Recent content by jarlostensen

  1. J

    Proving Surface Gravity with Killing's, Hypersurface, Geodesic Equation

    Ok, that gets me to; 0 = \frac{K^{\alpha} K^{\beta}}{V^4} ( K_{\alpha;\beta} V - K_{\alpha} V_{;\beta}) Can we have just one more hint please? :smile:
  2. J

    Proving Surface Gravity with Killing's, Hypersurface, Geodesic Equation

    Btw, I got; \frac{1}{V^{2}}g_{\mu \nu} K^{\mu} K^{\nu}_{;\alpha}} which sort of looks right..?
  3. J

    Proving Surface Gravity with Killing's, Hypersurface, Geodesic Equation

    Just out of curiosity; what did you get when you calculated it..?
  4. J

    One more time on Hawking radiation

    If my memory serves me right this has to do with the fact that in order to have particle creation in pairs of particle/anti-particle you need both positive and negative frequency solutions. The negative frequency ones provide the negative energy particle. Furthermore, to be able to define +...
  5. J

    One more time on Hawking radiation

    It is my understanding that, since the wavelength of HR is comparable to the mass of the black hole itself, the whole idea of "particles" being created breaks down anywhere but at infinity (in the |out> state, with the |in> state on past-infinity being vacuum) - i.e. no particle detector will be...
  6. J

    Causal structure of spacetime: intuitive reason for non-compactness?

    Thanks Fredrik, I was following Wald's book on GR plus what I could gleam from "The Large Scale Structure of Space Time" on Google books - I think George Jones' reply that you refer to is very clear and helpful - I'm going to wrap my head around this last part in particular (I think it holds a...
  7. J

    Causal structure of spacetime: intuitive reason for non-compactness?

    Thank you for your response, the article looks very interesting and I'm rolling up my sleeves and digging into it! If I get to some sort of epiphany I'll post a follow up.
  8. J

    Causal structure of spacetime: intuitive reason for non-compactness?

    Apologies in advance if this has been asked and answered somewhere else, I searched but could not find anything. I just wanted to verify if my intuitive understanding of why space time (if it is to be physically plausible) can not be compact. According to Hawking and Ellis (and others)...
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