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  1. martinbn

    B 2020 Nobel prize in physics

    Didn't see a thread on this.
  2. martinbn

    A Entropy bounds

    There is something that is unclear to me, and because entropy bounds and their violations were discussed in the other thread, I thought it is a good opportunity to learn something. The problem is essentially a matter of impression. The statements go roughly in the following way: for a system...
  3. martinbn

    A Specifics of Bell's lambda

    A side question. Can one be a bit more specific about what ##\lambda## is? He says that it doesn't matter and it could be many things, and he treats it as a single continuous variable, but then he integrates over it. So whatever the set of lambdas is, it has to be at least a measure space, no...
  4. martinbn

    Dx before the f(x) in integrals

    Why do physicists like to write ##\int dx f(x)## instead of ##\int f(x) dx##? And also when did that start?
  5. martinbn

    Definition: Gravitational waves

    What are gravitational waves in general, not just in the weak field/linearized theory?
  6. martinbn

    Relativistic stars

    I haven't read these articles, but it seems that the claim is that there are spherically symmetric static space-times, which can describe compact isolated objects with arbitrarily large masses and arbitrarily small radi without being black holes. That doesn't seem right. What am I missing...
  7. martinbn

    Topology of black holes

    This might be well known or even discussed here, though I couldn't find a thread about it, but the questions is what are the possible topologies of a black hole i.e. the topology of a spacial slice of the event horizon. I know there is a result of Hawking that says the topology has to be that of...
  8. martinbn

    Cosmic censorship conjecture - status?

    What is the current status of the conjecture? I am interested in all possible aspects, counterexamples, attempts to formulate it in a mathematically rigorous way, proves in special cases, opinions, expectations and so on. Of course I have been trying to find information and have seen some things...
  9. martinbn

    Deutsch and Hayden on locality

    I couldn't find out if the following article had been discussed (it is probably well known), but there were many threads on locality/non-locality, so it might be of interest. On first reading I like it quite a lot, made some things clearer for me, but it will need some thinking and probably a...
  10. martinbn

    Ax-Kochen paper

    Has anyone read this paper? I am just curious what people think about it.
  11. martinbn

    Is there a spacetime which is timelike and spacelike complete but null

    Is there a spacetime which is timelike and spacelike complete but null incomplete?
  12. martinbn

    Penrose diagrams, reference request.

    Where can one find a general and detailed exposition of Penrose diagrams? What I have seen so far, in the books, are relatively brief general comments and a couple of specific examples. Usually Minkowski and Schwarzschild metrics, sometimes one or two more.
  13. martinbn

    General relativity from string theory

    This came up in another thread, but I have seen the statement many times in various places. The statement is that string theory implies general relativity i.e Einstein's field equations in some kind of a classical limit. So my question is how does that go? I am curious to see the details.