Recent content by Old Smuggler

  1. O

    I Can neutrinos be produced/detected incoherently?

    Yes, but the question was if these weak eigenstates can be produced incoherently, i.e., from e.g. only one mass eigenstate without interference from other mass eigenstates. As Orodruin said in #2, this is certainly possible in theory, but does it have experimental support?
  2. O

    I Can neutrinos be produced/detected incoherently?

    Sure, statistical evidence for incoherent neutrino detection would be fine. Does this exist? But for solar neutrinos, the wave-packet separation is so small that coherence is restored in the detector during the detection process. Thus the detection of solar neutrinos is in itself not evidence...
  3. O

    I Can neutrinos be produced/detected incoherently?

    Produced/detected incoherently: produced/detected as separate mass eigenstates with no interference from different mass eigenstates. (See arXiv:0905.1903) Thank you. Do you have a reference to experiments where neutrinos are produced/detected incoherently?
  4. O

    I Can neutrinos be produced/detected incoherently?

    In the wave-packet approach, different neutrino mass eigenstates have different mass and thus propagate with different speeds. This will eventually lead to wave-packet separation and decoherence. My question is, can neutrinos be produced/detected incoherently? (In other words, can different...
  5. O

    What is the current status on MOND

    For spiral galaxies, the observations indicate a very close relationship between the dark halo and the visible matter in the disk; this is called "the disk-halo conspiracy". That is, the dark and the visible matter distributions apparently conspire such that the rotation curve turns out to...
  6. O

    How to prove the stretching of space

    This non-relativistic decomposition is arrived at by using a Newtonian approximation to calculate the "gravitational" contribution. But this approach is misguided, and inconsistent with a relativistic approach. The cited statement should not be taken as a criticism of B&H, since the...
  7. O

    How to prove the stretching of space

    The problem is B&H's claim that it is "most natural" to interpret the cosmic redshift as a Doppler shift in FLAT space-time for sufficiently small distances. But as I have argued in this thread this claim is false; with a few exceptions said interpretation is in general simply inconsistent with...
  8. O

    How to prove the stretching of space

    A Doppler shift in curved space-time only means that the special-relativistic Doppler formula can be used after the described procedure of parallel-transport. Any further interpretation is not included. In particular, a Doppler shift in curved space-time has nothing to do with any possible...
  9. O

    How to prove the stretching of space

    Nothing is arbitrary with the procedure described in #43. That is, the world lines of the FOs and their 4-velocities are not arbitrary and neither are the null curves. (For sufficiently small distances the effects of geodesic deviation can be neglected, so the world lines of the FOs are still...
  10. O

    How to prove the stretching of space

    You misunderstand. If the redshift in a general RW-model were purely "kinematic", the procedure described in #43 would yield the same redshift for small enough distances both for the curved space-time geometry and for flat space-time. Since this does not happen in general, the nature of the...
  11. O

    How to prove the stretching of space

    Yes, cosmological redshifts can always be interpreted as Doppler shifts in CURVED space-time. However, they cannot in general be interpreted as Doppler shifts in FLAT space-time, and it is the latter meaning that is usually understood with "kinematic" redshift. There is no obvious intuitive...
  12. O

    How to prove the stretching of space

    Sorry for the late reply (no internet connection for the last week). The redshift depends only on the 4-velocities of the FOs and on the space-time geometry. (This is most easily seen by using said procedure of parallel-transport.) On the other hand, the INTERPRETATION of the redshift depends...
  13. O

    How to prove the stretching of space

    It is not a good idea to introduce coordinate-dependent quantities if they are not directly related to coordinate-free objects. That is, the proper objects to consider are the 4-velocities of the FOs and not some independently defined "recession velocities". The question of what speed to use in...
  14. O

    How to prove the stretching of space

    The Milne model is equivalent to an empty RW-manifold and is mathematically a subset of Minkowski space-time. The FOs are those observers moving orthogonally to the "preferred" hypersurfaces (with hyperbolic geometry) foliating this RW-manifold. There is no alternative set of observers involved...
  15. O

    How to prove the stretching of space

    Coordinates are irrelevant for interpretations of redshifts in the RW-models. What matters is the choice of observers emitting and receiving electromagnetic radiation being redshifted (but these observers are not chosen arbitrary since they are specific observers determined from the symmetry of...
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