[Chronos]

LQG is not believed to allow hypercomputation, i.e. the solving of Turing-uncomputable problems. Penrose's entire argument is based on the idea that the human brain is a hypercomputer, which is why it cannot in principle be simulated by a computer (or any other machine).

It's worth noting that Penrose's field of expertise is General Relativity, not quantum physics, and definitely not Computer Science / philosophy of computation. I see the situation with Penrose as equivalent to Linus Pauling's unfortunate foray into Vitamin C pseudoscience late in his life.

[manyoso]

Penrose' claim is much simpler. He thinks that gravity playing a role in wave function collapse will show that non-quantum computers are incapable of accurately modeling quantum gravity. IOW, he thinks gravity will end up showing the physical Church-Turing thesis to be false.

Say what you will about Penrose, but can you seriously deny that he is one of the world's foremost experts on gravity?? You might not like his conclusion, but to say that he is out of his element here is ridiculous. Are you in your element when discussing gravity causing wave function collapse? Who do you think would be more in their element on this subject than Penrose??

[Chronos]

Call me back when Penrose convinces a well-regarded quantum physics expert. At that point we can call up Scott Aaronson and ask him his opinion, as Aaronson is an expert on the intersection of quantum physics and computing.

[manyoso]

Scott is a friend of mine. I've talked with him face to face about this very subject. He disagrees with Penrose, but his objections are far more nuanced and respectful than anything I have seen here. He would be horrified to see Penrose belittled and his arguments not given a fair reading. Penrose is an intellectual hero to Scott and someone to be admired.

[cbennett]

That's good to know. I read his post on his 'debate' with Roger and really enjoyed it. Also of interest may be the discussion between him and Hameroff in the comments section. Meta-comment: It a sad sort of situation when intellectual communities, whether they be HN or another, tend to idolize a set of individuals and demonize others. Thanks @manyosos for your comments in this thread, you really helped elevate the discourse.