Seeing our world through the eyes of a migratory bird is quite a haunting experience. Something about their visual system enables them to ‘see’ our planet’s magnetic field, 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 observed an important reaction that is supposed to be behind the birds and numerous other creatures, to see the direction of the poles of the planet.
Importantly, it has been proven that quantum physics directly influences a biochemical reaction in a cell – something we have long assumed, but have not seen in action before.
Using a custom microscope that is sensitive to light flashes of light, the team looked at a culture of human cells that contain a special light-sensitive material that responds dynamically to changes in a magnetic field.
A cell’s fluorescence fades as a magnetic field moves across it. (Ikeya and Woodward, CC BY)
The change observed by the researchers in the laboratory is consistent with what would be expected if a peculiar quantum effect were responsible for the illuminating response.
“We have not altered or added anything to these cells,” says biophysicist Jonathan Woodward.
“We think we have very strong evidence that we have observed a purely quantum mechanical process that affects the chemical activity at the cellular level.”
How can cells, especially human cells, respond to magnetic fields?
Although there are several hypotheses, many researchers think that the ability is due to a unique quantum reaction involving photoreceptors called cryptochromes.
Kirtptochrome occurs in the cells of many species and is involved in the regulation of circadian rhythms. In species of migratory birds, dogs and other species, they are associated with the mysterious ability to detect magnetic fields.
Although most of us cannot see magnetic fields, our cells certainly contain cryptochromes. And there is evidence that humans, though unaware, are still capable of detecting Earth’s magnetism.
To see the reaction within cryptocurrencies in action, the researchers bathed a culture of human cells that contain cryptochromes in blue light, causing them to fluoresce poorly. As they glowed, the team repeatedly swept magnetic fields of different frequencies across the cells.
They found that each time the magnetic file moved across the cells, their fluorescent dipped about 3.5 percent – enough to show a direct reaction.
How can a magnetic field affect a photoreceptor?
It all comes down to something called spin – an innate property of electrons.
We already know that spin is significantly affected by magnetic fields. Arrange electrons correctly around an atom and collect enough of them in one place, and the resulting mass of matter can be moved by using only a weak magnetic field like the one surrounding our planet.
This is all well and good if you want to make a needle for a navigation compass. But without clear signs of magnetically sensitive pieces of material in pigeon skulls, physicists had to think smaller.
In 1975, a researcher at the Max Planck Institute named Klaus Schulten developed a theory of how magnetic fields can influence chemical reactions.
It called something called a radical couple.
A garden variety is an electron in the outer shell of an atom that does not cooperate with a second electron.
Sometimes these free electrons can take on a wingman in another atom to form a radical pair. The two remain unpaired, but are considered entangled due to a shared history, which in quantum sense means that their turns will correspond unequally, no matter how far apart they are.
Since this correlation cannot be explained by continuous physical connections, it is merely a quantum activity, something that even Albert Einstein considered ‘ghostly’.
In the bustle of a living cell their entanglement will be fleeting. But even this short correlating turn should only last long enough to make a subtle difference in the way their respective parent atoms behave.
In this experiment, as the magnetic field moves across the cells, the corresponding decrease in fluorescence indicates that the generation of radical pairs is affected.
An interesting consequence of the research may be in how even weak magnetic fields can indirectly affect other biological processes. Although evidence of magnetism affecting human health is weak, similar experiments may be another way to investigate.
“The joy of this research is to see that the relationship between the rotation of two individual electrons can have a major impact on biology,” says Woodward.
Of course, birds are not the only animals that rely on our magnetosphere for direction. Species of fish, worms, insects and even some mammals have the chance. Our humans can even be cognitively affected by the Earth’s faint magnetic field.
The evolution of this ability could have yielded a number of very different actions based on different physics.
Evidence that at least one of them connects the strangeness of the quantum world with the behavior of a living thing is enough to force us to wonder what other pieces of biology arise from the ghostly depths of fundamental physics.
This research was published in PNAS.