“I’m not saying it’s all true,” says , 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 . Quantumness tends to prosper in very cold systems that are carefully isolated rather than part of a tepid soup awash with other activity.
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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 , 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.
Quantum effects in cells
Hints of superposition have been observed in proteins called microtubules in cells in vitro, for example, but so far all these results are only “correlative”, says who leads the Quantum Biology Tech (QuBiT) Lab at the University of California, Los Angeles. That is because we haven’t pinpointed how microscopic quantum behaviour might produce macroscopic consequences. “No one has unambiguously proven or refuted whether quantumness survives inside cells for long enough for it to matter,” says Aiello.
She has a few ideas about how that might happen, though. Her research focuses on the surprising effect that magnetic fields have on a host of biological processes – from cell metabolism to DNA repair. “The whole machinery of cells might be responding to weak magnetic fields,” she says. The idea is that these fields influence a quantum property of electrons called spin, which is relatively resilient to loss of quantumness, with knock-on effects for the chemical products that form downstream in biochemical processes. “The macroscopic consequences would be felt for much longer than the quantumness,” says Aiello.
Scholes, meanwhile, is to tell us where – and how – to look for quantum effects in biology. His take-home message is that the usual quantum rule book, based on interactions between small numbers of particles, doesn’t apply. “We need to embrace [quantum biology’s] complexity,” he says. “Somehow, we need to develop a new kind of language.”
Broadly, coherence is characterised by the extent to which different waves are in step with each other, known as their phase, so Scholes began to look for an equivalent in biology. He borrows the mathematics of graph theory, which describes the relations between large numbers of objects, adding up biological oscillations to identify an emerging pattern of phases.
Scholes says that oscillations occur in living organisms, including in biochemical process inside cells and across networks of neurons in the brain. He suggests they could be behind some of the hints of quantum effects seen in experiments.
Scholes’s ideas have also begun to blur the boundary between what we think of as quantum and classical. Although these biological states are akin to quantum superposition, all of his calculations were done using classical laws of nature. For this reason, Scholes calls them “quantum-like” states.
He has even started to speculate about what these quantum-like states might be doing inside brains: “They could bring information from different regions together quickly and efficiently, to give a leap of intuition, or a moment of recognition.”
