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  1. C slows in a gravitational field relative to an outside observer but locally c is a ratio that remains the same. Gravity is a space/time energy gradient where increasing gravity amounts to a region of shorter space and slower time. The expansion of space would make c slower if time did not change with space but expanding space is like the emergence from a BB gravity well where time quickens as space expands so locally c remains the same since c is a constant by definition. In the BB theory, the changes in time that accompany the expansion of space are corrected for mathematically by the use
  2. The ER bridge and EPR entangled set appear equivalent to me but language purists may differ. However, the Einstein-Podolsky-Rosen effect was not quite "predicted" by the trio. The EPR effect was a thought experiment used to demonstrate the impossibility of action at a distance but it was invalidated the experiments of Bell and Aspect shortly after Einstein's death so Einstein's prediction was the opposite of what it is now taken to be.
  3. Yes, the transition from a gravitationally dense state to a less dense state would suggest that time was slower in the distant past and this would appear as an acceleration of space. I don't know but I suspect this is part of the calculations for the rate of expansion. An acceleration of time would necessarily accompany an expansion of space if c is to remain a constant.
  4. A quantum is a single unit of something and not necessarily the smallest possible unit of the same measure.
  5. Photon beams are necessary because the occurrence of a "split" photon is a rare event when the beam is passed through a SPDC crystal. The crystal does not split the beam itself as does a half silvered mirror but it splits a rare passing single photon. The photon is split into two halves with each half having 1/2 the energy of the original and 2x the wavelength. The beam is then blocked by a colored filter that allows only the pairs of split single photons to pass through.
  6. Light quanta can, on rare occasions, be split in half by passing a light beam through certain crystals. The result is two photons with twice the original wavelength and half the original energy. The effect is known as spontaneous parametric down-conversion. This may be the result of one photon being absorbed and two being emitted. https://en.wikipedia.org/wiki/Spontaneous_parametric_down-conversion
  7. In any model having an unbounded surface, the CMB radiation should be the first to go. Our universe appears to be internally curved so whatever energy that was there in the beginning should still be around in some form. It is hard to imagine that any form of early energy could remain in its primal state without having been absorbed and re-emitted by cold, non-luminous matter such as hydrogen atoms or dust particles so little radiation from the early and denser universe should maintain its original spectral signature. The energy behind the CMB is thought to have been generated by an intens
  8. The observer on the platform is inertially at rest and the “known length” of the train is no longer a part of his observation since the length of the train moving at relativistic speeds appears shorter than before as described by the Lorentz transform. Spacetime diagrams such as Minkowski’s or Epstein’s use c as a dimensional constant rather than as a speed and it would require a separate diagram for every observer and every speed to visualize events as if they were occurring at other than c. Diagrams using c as a variable speed would not depict events as they are observed so I see no purpos
  9. People in the past did not expect a shaded body to radiate its heat away until its temperature dropped to absolute zero. Any attempt to shade a body would eventually fail once the temperature of the shade reached the equilibrium temperature of that point in space and then the shade would become a radiant body itself. A shade would only work if it were a perfect insulator, in which case, the body (rock) would never cool. Astronomers had several predictions about the absolute lowest possible temperature in deep space and their estimates centered around 3K until 3K was identified as as the CBR
  10. Representing objects that appear to be moving faster than c on a space-time diagram would either be objects moving backwards in time, in which case they would not be visible, or it would require a 3-D diagram where the moving object appears to rise above the ‘real’ scale and move on to a scale that is expanded in all directions compared to the layers below.
  11. The value of c is ~300,000 km/ sec and c has all the properties of a space/time dimensional constant but it acts nothing like a velocity. I agree with JulianM. Stick to what is observed/detected and forget about what you think is happening. Light vanishes from a source and appears at a remote point with an observed time delay between the two events of one second delay for every 300,000 km of distance for all observers. This is what we observe. Observers having different velocities should see the speed of light as a variable because velocities add but, in SR, velocities do not add to c becaus
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