Why Life Is Physics, Not Chemistry
In the history of science, there are many examples of simple changes in perspective that lead to profound insights into the nature of the cosmos. The invention of the telescope is perhaps one example. Another is the realisation that chemical energy, thermodynamic energy, kinetic energy and the like are all manifestations of the same stuff. You can surely supply your own favourite instances here.
One of the more important examples in 20th century science is that biology is the result of evolution, not the other way round. By that way if thinking, evolution is a process, an algorithm even; albeit one with unimaginable power. Exploit evolution and there is little you cannot achieve.
In recent years, computer scientists have begun to exploit evolution’s amazing power. One thing they have experienced time and time again is evolution’s blind progress. Put a genetic algorithm to work and it will explore the evolutionary landscape, looking for local minima. When it finds one, there is no knowing whether it is the best possible solution or whether it sits within touching distance of an evolutionary abyss that represents a solution of an entirely different order of magnitude.
That hints at the possibility that life as it has evolved on Earth is but a local minima in a vast landscape of evolutionary possibilities. If that’s the case, biologists are studying a pitifully small fraction of something bigger. Much bigger.
Today, we get an important insight into this state of affairs thanks to a fascinating paper by Nigel Goldenfeld and Carl Woese at the University of Illinois. Goldenfeld is a physicist by training while Woese, also a physicist, is one of the great revolutionary figures in biology. In the 1970s, he defined a new kingdom of life, the Archae, and developed a theory of the origin of life called the RNA world hypothesis, which has gained much fame or notoriety depending on your viewpoint.
Together they suggest that biologists need to think about their field in a radical new way: as a branch of condensed matter physics. Their basic conjecture is that life is an emergent phenomena that occurs in systems that are far out of equilibrium. If you accept this premise, then two questions immediately arise: what laws describe such systems and how are we to get at them.
Goldenfeld and Woese say that biologists’ closed way of thinking on this topic is embodied by the phrase: all life is chemistry. Nothing could be further from the truth, they say.
They have an interesting analogy to help press their case: the example of superconductivity. It would be easy to look at superconductivity and imagine that it can be fully explained by the properties of electrons as they transfer in and out of the outer atomic orbitals. You might go further and say that superconductivity is all atoms and chemistry.
And yet the real explanation is much more interesting and profound. It turns out that many of the problems of superconductivity are explained by a theory which describes the relationship between electromagnetic fields and long range order. When the symmetry in this relationship breaks down, the result is superconductivity.
And it doesn’t just happen in materials on Earth. This kind of symmetry breaking emerges in other exotic places such as the cores of quark stars. Superconductivity is an emergent phenomenon and has little to do with the behaviour of atoms. A chemist would be flabbergasted.
According to Goldenfeld and Woese, life is like superconductivity. It is an emergent phenomenon and we need to understand the fundamental laws of physics that govern its behaviour. Consequently, only a discipline akin to physics can reveal such laws and biology as it is practised today does not fall into this category.
That’s a brave and provocative idea that may not come as a complete surprise to the latest generation of biophysicists. For the others, it should be a call to arms.
We’ll be watching the results with interest.
Ref: arxiv.org/abs/1011.4125: Life Is Physics: Evolution As A Collective Phenomenon Far From Equilibrium
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