RE: How Do Scientists Know It's Space Expanding Not Galaxies Moving?
August 10, 2017 at 9:30 am
(This post was last modified: August 10, 2017 at 9:34 am by Anomalocaris.)
(August 10, 2017 at 9:14 am)Alex K Wrote: When space expands, redshift is the sum of all expansion during the light travel. When Galaxies move, the redshift is the difference between movement speeds at the time of sending and receiving. Big difference.
The question is how does the observer tell the difference?
If I am not mistaken, there is no way to tell the difference in the causes of redshift through single direct observation.
The difference has to be inferred from patterns seen over a large body of observations, which shows galaxies exhibit a particular pattern of red shift highly correlated to their distance, as calculated by comparing the observed brightness of phenomenons believed to have narrow range of intrinsic brightness.
If the pattern of red shift comes from galaxies moving, there needs to be an explanation for how galaxies come to move in relative terms in this extremely regular manner. There is none so far that fits the data and is relatively free from large number of ad hoc assumptions.
I believe it so happens that the universe expanding rather than galaxies moving fits the pattern of data far better while requiring far fewer addition as hoc assumptions.
