We have seen that Einstein’s GR failed at predicting or knowing the existence of galaxies. It was so because Einstein was pursuing the assumption of a finite universe. However, while evaluating the idea of an infinite universe, Newton had duly reached to the concept of galaxies. Here I present the point of Newton:
In a letter to Isaac Newton, David Gregory declared in 1694: “A continual miracle is needed to prevent the Sun and the fixed stars from rushing together through gravity.” Newton pondered the issue over the years starting around 1685 and concluded:
“The fixed stars being… at such vast distances from one another, can neither attract each other perceptibly, nor be attracted by our Sun.”I. Newton, Principia (1728)
Newton reasoned that:
“if the matter of our sun and planets and all the matter in the universe were evenly scattered throughout all the heavens, and every particle had an innate gravity toward all the rest, and the whole space throughout which this matter was scattered was but finite; the matter on the outside of the space would, by its gravity, tend toward all the matter on the inside, and by consequence, fall down into the middle of the whole space and there compose one great spherical mass. But if the matter was evenly disposed throughout an infinite space, it could never convene into one mass; but some of it would convene into one mass and some into another, so as to make an infinite number of great masses, scattered at great distances from one to another throughout all that infinite space.I. Newton, letter to theologian Richard Bentley (1692)
Therefore, if we assume that both Einstein and Newton were logically correct and differed only in the underlying assumption, then we see that concept of galaxies is a logical outcome of the assumption of an infinite universe. If we say that Einstein’s cosmological constant prevented the collapse of whole universe but did not prevent the collapse at smaller scale of individual galaxies (or clusters) … then still the point remains that up to the year 1924 i.e. when existence of galaxies was confirmed through observations, there were at least three solutions (i.e. Einstein (1917), de-Sitter (1917) and Friedmann (1922)) to the GR equations (as applied to whole universe) available and none of them was able to describe such collapses at smaller than whole universe scale. Therefore, if their logic was correct and they did not derive such localized collapses in their works then our conclusion is that cosmological constant also won’t help in the derivation of localized galactic structures within a finite universe. In other words, mere existence of galaxies is the proof that either this is an infinite universe or at least the universe is much larger in size than what standard model has to tell.