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

Re:Roger Penrose Says Physics Is Wrong, From String Theory t... by flom on Friday May 04, 2012 @01:58PM (#3929534)

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 computer output, because that would perturb the dynamics). I find that prospect far more unsettling than having to account for a superposition of states until I obtain more information in the future.

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Re:Roger Penrose Says Physics Is Wrong, From String Theory t... by CrLf on Friday May 04, 2012 @02:24PM (#3929644)

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).

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Re:Roger Penrose Says Physics Is Wrong, From String Theory t... by flom on Friday May 04, 2012 @03:39PM (#3929984)

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?

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Re:Roger Penrose Says Physics Is Wrong, From String Theory t... by olalonde on Friday May 04, 2012 @06:29PM (#3930615)

1) Don't underestimate the butterfly effect. 2) We can already predict the future to a certain extent. 3) What you wish the universe was like is irrelevant. http://en.wikipedia.org/wiki/Wishful_thinking

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Re:Roger Penrose Says Physics Is Wrong, From String Theory t... by flom on Saturday May 05, 2012 @12:58AM (#3931393)

Re 2: There should be an obvious qualitative difference between being able to predict where a ball will land if I throw it, and predicting who the passengers riding a particular train in 15 years will be.

Re 3: I was commenting on Roger Penrose's assumption that quantum must be "wrong" because it's "unintuitive" by expressing my opinion that I think quantum is more intuitive than deterministic theories. Indeed, Dr. Penrose and I are both using "wishful thinking," as did Einstein when he hypothesized that the speed of light is "constant in a vacuum." http://en.wikipedia.org/wiki/Speed_of_light#Special_relativi...

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Re:Roger Penrose Says Physics Is Wrong, From String Theory t... by gibybo on Friday May 04, 2012 @09:12PM (#3931022)

I don't think modern quantum theory holds that the universe is non-deterministic. I think it's still somewhat of an open question.

However, I also don't think a deterministic universe would be sufficient to allow you to predict it, because getting the state of the universe is still impossible following the uncertainty principle.

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Re:Roger Penrose Says Physics Is Wrong, From String Theory t... by flom on Saturday May 05, 2012 @01:28AM (#3931437)

I'm not a physicist, but my understanding is that the debate about whether or not "quantum is deterministic" centers around what your interpretation is of the wave function. I think most physicists, who Penrose would probably criticize, believe the "Copenhagen Interpretation," which says that the wave function of a system is literally the function that, when you take the inner product with its conjugate, gives you the probability distribution of the state of the system, and hence, the state is non-deterministic.

The uncertainty principle arises from quantum. Specifically, it's a statement about the commutativity of operators that act on the wave function, which, going by the Copenhagen interpretation of physics, means it's a consequence of the non-determinism of the universe. I think this is a philosophically satisfying explanation for why getting the state of the universe is impossible.

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Re:Roger Penrose Says Physics Is Wrong, From String Theory t... by jakeonthemove on Friday May 04, 2012 @03:10PM (#3929851)

But you can in fact build such a computer - you'll just have to solve the little problem of accounting for absolutely all the factors that directly and indirectly affect the result. Then predicting the future is easy peasy :-)...

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Re:Roger Penrose Says Physics Is Wrong, From String Theory t... by Peaker on Saturday May 05, 2012 @01:37AM (#3931450)

Software execution is an entirely deterministic process (at least in theory), and even then, we cannot actually compute the result of that process on a sufficiently large computer.

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