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I think this post title is misleading.

Roger Penrose is not merely saying that quantum mechanics is wrong. Instead it would be more fair to say that he views quantum mechanics as an incomplete theory, and one that should be continually challenged.

It's like Newtonian mechanics. Newtonian mechanics is correct, within its domain (for velocities much less than the speed of light). No one argues with the predictions of Newtonian mechanics within their domain. Einstein's achievement with special relativity, then, wasn't showing that Newtonian mechanics was wrong; instead, he just showed the world the true extent of its domain, and developed a theory (special relativity) that generalized Newtonian mechanics to a larger domain (velocities less than the speed of light). It's terribly unfair to Newtonian mechanics to call it 'wrong' in the same way that the statement 2+2=5 is 'wrong'.

Similarly, the fantastic experimental success of quantum mechanics ensures that it would be unfair to call quantum mechanics 'wrong'. Incomplete? Certainly. Worthy of being challenged? Absolutely. Is it taken as gospel by too many physicists? Probably. But is quantum mechanics wrong? No, decades of successful experiments, and practically the entire modern electronics industry, would disagree with that sentiment. The problem is that we just don't know where the domain of quantum mechanics ends, nor the more general theory that will take its place.

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Instead it would be more fair to say that he views quantum mechanics as an incomplete theory, and one that should be continually challenged.

Which is not an unusual view. Nobel prize winner 't Hooft has expressed the same sentiment.

What you say is well-put, but to nitpick the last paragraph: the limits of quantum mechanics are well-established. QM is a special case of quantum electrodynamics, which is a low-energy special case of the Grand Unified Theory.

http://en.wikipedia.org/wiki/Quantum_electrodynamics http://en.wikipedia.org/wiki/Unified_Field_Theory

While the latter is not fully fleshed out, its uncertainty only begins in circumstances far weirder than what gives Roger Penrose pause.

Penrose says that "The [QM] equation should describe the world in a completely deterministic way, but it doesn’t." But work such as Bell's theorem shows that no deterministic equation could ever be consistent with quantum mechanics:

http://en.wikipedia.org/wiki/Bells_theorem

"What you say is well-put, but to nitpick the last paragraph: the limits of quantum mechanics are well-established. QM is a special case of quantum electrodynamics, which is a low-energy special case of the Grand Unified Theory."

Somewhat misleading. The difference between quantum mechanics and quantum electrodynamics is not really pertinent to a discusion of the limits of quantum mechanics. Most people who are familiar with quantum mechanics will use the term to refer to the whole tree of theories that require quantization anyway (quantum mechanics (QM), quantum field theory (QFT)). The limits of QM is that we are really not able to calculate things in certain energy regimes.

Also, it is not really accurate to call QM a special case of QFT because different things are being quantized (particle states vs field states). Certain operators in QFT are then interpreted as particles.

Quantum Electrodynamics (QED) is an example of a QFT. People postulate the existence of a Grand Unified Theory (GUT), of which QED would be special case. The only evidence of the GUT is a plot that extrapolates the strength of strong, weak, and electromagnetic interactions over many orders of magnitude.

> But work such as Bell's theorem shows that no deterministic equation could ever be consistent with quantum mechanics:

This isn't quite right, because you left out the word 'local' - see http://en.wikipedia.org/wiki/Bohm_interpretation

Bell's theorem applies only to _local_ hidden variables.

Right, but non-local determinism is difficult to square with general relativity.

Indeterministic laws and the non-existence of particle positions and trajectories are difficult to square with general relativity too - and Bohm's interpretation doesn't 'suffer' those problems, while it predicts the exact same observations. (Though I should say this is way out of my amateur-physicist league - I'm taking my cue from 'Quantum Mechanics: Historical Contingency and the Copenhagen Hegemony' http://www.amazon.com/Quantum-Mechanics-Historical-Contingen... ).

I actually like to hold on to the idea that the universe is non-deterministic. It keeps the concept of free will alive.

Do you also enjoy Employee Empowerment?

Even more importantly.... this is a lovely interview, that hits on many topics, of which the biographical details are much more interesting than the bit about quantum mechanics. Hopefully the fake-controversy of the title won't scare anyone away from reading it.

Were we reading the same article?

"But when you accept the weirdness of quantum mechanics [in the macro world], you have to give up the idea of space-time as we know it from Einstein. The greatest weirdness here is that it doesn’t make sense. If you follow the rules, you come up with something that just isn’t right."

"You’re led to a completely crazy point of view."

"My own view is that quantum mechanics is not exactly right, and I think there’s a lot of evidence for that."

"INTERVIEWER: In general, the ideas in theoretical physics seem increasingly fantastical. Take string theory. All that talk about 11 dimensions or our universe’s existing on a giant membrane seems surreal.

PENROSE: You’re absolutely right. And in a certain sense, I blame quantum mechanics, because people say, “Well, quantum mechanics is so nonintuitive; if you believe that, you can believe anything that’s nonintuitive.” But, you see, quantum mechanics has a lot of experimental support, so you’ve got to go along with a lot of it. Whereas string theory has no experimental support."

"[My new book] is called Fashion, Faith and Fantasy in the New Physics of the Universe. Each of those words stands for a major theoretical physics idea. ['Fantasy'] is quantum mechanics at all levels...."

All of those quotes sound to me like pretty clear rejection of string theory and quantum mechanics and an implied rejection of much of modern higher physics. Yes, he accepts experimental proofs where available, but he seems to be saying that these theories are wrong because they don't make sense to him, or because they don't match the way we perceive the world. But when I look at the Hacker New logo, I don't perceive photons of wavelength 590 nanometers bouncing off my retina--I pereceive the color orange.

Personally, as I read this, I kept hearing Clarke's 1st law (http://en.wikipedia.org/wiki/Clarke%27s_three_laws) looping in my head:

"When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."

But when I look at the Hacker New logo, I don't perceive photons of wavelength 590 nanometers bouncing off my retina--I pereceive the color orange.

If you did perceive photons at 590nm that would be rather remarkable! More likely, you would perceive a mixture of photons at different wavelengths, mainly a combination of 615nm and 550nm or thereabouts.

In actuality, you perceive this "orange" concept; in fact, you would perceive the same orange whether exposed to 590nm photons or the mixture, which emphasizes the point that what we experience in the real world doesn't necessarily relate to reality in an obvious way.

I agree that the title is misleading. But I think his view is really important. Or maybe better said, it's really important that a great man like Penrose comes out and unequivocally makes this statement to generations who have too often been told to "shut up and just learn the theories".

In college it drove me mad that I could not find any resources to question the "absolute validity" of paradoxes that arose in modern physics. To me, a paradox could not represent a universal truth - it must be seen as an opportunity to understand why our tools are insufficient to fully understand the universe. But the response to my questioning was always "who are you to question 100 years of experts?"

Finally I found one physics professor who confided in me that he too had been trying to start a fertile dialogue about these things, but other professors would just scoff. He felt it was futile at best or career damaging at worst.

So I learned that, truly the 'old experts' took modern theories with a grain of salt - it was only today that we took them so literally. But none of my classmates believed it and they thought I was brash and stupid for bothering to think about it.

For a while, I met with that professor once a month or so to try to steer my knowledge in a direction that wasn't jaded by a blind acceptance of theories that were inconsistent with one another. I hated the feeling that it had to be some half-valid historical truth. It made me feel half-way delusional. It made me lose trust that the academic system would prepare me to really truly think.

I wanted to learn about the paradoxes, the holes in our thinking, how we were wrong, because those are the exciting areas that need development. If you spend your whole education learning fundamentals while detached from the burden of these kinds of questions, how can you be prepared to tackle them once you raise your nose up out of the textbooks?

So yes, it's misleading to make the title, "String Theory and Quantum Mechanics are wrong." But I hope his important point doesn't get lost, that it is also wrong to say that String Theory and Quantum Mechanics are completely right - end of story - no questions." Thank you Roger Penrose for taking this stance loud and clear.

That's how every scientific theory should be approached, as that's what sets them apart from dogmas.

Fully agreed. QM is like ... our knowledge of the Moon before the 1960s. Until we got 'out there' we couldn't see the whole thing.

Lots of people like to look at the very complex stuff. But the year Einstein published several papers, it was all about very basic observations. We don't puzzle enough about the 'simple'.

Heisenberg: "We have to remember that what we observe is not nature herself, but nature exposed to our method of questioning."

2+2=5 for sufficiently large values of 2