That link is wrong. The redshifts are not doppler shifts in the expanding universe explanation. They changed it to something else; the metric expansion of space:
https://www.slac.stanford.edu/pubs/beamline/25/1/25-1-trimble.pdf --
“ Everybody is occasionally tempted to think in terms of matter expanding from a point or small region into previously existing space. This is the wrong image. The space itself is expanding and carrying the matter with it.
The redshifts we see are not Doppler shifts, caused by relative motion through space, but are rather the stretching out of wavelengths with the metric they propagate on. ”
“ If the redshifts are a Doppler shift...the observations as they stand lead to the anomaly of a closed universe, curiously small and dense, and, it may be added, suspiciously young. ”
—Edwin Hubble, Monthly Notices of the Royal Astronomical Society, 17, 506, 1937.
Stephen Hawking says there is no scientific evidence for this hypothesis:
“ ...all this evidence that the universe looks the same whichever direction we look in might seem to suggest there is something special about our place in the universe. In particular, it might seem that if we observe all other galaxies to be moving away from us, then we must be at the center of the universe."
There is, however, an alternate explanation: the universe might look the same in every direction as seen from any other galaxy, too. This, as we have seen, was Friedmann’s second assumption.
We have no scientific evidence for, or against, this assumption. We believe it only on grounds of modesty: it would be most remarkable if the universe looked the same in every direction around us, but not around other points in the universe. ”
—Steven Hawking, A Brief History of Time, p. 44
No scientific evidence. Believed only on grounds of modesty.
Edwin Hubble:
“ Such a condition [the red shifts] would imply that we occupy a unique position in the universe, analogous, in a sense, to the ancient conception of a central earth. The hypothesis cannot be disproved but it is unwelcome and would be accepted only as a last resort in order to save the phenomena. Therefore, we disregard this possibility and consider the alternative, namely, a distribution which thins out with distance.
A thinning out would be readily explained in either of two ways. The first is space absorption. If the nebulae were seen through a tenuous haze, they would fade away faster than could be accounted for by distance and red-shifts alone, and the distribution, even if it were uniform, would appear to thin out. The second explanation is a super-system of nebulae, isolated in a larger world, with our own nebula somewhere near the centre. In this case the real distribution would thin out after all the proper corrections had been applied.
Both explanations seem plausible, but neither is permitted by the observations.
The apparent departures from uniformity in the World Picture are fully compensated by the minimum possible corrections for redshifts on any interpretation. No margin is left for a thinning out. The true distribution must either be uniform or increase outward, leaving the observer in a unique position.
But the unwelcome supposition of a favoured location must be avoided at all costs… Such a favoured position, of course, is intolerable… Therefore, in order to restore homogeneity, and to escape the horror of a unique position, the departures from uniformity, which are introduced by the recession factors, must be compensated by the second term representing effects of spatial curvature. There seems to be no other escape. ”
— E. Hubble The Observational Approach to Cosmology, 1937, p.58
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