(February 13, 2016 at 2:14 pm)Alex K Wrote:(February 13, 2016 at 10:42 am)Brian37 Wrote: Read the wiki article, those are the experts. I would assume that after the distances between galaxies become so great, if the expansion continues it would end up pulling those things apart too, but again, that article explains it better than I can.
Depending on who wrote the article, I'm likely as much of an expert. So the crucial point is that for such a 'big rip' to occur, one needs to postulate an extreme form of dark energy which increases in density without bounds as the universe expands. This is rather unusual, and current observations do not really suggest that something like this will occur. The simplest version of dark energy is the cosmological constant (which is a standard part of Einstein's theory anyhow) and it is so far nicely compatible with observations afaik. With this simplest hypothesis, constant dark energy density, the universe approaches an exponential expansion with a *constant* Hubble constant, which will just go on in a stationary fashion with a constant, negligible force on objects smaller than a galaxy cluster.
You're a physicist, right?
