Quantum Biology

The one thing that we have to remember is that quantum mechanics and then developing in quantum field theory and so on was developing in parallel with the new areas of biology, genetics and molecular biology. The geneticists and molecular biologists by the 1930s and 1940s and indeed 1950s, when the double helix structure was discovered, really felt they had no need for quantum mechanics, they were so successful. They were learning so much about the molecular structure within living systems. They saw no requirement to bring in the strangeness of quantum mechanics. So to a large extent quantum biology really sort of went into the background. Particularly after the discovery of the double helix of DNA, spectroscopists and molecular biologists really were learning so much more about the building blocks of the cell, the instruction manual of life, they had no room for quantum superposition and the measurement problem, the uncertainty principle, and on all that silly business, they would leave that to physicists.

At the same time physicists had their hands full. We’ve also been very successful in the 20 th century from quantum mechanics to quantum field theory, nuclear and particle physics developed, we learned about the building blocks of matter. On the theoretical side we started looking at how we unify the different ideas, the different forces of nature. Quantum field theory itself then evolved into quantum electrodynamics, quantum chromodynamics by the 1960s and 1970s. We were building bigger and bigger accelerators to look at smaller and smaller constituents of matter.

Physicists didn’t want to go and look at the messy world of biology. Biologists didn’t have the quantum mechanical background to apply some of this hard maths to the processes of life. So until all the way for several decades, probably until the 1990s very little was done.

Quantum biology was seen as an outside, rather controversial, somehow wacky area of science. Particularly when you think about some of the ideas that grew up during the late 1960s, late 1970s, when people were using quantum mechanics to describe all sorts of strange phenomena such as telepathy or ideas in pseudo-science. Quantum mechanics developed this mystical arm.

One of the most famous examples was the work of Roger Penrose and Stuart Hameroff. They proposed a mechanism that they argued explained the nature of consciousness. The idea is that there were these proteins within the neurons of the brain that could exist in a quantum superposition of two configurations and when enough of them became entangled together that’s when consciousness switched on. There was some brief excitement about this idea initially, but I think very quickly most scientists said: “No, hang on a minute, just because quantum mechanics is mysterious and we don’t understand it and consciousness is mysterious and we don’t understand it, it doesn’t mean that the two have to be connected.” And so that was another reason why people were rather nervous about approaching some of the ideas in quantum biology.

That changed. In the 1990s suddenly there were experimental techniques using fast pulsed lasers, 2D spectroscopy, where you could pump biomolecules, excite them and see how they decay. And suddenly some of these experiments were beginning to show that there were quantum effects going on, long living coherence, long lived interference effects that you couldn’t explain otherwise. Think of the two slits experiment in quantum mechanics, firing a beam of particles, photons or electrons, through the two slits and you see the interference pattern. Even when you fire one at the time, you can’t explain that interference pattern using classical mechanics, you need quantum mechanics. Well, they were seeing the equivalent of that taking place in certain special mechanisms with living cells, for example the way enzymes transfer particles from one part of the molecule to another, electrons and later even protons, 2000 times more massive than electrons, they were seeing these protons quantum tunnel from one place to another.

Jim Al-Khalili CBE FRS is an academic, author and broadcaster. He holds a Distinguished Chair in Theoretical Physics at the University of Surrey where he conducts research in quantum physics. He has written fifteen books on popular science, between them translated into over twenty-six languages. He is a regular presenter of TV science documentaries and the long-running BBC Radio 4 programme, The Life Scientific.

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