Re: Relativistic aberration

Am Dienstag000016, 16.07.2024 um 16:47 schrieb gharnagel:

 Yes, I understand what you're saying.  What needs to be understood is
just how many molecules make up the normal matter around us (think
Avogadro's number).  Interstellar space contains between 20 and 50
hydrogen atoms per cubic cm:
 https://en.wikipedia.org/wiki/Interstellar_medium
 Half of the distance to the Large Magellanic Cloud is outside our
galaxy,
so the density is even lower.  At 50/cm3, the entire 168,000 light years
amounts to only a two meter thickness of hydrogen at STP!  So I'm afraid
the astrophysicists cannot use that to save their precious
speed-of-light
skins.
 "Why is the speed of light so slow when the universe is such a really,
really big place?" -- G. L. Harnagel

This is a tautology:
What we see in the night sky is actually our own past light-cone.
This means: light is relatively slow for the wastness of the universe, hence we can see everything only with a certain delay and the further away, the longer the delay, according to x = c* t
(with x= distance in meters, t = delay in seconds).
This 'longer away' is usually measured in light years and the delay in years.
Since the night sky shows only a delayed image of past events, the speed of light cancels out of the equations and we can put any value into it and always get a valid picture of the universe.
So we only assume, that light moves always with ~300 million meters per second through the entire universe.
But if light would speed up or slow down, we would not be able to measure this, because we always see the own light cone in the night sky and c is already embedded into it (for whatever a value c actually has in outer space).
TH