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

discovermagazine.com

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

#61

Post by regularfry »

planetguy wrote: post #53
Symmetry wrote: post #47

Earlier quoted context omitted.

Telescopes don't show you that (contrary to what your inner ear is telling you) its the Earth that moves rather than the sun. At best they tell you that Jupiter has things orbiting it.

Also, astronomers in the Renaissance didn't have telescopes, so the moons of Jupiter weren't part of what they saw around them anyway.

I hate to point this out to someone with the username "planetguy", but Galileo certainly had telescopes, definitely lived in the Renaissance, and discovered four moons of Jupiter.

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

#62

Post by T-hawk »

Symmetry wrote: post #47
maxharris wrote: post #42

Earlier quoted context omitted.

> astronomers in the Renaissance would have been equally justified in rejecting the heliocentric system on account of it being at odds with what they saw around them False. Sights observed through a telescope were also part of "what they saw around them." A true theory accounts for all the evidence (and if it's not ultimately reducible to or based on something you can get from the five senses, it's not evidence).

Telescopes don't show you that (contrary to what your inner ear is telling you) its the Earth that moves rather than the sun. At best they tell you that Jupiter has things orbiting it.

Telescopes show that Venus displays phases like the moon while Mars and Jupiter don't, which is important evidence for heliocentrism and the order of the planets relative to Earth.

Telescopes also show that Jupiter's satellites experience eclipses, which isn't direct heliocentric evidence, but does tell you that Jupiter and its moons shine by reflected sunlight rather than intrinsic luminosity.

Telescopes also show sunspots, leading towards the discovery that the Sun is an active body, and to some notion of its size and mass. Telescopes can also show Venus transiting the Sun giving you a great idea of their sizes, which happened in 1639. http://en.wikipedia.org/wiki/Transit_of_Venus#First_scientif...

The switch to heliocentrism didn't happen overnight or as the result of a single observation or event, but telescopes brought in many different streams of evidence for it.

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

#63

Post by snowwrestler »

planetguy wrote: post #28
snowwrestler wrote: post #17

Of course it's wrong; all scientific theories are provisional approximations, and the conflicts between quantum mechanics and general relativity are well known. The hard part is proposing an alternative theory that fits all the known evidence. Quantum mechanics and general relativity both match a ton of observations; anything that is going to replace them will need to at least match the same set of evidence at least…

You seem to be engaging more with the headline writer than with Penrose. They're both, perhaps, wrong, but Penrose is wrong in a far more interesting way. Penrose doesn't just think quantum mechanics is wrong in the sense that it can't quite be lined up with general relativity, he thinks that quantum mechanics and consciousness are the same problem and that we can't understand one without the other. Now, to me this s…

Oh I definitely am just responding to this headline and article; I won't pretend to be any sort of expert on Penrose's views.

Personally I agree with you that consciousness is an emergent property of certain complex systems. I think some folks would like to rest free will on the probabilistic uncertainties we see in quantum equations. But IMO that is not necessary since we know through chaos theory that deterministic systems can still produce unpredictable results at high levels of complexity. And the brain is pretty damn complex.

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

#64

Post by tanvach »

Personally I like the article, and I agree with his concluding paragraph that there must be coherence preservation somewhere.

You need to look at one of the pillars of quantum mechanics he mentioned, where the observables of a system are only the probability, and this is due to 'decoherence' from a measurement. What he's trying to point out is that the coherence in the system must be preserved somehow, otherwise where could it go? It seems that this is very central to the difference between quantum mechanics and general relativity, and that the tiny connections to marry these two are yet to be found. His position is clearly 'it's in the details' not 'we must change everything' of string theory.

This argument reminds me very much of Thorne–Hawking–Preskill bet about information paradox.

PS: fascinating development in quantum weak measurement, where trading off measurement accuracy provides a window into coherence of a system.

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

#65

Post by snowwrestler »

planetguy wrote: post #59
codexon wrote: post #51

Earlier quoted context omitted.

We understand parts of the brain classically. There are parts of the brain that operate like organic circuits of boolean operators. There is no quantum level magic.

A large slab of Penrose's book The Emperor's New Mind is, if I recall correctly, devoted to describing how certain structures of the brain just might have some quantum mechanics involved. I don't recall the details and I don't know whether it's all been disproven as we understand the brain better.

I really have to read this book, since I've heard this sort of thing before and it never made sense to me why this matters. I mean, of course quantum mechanics is involved in the operations of the brain; it's involved in the operations of literally every single aspect of physical reality except gravity. People say things like "the brain uses quantum mechanics" and I think "yes, but so does Coca Cola, erosion, and rust."

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

#66

Post by obfuscate »

ktizo wrote: post #57
codexon wrote: post #51

Earlier quoted context omitted.

We understand parts of the brain classically. There are parts of the brain that operate like organic circuits of boolean operators. There is no quantum level magic.

Quantum biology is making inroads in a few areas, such as in the mechanism of chlorophyll. I would not be surprised if it starts popping up in bits of neurology, even in the parts that we currently understand classically.

There's a huge difference between molecule-scale quantum chemical phenomena (as in photosynthesis) and quantum computation. Finding the former in the brain would be very cool, but it wouldn't be terribly surprising or revolutionize cognitive science the way the latter would.

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

#67

Post by flom »

CrLf wrote: post #48
flom wrote: post #44

Due to the inconsistency between quantum and relativity, I'm more inclined to believe that the problem is with relativity. The idea that physics is fundamentally non-deterministic satisfies me philosophically. If physics were deterministic, than I should be able to theoretically build a computer, input the state of the universe, and then be able to know what will happen in your life (assuming I don't tell anyone the…

You would never be able to predict future states of the universe, simply because you cannot represent such states within the universe they represent. Without the ability to predict, the universe is effectively non-deterministic (literally, no one within it can determine its future states).

You make a good point. In my earlier post, replace "universe" with "solar system." Then, I can represent the states of the solar system in some subset of the universe, and I'll place this computer sufficiently far from the solar system so it doesn't interfere. Now I should be able to predict what happens on earth, unless you think that variables outside of our solar system significantly affect activities on earth, right?

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

#68

Post by rudiger »

snowwrestler wrote: post #17

Of course it's wrong; all scientific theories are provisional approximations, and the conflicts between quantum mechanics and general relativity are well known. The hard part is proposing an alternative theory that fits all the known evidence. Quantum mechanics and general relativity both match a ton of observations; anything that is going to replace them will need to at least match the same set of evidence at least…

Can you recommend a good introduction to the theory of conciousness, especially one that relates it to physics and the Universe? I've seen the term "consciousness" in relation to these topics used before, but have a hard time getting information beyond "human conciousness" and how the brain works. Definitionally.

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

#69

Post by troystribling »

obfuscate wrote: post #66
ktizo wrote: post #57

Earlier quoted context omitted.

Quantum biology is making inroads in a few areas, such as in the mechanism of chlorophyll. I would not be surprised if it starts popping up in bits of neurology, even in the parts that we currently understand classically.

There's a huge difference between molecule-scale quantum chemical phenomena (as in photosynthesis) and quantum computation. Finding the former in the brain would be very cool, but it wouldn't be terribly surprising or revolutionize cognitive science the way the latter would.

It is thought that photosynthesis uses quantum computation to determine how to move energy internally within a cell. http://www.rsc.org/chemistryworld/Issues/2007/May/Photosynth...

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

#70

Post by planetguy »

regularfry wrote: post #61
planetguy wrote: post #53

Earlier quoted context omitted.

Also, astronomers in the Renaissance didn't have telescopes, so the moons of Jupiter weren't part of what they saw around them anyway.

I hate to point this out to someone with the username "planetguy", but Galileo certainly had telescopes, definitely lived in the Renaissance, and discovered four moons of Jupiter.

And as someone with the username "planetguy" I hate to be corrected, but you're right. My defense is that I am planetguy, not historyguy. :)

Historical brainfart.

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