I still remember, so many years ago, when the big telescopes became powerful enough, that they brought us pictures of distant galaxies.
For the first time the images of far away, rapidly escaping galaxies were clear enough, that you could see their relativistic contraction. Not only the big Doppler red shift which proved how fast they travel away from us, but also all the relativistic effects of a high relative speed that Dr. Einstein had correctly predicted so many decades ago.
Another magnificent triumph for Relativity and late Albert Einstein.
Except that this never happened. Yes, we saw those distant galaxies quite clearly, but there was no trace of a contraction whatsoever. Not even when the Hubble Space Telescope caught its famous Deep Field series of pictures. The oldest, the fastest the most distant galaxies from the edge of space, showed no relativistic contraction. Not a single one of them.
The standard explanation goes like this:
They are not that fast. A few thousand kilometers per second at the most. What brings them to such apparent speed is the inflating of space. They are moving away from us with nearly the speed of light, but that’s not a speed, it’s an apparent velocity. Thus justly there is no relativistic contraction here!
Let’s say, that a galaxy had been ejected from our cluster, long ago at near light speed, so that it would be a relativistic contraction clearly visible from the beginning. By now, this galaxy would have already been among those caught by the HST camera. And would be static relative to those from HST pictures. The ejected galaxy is shrunken, when the neighboring ones aren’t, despite all of them moving with an equal, highly relativistic speed.
Embarrassing images, aren’t they?