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“I’m not saying it’s all true,” says Christoph Simon, a physicist at the University of Calgary in Canada. “I’m just saying it is not crazy to look for it.” He is talking about the possibility that life has found ways to make use of quantum effects in a host of essential phenomena, from photosynthesis and the navigational abilities of birds to consciousness.
The idea has long been seen as a bit fringe, on the assumption that such fragile effects must quickly disappear in the warm, wet environment of cells. Quantumness tends to prosper in very cold systems that are carefully isolated rather than part of a tepid soup awash with other activity.
But that is beginning to change, with tentative evidence for quantum behaviours in the machinery of cells and hints that quantum biology may not play by the conventional rules governing the subatomic world, raising new questions about the boundary between the classical and quantum realms.
“You could say, ‘well, all molecules are quantum mechanical, so everything in biology is quantum mechanical’,” says Greg Scholes, a chemist at Princeton University. But the idea of quantum biology only really gets interesting, he says, with the possibility that it explains emergent macroscopic behaviour that can’t be predicted using classical laws.
Finding such behaviour typically means searching for evidence of archetypal quantum traits such as superposition, in which a system appears to exist in multiple states simultaneously before it loses this so-called quantum coherence and “collapses” into one state or another – a process called decoherence.
