A quantum effect known as entanglement may be part of the compass that birds use to sense Earth’s magnetic field, researchers report in an upcoming Physical Review Letters.
Critters from bacteria to mole rats use tiny variations in the Earth’s magnetic field to navigate, but exactly how they sense the magnetism is a mystery. One idea is that magnetic fields disrupt pairs of entangled electrons in a light-sensitive protein in the retina. In quantum entanglement, particles are linked to each other so that one always knows instantly what the other is doing, even if they get separated.
In the new research, physicists at the University of Oxford and the National University of Singapore calculated that quantum entanglement in a bird’s eye could last more than 100 microseconds — longer than the 80 microseconds achieved in physicists’ experiments at temperatures just above absolute zero, says Elisabeth Rieper, a physicist at the National University of Singapore. That would be a surprising feat for a bird warbling at room temperature, which people thought was too hot to see quantum effects.
“It may all be right, but I would personally like to be cautious about this,” says Thorsten Ritz, a biophysicist at University of California, Irvine, who is a proponent of the model but wasn’t involved in this research.