What's quantum physics got to do with biology?

Photosynthesis allows plants to convert light from the Sun into energy, and, in some cases, it does this incredibly well. In fact, certain bacteria can capture 95% of the light that hits them and turn it into useful energy.

Solar panels also convert light from the Sun into energy—but they aren't nearly as good at it. The very best solar panels ever tested in a lab (i.e., not the ones actually available for sale and installation on your house) were able to convert about 34% of the light that hit them into electricity. (Individual experimental solar cells can do better than that. But those are even further away from being incorporated into commercially available panels.)

Why can't we use the Sun's energy as effectively as bacteria can? The secret may be that the bacteria are using quantum physics to transmit energy. It's sort of like the bacteria have a method for keeping boxes of energy from falling off the truck during transport.

We don't often think of biology and quantum physics as overlapping realms of science. But, truth is, quantum physics could be incredibly important to understanding the way biology works and to the very development of life on Earth itself.

Tonight at the World Science Festival, astrophysicist Paul Davies and quantum computing innovator Seth Lloyd will talk about the growing field of quantum biology—why it works, what it means, and how it might shape our future. The Bad News: The Festival is happening in New York City and tonight's panel is sold out. The Good News: You can watch a live webcast of the event online.

I'll be hosting the webcast tonight, starting at 8:00 Eastern time. You can watch the video feed and join in the conversation at the World Science Festival's website.

EDIT: Thanks to the readers for pointing out that I'd made some big errors in this. Should be fixed now.

Image: Jatropha hybrid - Leaf detail (129 DAS), a Creative Commons Attribution Share-Alike (2.0) image from 47108884@N07's photostream



  1. I’d expect the leaf to be much blacker if it captured 95% of the light that hit it.

    1. Because its pulled out of someones ass

      “For actual sunlight, where only 45% of the light is photosynthetically active, the theoretical maximum efficiency of solar energy conversion is approximately 11%”

  2. Hate to be the polemicist here, but I just read an article about renewables from photosynthesis last week in the New Yorker. The portion I’d like to link to is for subscriber’s only, but it reads:

    “Natural photosynthesis is starkly inefficient: many plants convert as little as one per cent of the energy in the sunlight that falls on them.”

    From the article “The Artificial Leaf” by David Owen in the May 14, 2012 issue of the New Yorker

    1. Don’t know the article in question or any actual facts, but I’d like to point out that technically both statements can be true. Plants are not entirely made of green photosynthetic cells, so that will certainly lower the conversion rate over the whole plant. More importantly, not all plants are the same. There may be crappy plants and 95% efficient plants, and we need only concern ourselves with the 95% version since that’s our goal and that’s what we want to copy.

  3. plants are using quantum physics while we try to muddle through with the classical stuff

    Quantum mechanics is deeply involved every time we breathe – and with some very similar molecules to those involved in photosynthesis. I tried to explain in some detail a while ago here

  4. This is very poorly described. The recent result in photosynthesis research shows that energy TRANSPORT within the leaf utilises entanglement, and is extremely efficient. Every possible path is explored in parallel and the most efficient one automatically selected. Feynman, the inventor of the “many paths” method in quantum mechanics, would have beamed with pleasure.

    The real mystery here is how decoherence is avoided in a sloppy, warm and wet biological ensemble. That would be a very useful trick to learn.

    1. What an extraordinary claim! I looked it up:

      …and I STILL don’t believe it. I wonder, do you know, are they using ‘entanglement’ in the EPR sense? I’m willing to believe that, somehow, the plant has developed a wave whose coherence length is longer than the mean free path–but ‘entanglement’…I hear that and I think that the plant is using something like quantum computation. Is that accurate?

  5. plants are using quantum physics while we try to muddle through with the classical stuff

    Not to pile on, but I think the photoelectric effect is pretty solidly rooted in quantum physics.

  6. Nate Lewis has had his finger on this for a while:

    Basically, photosynthesis IS incredibly inefficient at electron transport, but it is better at making/breaking chemical bonds. So, perhaps, one could use photons to drive useful chemistry.

    Let me join the chorus: I’ve always heard that photosynthesis is inefficient, more 1% than 95%.

  7. It’s sort of like the bacteria have a method for keeping boxes of energy from falling off the truck during transport.

    I keep picturing Energon Cubes…

  8. I find this article very interesting!

    It reminds me of how (i’m pretty sure) it is impossible to explain in a linear thermodynamics way how i eat only a chocolate bread in the morning and am able to kick nonstop whole day long carrying a 155 pounds of body around. Of course, to any ChiGong practitioner it is clear that the mere tingling in the arms when you lift them is already vital energy entering into you.

    Compared to the magic (yes, quantum magic) of the living beings gifted with intentionality, a mechanism performs myserably: i construct very light radiocontrolled planes and even with the optimum parameters and a very fat LiPo battery they can’t even come closer to 1/50 th of the performance of the living body if you compare to how much energy you put and how much you can spend with it… 

  9. Hi Maggie maybe you want to relate this to your energy pieces  — The human world pretends that a Euclidean visual image represents a fractal and a Newtonian calculation represents a quantum one >>>>>>>  
    well my friend as 60% of the design and action is lost in the translation and the efficiency as well. Fortunately electrons KNOW what world they belong to and how it works

  10. I’m reminded of a theme from Neal Stephenson’s Anathem

    Spoilers Ahead — maybe not Big Spoilers, but Spoilers.

    Here’s a relevant passage from Wikipedia (not sufficiently Stephensonian for my taste, but it’s what I have at hand):

    It was later recognized as some sort of many-worlds interpretation”narrative shifting”, in being able to shift consciousness – which is hypothesized as the driving force behind reality, as something is not measurable until it is observed in quantum theory, thus a phenomenon called wave function collapse occurs from many very similar cosmi to the “real” one. This is made possible because the mind is found to inhabit many slightly different cosmi, and moments of thought where everything “falls into place” are recognized as the mind’s reaction to waveform collapse. 


  11. This is the future.

    If politicians had any sense they’d be investing every penny we have in researching the shit out of this.

    Y’know, before it’s too late and we’re scrabbling around in desperation as our economies and civilizations collapse with the death of our meagre petro-chemical resources.

  12. I’d like to point out that 95% efficient photosynthesis would be Carnot-equivalent (sun at ~6000K, earth at ~300K). That is, there would need to be absolutely no waste in order for that to be true.

    Of course in practice photosynthetic organisms are not optimized for maximum energy production. Water and CO2 and soil nutrients are more limited, as is the ability to dissipate heat. Sunlight is never the limiting factor, so why spend a lot of effort optimizing to use every photon? Evolution drives you away from that, towards putting the extra energy into other priorities.

  13. Efficiency info: The light-harvesting antenna structure is not continuously processing incoming photons. After an electron has absorbed the photon, the energy is shuffle to the next system as the molecules in the light-harvesting structure reset. That reset process takes about 75% of the cycle. So the photons are actually being absorbed only 25% of the time!

    This implies that, if the timing is right, an artificial lighting regime that flashes the plants for only 25% of the time can be as efficient as full, continuous  light.

    Now to envision that efficient grow-light scheme.

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