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decarmony
2004-May-19, 06:16 PM
First of all I am not a scientist or astronomer so maybe someone with knowledge in those areas can help me out.I"ve always heard and accepted the idea of the universe expanding, but if thats the case,why do galaxies merge such as us and sagi and later on I think andromeda?If the big bang happened and everything expanded this shouldn"t be possible.Someone explained this with galactic gravity but wouldn"t that gravity been equally effective at the beginning.As a wild thought.isn"t it possible the universe is contracting and that the supernovas and things we are looking at far away are incredibly smaller as they race towards a possible big crunch? Or-a good way to get an answere would be to pose this question....If the big crunch were a given and we were indeed contracting , would that produce the effects we are now seeing or similar effects that suggest an expanding accellerating universe?

Normandy6644
2004-May-19, 06:37 PM
Gravitational effects will still pull objects together forming "clumps" or clusters. That's the basic deal.

Kaptain K
2004-May-20, 04:30 PM
Just as the Sun keeps its planets in orbit and the Milky Way (and other galaxies) keeps its stars, globular clusters and satellite galaxies in orbit, gravity keeps galactic clusters and super clusters together. On the local scale (up to the level of galactic super clusters) gravity overcomes expansion. Beyond that, expansion rules.