Further Evidence That Photosynthesis Involves Quantum Mechanics

By Veronique Greenwood | December 8, 2011 12:20 pm


Biologists have recently had cause to wonder whether the molecules they know and love are pulling some quantum trickery while they’re not looking: one of the large proteins that captures light in photosynthesis was observed in several studies apparently using coherence, one of the hallmarks of quantum mechanics, to determine the best possible route for shunting energy through its atoms. Now, further experiments that use lasers to tweak such proteins and observe their response have provided more evidence that this is happening—an exciting indication that the strange laws of quantum mechanics can affect the behaviors of large agglomerations of atoms.

Our own Sean Carroll of Cosmic Variance explained how coherence works when this phenomenon was observed in real plants at room temperature last year:

We can think about this in terms of Feynman’s way of talking about quantum mechanics: rather than a particle taking a unique path between two points, as in classical mechanics, a quantum particle takes every possible path, with simple paths getting a bit more weight than complicated ones. In the case of the [photosynthesis] protein, different paths for the energy might be more or less efficient at any particular moment, but this bit of quantum trickery allows the energy to find the best possible route at any one time. Imagine at rush hour, if your car could take every possible route from your home to the office, and the time it officially took would be whatever turned out to be the shortest path. How awesome would that be?

The reason you can’t do that is that your car is a giant macroscopic object that can’t really be in two places at once, even though the world is governed by quantum mechanics at a deep level. And the reason for that is decoherence — even if you tried to put your car into a superposition of “take the freeway” and “take the local roads,” it is constantly interacting with the outside world, which “collapses the wave function” and keeps your car looking extremely classical.

Proteins in plants aren’t as big as cars, but they’re still made of a very large number of atoms, and they’re constantly bumping into other molecules around them. That’s why it’s amazing that they can actually maintain quantum coherence long enough to pull off this energy-transport trick.

We humans, of course, are made up of a large number of molecules each made up of a large number of atoms. When we get these kinds of insights into quantum mechanics at the molecular level, it’s hard not wonder—what about our own bodies is quantum mechanical?

Image courtesy of saturn / flickr

  • Monique

    To answer that last question, most likely far, far more than we can measure yet. Of course, the first place to look for it is in the brain and nervous system. So, I have a great deal of faith that at some point in the not too distant future we will be finding ways to try to measure it.

  • http://discovermagazine.com Iain

    I read something a few years ago about quantum tunnels in the brain giving us a sense of time.
    It may even have been in this magazine.

  • http://www.skepdic.org Don Gwinn

    Awesome, but I’m so jaded . . . . I’m just waiting with dread in my stomach for every psychic/medium/dowsing/radionics huckster to start yelling, “I TOLD YOU! EVERYTHING IS QUANTUM! EINSTEIN WAS RIGHT ABOUT SPECIAL SPIRITUAL ENERGY FIELDS! YOUR DEAD GRANDMA SAYS HELLO . . . . WITH QUANTUMNESS!

  • John Lerch

    Don should be jaded. This description makes it sound like quantum particles have some goal in mind and they take the shortest path there. This is the same problem we have with pop understanding of evolution–everyone ( pseudo-science creationists and even scientists alike) make it seem like evolution has a goal in mind. Instead it’s a random walk just like QM. The goals that quantum particles reach are just the non-interfering results of the particles taking all paths. The paths that are not “shortest” interfere with each other. They are still executed; but the oscillations are so quick and interfering they are lost in the noise. IOW our individual atoms still make it all the way home by the shortest path, but the RELATIONSHIPS (AKA negentropy) do not. Relationships are a macroscopic object and macroscopic objects’ behavior oscillates very very quickly like sine (Mass*time). So as the mass goes up the frequency goes up.
    The photosynthetic machinery here has more in common with the interferometer than with the light; so it’s not surprising that coherence is exhibited.

  • http://paibeiramar.org Runyan Wilde

    My theory is that ALL of our experience is quantum, in that the ‘path’ of experience keeps adjusting for longest survival by deselecting non-viable branches (such as standing, unscathed, outside of your flattened car in a freeway crash, or getting some ‘lucky’ break when it looked like you were doomed). These ‘rebranchings’ have happened to all of us, many times, but we have been taught to ignore the ‘impossible’ outcomes — the ‘miracles’. By careful observation, you can prove this for yourself but, for practical reasons, not to anyone else’s satisfaction, unless they, too, have made the effort to notice the gaps and mismatches in their “life experience.”

  • Jay Fox

    Then there is quantum entanglement. Once entangled, how long do pairs persist? Is it possible that when people experience “distance communication,” that phenomenon when two people a continent apart somehow know what the other is doing, is actually a quantum entanglement event?

    For that to be possible, the human body would have to have some way of accessing, and recognizing, quantum entanglement. We have so much to learn.

  • scott

    great book called quantum evoltution….our consciousness at the quantum level as a wave directs actions and thoughts


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