Paul Davies on the Three Origin Mysteries: Universe, Life and Consciousness

Paul Davies introduces himself as a theoretical physicist and cosmologist, a professor at Arizona State University and director of the Beyond Center for Fundamental Concepts in Science, who has written more than 30 books, including The Demon in the Machine on the nature of life.

He says there are three origin mysteries: the origin of the universe, the origin of life, and the origin of consciousness. In his view, the origin of the universe is reasonably well understood. The origin of consciousness is harder, because researchers do not yet know how to frame the questions or which conceptual structure applies, so he calls it deeply mysterious. The origin of life is being worked on, and he says he can imagine a good understanding within a few decades.

Davies says life is best understood as hardware and software, which he describes as parallel narratives that do not conflict. He adds that the software aspect has been largely neglected until recently in attempts to understand the origin of life.

He argues that a full understanding of life requires integrating the two, and that science is still very far from achieving that.

Davies recalls that 100 to 150 years ago, some believed life required an additional force, the élan vital in French, to animate matter. Over time, this vitalism came to be linked with other mysterious forces in physics, such as electricity or radioactivity.

He says these ideas became thoroughly discredited.

Davies says Charles Darwin offered a theory of how life evolves once it is established on Earth, explaining how it produced the complexity of today's biosphere over billions of years. Darwin, however, would not address how life first began.

This leaves the question of how non-life becomes life. Davies quotes Darwin as saying that talk of the origin of life was mere rubbish at that time, comparing it to talking about the origin of matter.

By around the 1920s, interest had shifted to the chemical pathway. In the early 1950s, chemist Harold Urey managed to interest a young student, Stanley Miller, in recreating the conditions of the early Earth. They did not really know what those conditions were, but they guessed there would be certain gases in the atmosphere, along with water and lightning. Miller put a number of gases in a flask and sparked electricity through it for a week. He was gratified to find that amino acids, the building blocks of proteins, had been formed, and a brown sludge had collected at the bottom of the flask.

Davies says this addressed the hardware of life but not the software, because it defined life by its chemical components rather than by what it does, and he considers this still a deep problem.

Davies says the concept of information is critical to understanding the difference between life and non-life, even though people use the term informally. He offers a general definition: information is reduction in uncertainty.

His example is a coin flip. Before looking, the outcome is uncertain at 50/50; once you learn it is heads, that uncertainty is reduced and you have acquired one bit, short for binary digit.

He then turns to life. Removing a bacterium's DNA and scrambling its base pairs leaves the same amount of information but makes the cell effectively dead, much as shuffling the words of a book keeps the content count but destroys its meaning. For Davies, the point is that information in living things must function in context.

Davies asks whether there was a simpler precursor code four billion years ago, and whether early organisms used a different code, perhaps with fewer amino acids than the triplet code used today.

For him, the key question is how complex molecules came to write their own code, which amounts to a computer code. He says he thinks this is a deep mystery and that researchers have not come close to understanding that step.

He identifies the critical point at which something becomes alive as the moment when an abstract mathematical code appears, and he says science does not yet know how that happened.

Looking at life's feats, Davies says the right description is information management: information must be embedded in a larger biological system and organize what the organism does. He notes that physicists find this difficult because they usually think locally about forces, while biology requires looking at the organism as a whole.

Davies describes experiments by Michael Levin and colleagues at Tufts University using planarian worms. If a worm is cut in two, the head grows a tail and the tail grows a head, and a worm can be divided into around 100 sections, each of which regenerates into a worm that knows its front from its back.

Chemical manipulation can produce two-headed and two-tailed worms. When a two-headed worm is cut, it produces two more two-headed worms rather than reverting to the original form. Two labs can thus have populations of two-tailed and two-headed worms with identical DNA.

Davies says this shows that the body's form depends on much more than DNA content, and that the form-related information is stored somehow, possibly electrically or chemically, though not yet well understood. He treats this as a clue that focusing only on genes misses a large part of the picture.

Some people think life's mystery lies in the second law of thermodynamics, because living organisms seem to create order from disorder. This has led some non-scientists to suggest a mystical life force or a guiding hand.

Davies calls this a total misunderstanding. The second law, strictly stated, says that entropy in a closed system can never go down, but living organisms are open systems that exchange energy and material with their environment. They can export their entropy into the wider environment. Eating food maintains internal order while creating disorder in the surroundings.

He notes that a refrigerator does a similar thing: it moves heat from cold to hot, which is against the spontaneous flow, but it does so because electricity is paid for. Considering the whole system, including the electricity supply and generator, the total entropy still increases. He adds that life's overall trend is toward higher entropy, and that life is simply playing the margins of that trend.

Davies recalls that Erwin Schrödinger wrote in What Is Life? that a new kind of physical law must be operating in living things. Davies says the key word is kind: Schrödinger was not saying a single undiscovered law would explain life.

Davies says he has taken this seriously and believes a new concept of law is needed, not simply another force. At present there is no general lawlike framework for describing how biological information and matter, the hardware and software, interact in living organisms. Local laws, such as gravity acting on an object, are not enough; the organization of the whole system must be taken into account, and he suggests this would need physical laws at the bottom level and higher-level laws of organization at the top.

Davies says the definition of life and its origin is shaped largely by life on Earth, so researchers look at early Earth conditions and today's conditions for life. These may not be the same. The origin of life might require one set of conditions, while thriving requires another.

He notes that microbial life can travel between planets through impact ejecta, so early Mars could have been a better place for life to begin, while early Earth was better for it to flourish.

When searching beyond Earth, researchers tend to look for Earth-like planets. Davies recalls that when he was a student, the prevailing view was that life was a bizarre chemical fluke, and that interest in life elsewhere was almost unthinkable. He says that view has since shifted, and that many scientists now say the universe is teeming with life, a change he questions because life's known limits have widened.

Davies says organic does not necessarily mean living. Organic molecules are complex carbon molecules that may come from living organisms or from ordinary complex carbon chemistry, and telling them apart is difficult.

He describes the hope for a spacecraft instrument that could fly through a plume, collect material and deliver a verdict on whether it is living. He acknowledges that researchers do not know what such an instrument would detect, or what would distinguish something living from something that has broken down.

He also raises dormant life. A bacterium cooled to very low temperatures becomes dormant rather than dead, and some bacteria trapped in ice or salt have been revived after millions of years. He compares this to a stopped clock, which is still a clock.

Davies describes Titan, a moon of Saturn, as very cold and unlikely to host life as we know it, but full of organic molecules, like a prebiotic smog in its atmosphere. He suggests it may have carried out a kind of cosmic Miller experiment for four and a half billion years.

He asks how one would know whether such chemistry had succeeded. A life meter sent into Titan's atmosphere might report no life, or might say it reached a percentage of the way to life, but researchers do not know how to measure partial progress toward life or how to think about almost-life.

He ties this to Richard Dawkins's book Climbing Mount Improbable, in which each step may be improbable but natural selection locks in gains, climbing a mountain of complexity that starts with chemistry.

Davies says nobody has seriously pursued the idea that life could have arisen on Earth many times. He suggests life may have started around 500 times and only one form survived, and asks whether another sample of life might persist in some niche beyond the reach of known life.

He calls this speculative idea the shadow biosphere: microorganisms from another genesis event, which would be a different tree of life altogether rather than a new branch. He says that, on careful examination, we would probably not have noticed such organisms, so they could be around us now without anyone looking for them.

Davies says photosynthesis appeared around two and a half to three billion years ago and led to a buildup of oxygen in the atmosphere. Oxygen is a corrosive poison, and when it first appeared it threatened to wipe out life. It was a pollutant until some life adapted and used oxygen as an energy source.

Oxygen also changed rocks. He contrasts Earth with Mars, which looks red because of rust, and which lacks plate tectonics and the recycling mechanisms that keep Earth's elements cycling. He describes a feedback loop in which life and planetary cycles affect each other over billions of years, and says it is unclear how often a planet with such interlocking cycles would exist.

Davies says a super-intelligent, multi-generation designed system would likely have godlike features and be well beyond human understanding. He says combining AI with quantum computing makes the picture even more profound, calling it quantum artificial intelligence, or quintelligence as Frank Wilczek calls it.

Such an entity could explore not only the possibilities human minds can conceive but all possible quantum alternatives and worlds, with a far greater range of possibilities and processes. He suggests that a civilization that had existed for around 500 million years would be overwhelmingly likely to be dominated by these godlike, mysterious entities.

Davies says the traditional view of physical laws, since Newton, treats them as fixed, immutable mathematical relationships stamped at the origin of the universe. He asks whether they might instead be more malleable, and whether the emergence of life and mind could be causally connected to the laws that give rise to them.

Davies describes a possible feedback loop in which life affects the laws that then produce life. At first sight, he says, this seems completely impossible, but he points to a loophole in quantum mechanics based on uncertainty. John Wheeler's delayed-choice experiment suggests that the past is not a single fixed history: whether a photon was a wave or a particle in the past can be settled by the experimenter's choice made in the present. Davies stresses that this does not send information back in time or change the past. Instead, the past is ambiguous, and if something done today resolves an ambiguity about the past, then what happens now is linked to what happened before, without backward causation. Davies says this is the view he favors, and that Wheeler, who came up with the delayed-choice experiment, strongly influenced him.