Researchers with the University of Tokyo may have directly witnessed the quantum reaction that results from the exposure of biological tissue to a magnetic field, a mechanism hypothesized to be behind the magneto-receptive sense that can guide birds on their long migratory routes. Although it has been long established that certain species can detect magnetic fields, the mechanism behind such a sense has remained a mystery, but this new experiment may have shed some light—quite literally—on the matter.
“We think we have extremely strong evidence that we’ve observed a purely quantum mechanical process affecting chemical activity at the cellular level,” according to biophysicist Jonathan Woodward, one of the researchers involved in the study. The experiment made use of a quantum reaction involving crypto-chromes, a class of proteins that are sensitive to blue light that are involved in the circadian rhythms of both plants and animals, including humans.
To see this quantum reaction in action, the researchers exposed a culture of human cells containing crypto-chromes to blue light, causing them to faintly fluoresce—a glow too weak to be seen with the naked eye, but one that could be detected by a sensitive custom-built microscope. While the crypto-chromes were fluorescing, the cells were exposed to magnetic fields of various frequencies to see how they reacted.
The researchers found that the magnetic fields caused the fluorescence of the crypto-chromes to drop by around 3.5 percent—a definite reaction shown by the experiment. But how does a magnetic field affect something without any magnetic material present, as was in the case of the test cells? A long-standing theory posits that magnetic fields can instead affect chemical reactions through an effect on what are known as radical pair electrons.
Typical radicals are electrons in the outer orbits, or “shells”, of the atoms they inhabit, but lack a second election that they usually would usually be partnered with to balance out that shell. Occasionally, these lone particles will become partnered with another electron in another atom through quantum entanglement. Although these connections would be brief, the communication between the linked electrons would cause both to have matching spins, and in turn could affect the behavior of their respective host atoms.
And it’s this spin-state of an electron that can be affected by magnetic fields; while the change in the spin in random elections within a given set of molecules wouldn’t have much of an effect on the properties of the overall substance, a series of entanglements within the individual atoms of the molecules involved could have a magnified effect, such as the drop in fluorescence seen in the experiment’s crypto-chromes.
The experiment only used magnetic fields at strengths of less than 25 millitesla (mT), weaker than the Earth’s magnetic field, meaning that these quantum effects are probably happening to your own cells right now. Aside from unlocking the mystery of the magneto-receptive abilities of other animal species even further, these findings may open new medical applications using magnetic fields applied to biological tissue.