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Also, humans often believe things that aren't provable in any formal system S because they're not true. Even good mathematicians believe (hopefully temporarily) false propositions. So the argument "some true things are not provable by formal logic in S, therefore if a human can believe something not provable in S, they must not be a formal system" is valid, but does not imply "no machine can be constructed that believes something not provable in S" since a little sprinkling of randomization can make anything possible. A machine that can prove any true proposition with p>2/3 and only believes false propositions with p<1/3 would be pretty useful.

So your claim is that the Human mind is a physical machine and that computers are also physical machines and thus both are bound to physical laws... and this negates Penrose how?

Do you think Penrose disagrees that the Human mind is bound by physical laws??

I think Penrose is handwaving to try and have it both ways: he's saying the brain obeys physical laws, but that it does not embed a formal computational model. But that's impossible: the second is a logical consequence of the first.

"But that's impossible: the second is a logical consequence of the first."

No, it is not. It is far from proven that universal physical law can everywhere be simulated by a Turing machine. If you had proof of that you'd be up for a Nobel. So publish your paper or perhaps consider that Roger Penrose is not an idiot and you might not know what you are talking about.

It is not proven and possibly it can never be proven. But it can be disproven, and given the success of the Church-Turing thesis, I would say that the burden of proof rest on those that claim that a system more powerful than a Turing machine exist.

Fair enough, but that is a far cry from 'logically impossible' which the parent comment explicitly stated.

I'm not making a claim, I argue based on what we already know. Penrose is the one claiming something here.

> Do you think Penrose disagrees that the Human mind is bound by physical laws??

Yes. Having read his work in the past, I know that he disagrees the human mind is bound by physical laws. This is the whole reason behind the argument they're putting forth to begin with: they postulate that humans are capable of making an inference that could not possibly be made by a machine intelligence.

However, it has never been shown that we are not a machine intelligence.

Then I am sorry to say you have no idea what you are talking about. Penrose nowhere claims the human mind is not bound by physical laws.

Cite one place where he says anything like this or go home.

He argues that quantum magic enables human minds to do things that formal computer systems cannot do. I'm not sure what his position is on computers that incorporate quantum magic though.

I suspect the argument manyoso is setting up here is based on sophistry around the concept of "physical laws". His stance is most likely that quantum woo is part of the physical laws, in the same way a fundamentalist religious person would assert that the content of a holy book is part of the physical laws.

What I - and I hope most people - mean by the phrase is different though, it's the body of actual physical laws that have been shown scientifically.

> I'm not sure what his position is on computers that incorporate quantum magic though.

Interesting thought experiment. I suspect he would be fine with those in theory, however since he already declared this special connection to the supernatural for humans it'd be interesting what computer components he would consider equivalent. But the beauty of his position is that, in the event of a generally intelligent computer emerging, he could always claim that any given nanoscale computing component is the silicon analogue of "quantum microtubules" (which was his woo-related organelle of choice in neurons). It's not like he ever has to prove his claims in order to be taken seriously.

It is not quantum woo and it is not quantum magic. Objective collapse theories are the complete opposite of what you are disparaging. Objective collapse theories are more physical than what we currently have.

Few people have made more contributions in the twentieth century to actual physics than Penrose. He is one of the world's leading experts on general relativity and his objective collapse theory is nothing more that when quantum gravity is understood that gravity will play a role in the collapse of the wavefunction.

To describe Penrose as engaging in 'quantum woo' or 'quantum magic' is grossly inappropriate. It just gives evidence that you don't understand what he is proposing. See Scott Aaronson for what an rebuttal to Penrose looks like not the ham fisted straw man takedowns from the likes of people in this comment section.

Penrose is not just arguing for objective collapse. Penrose is arguing for something computationally more powerful than objective collapse.

If gravity plays a role in wave function collapse that will pose serious questions for the Church-Turing hypothesis. It might very well make it impossible for non-Quantum computers to accurately model quantum gravity.

Penrose does not argue for "something computationally more powerful than objective collapse" rather, he argues that the physical Church-Turing thesis is false due to quantum gravity. Something he is an expert on, btw.

"gravity plays a role in wave function collapse that will pose serious questions for the Church-Turing hypothesis"

Says who? Penrose is blacklisted, cite someone else.

> I suspect the argument manyoso is setting up here is based on sophistry around the concept of "physical laws". His stance is most likely that quantum woo is part of the physical laws, in the same way a fundamentalist religious person would assert that the content of a holy book is part of the physical laws.

That falls far below the standard of discussion we ask users to abide by here. Please make your points directly and without such cheap insinuations.

Er, I have met and talked to religious people who have said exactly this.

It's not an incorrect summary of his position. I agree it may not look like a totally objective characterization on my part, but you're saying this in a discussion where I was literally told to "go home", by the same user you're protecting here.

If you think my comments in their entirety detracted from the discussion, I'd like you to tell me. Otherwise I'm asking you to consider this statement in the context of both manyoso's and my comments as a whole.

This is a discussion about quantum quackery, and you're stepping in on behalf of the pro-quackery side that has no problem telling me personally that I "have no idea what" I'm "talking about", and other dismissive discourse.

It is incorrect. Penrose emphatically says the human brain is governed by physical law. To assert otherwise is just factually incorrect. Read his books or read his papers. If you disagree, please provide one quote that shows otherwise.

I am sorry to have said "go home" and will refrain in the future. Still, you have lodged what I consider factually incorrect assertions about Penrose's argument. When asked for evidence you have provided none.

You misunderstand what I'm talking about. What dang criticized me for is a correct summary of your position. Let me elaborate:

> "We proposed [...] that consciousness depends on biologically ‘orchestrated’ coherent quantum processes in collections of microtubules within brain neurons, that these quantum processes correlate with, and regulate, neuronal synaptic and membrane activity [...] This orchestrated OR activity (‘Orch OR’) is taken to result in moments of conscious awareness and/or choice. [...] We conclude that consciousness plays an intrinsic role in the universe." ( Stuart Hameroff, Roger Penrose; Consciousness in the universe; Physics of Life Reviews, Volume 11, Issue 1, March 2014, Pages 39-78 )

and

> "If gravity plays a role in wave function collapse that will pose serious questions for the Church-Turing hypothesis. It might very well make it impossible for non-Quantum computers to accurately model quantum gravity. Penrose does not argue for "something computationally more powerful than objective collapse" rather, he argues that the physical Church-Turing thesis is false due to quantum gravity. Something he is an expert on, btw." ( manyoso, Hacker News, discussion id 14444443 )

None of these statements, while they are using the language of science, bears any discernable relationship to physical reality in a scientific sense. The postulate that any consciousness-related activity of neurons happens in structural elements like microtubules is a collection of unproven hypotheses divorced from both empirical and theoretical experience. The same goes for this preposterous claim about quantum gravity: there is currently no workable theoretical framework for quantum gravity, but this doesn't stop Penrose from confabulating properties onto the term so it can become a new go-to locus for his ideas on quantum consciousness.

An observer will notice a pattern here: mystical truth claims about a hypothesis with no basis in either experimentation nor theory are being "supported" by hiding their supposed mechanisms of action inside yet-unexplored regions of the map. It's a god of the gaps argument.

Now, you know this, as does Penrose. Both of you are trying to preempt this criticism by professing quantum consciousness is a fundamental part of the laws of nature, and hence it should not be categorized as woo. You are essentially rejecting the accusation of mysticism by asserting that magic is not metaphysical. Which was the observation dang chided (and apparently penalized) me for.

For what it's worth: you decisively won the argument, both by popular opinion and the support of the site's admin. Accept a victory when it presents itself.

I chided manyoso elsewhere. The problem with your comment was not that it incorrectly summarized anything, it's that it broke the HN guidelines by calling names ("quackery", "sophistry", "woo", "fundamentalist"). That matters far more to HN than whether Penrose is wrong about Gödel.

Commenting here requires being scrupulously civil, even when others are not. Any lower standard would lead to an unstable system.

In a discussion where one side freely makes stuff up as they go along and attempts to put the burden of proof on everybody else, I stand by these characterizations.

When someone asserts in an authoritative tone that quantum gravity is the key to unlocking consciousness at the heart of the universe, that is utter hogwash and deserves to be called out as such. You may personally not like my pointing this out, but the entire "field" of quantum consciousness is a religious movement that makes unsubstantiated claims about the nature of reality.

It actually is quackery. Redefining the term 'physical laws' to include magic in order to shield an opinion from criticism is actually sophistry. Insisting that spiritual convictions are factual statements about the universe is actual fundamentalism. These aren't bad words wielded to hurt someone, they are supposed to convey meaning.

I never meant to denigrate anyone personally. I strongly feel that opinions must be fair game though when it comes to criticism. In doing so suppose I must come across more harshly than I intended or maybe I'm just exceptionally bad at articulating myself. Whatever my intent, it's clearly not working out all that well. It's probably a good idea for me to take a break from HN for a while.

> I know that he disagrees the human mind is bound by physical laws.

Last I heard, Penrose appeals to quantum woo to claim that the human mind isn't strictly algorithmic. But sources of quantum randomness isn't enough to push you into dualism, quantum shit is part of our physical universe and while there is no proof that the human mind critically exploits quantum phenomena for it's computation, we can certainly build machines that have RNGs exploiting quantum randomness.

> Penrose appeals to quantum woo to claim that the human mind isn't strictly algorithmic.

Penrose doesn't appeal to quantum woo, he has a quite well articulated set of assumptions and arguments , related to loop quantum gravity [1], about how objective collapse of the wave function may occur at bio-physically feasible decoherence times.

Now, whether you think his biophysical theories of consciousness are valid, or even required (whether you buy the microtubules argument/hypothesis), is one thing. But stating that Penrose- arguably the 20th century's foremost mathematical physicist- is a practicioner and/or a spreader of 'quantum woo'-- that belies a level of mis-informantion so catastrophically high that it renders your quoted statement indistinguishable from a pure ad-hominem.

[1] https://www.wikiwand.com/en/Loop_quantum_gravity

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.

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??

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.

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.

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.

@Chronos (can't reply for some reason, so I'm just replying to my own post and tagging you)

Its true that LQG is not known a natural schema to implement hyper-computation. However, since we don't well understand the time-dynamics of twistors ( how these operators may interact non-linearly through time), i don't see any a-priori reason why it is not a possible scheme for super-computation (you could make a good counter- response based on occam's razor, which I'd grant).

Look, lots of thereotical CS folks get disturbed by the idea of hyper-computation/super-turing machines, but in truth Turing machines are a toy model in comparison to true physics; as such, it doesn't take a whole lot more to get something more powerful; Siegelmann and colleagues have shown that real weighted, analog recurrent nets have super-turing abilities [1] [2]. While Aaronson and other raise good questions about physical realizability of such systems, a good thing to keep in mind is that these discussions often take place at computational 'limit' cases, eg solving intractable PSPACE problems, which may not be as relevant to more pedestrian problems solvable by biological systems. Central point: dynamically evolving systems iteratively exploring through (from) in-consistent systems towards more and more consistent ones have many of the same compelling qualities we would call 'super-turing'. Also see the lit on evolving turning machines.

Finally, while I don't agree with the magnitude your Pauling analogy, I certainly agree with you statement that Penrose is out of his depth here. While I do not , presently, buy his argument that quantum effects are necessary to realize consciousness, I remain open to the idea until we know more about BOTH physics and computation.

[1] http://www.mitpressjournals.org/doi/abs/10.1162/NECO_a_00263 [2] http://www.kurzweilai.net/super-turing-machine-learns-and-ev...

Well I wasn't intending it as an argument. I was actually just interested to see what someone who had actually thought about it would say.