"Island universe" eventually true?

Loren Booda

With the acceleration of the universe outward, will our universal horizon eventually be reduced to include only the local neighborhood of the Milky Way, an island universe, whose concept predates Hubble's discovery of linear universal expansion?

Nabeshin

Yes.

sysreset

Wait..... I thought that gravitationally bound systems do not experience Hubble expansion. The Milky Way is gravitationally bound to the Andromeda galaxy (the two galaxies are either orbiting each other or colliding). So our island will include Andromeda.... and the other galaxies of our local group....... no?

Wallace

I think it's an open question of exactly what objects are bound within the Local Group but yes in principle our little collection of galaxies will remain together forever, even once everything else in the Universe is too far away to see ever again.

Note that by this time all the galaxies in the Local Group will have merged together, probably resulting in a single large elliptical galaxy containing the mixed up remains of the Milly Way, Andromeda, the Magellanic clouds and a host of other nearby dwarf galaxies.

Nabeshin

There was an interesting article on this subject in popular science magazine (I think). It talked a little about how we live at a somewhat privileged time because we're at an era where we can discern the origin and nature of the universe through telescopic observations. Any later, the article stated, and we would become an island universe and thus unable to observe even expansion. Interesting stuff, although I do believe they ruled out gravitational binding of objects, because it talked about how the milky way would eventually split up.

George Jones

http://www.sciam.com/article.cfm?id=...d-of-cosmology

http://arxiv.org/PS_cache/arxiv/pdf/...704.0221v3.pdf

Loren Booda

George,

Thank you. The SciAm article is where I must have gotten my idea.