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Penrose vs. QM?

  1. May 19, 2005 #1
    Anyone else see the Penrose article in DISCOVER? "Two places at once"

    Not sure what he’s thinking with the “Experiment” he’s proposing on page 35. He seems to be claim that any interference between “states” or parts of an individual photon when if they come back together will always be destructive based on QM. But in the same article on page 31 shows a double slit example showing reinforcing interference, I don’t think QM has a problem with that.
    Just don’t see where his tiny mirror “gravity” experiment makes any sense at all, QM should always expect to see light at his detector. It may include a pattern, but it will be there.

    Last edited: May 19, 2005
  2. jcsd
  3. May 19, 2005 #2


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    I think your confusion may be from the author of the article rather than from Penrose. His description of the experiemnt in Road to Reality seemed a lot clearer than the magazine one for all the pretty pictures. Of course I may not have read the artcle as carefully as I did the book!

    Penrose believes something called the "nonlinear graviton" may be responsible for collapsing the wave function. The rest of QM, the unitary part, uncertainty, and so on, he seems to accept, so he's not looking for a hidden variables theory as such, just a resolution of the measurement problem.
  4. May 19, 2005 #3
    What do you mean by the Measurement problem?
    Is it represented by a ‘paradox’?
    Or are you just referring to not being able to measure below a “Plank” for either time or distance as we try to see “where” and “when” a particle 'IS’.

    Don't see how the "plan" as explained by the author of the artical will be helpful at all.
    I'll look in his book for a better explaination of the intent.

  5. May 19, 2005 #4


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    Measurement Problem

    The Measurement problem in QM is that in order to find anything out about a quantum system, you have to do a "measurement"; mathematically this is represented by operating on the quantum state with a Hermitian or self adjoint operator, producing real eigenvalues, one of which the measurement selects for you find as the value you have measured. This roundabout procedure is problematical because it seems to imply a favored place for consciousness at the heart of physics.

    Various interpretaions have been given for this, of which the two best known are the Copenhagen Interpretation("Yes mind is at the center because quantum physics isn't about quantum systems it is about our interactions with quantum systems") and the Many Worlds Interpretation (MWI) ("the wave function never collapses, all of the eigenvalues are manifested in different observational "sectors" of relativity). Penrose, in Road.. expresses dissatisfaction with both of these.
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