Sunday, July 19, 2009

Origin of life: Quantum mechanics provided the ... ooomph!! ?

In "The Quantum Life" (, July 1, 2009), Paul Davies, astrobiologist and director of BEYOND: Center for Fundamental Concepts in Science at Arizona State University, examines the case for quantum mechanics kickstarting the origin of life (Q-life):
But why should quantum mechanics be relevant to life, beyond explaining the basic structure and interaction of molecules? One general argument is that quantum effects can serve to facilitate processes that are either slow or impossible according to classical physics. Physicists are familiar with the fact that discreteness, quantum tunnelling, superposition and entanglement produce novel and unexpected phenomena. Life has had three and a half billion years to solve problems and optimize efficiency. If quantum mechanics can enhance its performance, or open up new possibilities, it is likely that life will have discovered the fact and exploited the opportunities. Given that the basic processes of biology take place at a molecular level, harnessing quantum effects does not seem a priori implausible.
It's intriguing, the way he attributes to "life" and, elsewhere, "evolution" the attributes of a planning and thinking intelligent agent.

He almost persuades himself but
Although at least some of these examples add up to a prima facie case for quantum mechanics playing a role in biology, they all confront a serious and fundamental problem. Effects like coherence, entanglement and superposition can be maintained only if the quantum system avoids decoherence caused by interactions with its environment. In the presence of environmental noise, the delicate phase relationships that characterize quantum effects get scrambled, turning pure quantum states into mixtures and in effect marking a transition from quantum to classical behaviour. Only so long as decoherence can be kept at bay will explicitly quantum effects persist. The claims of quantum biology therefore stand or fall on the precise decoherence timescale. If a system decoheres too fast, then it will classicalize before anything of biochemical or biological interest happens.
.So we are now into the business of persuading ourselves that, based on a few studies, that would not be the normal fate of Q-life. And in the end,
How would Q-life evolve into familiar chemical life? A possible scenario is that organic molecules were commandeered by Q-life as more robust back-up information storage. A good analogy is a computer. The processor is incredibly small and fast, but delicate: switch off the computer and the data are lost. Hence computers use hard disks to back up and store the digital information. Hard disks are relatively enormous and extremely slow, but they are robust and reliable, and they retain their information under a wide range of environmental insults. Organic life could have started as the slow-but-reliable “hard-disk” of Q-life. Because of its greater versatility and toughness, it was eventually able to literally “take on a life of its own”, disconnect from its Q-life progenitor and spread to less-specialized and restrictive environments — such as Earth. Our planet accretes a continual rain of interstellar grains and cometary dust, so delivery is no problem. As to the fate of Q-life, it would unfortunately be completely destroyed by entry into the Earth’s atmosphere.
All this reminds me of a beautiful Edith Wharton short story, "Fern Seed", which I can't find on line, or worse, it might be wrecked by some clueless "ethnicity/class/gender" analysis.

The point of "Fern Seed" is that it looks as though a ghost drove a story character to suicide - but there is no actual evidence. (If you ever think of writing a ghost story, take Wharton as your guide. What make her stories work is: No one can prove anything happened, apart from catastrophic emotional impacts, and yet everyone is sure that something happened.)