It would be a horrible thing to see our world through the eyes of a migratory bird. Something about their visual system allows them to see the ‘magnetic field’ of our planet, a clever trick of quantum physics and biochemistry that helps them navigate great distances.
Now, for the first time ever, scientists from the University of Tokyo have seen exactly a key reversal that has been behind the talents of birds, and many other creatures, for the sense of direction the poles of the planet.
Importantly, this is evidence of quantum physics directly affecting biochemical reactivity in a cell – something we have long thought about but have not seen in action before.
Using a specially made microscope that is sensitive to scarce flashes of light, the team looked at a culture of human cells in which a special light-sensitive material responds dynamically to changes in a magnetic field.
Cell fluorescence ignites as a magnetic field passes over it. (Ikeya and Woodward, CC BY)
The change observed by the researchers in the laboratory matches exactly what would be expected if a fragile quantum effect were due to the illumination reaction.
“We didn’t alter or add anything to those cells,” says biologist Jonathan Woodward.
“We believe we have very strong evidence that we have observed a direct quantum mechanical process affecting chemical activity at the cellular level.”
So how are cells, especially human cells, able to deal with magnetic fields?
Although there are several theories, many researchers believe that the potential is due to a specific quantum reaction involving photoreceptors called cryptochromes.
Cyrptochromes are found in the cells of many species and are involved in the regulation of circadian rhythms. In species of migratory birds, dogs, and other species, they are linked to the mysterious ability to sense magnetic fields.
In fact, while most of us cannot see magnetic fields, cryptochromes certainly exist in our own cells. And there is evidence, though not conscious, that humans are still able to discover the Earth’s magnetism.
To see them inside cyrptochromes in action, the researchers created a culture of human cells containing cryptochromes in blue light that caused them to weak fluoresce. As they shone, the team swept magnetic fields of different frequencies again across the cells.
They found that each time the magnetic file passed through the cells, their fluorescent decreased by about 3.5 percent – enough to reveal a direct response.
So how can a magnetic field affect a photoreceptor?
It all comes down to something called spin – the inherent property of electrons.
We already know that spinning with magnetic fields has a great effect. Arrange electricity in the right way around an atom, and gather enough of them together in one place, and the resulting mass of material can be made to move by using nothing more than a weak magnetic field like the one is all around our planet.
This is all well and good if you want to make a needle for a sailing compass. But without obvious signs of pieces of material sensitive to magnets inside a pitcher skull, physics need to think less.
In 1975, a Max Planck Institute researcher named Klaus Schulten developed a theory on how magnetic fields affect chemical reactivity.
It involved something called a radical pair.
A garden-type radical is an electron in the outer shell of an atom that is not in association with a second electron.
Sometimes these blocking electrons can take a wing in another atom to form a radical pair. The two remain unrepaired but thanks to a shared history they are thought to be engaging, which in quantum terms means their spins will respond seamlessly no matter what. how far apart they are.
Since this relationship cannot be explained by continuous physical connections, it is a quantum activity, something even Albert Einstein considered to be a ‘sputum’.
In the turmoil of a living cell, their connection continues. But even these correlated spins should last long enough to make a small difference in the way their parent atoms behave.
In this experiment, as the magnetic field passed over the cells, the corresponding decrease in fluorescence indicates that the generation of radical pairs was affected.
An interesting result of the research could be how even weak magnetic fields can have an indirect effect on other biological processes. While evidence of magnetism affects the health of frail people, experiments like this could be another research method.
“The exciting thing about this research is that the relationship between the spins of two separate electrons can have a profound effect on biology,” says Woodward.
Of course birds are not the only animal that relies on our magnetosphere for guidance. There are species of fish, worms, insects, and even some mammals. Humans could even affect the Earth ‘s magnetic field.
Evolution of this ability could deliver a number of very different tasks based on different physics.
Having evidence that at least one of them connects the neural world of the quantum world with the behavior of a living thing is enough to make us think about what other pieces of biology arise from the sputum depth of basic physics .
This research was published in PNAS.