Friday, February 01, 2013

quantum biology

BBCNews | Until recently, the delicate states of matter predicted by quantum mechanics have only been accessed with the most careful experiments: isolated particles at blisteringly low temperatures or pressures approaching that of deep space.

The idea that biology - impossibly warm, wet and messy to your average physicist - should play host to these states was almost heretical.

But a few strands of evidence were bringing the idea into the mainstream, said Luca Turin of the Fleming Institute in Greece.

"There are definitely three areas that have turned out to be manifestly quantum," Dr Turin told the BBC. "These three things... have dispelled the idea that quantum mechanics had nothing to say about biology."

The most established of the three is photosynthesis - the staggeringly efficient process by which plants and some bacteria build the molecules they need, using energy from sunlight. It seems to use what is called "superposition" - being seemingly in more than one place at one time.

Watch the process closely enough and it appears there are little packets of energy simultaneously "trying" all of the possible paths to get where they need to go, and then settling on the most efficient.

"Biology seems to have been able to use these subtle effects in a warm, wet environment and still maintain the [superposition]. How it does that we don't understand," Richard Cogdell of the University of Glasgow told the BBC.

But the surprise may not stop at plants - there are good hints that the trickery is present in animals, too: the navigational feats of birds that cross countries, continents or even fly pole to pole present a compelling behavioural case.

Experiments show that European robins only oriented themselves for migration under certain colours of light, and that very weak radio waves could completely mix up their sense of direction. Neither should affect the standard compass that biologists once believed birds had within their cells.

What makes more sense is the quantum effect of entanglement. Under quantum rules, no matter how far apart an "entangled" pair of particles gets, each seems to "know" what the other is up to - they can even seem to pass information to one another faster than the speed of light.

Experiments suggest this is going on within single molecules in birds' eyes, and John Morton of University College London explained that the way birds sense it could be stranger still.

"You could think about that as... a kind of 'heads-up display' like what pilots have: an image of the magnetic field... imprinted on top of the image that they see around them," he said.

The idea continues to be somewhat controversial - as is the one that your nose might be doing a bit of quantum biology.

Most smell researchers think the way that we smell has to do only with the shapes of odour molecules matching those of receptors in our noses.

But Dr Turin believes that the way smell molecules wiggle and vibrate is responsible - thanks to the quantum effect called tunnelling.

The idea holds that electrons in the receptors in our noses disappear on one side of a smell molecule and reappear on the other, leaving a little bit of energy behind in the process.