Despite the insistence of some physicists that quantum effects only affect things on an extremely small scale, new theories continue to be put forward that the smallest known processes may be responsible for some very, very big phenomena, ranging from things such as the navigational sense of migratory birds, to the potential that they may also be responsible for the very existence of life as we know it on Earth.
Photosynthesis is the biological process used by organisms such as plants and phytoplankton where sunlight, carbon dioxide and water are converted into oxygen and carbohydrate molecules that fuel the organism’s cellular functions. It is a process that is responsible for the oxygen content of the Earth’s atmosphere, and globally produces 130 trillion watts of energy each year, fueling virtually all life on Earth, as other organisms gain energy from eating the carbohydrates produced by photosynthesizing organisms.
The process of photosynthesis takes place inside the organism’s chlorophyll pigments, where an incoming photon strips an electron off of a water molecule, creating an oxygen molecule, and the free electron is absorbed into the carbohydrate molecules that are formed from the reaction, providing metabolic fuel for later.
But there’s a snag, albeit a fortunate one: the process of photosynthesis is too efficient for classical physics to account for. The excited electrons ricocheting around in the cell’s chloroplast lose extremely little energy, and the time taken by the reaction is also much shorter than one would expect. These effects, while unexplainable by classical physics, can be accounted for if the phenomenon of quantum superposition is applied to the process. If this were the case, the electrons involved would effectively exist in two places in the cell at one time, eliminating both their travel time around the cell, and allowing their transmission with no loss of energy.
Although there is currently no hard evidence that photosynthesis employs the quantum superposition effect, the idea could revolutionize the way we see biological processes. “I think this was when people started to think that something really exciting was going on,” says quantum physicist Susana Huelga, with the Ulm University in Germany. "The wet, warm, bustling environment of living cells is the last place you might expect to see quantum events. “[But] even here, quantum features are still alive.”
Migratory birds have also presented a conundrum to researchers throughout history: despite their ability to accurately navigate over extremely long distances each year, scientists have yet to find the mechanism responsible for this phenomenon. It was long believed that they contained some sort of physical compass that interacted with the Earth’s magnetic field, but science hasn’t found any ferro-magnetic material in them that might be used for such a purpose. But once again, perhaps quantum mechanics can explain what’s going on.
Using a specific range of radio frequencies, researchers have been able to temporarily disorient the navigation sense of robins. If the radio frequencies are resonating with electrons in the birds’ internal compasses, they could be disrupting the quantum spin of the electrons, an effect that would otherwise keep the birds properly oriented.
The theory behind this quantum effect is combined with excitable solitary electrons called radicals, found in pigments at the back of the bird’s eye, that responds to the planet’s magnetic field. The magnetic field causes the radical to prompt a chemical reaction in the bird’s biology, building up a chemical that lets the avian know it’s pointed in the right direction — acting as a quantum compass for the creature.