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by thraway180306
2764 days ago
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All chemistry is ultimately quantum, same with rocks and everything up to celestial bodies (meaningfully, the moon Hyperion decoheres). For most of calculations though classical models are good enough, vast majority of chemical reactions behave as if molecules were newtonian springs. When people talk of quantum effects in chemistry they really mean it. In case of photosynthesis the basic molecule's efficiency was found hinging on stuff that is very quantum. This was described by Gregory Engel et al. Alan Aspuru-Guzik interprets some of what's happening as a realization of quantum computation running a tree-walking algorithm. The wider conclusion is that living organisms do evolve around quantum effects (if the molecule existed a priori somehow) or maybe even evolve to the point of reaching and then harnessing them (making the molecule). Now to what's Penrose about. Seldom anybody actually reads the guy or know the context. He was after the computational theory of mind. Not necessarily looking for a theory, but sneering at one big non-theory. This is in context of the 80's with unhinged stuff coming from the AI community (same as today). He was wondering if brain could really be this reducible and a known model of computation (he hasn't done a good review) from the physical point of view. For him a full logical reductionism necessiated excissing the measurement problem (the basic point goes back to Niels Bohr who thought biology cannot be entirely physics because of this). So he proposed a crude version that fleshes out measurement as a real physical process. His idea has the main upside of removing both quantum and AI mysticism. This received angry and mostly off-topic response based on caricature summaries like elsewhere in this thread. Of course lending themselves to such caricatures says a lot about writing if not the ideas, but it's an honest try that ain't entirely silly and without upsides. The microtubules guy is someone else who Penrose was just happy to see come and collaborate with later. He'd be happy with any kind of other stuff, such as from the original article. BTW the author is Philip Ball, a long time editor of the Nature journals, and he's got a new book out about interpretations of quantum mechanics that is really superb to anything else on the market by far (that is could be better but isn't worthless). |
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