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18 Dec, 2020 07:09

God does play dice – physicist

What is life? Despite the best efforts of scientists, this fundamental question is still a conundrum. Professor Paul Davies, physicist, astrobiologist, cosmologist and best-selling author has his own formula for tracing the answer.

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Sophie Shevardnadze: Professor Paul Davies, physicist, astrobiologist, cosmologist, best-selling author, really great to have you with us today. So much to talk about, especially information because I'm a journalist and I work with information a lot. Now you're interested in this concept of organised information. For me as a journalist, information is more abstract of a concept than mathematicians think of it as like bits and binary codes and stuff. Without making it too complicated for my audiences, сan you explain, what is information in physics?

Paul Davies: Right, you're correct that we use that word in daily life and we have a sort of rough and ready idea of what information means. The best definition is that it reduces uncertainty. So for example, if you're going to go in Moscow, to the metro, and you just go random, you might wait, I don't know, 10 minutes or something for a train to come along. But if you have a timetable, it reduces your uncertainty as to when the train will arrive. And that definition actually can be made very mathematically precise. About 70 years ago, what we now call ‘information theory’ was based on that notion of reduction in uncertainty. I’ll give another simple example: you toss a coin, did it come down heads or tails? I don't know if you use that expression in Russia, but one side or the other. And you don't know. But when you look , you get the definite information, you acquire one bit of information. So that's the technical definition. And so in using that we can apply it to biology, to the nature of life. And it was recognised a long time ago, when the famous double helix of the structure of DNA was worked out. The DNA stores the genetic information, it's the blueprint, if you like, of what makes you you and me – me. And that information has to be stored and processed, and read out, and managed, and manipulated. And so we all recognise that part of what makes living systems so important is that they can pass on or express that information and pass it from one generation to the next, while they express it by the DNA, making proteins or carrying out certain functions. So that's the basic idea about how all that came to exist in the first place, is still a very big mystery.

SS: All right, so treating information as if it, not matter, was the stuff out of which the world is built, is one of the avenues in thought that you're pursuing, right? So what do you get as a scientist when you treat information this way? What kind of new understanding about the universe can you find if you accept hypothetically that information is the primal building block of our world?

PD: You've raised a very interesting issue that we understand that as a practical matter, information is critical to the operation of biological systems. And there's a whole field called ‘bioinformatics’. And now you all know about gene editing, that we can treat DNA like the code book of life, and you can get in there and you can actually edit it and change some of the letters and some of the meaning and you can create your own life form. So this is current technology. So we all understand that. But you've asked a deeper question about whether somehow, information is the primary stuff out of which the universe is built. And the American physicist John Wheeler, who coined the term “black hole,” he was a great advocate of this idea that at the bottom of what we might call ‘the great chain of being’ is information, not matter. We think of atoms or electrons or something, we normally think they are the primary stuff, but he said, “No-no, information is the primary stuff, matter is simply a manifestation of various states of information.” And so he coined a wonderful term – “it from bit.” “It” might be an atom and the “bit” is the bit of information. And he felt that information is a primary source. Now that's still a minority view. But a number of my colleagues feel, “Yes, the universe is really a vast information processing network,” that  that is the ultimate reality. This thing we call “matter,” you can kick it, you can touch it, it seems solid, but that’s illusory. Deep down is all about information.

SS: So, regarding that question of matter, there's an equation of yours that I came across: Life=Matter+Information. So that means Information=Life–Matter, right? Can information be interpreted as ‘soul’ out of this equation?

PD: Well, ‘soul’ is a loaded term, of course, and it comes from a religious view of the world. So most scientists wouldn’t talk about soul as a separate thing, some fluffy thing that floats around alongside matter. But if by that, by the word ‘soul’, I would rather use the word ‘mind’, we think, how does the brain work? How do we have consciousness? So we've got this rather abstract thing called the ‘mind’, we have consciousness and we don't think of it as a substance, at least I don’t. But somehow, there's a matter story to tell, we have the brain, we have circuits in the brain, we  talk about electrons and signals going around in the brain. And then we've got this extraordinary phenomenon, called ‘consciousness’ and the two of them have to be fitted together. Now, I don't think we've done that yet. But I suppose your question is leading me in the direction to say, well, if information is primary, maybe we should think of mind as being primary and matter as being secondary. I'm carrying this a little bit far but that idea goes back into ancient history. It's called ‘idealism’. It goes back to ancient Greek philosophy that ultimately the world is built out of, as it were mind stuff, rather than matter stuff. That's a big stretch for modern physicists to go. But like many of these ancient ideas, there’s often a grain of truth in it. I think we're circling back to some of that ancient thinking.

SS: But I still want to like ponder on that a little bit because you talk in your recent book  how it works in cells and atoms, but how can information be on the same level as matter? I mean, doesn't information only exist when there is something or someone to read it? Isn't information basically confined to the eye of the beholder?

PD: Yes. You're absolutely right. And one of the founders of this whole fascinating area of information theory, in physics, Rolf Landauer, he famously said, ‘information is physical’. What he meant by that is that it doesn't sort of float free in the ether, it's always tied to matter. So, for example, I mentioned DNA, the position of nucleotides in DNA encodes the information in a biological organism. In a computer, it will be, you know, 1s and 0s stored in the hard drive or something like that. There's always a physical medium. But the same is true of energy. We talk about energy in an abstract sense, there's more of it or less of it, energy can be converted from one form to another and passed on between different systems. And the energy itself doesn't go away, make it spread out a bit . It's always somewhere in a physical system. But in a sense, it has a life of its own. So information is a bit like that. We can talk about it as if it has an independent existence and we do all the time. After all, Silicon Valley, in the United States, makes billions and billions of dollars by selling and manipulating information. And so, you know, it must, in some sense, be real. But it's always got to be instantiated in matter somehow, somewhere. But that doesn't mean that it can still be a primary concept. So information and matter go hand in hand, there's no doubt about it.

SS: If we're assuming that information is the primal thing or at least as primal as the matter, assuming that information is the foundation of the universe, isn't it kind of like saying that map of a town is the town?

PD: Yes. When does the map become the territory? If it's a 1:1 map, mathematicians will tell you then that the map is the territory. And I think what we're discussing here, and maybe we're hung up on this point, it's a little bit like the dichotomy between hardware and software in computing. We understand that a computer will only work if it's loaded with the appropriate software. And I often draw the analogy here with life. Life seems to me like magic but so does this computer. I'm talking to you on this computer. It looks like it's magic. How does it work? Well, if you went to a computer science department, and you went in and they pulled the back off, and they said, ‘well, if you look in here, there's silicon here and there's bits of copper and some other components and plastic’, and we're not completely sure how, how it all goes together but we're beginning to understand that what you’ve known that that was wrong, that you have to go to a computing department and they'll tell you all about the software, all about the code that's been written and uploaded into the machine and so on, you need both. But the software can't run without the hardware. But the computer is more than the hardware. And so you can argue, well, does the software have independent existence? Well, sure, in a sense, it does. Because I can copy it, I can put it on a memory stick, I can send it down an optical fiber, it's still there, it's like a pattern. So like patterns, you know, patterns exist in nature, but they always exist in something. They're instantiated in something. And so I think that's really what we're dealing with here. When it comes to biology, we have to go beyond just saying, well, there's a path, because we know that information has a more active or supervisory role in living things. So just think of the development of the embryo. It's not just a matter of information being read out. Everything has to be done – choreography has to be done in great detail. It's like a Bolshoi ballet unfolding, in the development of the embryo. So there's more to it than just counting bits of information. And I don't think we understand that more. There are laws that operate in living matter, involving information that we’re only glimpsing, we haven't yet completely worked them out. There's new physics in living better, I believe. So did Erwin Schroedinger, who started thinking about this way back in the 1940s.

SS: Paul, how is information connected to life in your eyes? I mean, I heard you say that living beings are information processing systems. This could sound too simple, but if we can for a moment accept that, is this what we are for – to process information, kind of like what we make computers for?

PD: Well, some cynics will say, yes, that your body is just a vehicle for mapping one lot of information into another lot of information. And so that's one way of looking at it. Stopped from havingto think about the nature of information in biology, so we've discussed already the example everybody knows, which is the information in DNA, which is copied, passed on to the next generation, it's expressed in the development of the embryo in a very complicated way. But it doesn't stop there because a cell – we all know we have genes and these genes can be switched on or off. But they don't act in isolation, they form complex networks, and information swirls around these networks. You can map it, people do. Biologists figure out what genes switch others on and they draw these network diagrams, like wiring diagrams in computation. And so there's a lot of information processing in those networks, and then cells signal each other, they are signaling molecules that send information from one to the other. There's great information processing system up here, between our ears. Everybody knows about that. And it doesn't stop, it goes right up that through ecosystems, right up to a planetary scale. And I think we're all these days obsessed by viruses and COVID-19. But you know, viruses are a central part of the planetary system, the planetary ecosystem, viruses get everywhere, they're like mobile, genetic elements or little bits of information that are passed around, and are essential for the health of the planet. And so I like to say that the planetary ecosystem, that life is the original World Wide Web. It's a web of information that extends to a planetary scale. So it's everywhere in life. But we understand only the bottom level of this information. I'm sure there are laws, I don't think these are miracles. I don't believe in anything like that. But I think we don't yet fully have that physics worked out. So that's the next great frontier. We have any young people, and I hope we do, watching us today, listening to this conversation that I would say, if I was going to make a career in science again, be  that intersection of physics and chemistry, and information theory, and biology, and computing. That's where the big discoveries will be made in the coming decades.

SS: So in one interview, you described life as a complexity that cannot be achieved through fixed rules. And there's a famous quote by Einstein, ‘God doesn't play dice’, meaning that there's got to be underlying laws for what seems random at the moment. Are you actually saying that God indeed plays dice if the rules of nature are not fixed, but flexible?

PD: Well, using Einstein's language, I am indeed saying, God does play dice. He was very much in a minority at the time. And experiments in foundations of quantum mechanics over the last few decades have really left no doubt that nature is intrinsically uncertain or indeterministic. So what Einstein meant by ‘God does not play dice’, he recognised that at the atomic level, things look sort of pretty random and chancy, but he thought that beneath that was a hidden layer of deterministic order, where everything that happened, happened for a very particular reason, that in principle, you could predict exactly what an atom would do, if you had that level of detail. We now know that that is not correct, that experiments have refuted that. So there is something intrinsically, indeterministic or chancy or open, if you like, it’s the term I’ve used, about systems on the atomic and molecular level. So quantum physics introduces that, absolutely, and quantum physics is essential to understanding life. But how these things fit together, how the uncertainty of quantum mechanics might fit together with the information processing that living organisms can carry out at a somewhat higher level, we don't know. But this is an area of active research at the moment. And so somewhere in that mix is the secret of life. And I come back to Erwin Schroedinger, one of the founders of quantum mechanics, who, in 1943, in Dublin, Ireland, gave his famous lectures with the title ‘What Is Life?’ and then wrote a book about that. And he recognised that quantum mechanics was essential for understanding the stability of the information content of cells. But he also left open the idea that there may be a new kind of physical law, operating in living matter. He didn't say what and he wasn't definite about it, but he was open to that idea. I think he was right. I think it is a new kind of physical law operating in living matter. It doesn't contradict the underlying laws, that's for sure, but it transcends, it’s in addition to them, because living systems are open systems. You can have both.

SS: One of your biggest ambitions, as far as I understand, is to find extraterrestrial life. And you say one of the reasons why we still haven't found it is because we don't really know how life on Earth first started. How is knowing how life on Earth started going to affect our research on alien life?

PD: Well, when I was a student, that was a long time ago, I’m a lot older than you, I was a passionate believer in life beyond Earth, and everybody told that it was crazy looking for aliens, people said that you might as well look for fairies, it's obvious that life is so complex, that it can surely have happened only once, the idea being that there was some sort of amazing chain of chemical reactions, leading to this very extraordinary, improbable thing we call life on Earth. But during my career, the pendulum has swung the other way. And now, many, many scientists say, ‘Oh, the universe is teeming with life, wherever you have Earth-like planets, it is a good chance life would emerge. But the truth is we absolutely don't know because the big step is how do you go from non-life to life? Is that something that is going to happen fairly easily, inevitably? Wait a few million years and it will happen? Or is it the case that it's like a freak, a sequence of chemical reactions, which put together are extremely improbable and may happen only once in the universe? And we don't know how to answer that because nobody's made life in the lab. We're a long way from understanding how chemistry turns into life, how the molecules organise themselves into something, even a primitive living thing. The gulf is huge between a mishmash of chemicals and even the simplest living thing. So we don't know, we don't know what numbers to put in there. And so if we don't know that number, we can't estimate how many inhabited planets are. We know that in the Milky Way galaxy, there are billions probably of Earth-like planets, of which life, as we know, it could emerge, at least if we took it there, it could survive. So we know there are plenty of candidates. But we don't know the chances that on those planets, chemical mixtures will turn into life. It could be that such an improbable thing, such amazing unlikely step, that it won't have happened anywhere else in the galaxy. Or it could be that if I'm right about these deep principles in operating and living matter, there are laws of life in living matter, but if we knew those laws of life, we might be able to say, ‘Oh, yes, those laws will operate to turn chemistry into life with 50% probability or 30% probability’, then we can put a number to it. At the moment, we don't have those laws, and we have no evidence whatever for life beyond Earth. So this is complete speculation, your beliefs, my beliefs are as good as each other’.

SS: So if we connect life to information in a meaningful way, does that mean that alien life could just be some form of information that is not related to having cells or certain chemical elements? Like could it be, as Douglas Adams suggested, ‘a particular shade of blue’, for instance?

PD: It’s a very good question and it goes to the heart of what we're trying to achieve in our research in the Arizona State University because everybody knows it’s a field of astrobiology, it means, going to look for life beyond Earth. But of course, you have to know what to look for. And we know what terrestrial life is like. But what we would like really is to have some sort of more general definition of what is life. And that definition, in my view, is based on the software, not the hardware, it doesn’t matter the stuff of which a living organism is made, it's the way that information is organised and processed. So if it's the case, that life, if we can define life as a particular type of information or pattern or organisation, it's organised information, not as any organization… but let’s give it a very specific definition, it has to be organised in a certain way. Then, for my money, we would go look for that informational signature, the software signature, if you like, instead of the hardware signature. So instead of concentrating on does this or that planet have the right sort of molecules, we will be more thinking about does it have the right conditions to allow information processing to take place in the manner that we think represents life. This is all wishful thinking at the moment, we don't have a fully worked out definition of life, which is independent of the stuff of which it’s made. But at the end of the day, that's what it will be about. If life beyond Earth exists it won't be a replica of our life. There will be some common principles and those principles, I think, are software rather than hardware. Just like you have different makes of computers and they're all made of, you know, with silicon chips or germanium or something and plastic and copper wires, they're all made of the same sort of stuff, but what gives individual computers a distinctive brand is the software and that software, just like the hardware has some deep principles, it all flows from certain basic ideas of coding, and so forth. The same is true of life, I'm sure.

SS: Well, Paul, it was such a pleasure talking to you, a true delight. And I hope we get to do this again because the subject is endless and there's so many unanswered questions still. Thanks a lot for this chat and good luck with everything. Stay safe.

PD: Thank you. I really enjoyed talking to you and I hope we can talk again.

SS: Thank you. Absolutely. Bye!