Recent content by hellfire

  1. H

    Spin-2 exchange particle and GR

    The metric tensor has 10 independent components that reduce to 6 if one imposes local conservation of energy and momentum. The graviton, on the other hand, only has two degrees of freedom. Given this, how does it then that a theory of the graviton can be equivalent to general relativity at least...
  2. H

    How many stars in the Solar neighbourhood

    Go to this site: http://www.solstation.com/index.html and try the links under "Maps" and the link "Stars" and "Orbits" under "Support".
  3. H

    Status of Gravity & Net Energy of Universe: Is Theory Viable?

    This was recently discussed here: https://www.physicsforums.com/showthread.php?t=285100
  4. H

    Graininess of Space-Time found at GEO600?

    If the indeterminacy in the transverse position of null geodesics goes as \sqrt{L \, l_P}, shouldn't this have been already detected in applications of optics? Why do gravitational waves have any special significance here?
  5. H

    Is Inertia Truly Uniform in All Directions?

    I had argued above with a somewhat obscure argument that anisotropic inertia might be a matter of convetion, but your argument is great, very clear and convincing.
  6. H

    Configuration space vs physical space

    Thanks for your answer to my question, it clarified more to me what you have in mind. I actually was thinking of that lagrangian with the constraint - \dot q^{\mu} \dot q_{\mu}=1 and I still do not see how the problem arises (that condition removes the 4 particle interpretation as you said). I...
  7. H

    Configuration space vs physical space

    Consider the lagrangian of a free relativistic particle \mathcal L = m \sqrt{- \dot q^{\mu} \dot q_{\mu}}. How does the problem arise in such a case?
  8. H

    Configuration space vs physical space

    May be it is meaningful to ask first about the relativistic theory. Shouldn't be a constraint between the components of the linear momentum in case that you are talking about one single particle?
  9. H

    Is Inertia Truly Uniform in All Directions?

    If inertia is anisotropic, so is the propagation of light. It is not difficult to show that there exists a relation between the convention of a simultaneity definition and the isotropic and anisotropic propagation of light. Only the Einstein simultaneity definition leads to an isotropic...
  10. H

    Origin of Universe: Exploring Current Scientific Theories

    I agree with marcus that the claim of a zero energy universe is not rigorous. Specially because we do not have a definition of gravitational energy in a FRW universe. As far as I know, this idea is suggested by an argument similar to this one: Assume that the zero energy balance between energy...
  11. H

    Accelerating Expansion Threshhold

    The topic is quite complex and the answer depends heavily on the cosmological model. See In an expanding universe, what doesn't expand?.
  12. H

    Universal Constants: Books for Laymen about Observable Effects

    Lisa Randall's "Warped Passages".
  13. H

    Gravity Leaking = Dark energy increasing

    There is no inmediate - or intuitive - link between leaking of gravity and accelerated expansion. Leaking of gravity will arise in models of a 3D-brane embedded in 5D spacetime, with afaik some general assumptions about the quantum behavior of gravity. However, for cosmological models derived...
  14. H

    Mysterious Motion of Galaxy Clusters Detected

    Interesting, thanks wolram.
  15. H

    Mysterious Motion of Galaxy Clusters Detected

    I am aware of that paper, but it does not answer my quetion. They do not relate this to any other postulated inconsistency in the large scale WMAP data, do they?
Back
Top