Professor Paul Davies has a radical theory about the building blocks of life. They are reasonable enough assumptions to make, but what if they are plain wrong? Davies and co-author Dr Sara Imari Walker, both from the Beyond Center for Fundamental Concepts in Science at the Arizona State University, suggest that fleshiness and double-helixes might be things confined only to life on Earth. Life in the rest of the universe, they venture, could be based on something much more unlikely: information. What's more, Davies and Walker leave the door open – some say – to the involvement of a non-physical, perhaps godlike, influence in the development of life in the cosmos. The questions the pair raise might seem abstruse, but they are critically important. If humanity ever does encounter alien life it almost certainly won't look like the dreadlocked guys or insect-monsters in Alien vs Predator. It will be life, Jim, but not as we know it. Real aliens may well be completely unrecognisable as living.

Dr Sara Imari Walker, from Arizona State University, has co-authored a paper with Paul Davies arguing that information rather than chemicals could be the basis for life. "Without an understanding of 'life'," Davies and Walker write, "we can have little hope of solving the problem of its origin or provide a general-purpose set of criteria for identifying it on other worlds." The nature of information Their paper – The "Hard Problem" of Life – has yet to be formally published. Drew Barrymore in ET.

Last month the pair posted it on a science pre-print server called arXiv, and already it is generating discussion among astrophysicists, bioastronomers and science philosophers. The reason is clear. If "information" is shown to be the fundamental building block of life, the discovery will be a scientific revolution as game-changing as those of classical physics and quantum mechanics. Many pop culture extra-terrestrials, including the Sontarans from Dr Who, are assumed to have similar life structures to Earth's life forms. Mind you, it's a very big "if", and one that is attracting curt dismissal from some of Davies' peers. "I think their idea is interesting, but it begs the enormous question of how information can be causal in a physical system," said Dr Charley Lineweaver, of the Planetary Science Institute at the ANU's Research School of Astronomy and Astrophysics at the Mt Stromlo Observatory in the ACT.

The aliens from Mars Attacks!. "I see no way to get around this obstacle." Lineweaver's objection was echoed by many – though not all – scientists and philosophers contacted for this story. It can be illustrated by a simple example. Yoda with R2D2 and Luke in The Empire Strikes Back. The fundamental unit of DNA is the gene – humans have around 25,000 of them. If you were to make a computer model of the human genome you could represent each gene with the smallest unit of computer code, known as a "bit".

One gene equals one bit. Dr Charley Lineweaver says the theory raises questions about how information can be causal in a physical system. Credit:David Moir But the gene exists in the real physical world, and does stuff – like giving you brown eyes or red hair, for instance. The bit is a description of the gene. It does nothing, because it does not exist in the physical world. Davies and Walker, however, raise the possibility that this basic distinction between real and not-real might be way wrong. Mr Spock of Star Trek.

It is a contentious suggestion. "This is a category error," said Dr John Wilkins, honorary fellow at Melbourne University's School of Historical and Philosophical Studies. Jar Jar Binks - formerly of Star Wars fame. Philosophical roots Wilkins specialises in studying the relationship between information and evolutionary theory. Davies and Walker's paper, he noted, being speculative, falls as much into the realm of philosophy as physics.

"It's a long-standing category error that goes back a very long way in philosophy – arguably back to Plato," he said. "It's the idea that the way we represent something is somehow the essence of the thing being represented. It's mistaking the map for the territory." Wilkins suggested that the authors had fallen into the trap of failing to distinguish between the complex mathematical modelling that physics demands and the actual physical world being thus modelled. Their conclusions, he said, "are not philosophically well supported". Which brings us, in a weird kind of way, to the bit about gods. Wilkins' assertion that mathematics model and measure a separate physical reality seems obvious – in the same way that you wouldn't confuse a map of a town with the town itself. Surprisingly, however, it is not a universally held view, even among hard-nosed scientists. From the Big Bang onwards, the universe has developed in line with precise mathematical laws, leading to the idea (seductive or repulsive, depending on your point of view) that maths is not a human invention but a fundamental force.

"Scientists have embraced a kind of mathematical creationism," wrote New York Times science writer George Johnson back in 1998, "God is a great mathematician, who declared, 'Let there be numbers!' before getting around to 'let there be light!'" Davies and Walker come intriguingly close to allowing a Great Mathematician to enter the story of how the universe, and thus life, came into being. From one perspective it is the central assertion – revolutionary or shocking, take your pick – in their paper. The 'hard problem' Bear with us here. This requires a short diversion. By using the term "hard problem" to describe life Davies and Walker are deliberately echoing the landmark work of Australian philosopher and cognitive scientist Dr David Chalmers. In 1995 Chalmers declared consciousness to be a "hard problem" – by which he meant that although it is theoretically possible to measure precisely every neuron in the human brain, and track the sparks that flash between them, this understanding still doesn't explain how thoughts, daydreams, or states of mind arise.

Self-awareness, he said, is not an obvious product of the electrical activity inside your head. Davies and Walker see a possible similarity with life. Assuming things live on other planets, they say, the question is whether all types of alien can be "accounted for in terms of known physics and chemistry, or whether certain aspects of living matter will require something fundamentally new". The "hard problem" in this instance, they add, "is the problem of how 'information' can affect the world." It is a problem that they suspect "will not ultimately be reducible to known physical principles." Or, in plainer terms, physics and chemistry won't cut it alone: there's something else in the mix. That something, they think, is "information" – but what exactly is that, and where did it come from? The Reverend Dr Stephen Ames thinks he might have an idea. He is a canon at St Paul's Cathedral in Melbourne, and a lecturer at Melbourne Uni who holds dual doctorates in physics and the history and philosophy of science.

"I do think of the universe as being structured towards an end, and part of that end is that it is knowable through empirical inquiry," he said. In other words, the laws of physics are what they are – but studying them, in time, over generations of scholarship, will lead to the understanding that in a fundamental way the universe was kick-started by what Ames terms a "powerful agent" – or, in more traditional terms, God. External force Regardless of what anyone chooses to call it, the interesting (and to many scientists troubling) thing is that by suggesting that life may not be completely explicable through physics and chemistry, Davies and Walker implicitly leave open the possibility of some sort of metaphysical force playing a hand. The pair is quick, however, to rule out one popular, contentious idea. Basic logic (and math) tell us that in order for the universe, and life, to develop in the way that it has, there must have been very precise initial conditions at the instant of the Big Bang. Even the most minuscule difference in any one of scores of things – the number of electrons, for instance, or the ratio of matter to antimatter – would have resulted in a universe in which planets and people were impossible.

The problem, say Davies and Walker, is that to get to where we are today those initial conditions "must be selected with extraordinary care, which is tantamount to intelligent design: it states that 'life' is 'written into' the laws of physics". There is no evidence, they conclude, of "this almost miraculous property". Ames agrees with them in dismissing ideas of intelligent design, a largely creationist idea equally unpopular among mainstream physicists and theologians (of which, of course, he is equally representative). "The word 'design' brings to mind too many ideas of engineering and blueprints," he said. "But I'm personally very interested in Davies' endeavours to give an account of the universe in terms of information and in terms that would appear not to need any special initial conditions. If he can do it, that would be remarkable." For many in the physics and astrophysics games, however, even the simplest suggestion that hard science can't ultimately account for the entire universe and everything in it – alive or not – sets off warning bells.

And in this area, it should be noted, Davies has form. You would struggle to find a definite pro-deity statement is any of his writing, but he is very fond of religious metaphor – one of his books is called The Mind of God – and some of his statements are, well, a tad ambiguous. "If there is an ultimate meaning to existence, as I believe is the case, the answer is to be found within nature, not beyond it," he wrote in a 2007 newspaper article. For mainstream physicists any suggestion of "ultimate meaning" is close to salivating, revival tent fundamentalism. "He's on that edge of philosophy and physics all the time," said Ames. 'Deliberate' ambiguity Sydney astrophysicist and bioastronomer Dr Maria Cunningham, of the UNSW School of Physics, said she found Davies and Walker's paper fascinating but was troubled by its possible theological implications.

"Davies' ambiguity is deliberate, I think," she said. "Since before the term intelligent design was coined – going back 25 years or so – he has maintained that the parameters and constants of our particular universe are so finely tuned that it does make you wonder whether this is just a random thing. "It's something that physicists and philosophers have been talking about for a long time. I think maybe [Rene] Descartes was one of the first to actually come up with the idea that there had to be something separate for life – that it couldn't just be a mechanistic process." Cunningham described herself as a "hard-headed reductionist" who sees neither a way, nor a need, for information to exert an influence. Eventually identifying the deep laws that govern life – which she feels to be rare in the rest of the universe, but there, nevertheless – will not need the "new physics" Davies and Walker suggest. "I don't feel comfortable with the suggestion that because living things exist there has to be new physics explaining living things," she said. She pointed to recent studies revealing that hydrogen cyanide and hydrogen sulfide – both floating around in outer space – when exposed to ultraviolet light can form nucleic acids, amino acids, and lipids, the basic building blocks of life. These and similar research projects may one day sufficiently answer the question of how life comes to exist, without reference to new science or old gods.

Of course, perhaps somewhere in the universe, a few dozen light years away, one of Douglas Adams' Hoovooloos already knows that answer. The trouble, as people familiar with Adams will be aware, is that it is very likely to be "42". Which doesn't help at all. (Paul Davies' office was approached with a request for an interview for this story. There was no response.)