaps we will have them but I don’t think we (ph) need anything else but physical law to describe ultimately what’s happening inside of our heads. And from that point of view, consciousness would simply be a quality of the physical world when there’s a certain kind of collection of particles that come together in the right way and perform the right operations.
ISAACSON: You’ve been working — whether it be string theory and other things — on trying to capture what Einstein wanted to do. Which is a unified theory that would connect quantum to gravitation to relativity and everything else. If we had a unified theory, wouldn’t we — wouldn’t it all fit together again and not everything would be probabilities?
GREENE: Well, if you believe Albert Einstein’s vision, then indeed that’s where we would be heading. Einstein thought that if we could just get a unified theory, all of this quantum stuff — that was certainly working at describing the data, he couldn’t deny that. But he thought it’s just a stepping stone to the deeper understanding and when we get there, no more talk of probabilities, no more talk of entanglement, no spooky action. That’s what he thought. But you know, he passed on a while ago, right? 1955. And in the half century since, every single piece of experimental data, every single mathematical development has pointed away from that vision. The vision that we have now is that the quantum world is here to stay and just accept it and get on with it, because having that old vision is coming from an intuition that was built up over a long course of human history, but it’s the wrong intuition.
ISAACSON: So you don’t think there’s a unified theory?
GREENE: I do think there’s a unified theory. I don’t think it will accomplish what Einstein hoped it would.
ISAACSON: In other words, we’ll still have uncertainty —
GREENE: We’ll still have quantum uncertainty and we’ll still have quantum probabilities and all this weird quantum stuff will still be with us. The advantage of the unified theory is finally we’ll put together our understanding of gravity and our understanding of quantum physics into one unified whole. That would be progress. But I don’t think that progress will wipe out the quantum understanding.
ISAACSON: The other great advance in the past couple of years was cosmic background radiation came along. What did that explain to us?
GREENE: Well the cosmic microwave background radiation is our most powerful insight into cosmology. We all want to know how the universe began. And again, with Einstein’s general theory of relativity updated by more sophisticated versions of the cosmology that it gives rise to in recent years, we have a pretty good sense. In the early universe we believed that there was a kind of repulsive gravity that drove everything apart, rapidly stretched the fabric of space. And when we do our calculation, that stretching would have also stretched out little, tiny quantum uncertainty in the early universe. Sort of like if you have a piece of spandex. When you stretch out the spandex, you can begin to see the pattern of the stitches. We believe that we can see the stitching of the fabric of space through the stretching, and that is the microwave background radiation. And we can do calculations that predict how the stitches should look, tiny temperature variations across the night sky. And holy smokes. When we do the observation and we compare it to the calculations, they’re spot on accurate. We’re talking about processes that happened 13.8 billion years ago —
ISAACSON: Wait, wait. So 13.8 billion years.
ISAACSON: Something happened. And then what? This wave came and it finally hit us?
GREENE: That’s right. That’s right. When we look up in the night sky and see the microwave background photons, they’ve been traveling toward us for over 13 billion years. And those little tiny packets of light have just the right properties that our mathematics predicted they should. So we human beings crawling around on this little planet 13.8 billion years later are able to develop equations that seem to give us insight into processes that happened billions of years ago.
ISAACSON: So what does that tell us about how the universe began?
GREENE: Well, we think it probably began as this very compressed, tiny nugget that was filled with an exotic cosmic fuel. We call it the inflation field. The name doesn’t matter much. But it’s a fuel that gives rise to an exotic kind of gravity, this repulsive gravity that pushes everything apart. That’s the bang in the big bang and we’ve been living through the aftermath of that cosmic explosion ever since. And the only reason why we believe these ideas is because of microwave background radiation so completely agreeing with what our predictions say it should look like.
ISAACSON: You know, the cosmic background radiation helps understand what happens in black holes. That’s been one of your fascinations, which is the edge of black holes. First of all, let me ask you about your “Icarus at the Edge of Time”, how you try to explain that through art, through children, through music.
GREENE: Yes, well I think that these ideas need to be widely understood, widely discussed, widely shared. And so if they stay within the hallowed halls of universities or esoteric journals, it really doesn’t get out there. So we’ve tried various — you know, unusual blendings of science and art to try to reach a broader audience. In this piece you’re referring to, I collaborated with Philip Glass. I wrote a short story. Journals, it really doesn’t get out there. So we’ve tried various, you know, unusual blendings of science and art to try to reach a broader audience. And this you’re referring to, I collaborated with Philip Glass, I wrote a short story. It was a rewriting of the myth of Icarus, where the boy doesn’t go near the sun with wax wings. He built a ship and flies through the edge of a black hole. And what happens is near the edge of a black hole, time slows down. So when he comes back, thousands of years have gone by on earth, but only a couple hours for him. So his dad is gone, his family’s gone, so it’s kind of a traumatic story. But Philip liked it and we turned it into a live stage work where there’s an orchestra, a film and a narrator that kind of takes the audience to the edge of a black hole.
(BEGIN VIDEO CLIP)
UNIDENTIFIED MALE: We’re navigating to avoid an unchartered black hole. A black hole? Cool.
(END VIDEO CLIP)
And when you have that kind of experience, it doesn’t just make your head hurt it kind of makes your – your heart pound, right? If you get into the story, you can feel the chill of the experience. And I’ll tell you – you know, let me just tell you one thing, my son when – when he first encountered the story that I wrote, at the end he was crying. And someone said well don’t you feel bad? You wrote this story that made your son cry because the dad is dead. And so I said no, if general relativity which is ultimately what’s in this story can make a five year old cry, it’s a good thing. That kid is feeling the science. And you need to feel these ideas in order that they aren’t just esoteric, abstract nonsense.
ISAACSON: So much of this stuff is not something we can apply in our daily lives. We’re never going to go near the edge of a black hole, we’re never going to travel near the speed of light. Why is it important that we understand it?
GREENE: Well my own sense is that the universe is incredibly rich and you don’t have to know these ideas to live in this world. My mother doesn’t know these ideas. She says they give her a headache, and I totally get that and I respect it. But if you can get these ideas, it opens up a reality in wondrous ways. I mean to walk down the street and think that time for you is elapsing at a different rate from somebody on a street bench, right? To look up into the night sky and be able to think about the quantum processes that do give the microwave background radiation. To think about quantum physics, allowing us to tunnel through barriers or have these strange, spooky connections, it’s just wondrous. And how tragic if people are cut from these ideas simply because they don’t speak the language of mathematics and physics. That’s why I think these ideas need to be brought out to the world in many various ways.
ISAACSON: Explain to me, though, that notion of you walking down the street and you’re saying to yourself time is traveling for me differently than this person moving in the other direction?
GREENE: Yes, well you know I’ve tried to see what it would be like to live these ideas. So at times I’ve forced myself to go around the world and really imagine in detail what’s going on, the time and the space and the quantum physics. And yes, one of the key ideas of relativity is when you move relative to somebody else, your clock is ticking off time at a different rate. And it is very hard to hold these ideas in mind, because you are assaulted all the time by conventional reality telling you that all clocks tick off at the same rate, which is wrong. It’s false. But it’s hard to live with the truth because so much of your experience contradicts it, it’s counterintuitive because these effects are very small in everyday life. But I find there’s something deeply wondrous every so often in actually living these ideas.
ISAACSON: So if I walk down Broadway today, what am I supposed to observe and watch and think?
GREENE: Well first of all, recognize that the sidewalk is mostly empty space and that you’re actually not touching the sidewalk because it’s actually the electrons in your shoes that are repelling against the electrons in the concrete. So you’re floating as you’re walking along Broadway. And yes, your time is elapsing at a different rate than someone who’s sitting relative to your motion, your time is also elapsing at a different rate from someone who’s at the top of the Empire State Building. Your watch is going slower than theirs.
ISAACSON: Because their gravity is different?
GREENE: Their gravity is a little bit less.
ISAACSON: And so why – why is that?
GREENE: Well the answer comes from Einstein’s theories. I can imagine a world where that isn’t the case. So it’s not like I can say logically it had to be that way, but in Einstein’s general relativity, gravity doesn’t just pull on matter, it also pulls on time. And when it pulls on time, it makes time elapse more slowly. So at the surface of the earth where gravity is a little bit stronger, the pull is stronger, time goes slower than at the top of the Empire State Building. Yes, it’s crazy.
ISAACSON: Brian Greene, thank you, pleasure.
About This Episode EXPAND
Christiane Amanpour speaks with CNN Correspondent Bill Weir and former Mexican Foreign Minister Jorge Castañeda about the migrant caravan traveling through Mexico, and former Commander of U.S. Forces in Afghanistan Ret. Gen. Stanley McChrystal on whether America is losing its longest war. Walter Isaacson speaks with theoretical physicist Brian Greene about the origin of life and the universe.LEARN MORE