Quantum flair helps birds sense the Earth’s magnetic field

Seeing our world through the eyes of a migratory bird would be a little creepy. Something in their visual system allows them to “see” our planet’s magnetic field, a clever combination of quantum physics and biochemistry that helps them travel great distances.

In early 2021, scientists at the University of Tokyo first observed a reaction to the talent of birds and other creatures to determine the direction of the Earth’s poles. Using a microscope sensitive to weak flashes of light, the team observed the activity of cryptochromes, light-sensitive photoreceptors in the brain, and their dynamic response to variations in the magnetic field. Cryptochromes are found in the cells of many animals and are involved in the regulation of circadian rhythms.

Researchers stained human cryptochromes with fluorescent dye and passed different-frequency magnetic fields through them. Each time a magnetic field was passed, the luminescence decreased by 3.5 percent, enough to establish a direct correlation. What came out was a bizarre quantum effect, as if the response was directly to the change in light. This is a pure quantum-mechanical process, affecting chemical activity at the cellular level. It is commonly believed that humans are incapable of seeing magnetic fields, but this research suggests that on some unconscious level we are in fact quite capable of reading the Earth’s magnetism.

It all comes down to a natural property of electrons. Properly arranged electrons around an atom can be made to move in a weak magnetic field similar to the one surrounding our planet. A free radical is an electron without a pair in the outer shell of the atom. Sometimes these “bachelor” electrons take another atom as the slave. The two remain unpaired, but their rotational trajectory begins to coincide, no matter how far apart they are. This correlation cannot be explained simply by physical connections; it is a purely quantum influence, which Albert Einstein called “strange.

Scientists concluded that, in the experiment with fluorescent cells, the luminescence failure was a consequence of the generation of free radical pairs. Even weak magnetic fields turned out to be able to affect biological processes indirectly. Of course, birds are not the only ones that depend on the magnetosphere of the planet. Fish, worms, insects, and some mammals have similar abilities. And we can even be influenced cognitively by the Earth’s magnetic field. All this makes one wonder what other laws of biology derive from the depths of fundamental physics.