Professor at Arizona State University, Paul Davies is a theoretical physicist, cosmologist and astrobiologist who has researched the origin of the universe and life.
At the Quantum Bio BR Summit, organized by Pioneer Science in partnership with the University of California (UCLA) and the D’Or Institute for Research and Education (IDOR), he presented a lecture inspired by the book “What is Life?”, written by physicist Erwin Schrödinger, in 1944.
In this interview, Davies talks about the origins of life, a fascinating research topic that hinges upon an exciting new field of science that connects chemistry, physics, biology and information science. He talks about how quantum biology can play an important role in explaining the behavior of living things.
Paul Davies: I’m trained as a physicist and when I look at living systems and at living matter, it seems like some sort of magic, like something extraordinary, quite unlike anything else that physicists encounter. And the reason that it is fascinating is, of course, because when you have two different sciences that don’t meet properly in the middle, it suggests there might be some new laws or principles at work. There are two sciences: one is physics, and the other is biology, and they don’t clash with each other, but they don’t mesh with each other either.
That was also what one of the founders of modern physics thought: Schrodinger, who in 1943, in Ireland, gave a series of lectures called “What is life”, which became a very influential book published the following year. As a physicist, Schrödinger was also like me: mystified by the nature of life, but he felt that physics might be able to come to understand it in some way. Well, all these decades later, we are still deeply mystified by the fundamental principles that make life tick.
But let me not confuse people, because if we look at any given process in a living organism, such as DNA and the way it is replicated, at the molecular level, everything seems to obey the known laws of physics. But when we put everything together and look at the system as a whole – the way it behaves, how it seems to have purposes and goals and engage in very complex behavior – these are very difficult things for a physicist to describe. We don’t even have yet the right conceptual framework to be able to say this is the way forward.
So, we’re stuck! At the level of atoms and molecules it’s known physics; at the level of the organism, it looks like magic.
Somewhere between the known physics and the magic, I suspect there is new physics, but we don’t know what it is yet, and that is a challenge for future generations of scientists to try to understand it: to see if there’s something emerging at some level of complexity in living organisms that would explain life’s remarkable properties. I’m not satisfied that life is explained by known physics – and we must keep an open mind about that.
If you go to a physics department and ask “what is life?”, the story you’ll be told is in terms of molecules, the forces between molecules, the shapes of molecules and quantities like entropy and free energy. In other words, it’s a narrative that people tell in terms of matter: of material objects and the forces between them. And that’s fine, but if you go to a biology department and ask “what is life?”, you’ll be told a very different story. They will talk about things like signals and replication – and these days very much about editing. In other words, they will talk about information.
We’re used to the fact that there is information in DNA and now we have the technology to rewrite the book of life: we can edit that information and create new life forms. So, biology is really all about information: not just information storage and information replication, but information management.
When I say life is chemistry or matter plus information, this is like in a computer, with hardware and software. People worry about the origin of life: how did life come to exist from no life. And most of the people who work on that problem are chemists, who hope that it’s possible to mix up molecules in some way and make life in a test tube. So, they see it as a problem of chemical complexity. But I think that’s only half the story – the easy half, that says that if you get all the right ingredients, eventually you could make the stuff of life. But what about the software? What about information management? And if you think again about a computer, to me, it seems like magic too.
But what we know is that the explanation for this magic does not lie with the fact that there is silicon, copper, plastic or any of the other things in my computer. We know that without that, there would be no computer. But if we want an explanation, a software engineer will tell you about the coding that had to be written to make the computer do its things so well. And it is the same thing with life. There is no point just getting the living material, the stuff of life: it must have an operating system, the software, and the data input, just like a computer.
The hard part of understanding life is the origin of that software – how was it that just molecules were able to write the software that makes life run. That’s the big mystery for me.
And what it suggests is that we’re probably missing something that is going to be some sort of a new law or physical principle, which emerges in living systems, and that explains that the way matter behaves depends not just on the forces in its immediate neighborhood but on the information content of the system. Now, I haven’t worked all that out in detail, I’ve only got just some sort of ideas about it. A lot of people are thinking about it too. But that’s where I think we will find new physics: somehow coupling the hardware and the software.
Of course, computers are designed by human beings – so there’s an intelligent designer. We would like to understand how life came to exist without an intelligent designer, because we don’t want real miracles or real magic, we would like a scientific explanation.
Yes, exactly. So, when we’re down at the molecular level, the laws of physics are not just the ones that we use in everyday engineering (the Newtonian laws), they are fundamentally quantum mechanical (the laws of atoms and molecules). And the difficulty we face is that if you take an individual atom in a living system, it obeys the laws of quantum mechanics, but if you take the whole organism, it doesn’t. So, there’s not an answer on how we go from the quantum realm, of molecular level, to the realm of cats and humans.
But we must be open to the fact that there could be some aspects of living systems which are fundamentally quantum mechanical even if they are on a relatively large scale. I don’t mean like a cat itself, but maybe something that would involve a very large number of molecules, because if they’re organized in a certain way there can be non-trivial quantum effects. We know this for example with the phenomenon of superconductivity – a material that conducts electricity perfectly because there are certain quantum properties that operate at low temperatures. So we know that it is possible: that quantum mechanics doesn’t break down on a scale of physical size. It seems that there are some phenomena in biology where quantum effects do occur even on length scales, which are large by normal quantum standards.
But we don’t know, and this is the big question that interests me: if these individual phenomena are just a few quantum quirks or if quantum mechanics is fundamental to the nature of life.
Of course, in one sense life is obviously quantum mechanical, because life is chemical and chemistry can be explained by the laws of quantum mechanics. But when we talk about the term quantum biology in this more modern setting, we’re really referring to processes such as entanglement and tunneling, where we see peculiar quantum effects that go beyond just molecular forces and shapes. It’s too soon to say whether life is fundamentally quantum mechanical in that sense or if it just got little bits and pieces where quantum mechanics is important.
The fundamental difficulty in trying to get to the bottom of this is that if you want to experiment with quantum systems, you usually want them to satisfy two things: one is to be simple and the other is to be isolated. And so if you take a single atom, for example, and put it in a magnetic trap (you can do this, you can trap atoms) and then interrogate it with a laser, you can do some very precise experiments to test its quantum effects. But if you’ve got trillions and trillions of atoms muddled up together inside living tissue, and if you’ve got a room temperature or body temperature, there are a lot of disturbing influences, and that makes it very hard to tease out the quantum effects that might be going on.
So that’s what’s standing in the way of us being able to answer this question, it’s just the sheer difficulty of dealing with warm wet microscopic systems.
If there is something new and exciting that might come out of a quantum effect on a larger scale, it would be at the level of assemblies of molecules. And maybe we need some new type of experimental technique that could get into that regime. You know, laboratory experiments are improving all the time and so there’s every hope that in the coming, say ten years, there will be a lot of progress made in that area. I think it’s particularly exciting at the intersection of chemistry, physics, biology, computing and information sciences, which we see at the level of molecular machines and large assemblies of molecules.
Well, I think history speaks for itself. Darwin conjectured in the middle of the 19th century about the origin of life: he talked about what we would now call chemical self-assembly. For at least 100 years chemists have experimented with different processes trying to get to the building blocks of life and they’ve had a little bit of success, but nobody has really tried to tackle this problem of information. And that’s why I think we need something new, because it’s not just a matter of somebody making the machinery of life and handing it over to another scientist who then uploads an operating system.
Many of my colleagues are reductionists, which is to say that they think everything will be explained at the molecular level and that we don’t need any mystical additional principle operating at higher levels. But that’s not science, it’s an ideological position, and I understand it and I think reductionism has worked in science very well. But when it comes to life it’s not a good fit, so we need something new.
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