[mannykannot]

Furthermore: "Photosynthesis is shown to be quantum mechanical" - well, yes, just like everything else in physics, with the possible exception of those issues, like black holes, where gravity is dominant. The quantum-mechanical basis of chemistry has been included in high-school chemistry curricula for at least half a century, so it would be quite remarkable if photosynthesis were a exception.

While it is possible that the human mind has no classical-approximation explanation, the equating-of-ignorance argument, stated in the article's subtitle, is no reason to think it is so (and quantum mechanics is much better understood than the human mind, anyway.)

[thraway180306]

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).

[adrianN]

My problem with his theory is not that consciousness in the brain might be dependent on quantum effects, but that he seems to conclude that this makes it impossible for computers to have consciousness. Quantum computers can be simulated by classical computers.

[thraway180306]

That's a significant goalpost move. From debating particular mechanisms and postulated inevitability of AI, to assuming full blown strong Church-Turing-Deutsch principle and moving from there. Along with moving whole discussion from practical concerns into philosophy and really arguing from the thesis, at which point most people lose interest.

[jungletime]

Somewhat related, Giulio Tononi on his theory of consciousness and why computers can't have consciousness.

https://youtu.be/eskWYOH-Oxs?t=270

Starts at 4:34

[lloeki]

> Hyperion decoheres

Fascinating!

http://blogs.discovermagazine.com/cosmicvariance/2008/10/23/...

[noetic_techy]

They are referring to the finding that plants utilize coherence to transport photons efficiently to reaction centers to be converted to chemical energy. A quantum trick not thought possible in biological settings.

https://www.bbc.com/news/science-environment-22996054

[mannykannot]

My issue is with how the author is using this fact as if it were an argument for the proposition that consciousness cannot be explained without invoking quantum 'weirdness' (and, conversely, will be explained with it.)

The way the author presents it seems calculated to suggest that it is a more relevant fact to his claim than it is, mainly by leaving out any context and details that show it is not.

This is not even the worst case, which I think goes to this: "Might it be that, just as quantum objects can apparently be in two places at once, so a quantum brain can hold onto two mutually-exclusive ideas at the same time?"

Note how the author phrases it in a way that would allow him to brush it off as mere speculation or analogy if he is challenged on it - a case of the motte-and-bailey tactic. I think this passage qualifies as being "not even wrong", and the whole article clearly fits Feynman's definition of cargo-cult 'science'.

Meanwhile, I have a computer that can do two tasks at the same time - does that mean that it is a quantum computer? I see D-Wave is selling quantum computers for upwards of $15M, but mine is available with bids starting at a mere $5M.

[noetic_techy]

I completely agree. It was by and large a very good article, but could have been better if it presented the other side. I'd like to know what the counter evidence is. The author seems to imply that the other side is "in the dark" on this question, and has no hypothesis and speculation of their own.