Scientists have proposed a model of a molecular rotor (about 1 nm) to explain how weak magnetic fields affect biology. This rotor shows quantum properties like superposition and interference. Calculations reveal its high sensitivity to weak fields, but not strong ones. Thanks to a larger moment of inertia, it maintains quantum coherence relatively long, even in the noisy cellular environment, operating at the crossroads of the quantum and classical worlds. Embedded in the cell's cyclic processes, such a rotor can produce noticeable biological effects.
Inside a living cell, a tiny carbon spinning top whirls — a molecule billionths of a meter across. An ordinary top falls quickly, but this one behaves differently: it can spin in both directions at once, like a quantum coin perpetually frozen mid-fall. This superposition of motions is key to its strange selectivity. The top detects magnetic fields of negligible strength but remains deaf to a powerful magnet.
The reason lies in its massiveness. Just as a top with a heavy rim spins longer, this molecular rotor, due to its weight, maintains its quantum properties even in the warm, watery environment of the cell. Disorder, or entropy, attacks it more slowly, preventing it from ‘smearing out’ in space.
Embedded in cellular rhythms — division, enzyme activity — such a sensor can steer the chemistry of life. Perhaps this is how migratory birds and some bacteria sense Earth’s magnetic field. This mechanism not only solves long-standing biological puzzles but also promises ultrasensitive detectors for medicine.
🎯 Some birds, like robins, literally ‘see’ Earth’s magnetic field during migration thanks to quantum effects in their eyes.