Cryptochrome and Birds With Quantum Eyes

"Reverse-Engineering a Quantum Compass"
Wired Science (April 30, 2010)

"If the weird rules of atomic physics do help birds find their way around the globe — as some scientists suspect — a new study has identified ways of finding out how.

"The study is among the first to propose a direct test of how quantum entanglement, an effect that inexorably links two electrons in a way that Einstein called 'spooky,' could change the behavior of whole animals.

" 'This paper has really made a contribution by suggesting an experimental test,' comments Thorsten Ritz, a physicist at the University of California, Irvine, who was not involved in the new work...

"...'For a long time people thought this couldn't be, because nature is just too messy,' Ritz says. But work over the past decade by Ritz and others suggests that the mechanism birds use to 'see' Earth's magnetic field and navigate accordingly could rely on quantum effects.

"Ritz and colleagues previously identified a molecule called cryptochrome, which is found in the nerves of avian eyes, as a candidate for controlling birds' ability to sense magnetic fields.

"Electrons in cryptochrome usually come in pairs, each with an opposite spin like a planet revolving on its axis. But when light strikes the molecule, it can carry one of the electrons away. The presence of a magnetic field can then make each spinning electron wobble like a plate balanced on a stick. When the wayward electron returns to its original molecule, any change it has picked up in its spin sparks a chemical signal that some scientists believe allows birds to see magnetic fields as a pattern of colors...."

If birds can see Earth's magnetic field, that would explain a few things. What's interesting about this paper is that the scientists have a specific mechanism in mind for how birds can detect magnetic fields.

About the "quantum eyes" in this post's title: I could have written, "eyes whose nerves contain cryptochrome," but I don't think that would have 'sounded' as cool - and would have made the title awkwardly long. Sort of like that last sentence.

Cryptochrome may not help birds see magnetic fields, though. entanglement can be helpful, but maybe not for birds. University of Innsbruck, Austria, Physicist Hans Briegel and colleagues ran some tests. They found that entanglement makes the electrons in pyrene, a molecule that isn't involved so much in things biological, more sensitive to magnetic fields. Cryptochrome? Entanglement doesn't make a difference.

It's early days - and I'm pretty sure that's not the last word on cryptochrome and birds' eyes.

As I've quoted in another blog:

"Not only is the universe stranger than we imagine, it is stranger than we can imagine."
Sir Arthur Eddington English astronomer (1882 - 1944)

- - - and that's what keeps it interesting.