Photosynthesis May Rely On Quantum Effect 234
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."
Comment removed (Score:5, Interesting)
Re:not solved, just possibly more understood. (Score:4, Interesting)
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.
Nuclear Sense of Smell vindicated? (Score:4, Interesting)
He's apparently gone on to success in the perfume industry.
Someone find the link... this is driving me nuts.
Re:I'm sure a lot more things rely on quantum effe (Score:5, Interesting)
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.
Re:I'm sure a lot more things rely on quantum effe (Score:3, Interesting)
Re:I'm sure a lot more things rely on quantum effe (Score:4, Interesting)
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.
Re:Even more amazing... (Score:5, Interesting)
Re:not solved, just possibly more understood. (Score:4, Interesting)
Re:I'm sure a lot more things rely on quantum effe (Score:3, Interesting)
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.
Re:100% efficiency (Score:5, Interesting)
But one thing we should also realize is that, nature has not produced a more efficient photosyntesis process. Plants do not use their energy for mobility. Just to grow. Growth is limited by other resources like minerals and water. So there might not be additional survival value in developing a more efficient photosynthesis process. But still we should be open to the possibility that 2% efficiency is probably the maximum for photosynthesis, using water+co2, producing C12H22O11 (sugar) and oxygen.
Re:not solved, just possibly more understood. (Score:4, Interesting)
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 [nanosolar.com]) 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.
Re:More to it than that (Score:3, Interesting)
[ignore this] (Score:1, Interesting)