Roger Penrose Says Physics Is Wrong, From String Theory to Quantum Mechanics

http://discovermagazine.com/2009/sep/06-discover-interview-roger-penrose-says-physics-is-wrong-string-theory-quantum-mechanics

by gnosis • 17 years ago

66 44 17 years ago

discovermagazine.com

carpdiem• 17 years ago

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.

tamas• 17 years ago

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

jacobolus• 17 years ago

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.

teeja3• 17 years ago

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."

Confusion• 17 years ago

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.

mjtokelly2• 17 years ago

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

Luc2• 17 years ago

> 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.

mattheww• 17 years ago

"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.

moron4hire2• 17 years ago

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

moron4hire2• 17 years ago

2+2=5 for sufficiently large values of 2

dstorrs• 17 years ago

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."

camccann• 17 years ago

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.

thinksketch• 17 years ago

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.

BRadmin• 17 years ago

"In my view the conscious brain does not act according to classical physics. It doesn’t even act according to conventional quantum mechanics. It acts according to a theory we don’t yet have."

Do most modern AI researchers disagree with this?

daeken• 17 years ago

I don't think we have enough information to say one way or another. We've gained a lot of knowledge about the brain, but it's still very much a black box. I think it's worth holding off on making any assumptions until we understand a whole lot more about it.

rw• 17 years ago

The sensible response is: "show me ". Quantum effects are not known to be significant. I believe that our mind is an emergent property: lots of neurons and chemicals interacting. Sure, there are a lot of variables, we need the dynamical systems perspective to even begin to understand the whole process... but a new kind of physics? Don't be so anthropic! AFAICT cognition happens at the multicellular level--huge, from a QM perspective.

This reminds me of that old anti-strong-AI bugaboo, "intelligence in the gaps": http://en.wikipedia.org/wiki/God_of_the_gaps

lkozma2• 17 years ago

Yes, most modern AI researchers believe that the functioning of the brain can be explained by electromagnetic and chemical phenomena, accurately described by 1900s theories. The fact that we don't fully understand its workings is due to its organizational complexity.

Penrose's arguments are discussed for example here: http://www.scottaaronson.com/democritus/lec10.5.html

10ren• 17 years ago

It's funny, but to be certain that consciousness can be explained by known laws - we just don't know exactly how - itself requires faith and is quite unscientific.

Although I too believe it.

kevinpet• 17 years ago

If I said that recovering from cancer does not act according to classical physics, or even according to conventional quantum mechanics, you would consider me a delusional wacko with nothing useful to contribute to the conversation.

Given the weight of evidence showing that anything we can measure about the brain can be explained by physical processes, the onus is on the person claiming that's not how it works to point to some phenomenon that isn't well explained by classical physics.

frig• 17 years ago

Generally overconfidence in our present abilities isn't conducive to stimulating new research.

I mean: I give you as much workup on the brain of an unknown individual as you care to have (fMRI, scans, dissection, whatever you want).

Can you detect which languages, if any, the person speaks (or spoke), with any robustness?

Can you detect if the person ever saw an ocelot in person?

Can you detect which sports team, if any, they like or liked to root for, or which instruments, if any, they played?

For most sections of the brain the level-of-detail at which functionality is decoded is still very primitive and coarse-grained. The reason god-of-the-gaps arguments have so much traction is b/c the gaps are still so very large.

pronoiac• 17 years ago

Penrose is the odd one out. IEEE spectrum surveilled the field of cognitive science a few years ago, for their Singularity issue - http://spectrum.ieee.org/static/singularity - & he was the only one that felt like that. I was annoyed with him because it seemed he wanted to shoot down the field without even trying, because clearly it would never work.

Max Tegmark looked into the timing required for quantum effects to be significant in synapses - http://space.mit.edu/home/tegmark/brain.html - & showed it was just not required to build an effective model. The rebuttals, such as they are, strike me as tenuous & argued from faith & dogma rather than evidence.

You can see a bit of this back-and-forth at http://en.wikipedia.org/wiki/Quantum_mind#Ongoing_Debate

Edit: Links, & fixing word wrap.

btilly4• 17 years ago

Penrose contributed a lot and I don't want to minimize that. However when he stepped outside of his own domain he makes some serious basic mistakes that make him ignorable.

As an example in The Emperor's New Mind he makes a number of claims about consequences of Gödel's theorem for human thought that were flat out wrong. I remember reading criticism of it from a logician in the mid-90s, and Penrose's response. While I'm no logician, I know enough about it to know that the logician was right and Penrose was wrong. Human thinking is known to accept inconsistencies and so you can't apply Gödel's theorem to derive any interesting conclusions.

When he moves from logic to physics he is even more out of his depth. Given his verifiable mistakes in logic, I am comfortable in concluding that his startling assertions about physics are far more likely to arise from further mistakes of his than from his having found serious reasons to question the foundations of modern physics.

anatoly• 17 years ago

I agree with your description of Penrose's Goedelian claims (the logician was Solomon Feferman), but I'm not sure why you say he'd be even more out of his depth in physics. Penrose is primarily a mathematical physicist, not a mathematican.

btilly4• 17 years ago

You are right. I had known his mathematical work, but didn't know his biography.

That said, his physics work seems to have been in general relativity, not quantum mechanics. Given what I know about how he messed up when he stepped out of his area in math, I find it more likely that he has made similar types of mistakes in quantum mechanics than that he has truly demonstrated that mainstream physics is wrong.

teeja3• 17 years ago

http://mindbody.blogspot.com/2009/10/penrose-kind-o-gets-it....

"Schrödinger, Einstein, and Paul Dirac. They were all quantum skeptics in a sense. Dirac is the one whom people find most surprising, because he set up the whole foundation, the general framework of quantum mechanics. People think of him as this hard-liner, but he was very cautious in what he said. When he was asked, 'What’s the answer to the measurement problem?' his response was, 'Quantum mechanics is a provisional theory. Why should I look for an answer in quantum mechanics?'"

http://www.afterourtime.com/wiki/index.php?title=Quantum_Gra...

nopinsight• 17 years ago

In a way, a wise creator of a theory should be the one least fixated by it, as he knows all its potential weaknesses inside-out and the messy way it came into being. From your description, Dirac seems to be one of those wise geniuses.

teeja3• 17 years ago

I'm sure you're right. Plus, in the sciences, he knows how his colleagues minds work (and all the politics). Dirac probably kept mostly quiet about his doubts because Bohr, the Godfather of QM, thought QM was the Cat's Meow, which Schrodinger didn't. And Schrodinger knew that he pulled his famous equation out of a hat (not derived).

Likewise with Feynman, who always repeated "nobody understands quantum mechanics."

Too, because of the very competitive culture in the hard sciences, you don't talk about things that are poorly understood. Because if you make a mistake, you'll catch a lot of (friendly or unfriendly) ribbing later.

thisrod2• 17 years ago

I'd love to hear why Penrose really thinks the Everett interpretation is crazy. He gives a very weak reason in the interview. No doubt he accepts the atomic theory of matter, despite his inability to see atoms, so his inability to see superpositions should not prevent him from accepting quantum mechanics. It would be interesting to hear him address that.

hegemonicon• 17 years ago

Probably the same reason everyone else seems to - it runs completely counter to our intuitions about how the world works. As far as I know (and my knowledge of QM can charitably be described as 'nonexistant') if you ignore intuitions and simply resolve the math, the Everett interpretation is what pops out of the equations.

Daniel_Newby• 17 years ago

But you can measure atoms indirectly. I have not heard of a many-worlds theory that is measurable even in principle.

thisrod2• 17 years ago

In principle, you could demonstrate superposition states of cats the same way you'd demonstrate them for atoms or photons: return the live and dead cats to the same state, and look for interference fringes. There are two difficult parts. First, you have to kill the cat, rescusitate it, and restore every molecule of its body to the original orbital, without leaving even one photon of evidence. Once you've done that, it's a simple matter of getting the cat to sit still while you measure its position within a tiny fraction of the diameter of an atomic nucleus.

I found a fascinating history of the atomic theory at http://www.aare.edu.au/02pap/har02049.htm, in the section titled "The History of the Particle Theory". Atoms were once as fantastic as superposition states are today, then they gradually became real.

The same page points out that the plausibility of atoms is largely a fluke. People imagine that solid gold has the color of a gold atom, and gas pressure comes from squeezing the atoms together. Quantum theory doesn't lend itself to such simple but wrong explanations.

Estragon• 17 years ago

To be specific, he's saying that the Copenhagen interpretation of QM is wrong. I'm inclined to agree.

Ixiaus• 17 years ago

Modern day science is built upon a mosh pit of physical theories that don't all fit together well.

The number one premise failing physical theory today, is the concept of a stationary container (the Universe) within which "matter" interacts. Traditional physical theory states that the Universe is one of matter, which is oh so limiting. Another hallmark of popular physical theory is much of it's theories are based on empirical findings rather than a set of purely theoretical postulates... Physical theory today is a posteriori rather than a priori and using scientific experimentation to verify the theoretical deductions.

Consider, for a moment, that the primary component of the Universe is not matter, but motion. Discard the idea that there is a static natural reference system (or stage) upon which things can be measured (you can tell actors are moving on the stage because the stage doesn't move).

Instead of there being three dimensions with a fourth dimension added for time; there are three dimensions of both space and time (time being a reciprocal of space).

Also consider, in this system, that there can be motion without anything moving. If the primary component of the Universe is motion, then material objects are a compound aggregate of motion; motion is, therefore, the antecedent to matter.

For more, look here: http://www.reciprocalsystem.com/nbm/nbm02.htm

Roger Penrose Says Physics Is Wrong, From String Theory to Quantum Mechanics

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