RE: How Do Scientists Know It's Space Expanding Not Galaxies Moving?
August 15, 2017 at 7:47 am
(This post was last modified: August 15, 2017 at 7:47 am by Jehanne.)
(August 14, 2017 at 2:55 am)Alex K Wrote:(August 14, 2017 at 12:22 am)bennyboy Wrote: How do we know that rather than space expanding, matter isn't contracting, the idea being that light is exempt from shrinkage? What, for example, if one of the fundamental four forces is actually in flux?Absolutely, because the receiving atoms would be smaller, the received light would look more long-waved to them.
This would also lead to a red shift, no?
If you take the equations of matter and spacetime in General Relativity, both interpretations are possible. One can interpret the change of the space metric as an increase in distance by changing the coordinates, or one can model it by rescaling all the masses and strengths of forces, which would lead you to a picture where the mass of the electron rises making the atoms smaller. This should be equally consistent, but one still has to change the definition of time (which comes natural though because all the physical clocks are ticking differently as well). The space expansion interpretation of the equations is much simpler though.
The nail in the coffin (in a positive sense) that proves the expansion of the Universe is gravitational lensing:
Quote:Distant quasars tend to change their brightness, causing them to flicker. As the light which creates the different images of the quasar follows paths with slightly different lengths, the images do not flicker simultaneously but are delayed with respect to each other by several days. This delay in flickering can be used to measure the Hubble constant which describes the speed of expansion of our Universe. While the relative time between two flickers is correctly represented in this animation, in reality the delays are in the range of days to two weeks.
https://phys.org/news/2017-01-cosmic-len...nsion.html