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More Evidence Found for Quantum Physics in Photosynthesis
December 7, 2011 12:01 AM   Subscribe

Previous experiments have hinted at the connection... Physicists have found the strongest evidence yet of quantum effects fueling photosynthesis. Multiple experiments in recent years have suggested as much, but it’s been hard to be sure. Quantum effects were clearly present in the light-harvesting antenna proteins of plant cells, but their precise role in processing incoming photons remained unclear. In an experiment published Dec. 6 in Proceedings of the National Academy of Sciences, a connection between coherence — far-flung molecules interacting as one, separated by space but not time — and energy flow is established. “There was a smoking gun before,” said study co-author Greg Engel of the University of Chicago. “Here we can watch the relationship between coherence and energy transfer. This is the first paper showing that coherence affects the probability of transport. It really does change the chemical dynamics.”
posted by aleph (64 comments total) 29 users marked this as a favorite

 
If I were smarter, I would understand this. Quantum physics just makes me feel stupid.

Hey, look at that shiny thing over there!

HELLO SHINY THING WE ARE FRIENDS NOW
posted by Avenger at 12:09 AM on December 7, 2011 [16 favorites]


Quantum physics just makes me feel stupid.

Based on my reading, there is some kind of "smoking gun" which far-flings molecules using the antennae of coherent plants. I welcome this new Super Weapon.
posted by twoleftfeet at 12:13 AM on December 7, 2011 [5 favorites]


I think the author could do a lot better job of explaining what, specifically, is being talked about that is new and "quantum" in a way that, oh, regular old bonding and electron excitation are not.

Is it just that the protein complex involved is large and one would not expect that particular mode of energy transfer over those distances, thus making photosynthesis unique/interesting?
posted by selenized at 12:23 AM on December 7, 2011 [2 favorites]


This is actually fairly simple as far as quantum mechanics goes. Basically the plants are using quantum effects to determine the most efficient path from the surface where the photon hits the plant cell to the energy storage area of the cell. It's able to do this because the photon remains a wave rather than a particle as it passes through the plant, which means that it's essentially able to travel all paths at once and the most efficient path becomes the real one after the wave function collapses and the energy is stored.

This is surprising because it was thought previously that this wouldn't be possible at room temperature.
posted by empath at 12:26 AM on December 7, 2011 [34 favorites]


There was a talk at The Perimeter Institute about this a while ago.
posted by empath at 12:27 AM on December 7, 2011 [1 favorite]


Maybe I'm just jaded, but wouldn't it be more surprising if something involving photons and electrons was quantum effect free? Or is the cool part that we can actually measure it here and wired is just doing typical science journalism?
posted by Kid Charlemagne at 12:28 AM on December 7, 2011 [2 favorites]


Maybe I'm just jaded, but wouldn't it be more surprising if something involving photons and electrons was quantum effect free?

Once the photon interacts with a large object at a warm temperature, generally you're dealing with classical physics because of decoherence.
posted by empath at 12:31 AM on December 7, 2011 [4 favorites]


And as far as what practical value this has -- trying to keep quantum states coherent at room temperature is the primary problem with quantum computing, so figuring out how plants do it could lead to breakthroughs.
posted by empath at 12:34 AM on December 7, 2011 [6 favorites]


Empath, you'll be two for two in my book if you can answer this question:

The link was so clear it could be described in derivative sines and cosines, mathematical concepts taught in college trigonometry.

Is the author just going to great lengths to not say Fourier Transform here? Or is there something else going on?
posted by Kid Charlemagne at 12:48 AM on December 7, 2011 [3 favorites]


Yeah, I have no clue. I can't find this paper, either.
posted by empath at 12:56 AM on December 7, 2011


Might he be referring to quantum beating? I didn't get that part either.
posted by selenized at 12:59 AM on December 7, 2011


Here's a paper (that appears to be from August?) called "Quantum effects in photosynthesis" that Google Scholar gave me in response to several search terms from the Wired article. The pdf is coming up as freely accessible for me. (And I don't have any subscription to anything, I'm not an academic.)
posted by XMLicious at 1:11 AM on December 7, 2011


Kid Charlemagne: Is the author just going to great lengths to not say Fourier Transform here? Or is there something else going on?

Honestly, it just seems like science-reporting-gobbledygook.

It's too bad the actual article will be hidden behind a paywall when it is publish, but luckily the same authors have put up a similar paper on the arxiv from last year that presumably led to these new findings.
posted by wjzeng at 1:16 AM on December 7, 2011


Honestly, it just seems like science-reporting-gobbledygook.

I hope it is not just that they used FT spectroscopy of some sort and the science writer got confused. That would make me so sad.
posted by selenized at 1:35 AM on December 7, 2011


It's able to do this because the photon remains a wave rather than a particle as it passes through the plant [...]

is it the photon that does this, or is it absorbed and then the excited state propagates through the whole mess of proteins in a wave-like way?
posted by selenized at 1:49 AM on December 7, 2011


Sometimes I feel like grammar is totally outfoxed by physics.
posted by From Bklyn at 2:19 AM on December 7, 2011 [4 favorites]


is it the photon that does this, or is it absorbed and then the excited state propagates through the whole mess of proteins in a wave-like way?

He explains it in the video I linked. Something about excitons, I think. I don't remember, it's been a while since I watched it.
posted by empath at 2:24 AM on December 7, 2011


Honestly, it just seems like science-reporting-gobbledygook.

I am very glad to read that sentence was as nonsensical as I suspected it to be.
posted by solotoro at 2:44 AM on December 7, 2011 [1 favorite]


I have hopes myself that this will get us a lot further in figuring out (and eventually duplicating) the efficiencies in photosynthesis. *That* would be Solar Power. I also wonder sometimes whether Quantum Mechanical tricks like these couldn't be added to increase the efficiencies of our photovoltaic solar power efforts as well.
posted by aleph at 2:58 AM on December 7, 2011 [1 favorite]


Einstein: not happy. *

Me? I find this an icredibly cool result. After all, photosynthesis is just converting EM to matter, right?




* Einstein had real issues with QM as a whole. See the Bohr-Einstein debates
posted by eriko at 3:54 AM on December 7, 2011


Is the author just going to great lengths to not say Fourier Transform here? Or is there something else going on?

I didn't understand that either. Any analytic function can be represented by cosines and sines, that doesn't mean much.
posted by atrazine at 4:15 AM on December 7, 2011 [1 favorite]


I have hopes myself that this will get us a lot further in figuring out (and eventually duplicating) the efficiencies in photosynthesis.

Actually even inexpensive mass produced solar panels are quite a bit more efficient than photosynthesis, unfortunately they take more resources to produce and their output isn't easily storable.

I agree with your hope though, artificial photosynthesis aims to produce liquid fuels directly from sunlight which would solve the storage and intermittency problems inherent in solar.
posted by atrazine at 4:18 AM on December 7, 2011 [1 favorite]


After all, photosynthesis is just converting EM to matter, right?

Photosynthesis doesn't create any atoms; it just uses energy to get them (starting as water and carbon dioxide) into an arrangement that they would not enter into otherwise (sugars).
posted by Jpfed at 4:39 AM on December 7, 2011 [4 favorites]


It's basically like rolling a ball up a hill. Or twisting a rubber band. It's storing energy that can be converted to useful energy later.
posted by empath at 4:55 AM on December 7, 2011 [1 favorite]


This is actually fairly simple as far as quantum mechanics goes. Basically the plants are using quantum effects to determine the most efficient path from the surface where the photon hits the plant cell to the energy storage area of the cell. It's able to do this because the photon remains a wave rather than a particle as it passes through the plant, which means that it's essentially able to travel all paths at once and the most efficient path becomes the real one after the wave function collapses and the energy is stored.


Beginning at 36min, Feynman makes it clear that photons are always particles. It's merely sometimes helpful to think about them (mathematiclly) in terms of waves...
posted by DavidandConquer at 5:32 AM on December 7, 2011


Beginning at 36min, Feynman makes it clear that photons are always particles.

They're always particles when you observe them.
posted by empath at 5:40 AM on December 7, 2011 [1 favorite]


They're always particles when you observe them

No. That's merely restating the commonly-held misinterpretation of the unfortunately-phrased "wave-particle duality". That misunderstanding is not helped by the fact that light was initially understood to be a wave up until 50 years ago because it looked as if it behaved as a wave and not a particle. However, as Feynman points out quite explicitly in the video I linked to above, a photon is a particle in every sense that an electron is a particle. The "wave properties" of light are a manifestation of quantum weirdness in the same way that electrons can "behave" (i.e., be best-explained) as waves. Neither electrons nor photons cease being particles when they take on wave-like properties.
posted by DavidandConquer at 6:00 AM on December 7, 2011 [2 favorites]


However, as Feynman points out quite explicitly in the video I linked to above, a photon is a particle in every sense that an electron is a particle.

I didn't say otherwise. They're both. But when you detect them, they act as particles. And when you don't, they act as waves. And if they interact with macroscopic objects, they generally act as particles, not waves.

Though obviously it's more complicated than that.
posted by empath at 6:18 AM on December 7, 2011


Neither electrons nor photons cease being particles when they take on wave-like properties.

But they definitely stop being waves when they take on particle-like properties?

My understanding has always been that they're something that can neither be completely conceived of as a snooker-ball-type particle nor as a wave in a medium. I am curious to understand, what particular quantum phenomena is it that you see as explaining how photons (and electrons, and atoms) can exhibit things like diffraction and interference patterns and still qualify as being inherently the same thing as infinitesimal particles bouncing around?
posted by XMLicious at 6:20 AM on December 7, 2011


I think the discovery of likely quantum effects in biological processes is fascinating. I wonder how much the process of a conscious mind may be dependent on quantum effects. If so it may explain the current inability to create a conscious AI with current hardware and possibly what used to be called ESP effects as well. Of course that is all wild speculation, but then again ten years ago it would have been considered the wildest speculation that photons take all possible paths through a chloroplast in order to find the most optimum reaction path.
posted by Poet_Lariat at 6:35 AM on December 7, 2011 [1 favorite]


I didn't say otherwise. They're both. But when you detect them, they act as particles. And when you don't, they act as waves. And if they interact with macroscopic objects, they generally act as particles, not waves.

My apologies if I misinterpreted what you wrote above. The earlier post just sounded an awefully lot like the common misconception that sub-atomic particles somehow stop existing ("the photon remains a wave") when they are not interacting with other particles.
posted by DavidandConquer at 6:37 AM on December 7, 2011


Yeah, I'm not seeing this at all in the Dec 6 issue of PNAS.
posted by unknowncommand at 6:43 AM on December 7, 2011


If so it may explain the current inability to create a conscious AI with current hardware and possibly what used to be called ESP effects as well.

Maybe the first part, but probably not the second. QM isn't magic.
posted by empath at 6:45 AM on December 7, 2011 [1 favorite]


Atomic physicist here. Empath is on the right track about the discovery here, though I'll make no endorsement of the wave/particle handwaving. It's the boring sort of quantum mechanics. There are two decay paths out of some initial state, the electron takes both, there's a brief window of time in which one can observe interference between the wavefunctions. After something like a trillionth of a second, the fun is over and the electron is in a definite state (it has de-cohered).

Maybe the most exciting thing is that at some level, everything in the universe is doing this, at least a little bit, essentially all the time and we're just not aware of it.
posted by fatllama at 7:03 AM on December 7, 2011 [6 favorites]


What happens within me when I read a popular science article like this:

Cynicism and Hope fight angrily with each other, while in the corner my weak, feeble Understanding sobs to itself "If only I were stronger I could settle this."
posted by benito.strauss at 7:35 AM on December 7, 2011 [2 favorites]


The citation given at the bottom of the Wired article doesn't exist.

Someone's confused about something.
posted by mr_roboto at 7:52 AM on December 7, 2011


“Here we can watch the relationship between coherence and energy transfer. This is the first paper showing that coherence affects the probability of transport. It really does change the chemical dynamics.”

Electricity can help coral grow:
http://reefbuilders.com/2011/09/02/coral-ark-electrified-artificial-reefs/
and
100+ years ago people were trying to get electricity to increase plant yields. Expect a new wave of yield increase promises via taking that old data and this new research paper.
posted by rough ashlar at 8:06 AM on December 7, 2011


here is a picture of the processs by which the FMO antenna complex transfer energy in this research from a helpful article about the blue-green algae which use them.

This is more evidence that the FMO protein, which apparently is the conduit (think: wire) for the energy released when the photon hits the chromatophor in these blue-green algae, is in a state of quantum coherence and I'm guessing this is coherence among each of the protein molecules making up the complex. The "FMO antenna" is a macroscopic system, other macroscopic systems exhibiting quantum coherence are things like superfluid helium, bose-einstein condensates i.e. made up of simple atoms. So, this is extremely surprising behavior for something as physically complicated as a protein molecule.

It seems like the thing that drives all of this is a measurement of the efficiency of energy transfer in photosynthesis which appears to be too good for purely classical processes. I'm not totally convinced that photosynthesis isn't an essentially classical system in the weird world of mesoscopic quantum mechanics but I'm not a quantum biologist (not your quantum biologist.) This is an effect being measured for blue-green algae with a particular mechanism (the FMO antenna). Photosynthesis of course occurs in lots of organism... I have no idea whether it's even plausible that the mechanisms for other organisms are similar to this one...
posted by ennui.bz at 8:16 AM on December 7, 2011 [2 favorites]


Speaking of biology leveraging quantum phenomena, there's the gecko feet utilizing Van der Waals forces thing.
posted by XMLicious at 8:34 AM on December 7, 2011


I think the discovery of likely quantum effects in biological processes is fascinating. I wonder how much the process of a conscious mind may be dependent on quantum effects. If so it may explain the current inability to create a conscious AI
*rolls eyes*
and possibly what used to be called ESP effects as well.
*rolls eyes even harder*

Look, there is no group of scientists sitting around trying to create an 'artificial consciousness' out there. It's a problem no one is working on. So if they're not trying, how can you say they've failed. What they are trying to do is create software that can answer questions as well (or better) then a human. So for example IBM's Watson isn't conscious, but it doesn't need to be to solve the problem.. Google search doesn't need to be conscious to be able to answer a broad range of questions.

And the other problem is there is no scientific definition of 'consciousness'. I mean, we do have a test of 'self awareness' that we give to animals, whether or not they recognize themselves in a mirror. But computers would have no problem with that at all.

So come up with a 'scientific' definition of consciousness (something you can measure) and then see if people can build computers that will be able to meet that criteria.
posted by delmoi at 9:01 AM on December 7, 2011 [2 favorites]


We need to take a bit of a step back here. This is, strange as it may seem, not about photosynthesis. It's about energy transfer within light-harvesting complexes (which are present in all photosynthetic organisms, so I'm being pedantic, sorta). The purpose of light harvesting complexes is to absorb photons from the light field and transfer the energy gained to the reaction centers where the photochemistry part of photosynthesis occurs. The nifty thing about this is that the pigment-protein complexes that make up the light harvesting complexes can 'pass on' the energy from molecule to molecule, like a bucket brigade, to reach the reaction centers. The mechanism by which this is passed on is often called 'resonance transfer' or the 'Förster mechanism' (google away), and it's assumed that it happens because "adjacent" molecules have overlapping energy levels so the exciton (the little quantum of excitation energy that resulted from a photon being absorbed) can 'hop' from molecule to molecule until it reaches the reaction center which has an energy state that's downhill a bit in energy terms from the initial absorbing chromophore (not chromatophore, that's a squid skin thing) And yes I am skipping a bit, but I'm not good at explaining this. Now it would appear that they don't have to be adjacent, and the mechanism works better than can be explained by the usual statistical approach. Cool.
posted by zomg at 9:13 AM on December 7, 2011 [6 favorites]


Basically the plants are using quantum effects to determine the most efficient path from the surface where the photon hits the plant cell to the energy storage area of the cell. It's able to do this because the photon remains a wave rather than a particle as it passes through the plant, which means that it's essentially able to travel all paths at once and the most efficient path becomes the real one after the wave function collapses and the energy is stored.

Why isn't that simply explained by longer paths having greater resistance?
posted by Durn Bronzefist at 9:15 AM on December 7, 2011


Why isn't that simply explained by longer paths having greater resistance?

Without the quantum effects the exciton can't tell what path will have more resistance: it can only jump to another molecule with the same energy state, which could be the wrong path altogether.
posted by zomg at 9:22 AM on December 7, 2011 [1 favorite]


The citation given at the bottom of the Wired article doesn't exist.

Someone's confused about something.


Confirmed. Article does not exist as cited.
posted by DavidandConquer at 9:32 AM on December 7, 2011


Look, there is no group of scientists sitting around trying to create an 'artificial consciousness' out there.

They surely are, and have been for decades. It's just sometime in the 70s or so, everyone realized that the problem is so vast that it was basically intractable. So everyone is working on subsets of the problem like natural language processing and game playing, etc. But I bet there's not a single AI researcher anywhere that doesn't see that as a long term goal for the field.
posted by empath at 9:55 AM on December 7, 2011


I wonder how much the process of a conscious mind may be dependent on quantum effects.

Eye rolling about drawn conclusions aside, this isn't the first time I've heard this idea. I have a book on my shelf at home which engages in some excitable speculation about quantum mechanics and comes to this conclusion. Can't provide title/author right now but will do if someone wants to know.
posted by illongruci at 9:57 AM on December 7, 2011


Why isn't that simply explained by longer paths having greater resistance?

Path of least resistance is a local phenomenon. There might be 'bumps' or 'valleys' in the energy level and there's no way of knowing which total path is more efficient without actually travelling all of them, which would be less efficient then what is happening here, which is that all path's are travelled simultaneously.
posted by empath at 10:01 AM on December 7, 2011


Poet_Lariat: "I think the discovery of likely quantum effects in biological processes is fascinating. I wonder how much the process of a conscious mind may be dependent on quantum effects. If so it may explain the current inability to create a conscious AI with current hardware..."

That's pretty much the conjecture of Hameroff and Penrose with their theory of microtubules. Not sure how "consciousness" would arise from a quantum effect over a classical mechanics, though at the same time I wouldn't be surprised if we found out QM did play a role in consciousness.

The only issue, as empath noted above, is that just because entanglement leads to weird things at the small level, doesn't mean those effects happen at the larger level (as he pointed out, due to decoherence). Then again, they seem to have successfully entangled diamonds at room temperature... But I try to stay away from the woo when it comes to my science.
posted by symbioid at 10:10 AM on December 7, 2011


I was actually really skeptical about quantum effects in biology before reading about this research last year. My thinking on it now is that if it's happening in bacteria, it's probably happening every where. That said, I don't know how it would tie into consciousness. I don't think quantum mechanics explains 'free will' or any other specific aspect of consciousness, but I wouldn't be surprised at all by quantum effects being involved in signalling between neurons.

Whether that has anything to do with why consciousness is difficult to reproduce, I don't have any idea, but it's absolutely worth looking for.
posted by empath at 10:17 AM on December 7, 2011


symbioid: I was just about to mention those two. Penrose and Hameroff's conjectures about anesthetic and some other interesting musings related to the topic of this thread can be found in their book:

Quantum Aspects of Life

Though it should be made clear that many of these opinions are in the very small minority. Remember, just because we neither understand quantum foundations nor consciousness doesn't mean they have to be the same thing.

Of course there are many cases where inspiration from the structure of quantum mechanics has been fruitful in interdisciplinary ways, e.g. in linguistics for understanding the interplay between syntax and semantics. <-- Full disclosure, this work goes on in my group. There are other examples from Scott Aaronson's and others applications of techniques learned in analyzing the complexity of quantum information to classical complexity problems in cs.
posted by wjzeng at 10:22 AM on December 7, 2011 [1 favorite]


(Ahem. Is this thing on? Okay then...)

The citation given at the bottom of the Wired article doesn't exist.
Someone's confused about something.


Confirmed. Article does not exist as cited.

Yep, article doesn't exist as cited. I did find this listing of papers which says it's been accepted by PNAS, but no preprint or link. It'll probably be in a future edition of PNAS.

I also found an earlier paper from the same group (arxiv abstract link) that describes quantum coherence at near room temperature (277K) in photosynthesis. The last line of that abstract is suggestive enough: "The persistence of quantum coherence in a dynamic, disordered system under these conditions suggests a new biomimetic strategy for designing dedicated quantum computational devices that can operate at high temperature."
posted by RedOrGreen at 11:56 AM on December 7, 2011


"Path of least resistance is a local phenomenon. There might be 'bumps' or 'valleys' in the energy level and there's no way of knowing which total path is more efficient without actually travelling all of them, which would be less efficient then what is happening here, which is that all path's are travelled simultaneously."

This reminds me somewhat of the Traveling Salesman Problem. I wonder if quantum computing could help solve that.
posted by klangklangston at 12:26 PM on December 7, 2011


Huh. Not 5 minutes I was wondering what our colloquium was on today.

Here it is. Man, and I was just going to go steal a cookie and get back to work.
posted by nat at 12:48 PM on December 7, 2011 [1 favorite]


I wonder how much the process of a conscious mind may be dependent on quantum effects.

There is at least one protein that uses quantum tunneling to move one of it's hydrogens from point A, to point B, through itself, to do it's business. They demonstrated this by replacing said hydrogen with a deuterium and instead of the reaction being half as fast (because deuterium weighs twice as much) it was like 1/1000th as fast (which apparently only makes sense if you assume that the hydrogen was taking a short cut through the rest of the protein. And once you find it going on once, you can pretty much but it's happening elsewhere.

So the odds are that, yes, a conscious mind IS dependent on quantum effects, but the same is true for the digestion of the sandwich I just ate. Kind of takes the Oooooo out of the Wooooo.
posted by Kid Charlemagne at 1:37 PM on December 7, 2011 [3 favorites]


@atrazine: The efficiency I was hoping could transfer to photovoltaic solar power was just the first light capturing step which is (I've heard) extremely efficient beyond what we can do. Perhaps something like using Quantum effects to guide the newly created hole/electron pairs in a Solar Cell to their respective sides rather than recombine immediately and lose their contribution to the cell's output. Don't know. That's for a vague possibility of the future. As you mention, the biggest immediate result, assuming we could master the effect, would be the conversion of sunlight into biofuels.
posted by aleph at 1:57 PM on December 7, 2011


Ok, so I went to the colloquium that I linked to above.

IAAP, but not at all this *kind* of physicist, so I don't have too much to say myself. There were a few interesting comments and questions near the end of the talk, though, which might be worth listing here:

1) The quantum coherence appearing here could be due to the fact that they're hitting these light-harvesting complexes with lasers, which being coherent themselves, can induce at least brief coherence in other systems. (One person asked if this was true, and I don't think the speaker gave a very convincing answer either way).

2) The speaker does *not* think that these protein complexes evolved in order to use quantum mechanics to maximize path efficiency for excitations moving from the surface to the reaction core. Instead, he thinks they evolved to maximize chlorophyll density; evidently some of these complexes have a density equivalent to a .25 molar solution of chlorophyll. Also evidently, if you just took a bunch of chlorophyll and threw it in a solution (that is, if you didn't build up these complex protein structures to house it) then at even lower densities (e.g. .1 molar) you'd find that most of the chlorophyll never really got hit by light and your energy conversion efficiency would drop.
But this isn't a quantum thing, really; it's just "let's click the legos together in the right way so light can get to the important bits of all of them."

3) Some of the organisms that produce these antenna complex proteins have multiple genes that code for several slightly different versions of the protein. In other words, the organism could make ProteinA, ProteinB, or ProteinC, all of which differ by just a few amino acids. Which gene it actually uses to make the protein depends on prevailing light conditions. So some optimization is happening in which protein is built depending on how bright the light is, what wavelengths come through, etc.

4) The speaker said that you might really need to understand the quantum mechanical effects here if you want to be able to build a feedback control setup. (I dunno why this should be true, we'd have to find a quantum control person to ask).

5) Speaker also seemed to agree with Kid Charlemagne-- everything biological is quantum mechanical at some level, but you might not really care for most purposes. Mmm, quantum sandwich.

Anyhoo, as I said, not at all my field, I got lost in the details halfway through, any errors are mine, and anyhow I've only heard what this one speaker said about this sort of research; who knows what the authors of the papers in the Wired link would say.
posted by nat at 2:40 PM on December 7, 2011 [3 favorites]


Oh also here's a review in Nature.
posted by nat at 2:41 PM on December 7, 2011 [1 favorite]


Thanks for that timely summary, nat. Neat stuff.

I don't agree with the speaker on Point 2. Maximizing chlorophyll density has to do more with energy transfer than with light absorption. At the density of pigments in plant cells there already is a loss of specific efficiency in light absorption due (essentially) to the pigment molecules shading each other. This is macro-scale measurable and is known as the 'package' or 'discreteness' effect. If your chromophores are too widely spaced they can't transfer energy to each other (using resonance transfer, not quantum effects) so the whole thing doesn't work, so if they're tightly packed that's why. I also can't see why, if quantum effects are important at all, you'd want to assert that the plants didn't evolve to use that. That's hmm. In terms of the legos fitting together, yes. That makes sense.

*twitches slightly remembering his dissertation work*
posted by zomg at 3:09 PM on December 7, 2011


I also can't see why, if quantum effects are important at all, you'd want to assert that the plants didn't evolve to use that

Yeah, I agree. I'm not sure if I understood him correctly, but it really seemed like he was saying that the quantum effects just weren't really important. Which.. well, I'm confused.
posted by nat at 3:17 PM on December 7, 2011


Well, maybe the quantum effects are not important to the photosynthetic system as a whole (which is true at some scales, really, plants are not light-limited in general). But the result is of interest because it demonstrates quantum effects in a natural system at room temperature? I'm just hand-wavey speculating at this point, sorry.
posted by zomg at 4:10 PM on December 7, 2011


From Bklyn: "Sometimes I feel like grammar is totally outfoxed by physics."

Are you kidding? Grammar and physics are the same thing.

Grammar: A sentence is a grammatical structure which is composed of a particular arrangement of words. Words may have multiple inherent definitions, but a word's context tends to clarify which definition is in use. Each word is itself made up of one or more letters, each of which tends to have particular roles (consonant, vowel) and characteristics (pronunciation). While isolated letters and letter groups may form identifiable word fragments (prefixes, suffixes), they are usually not meaningful by themselves outside the context of a larger word.

Physics: An atom is a physical structure which is composed of a particular configuration of subatomic particles. These particles may each be described by a wave function representing multiple positions, although interactions within the atom (and with nearby atoms) tend to cause them to collapse to particular states. Each subatomic particle is itself made up of one or more elementary particles, each of which tends to fall into particular categories (quarks, bosons) and have particular characteristics (spin, color). While isolated elementary particles and particle groups may have predictable behavior, they are usually not observable outside of their effects on larger structures.
posted by Riki tiki at 4:41 PM on December 7, 2011 [2 favorites]


aleph: I have hopes myself that this will get us a lot further in figuring out (and eventually duplicating) the efficiencies in photosynthesis. *That* would be Solar Power. I also wonder sometimes whether Quantum Mechanical tricks like these couldn't be added to increase the efficiencies of our photovoltaic solar power efforts as well.

One of the professors in my department does research on pretty much this--investigating how photosynthetic molecules structure themselves to efficiently create energy, and trying to make photovoltaic cells that use a layer of biological photosynthetic dyes (mostly betanin extracted from beets. They just buy cases of beets locally, and extract in-house.) It's still very preliminary work--the efficiency is still low compared to dye-sensitized solar cells using inorganic dyes (which in turn have low yield compared to traditional silicon cells), but it's a very interesting union of pure and applied research.
posted by kagredon at 12:31 AM on December 8, 2011


Why betanin? Does that have a more efficient rate of absorption? I'd imagine that a green color would make the most sense (i.e. chlorphyll) -- but that's just a guess based upon my utter lack of knowledge. So I am curious, why red and not green? Is it due to the longer wavelength of red?
posted by symbioid at 10:30 AM on December 8, 2011


Why betanin? Does that have a more efficient rate of absorption? I'd imagine that a green color would make the most sense (i.e. chlorphyll) -- but that's just a guess based upon my utter lack of knowledge. So I am curious, why red and not green? Is it due to the longer wavelength of red?

The main substrate used for dye-sensitized solar cells is titanium dioxide. Chlorophyll tends not to adsorb very well to titanium oxide (this paper mentions problems with both binding, because chlorophyll has fewer polar carboxyl groups, and not aggregating well due to having a lot of long chains), so different groups have tried a variety of different dyes (various betalains, anthocyanins, etc.) to get around that.
posted by kagredon at 12:30 PM on December 8, 2011


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