'I predict a great revolution': inside the struggle to define life
All the brain cells of life on Earth still cannot explain life on Earth. Its most intelligent species has uncovered the building blocks of matter, read countless genomes and watched spacetime quiver as black holes collide. It understands much of how living creatures work, but not how they came to be. There is no agreement, even, on what life is.
The conundrum of life is so fundamental that to solve it would rank among the most important achievements of the human mind. But for all scientists’ efforts – and there have been plenty – the big questions remain. If biology is defined as the study of life, on this it has failed to deliver.
But enlightenment may come from another direction. Rather than biology, some scientists are now looking to physics for answers, in particular the physics of information. Buried in the rules that shape information lie the secrets of life and perhaps even the reason for our existence.
That, at least, is the bold proposal from Paul Davies, a prominent physicist who explores the idea in his forthcoming book, The Demon in the Machine. Published next week, it continues a theme of thinking that landed Davies the $1m Templeton prize for contributions to religious thought and inquiry.
“The basic hypothesis is this,” Davies says. “We have fundamental laws of information that bring life into being from an incoherent mish-mash of chemicals. The remarkable properties we associate with life are not going to come about by accident.”
The proposal takes some unpacking. Davies believes that the laws of nature as we know them today are insufficient to explain what life is and how it came about. We need to find new laws, he says, or at least new principles, which describe how information courses around living creatures. Those rules may not only nail down what life is, but actively favour its emergence.
To understand what bothers Davies, consider a hypothetical device: a life meter. Wave it over a sterile rock and the dial stays at zero. Wave it over a purring cat and it swings over to 100. But what if you dunked it in the primordial soup, or held it over a dying person? At what point does complex chemistry become life, and when does life revert to mere matter? Between an atom and an amoeba lies something profound and perplexing.
Davies suspects that information is the answer because it seems increasingly fundamental to both physics and biology. In recent years, physicists have shown that information is more than the bits and bytes that course through computers. Information can be converted into energy, for example, such that physicists now build little information engines and information-powered refrigerators, if not with the appearance their names suggest.
Similar machines are found in biology. Constructed from proteins, they chunter away inside living cells where they manipulate information at the nanoscale. “What we’re seeing in the lab is these two worlds colliding in a very practical way,” he says. “The physics is really connecting with the biology and that’s why I think we’re on the verge of this great new revolution.”
Davies believes that life will turn out to bear telltale patterns of information processing that distinguish it from non-life. Few people would argue that a computer is alive no matter how the ones and zeroes zip around inside it. What Davies suspects is that life exploits, and arises from, particular patterns of information flow.
“When you look at a living system, the way information is managed is very far from random. It will show patterns that could lead us to a definition of life,” he says. “We talk about informational hallmarks and these might be used to identify life wherever we look for it in the universe.”
It is not always easy to convert speculation into science. One of the hurdles Davies raises is the difficulty in describing biological information in terms of mathematics. It is a necessary move if new laws of life are to have any meaning. “I really think we need new physics to understand how information couples to matter and makes a difference in the world,” he says.
Find these new rules and the future could look very different. Davies anticipates “digital doctors”, who will analyse information flows in cells to spot aberrant patterns driven by early cancers and other diseases. When pathological patterns are found, they could be corrected through some form of molecular shiatsu, he suggests.
Most radical, though, is Davies’s proposal that any laws of information that shape life might favour its emergence too. Under this scenario, life would not arise on habitable planets by random chance but would be nurtured by “biofriendly” rules. It is the kind of teleological argument that many scientists reject, but one that Davies cannot help finding attractive.
“People often say that the probability of life forming by chance is so low there must have been intelligent design or a miracle. I find that anathema,” he says. “Religious people have got to move on and get away from the idea that there’s a superbeing who fits it all up. What I find more congenial and much more intellectually respectable is the notion of fundamental laws of organisation that turn matter into life – a life principle built into the laws of the universe.”
He concedes: “It is wishful thinking because at this stage I can’t demonstrate it. But if we live in a universe in which the emergence of life is built into it in a fundamental way then we can feel more at home in the universe. It’s no substitute for a caring superbeing watching over us. It won’t help us deal with the problem of death, and it doesn’t help in a moral crisis, but it would certainly be more comforting than to believe we live in an empty, sterile universe.”
Before leaving Britain for posts abroad, Davies worked under Fred Hoyle, the maverick former director of the Institute of Astronomy at Cambridge University. Davies concedes that his one-time mentor helped him to keep an open mind in science. Hoyle was a brilliant academic but among his more fanciful proposals was that flu pandemics were spread by viruses that rained down on Earth from passing comets.
“He was one of these curious people who did some really great things and then some really crazy things,” Davies says. “What I did learn from Fred was not to be afraid of wild thinking.”
As director of the Beyond Center for Fundamental Concepts in Science at Arizona State University, Davies is well placed to spot the next wave that will crash over science. What he sees on the horizon is a revolution that brings physics and biology together through the common science of information.
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