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PeterDonis's Recent Activity

  1. PeterDonis replied to the thread I Exceeding the speed of light (stars seem to exceed c in our Earth's rotating reference frame).

    "Objective absolute property" is vague ordinary language, not physics. As @Nugatory said, when we say that the Earth is "rotating", if...

    Jan 21, 2018 at 1:58 PM
  2. PeterDonis replied to the thread I Why is position-space favored in QM?.

    He didn't say "time and space", he said "time and space coordinates". The coordinates are parameters; each unique set of 4 coordinates...

    Jan 21, 2018 at 1:43 PM
  3. PeterDonis replied to the thread I Classical chaos and quantum mechanics.

    Actually it has two families of timelike KVFs, which gives a good further illustration of why "timelike KVF" is not the same as...

    Jan 21, 2018 at 1:40 PM
  4. PeterDonis replied to the thread I Classical chaos and quantum mechanics.

    My argument for how any stress-energy tensor for gravity must be zero does not depend on gravity being "infinitesimally removed". It...

    Jan 21, 2018 at 1:37 PM
  5. PeterDonis replied to the thread I Classical chaos and quantum mechanics.

    Then there is an interesting change from your edition to my edition (the third). In the second edition, according to the table of...

    Jan 21, 2018 at 1:26 PM
  6. PeterDonis replied to the thread I Classical chaos and quantum mechanics.

    @bhobba, btw, I was able to get the Kindle version of the 3rd Edition of Ohanian--more precisely, Ohanian & Ruffini, Gravitation and...

    Jan 21, 2018 at 1:17 AM
  7. PeterDonis replied to the thread I Classical chaos and quantum mechanics.

    Ok, that helps. Here is how I would rephrase what is said in the quoted paragraph: the linearized field theory of gravity in flat...

    Jan 21, 2018 at 12:52 AM
  8. PeterDonis replied to the thread I Classical chaos and quantum mechanics.

    Here's the problem: this isn't possible. There is no tensor that can describe "energy contained in the gravitational field". The reason...

    Jan 21, 2018 at 12:45 AM
  9. PeterDonis replied to the thread I Classical chaos and quantum mechanics.

    Which part of your post is directly quoted?

    Jan 21, 2018 at 12:37 AM
  10. PeterDonis replied to the thread I Curvature and Schwarzschild metric.

    Ok, good. Yes. Or, to put it another way, we take a spacelike surface of constant time and treat it as a family of concentric...

    Jan 20, 2018 at 6:08 PM
  11. PeterDonis replied to the thread I Exceeding the speed of light (stars seem to exceed c in our Earth's rotating reference frame).

    Not quite. I think it's true that it was generally understood that proper acceleration was not relative. However, I don't think it was...

    Jan 20, 2018 at 5:45 PM
  12. PeterDonis replied to the thread I Exceeding the speed of light (stars seem to exceed c in our Earth's rotating reference frame).

    Not really, no. You are missing a key distinction between two types of acceleration: coordinate acceleration and proper acceleration....

    Jan 20, 2018 at 4:28 PM
  13. PeterDonis replied to the thread I Classical chaos and quantum mechanics.

    This is not correct, at least not as you state it. There is no "gravitational field" part of the stress-energy tensor. There is a valid...

    Jan 20, 2018 at 2:15 PM