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Photosynthesis May Rely On Quantum Effect
forgethistory sends us to PhysOrg for a summary of new research suggesting that the near instantaneous energy transfer achieved by photosynthesis may rely on quantum effects. From the article: "Through photosynthesis, green plants and cyanobacteria are able to transfer sunlight energy to molecular reaction centers for conversion into chemical energy with nearly 100-percent efficiency. Speed is the key — the transfer of the solar energy takes place almost instantaneously so little energy is wasted as heat. How photosynthesis achieves this near instantaneous energy transfer is a long-standing mystery that may have finally been solved."
I wonder if ferns ever look at us and laugh saying that non-quantum-sourced energy is so 3 billion years ago.
I was thinking about this just the other night, strange coincidence. There are probably a lot of functions like photosynthesis that rely on quantum effects. One of them might be the idea of consciousness. Consciousness may not be so easily explained without taking into account quantum effects. If self awareness is enabled through some sort of quantum effect, imagine the philosophical implications.
I'm sorry, please clarify: did you actually say anthing in that post?
... it's also been discovered that *all* physical phenomena may also rely on Quantum Effect.
I don't know about consciousness, but in his novel Blue Mars (last book of the Mars trilogy), published a decade ago already, Kim Stanley Robinson made use of research that suggests that memory relies on a quantum effect.
Was there any specific quantum effect you had in mind or did your spell checker mysteriously substitute the phrase "quantum effects" for the word magic ?
All interactions at the atomic level are quantum effects. A photon can only interact through quantum effects. The statement in the article is totally meaningless.
We have known that photosynthesis is a quantum effect since Einstein's paper on black body radiation.
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I can't seem to find the link (Google is not friendly today), but does this perhaps justify the researcher who postulated that the sense of smell comes from something akin to detecting nuclear resonance, not a simple chemical interaction? I recall that one detractor said that his theory was as outlandish as saying that food was digested in the stomach via tiny nuclear reactors. But it explained many things that didn't make sense otherwise -- like why cyanide smells like almonds.
He's apparently gone on to success in the perfume industry.
Someone find the link... this is driving me nuts.
Stressed? Me? Of course not. Stress is what a rubber band feels before it breaks, silly.
Would that mean that attempts to upload human minds to computers would fall foul of the no-cloning theorem? Such constraints on the duplication of quantum information would have interesting effects on philosophical problems of identity.
Real Daleks don't climb stairs - they level the building.
Maybe his spell checker uses quantum effects!
Well, back to rejecting software patent applications.
None that weren't already stated in numerous terms thousands of years ago in virtually every culture.
In one of the various debunkings of What the *bleep* do we know they cover that the neuronal activity in your brain is way too big to be affected by the very small quantum strangenesses that come up. On average they have no effect on your thinking.
Imagine if you weren't allowed to use roads because a bus company complained about your driving 3 times. --skunkpussy
When a photon strikes a chlorophyll, it adds its energy to an electron, allowing the electron to escape from its atom (previously known quantum mechanics). It was previously thought that the electron would then go bouncing around between chlorophyll molecules until it found a pheophytin molecule (slightly different chlorophyll). Once it hits that molecule, it activates an electron-transport chain (a similar process happens when burning glucose in a mitochondrion).
TFA suggests that the hopping uses quantum superposition to traverse the chlorophyll molecules more quickly. When the traversal reaches the pheophytin, the superposition collapses into that single state which found the pheophytin.
(IANAL)
It's quite possible given that think in terms of probability rather than absolutes even through our resulting probable answer borders on an absolute factual answer. Perhaps this is why we have such hard time processing mathematics in our head, yet not art or concepts.
Life is not for the lazy.
This explains why the hedge in my yard wasn't doing so well until it was temporarily taken over by the spirit of a wise and charming fern from the future, which corected everything that was wrong in the hedge's life before moving on to my neighbor's lawn ten years ago.
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The summary is slightly misleading, but this disconnect has big implications for the reader's understanding (imho)...
j ablonski.gif Unfortunately, this scheme doesn't show photofragmentation or energy transfer to another molecule, but I'm in a rush so it'll do.
I can name plenty of chemical reactions that are complete on the femtosecond scale, and while speed helps, that's certainly not the whole picture. What matters is how mismatched the energy levels between the reactant and the product are. When transitioning between energy levels, either energy is transferred out of the system by nonradiative release (heat), luminescence, photofragmentation, or transfer to a chemical partner - this last case is what the article is referring to. Getting to an energy level which can react is going to result in a heat deposition for at least some photons because any photon of a higher energy than the reacting state must deposit some of that energy just to be able to react at all.
http://www.monos.leidenuniv.nl/smo/basics/images/
The squiggly lines show possible heat depositions - the molecule starts in the ground state, absorbs a photon (the yellow up arrow), then relaxes to the excited state. This excited state then does whatever it's going to do. If 100% of the time under a set of conditions (i.e. a quantum yield of 1.00), the excited molecule follows a particular pathway we call that perfectly efficient. In the specific example of photosynthesis, this means that all of the absorbing chlorophylls transfer the energy along the photosynthetic pathway (I'm lumping all the subsequent processes together here). It does not mean that 100% of the energy got transferred along the way - there will always be some photon that deposits more energy than the reacting state has, meaning some energy will be converted to heat.
In short form (if you didn't feel like reading all this): efficiency in this case refers primarily to how often the molecule dumps its energy into photosynthesis instead of all to heat, luminescence, etc. It's not referring to the energy throughput, as some photons will always be an imperfect energy match, and the extra energy will end up as heat.
Be careful of your thoughts; they could become words at any minute...
Why do you need to invoke one mystery to "explain" another? I can't see why consciousness "may not be so easily explained without taking into account quantum effects". What particular things about consciousness seem to indicate quantum effects to you?
Other people have proposed this before, but present a theory of why quantum effects may be necessary. Roger Penrose makes the argument that we can compute things that a Turing-style computer could not compute, so something else must be going on. His proof that some things we do cannot be done by a Turing style computer isn't exactly accepted though, and no-one seriously believes that the brain works in this way in any case.
Also, consciousness is not the same thing as "self-awareness". Is a dog conscious? Is it self-aware? What about a rabbit? When I dream, I'm not usually self-aware, but there's some sort of consciousness there. What about phenomena like blind-sight, where a person is self-aware, but unconscious of visual information, even though they can access that information by guessing remarkably accurately, just without any direct consciousness of it. Does this mean that these supposed quantum-consciousness effects have broken down only for information originating in visual centers, but keeps working on all other information?
Of course, coming from quantum theory, there is the Copenhagen Interpretation which places a special status on the 'observer' - but no-one has managed to define what an observer is, or whether they must be conscious or not.
Yeah, sure the energy transfer efficiency is 100% for every photon that participates in the reaction. But of all the photons falling on the leaf, hardly 2% of them participate in reactions. Some gets reflected, some gets absorbed without any reaction. Even solar cells have better energy conversion efficiency than plants. Really. As for quantum effects, almost all the photo reactions are quantum mechanics. They have to be. The film camera emulsion has greater percentage of photons participating in reaction than chlorophyll.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Yes, but while knowing the mechanism netted someone their PhD (or some PhD their tenure,) a workable implementation will net some company billions of dollars. Nearly 100% efficient solar cells? Yes, please. Pass the chlorophyll over here.
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Red Mars was good, but by Blue Mars, I gave up partway through thinking I really don't care about these people or their dumb politics.
I believe he said, "I'm high."
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I must take issue with the 100% efficiency. Efficiency, as I know it, is a ability to convert stored energy into useful work. I know of no engine, artificial or natural, that can do this with 100%, which is of course prohibited by the known laws of thermodynamics. In particular, I have seen photosynthesis calculation that set the efficiency of photosynthesis as low at 3%. Even in the simplistic case, it appears that 50-70% of the energy in the process of photosynthesis.
"She's a scientist and a lesbian. She's not going to let it slide." Orphan Black
Contrary to popular belief, consciousness is not all that mysterious. We can with our knowledge today say with pretty good certainty that it's a post processing effect. After other mechanisms in the brain have done their processing and made a decision, consciousness kicks in in order to map the responses of the various parts of the brain into a coherent symbolic higher-level structure. Basically consciousness tries to explain on what grounds a decision is made in order to facilitate deductive reasoning.
The funny thing is that there is a quite long delay (average 500 ms) between when a decision is made in parts of the brain that you are not aware of to when you are aware of decision - and think that your consciousness is involved in making that decision. In reality the decision has been made a long time ago without the consciousness being involved.
The Orch-OR theory and similar ones are mainly a desperate attempt to explain away the data that rules out conscious thought as a first cause of decision. In reality though, consciousness is just another example of human exceptionalism that we have to abandon - just like we had to learn to live with the fact that earth is not at the center of the universe.
It erased you, but the data in storage stayed in place. Your neurocircuitry rebooted and launched a new instance of the consciousness process, which loaded in the existing memories seamlessly. You just think you're the original you.
Real Daleks don't climb stairs - they level the building.
Just kidding. I will leave now.
Well, that's only part of the story. The original capture loses very little energy...
1) If and only if the photon is of the proper energy. In general, during solar energy conversion of all kinds, you require a certain amount of energy to kick an electron out of the pigment. Less than that energy, and nothing happens. More than that energy, and the excess is wasted.
2) This only applies to the original photon capture. The total process of turning solar energy to sugars in plants is about 35%. Due to losses for biochemistry, the overall system is very inefficient -- usually just 1-2% in most crop plants, and a fraction of a percent in non-crop plants. Sugarcane is exceptionally high at 8%, still well below most silicon cells.
Now, dye-based cells *are* in development. The key for them is not that they're very efficient (they tend to be very inefficient), but that they should be very cheap to produce (no silicon refining needed). Of course, a few companies (such as Nanosolar) are working on commercializing high-efficiency dye-based cells. I read nanosolar's main patent at one point; basically, the efficiency problem with most organic solar cells is an uneven distribution of electron donors and receivers that leads to most of the electrons being wasted. In Nanosolar's case, they build a crystalline scaffolding that the dye gets embedded into at regular intervals, then dissolve the scaffolding.
The big brain am winning again! I am the greetist! Now I am leaving for no particular raisin!
I believe he said "I'm high."
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Hm. An interesting argument.
While in this particular case, the religious poster is being silly, I'm not sure I agree with your analysis of ridicule.
I suppose that ridicule being, "Well aimed", as you suggest, is the key.
Unfortunately, virtually every group I've ever seen uses ridicule to discredit whatever opposing viewpoint they find threatening. Not all of them are right, but they all believe they are right. In the end, no real progress is made and people stay in their fortified camps.
In the end ridicule is just another form of attack and control. Even though I have an imperfect track record, I have always, always found it better to ask questions and engage people in discussion and to offer genuine respect, (as opposed to pretended respect), when trying to find the truth of a given matter. People are far lessing willing to budge if you try to hurt them. Ego prevents it. If, however, they feel you hold truth as the ultimate goal and are happy to grant others the dignity of simply being another searcher who is human and capable of mistakes, then there is a greater chance of actually getting somewhere. And who knows? You might even discover that the other side has a better grasp on truth than you. If you don't attack others for being wrong, then you are less likely to attack yourself for being wrong, and are therefore more open to growth.
-FL
I'm not postulating anything, nor am I engaging in wishful thinking. I simply won't go so far as to assert that there is no "magic" me in my head that is not covered by current physics. Complexity theory may get involved in there somewhere, but I won't throw away the possibility that consciousness could be some kind of intrinsic property of the universe, as fundamental as anything else in our present theories. We simply have no idea. Until someone comes up with a more or less complete model of consciousness, I will not pass judgement. Maybe I've misunderstood, but I took your original post as an indication that you had already closed your mind to the possibility of new phyisics being discovered with relation to consciousness.
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