I have read this question:
So the average spacing is somewhere in the range of 10 - 100 times the size of the biggest galaxies. The peas I had for lunch today were (at a guess - I didn't measure them!) 5mm in diameter so the interpea spacing would be 5 - 50cm, or between 8 and 8,000 per cubic metre. However there is a take home message i.e. galaxies are much, much, much closer relative to their size than stars are.
Now this is a very nice description, but there is no explanation as to why this should be so. As far as I understand, both structures (galaxies of stars and clusters and superclusters of galaxies themselves) are governed by the same gravitational laws of our universe.
Naively I would think it should be the other way around, dark energy should make things fly apart faster if they are farther apart, and it should have been doing so for billions of years. Galaxies, and especially the intergalactic voids should (as fas as I understand) cause them (the galaxies) to be separated by far bigger relative distances (please note we are talking about distances relative to the objects' size) then the stars are separated inside them.
There are two things to consider:
galaxies are giant objects relative to the size of a star, that is understandable
but gravity holds stars inside galaxies closer, and has been doing so for billions of years, whilst dark energy has been making galaxies themselves fly apart for billions of years, at an accelerated rate
Though I cannot find any kind of explanation as to why this should be the way it is, that is, why are galaxies (relative to their size) much closer spaced the the stars inside them?
- Why are galaxies much closer spaced (relative to their size) than stars?