Slashdot Mirror
Quantum Mechanics Involved In Photosynthesis
Kristina at Science News writes "We all learn about photosynthesis in school: sunlight in, plant food out. Not well understood is how this process achieves its initial and uniquely high efficiency in capturing the energy of a photon. Quantum mechanics may be at work in the electron transfer process inside chloroplast, giving electrons the chance to consider many paths at once before choosing the best one."
The process involves photons that are absorbed while exciting the energy of molecules OF COURSE quantum mechanics is involved. Coming up next, thermodynamics may be at work in volcanic eruptions.
Unless you doubt the validity of the field of quantum mechanics, then you probably have to acknowledge that it's "involved" in all physical phenomenon. I mean, when you ask for an explanation of a specific phenomenon, you might want to know more about the larger scale interactions and forces, but still, electrons are involved and they're doing stuff. Probably all sorts of quantumy stuff that would blow your mind.
However, it does seem like quantum mechanics would turn up as much more relevant when you're talking about the conversion of light into some kind of energy a living organism can use. When you get down to the level of trying to analyze what happens to an individual photon in the process, I don't know how anyone expected to avoid talking about quantum mechanics.
To be honest, the result here, while important, is entirely unsurprizing. What you're dealing with here is bound electrons, moving from say, a chlorophyll group to a tyrosine amino acid residue. There's nothing knew that electrons, in particular bound electrons (such as in an atom or molecule) can only be accurately described quantum-mechanically. Electrons move through QM 'tunneling' quite a bit, so you simply cannot accurately describe electron-transfer kinetics (which is what's going on here) without QM.
No, it does not. First off, it spells trouble that you seem to view that as a desired end result. Hardly a good way to do science. Second, there is no good reason to believe that the brain cannot be described in terms of straight-up chemistry and biochemistry. We don't know how the brain works, but that doesn't mean it's unexplainable in terms of what we already know. There are plenty of things we haven't fully understood in biochemistry, but that doesn't mean they're generally believed to be unexplainable in the current framework of things. Occam's razor would dictate that that idea should be disregarded until there is some evidence that would make it necessary. No such evidence exists.
Further, your 'philosophical' points are simply invalid. Quantum mechanics says nothing about 'free will', or philosophical determinism for that matter. Quantum mechanics can be interpreted in either way, and has; e.g. the Copenhagen interpretation is nondeterministic, whereas the Bohm interpretation is.
I work with applying quantum mechanics at the molecular level, in biochemical systems, all day long. I have yet to find anyone in my field who thinks there are macroscopic quantum-mechanical processes going on in the human body. That is not due to lack of imagination, it's due to experience with actual quantum mechanics. All chemistry is inherently quantum mechanical. Physics cannot explain an atom even, much less a molecule, with classical theory. The relationship between chemistry and biochemistry is well-understood. The quantum mechanics of chemistry is fairly well understood (due to people doing what I do). And transition in the chemical domain from what is quantum-mechanical to what is classically describable is also well understood. There is simply no physics that explains how or why quantum mechanical effects would disappear and then re-appear orders of magnitude 'upwards' on the scale of matter.