why do scientists think this about the univerese?...?

Question

Well... stars and planets make up a galaxy... but then some scientists think that all the galaxies are just scattered around every where... how do we know that millions of galaxies, could make up one super galaxay? and then millions of those could form an even bigger galaxies... so yeah basically... how do we know that galaxies don't cluster together like stars and planets to make a bigger (MASSIVER) galaxy?

if we sent a probe out and waited a few hundred trillion years, i bet the univerese would look way different than what we think, doug.

Answer 1

We can actually see pretty far. As alluded too there are very large scale structures in the universe, with clusters of galaxys forming sheets of matter surrounding fairly empty large voids. There is a substantial observational evidence of the large scale structure of the universe, and many models reproduce this structure with varying degrees of success (from pretty good to excellent) based on fairly simple assumptions about the contents of the universe and the nature of the early universe.

We do know about galaxies clustering and we know that clusters form larger structures.

The universe is young enough however that there is no simple orbital organization like we see in a galaxy: this makes sense. The sun and its pre-solar gas has orbited our milky way a few dozens of times since the birth of the universe. Increase the scale one is examining and it quickly becomes apparent that at larger than galactic scales, nothing has completed a single orbit of any central mass yet.

Example: The Local Group of galaxies that houses our Milky Way is gravitationally bound to the its local super cluster with the Vega cluster at its center. The local supercluster has a mass of about 10^15 M_sun and a size of about 60 Mpc.

http://en.wikipedia.org/wiki/Local_Supercluster

One orbital period around this monstrosity is about 30 billion years. . . if you consider it takes dozens of periods to reach some sort of equilibrium. . .


Check out some references below:

Answer 2

so far we have found local groups, and local superclusters yes, but we really have no way of knowing anything beyond our light-time bubble (at least not yet). light has only reached us from within and around our supercluster of galaxies so far, so we really have no way of knowing if the pattern goes on infinitely upward. We can guess that it doesnt though from the fact that it only goes so far downward. if it has one end to the size scale (the plank length), another end is very likely. but who knows! we basically cant know until we figure out how to read carrier waves traveling faster than light or figure out how to use quantum pairing to probe particles beyond our lightcone. good question though

Answer 3

???
'Massiver?? Could you possibly mean 'more massive'??

And the answer is that they have large instruments (called telescopes) which allow them to actually see the way that the MIlky Way, Andromeda, and a few other galaxies make up the 'local group' and that our group and several other groups make up the 'local supercluster'.

Doug