Are galaxies moving away from a common center or are they moving in all directions with no common origin?

Question

The "BIG BANG" theory suggest that all galaxies are moving away in all directions from a common center biggining. Is this happening? or are galaxies moving in all directions without a common biggining?
Like when galaxies collide, is it because one is moving faster than the other in the same dirrection or do they collide because they are moving towards each other in different dirrections?
Just wondering.

Answer 1

The Big Bang Theory does not suggest everything is moving away from a common center. It suggests that space itself is expanding.

Picture a balloon. The center of the balloon is obvious - the surface is moving away from that point. However, if you existed as a two dimensional creature on the surface of the balloon, the 'center' would be imperceptible. You would just see everything moving away from everything else.

Similarly, the universe AS WE PERCEIVE IT is the three dimensional surface that is moving away from its center in four dimensional space. This four dimensional 'center' is imperceptible to us. We just see everything moving away from everything else. (at least generally speaking, there are certainly areas where gravity has a bigger local effect than expansion) Super clusters contain galaxies that do collide. However, in these cases, the total mass of the galaxies creates a gravitational effect that is larger for these galaxies than the apparent 'repulsion' of the universe as it, on the whole, expands.

This effect is similar to the strong nuclear force holding a nucleus together in spite of the fact that all the protons should be electromagnetically repelling one another. The protons are repelling one another but the strong force at that range is stronger than the repulsion on electromagnetism.

Its possible that there is another force - a repellent force that like electro magnetism vs. the strong, only overrules gravity with sufficient scale. Its a strange idea, but then again, the big bang, relativity and quantum mechanics are also strange ideas that have experimental and observational evidence to back them up - weird does not mean un-true - no matter how hard one wants to disregard the predicted observations and the experiments. End of the day, the weird theories do a far better job of making accurate predictions of reality than the more 'comfortable' and/or subjectively 'common sense' ideas.

End of the day, there is no universal 'center' of expansion in a three dimensional sense. This doesn't mean there isn't a 'center'. It does mean there is no three dimensional point of reference to define the 'center'.

This extra dimension, needed to define the 'center' could be the dimension of time or could be a different spacial dimension as implied in string theory.

Sure, it seems like voodoo, but like the creature living on the surface of a balloon, the third dimension needed to define the center of expansion of the balloon, it may not be voodoo but rather a lack of our own ability to perceive due to 'where' we exist.

Answer 2

One way to picture this is to think of a balloon, with little galaxies painted on it. As you blow up the balloon all the galaxies move away from each other, but there is no common "centre" on the surface of the balloon.
The galaxies are moving apart (generally) from each other in a random manner, but motion imparted during the formation of a galaxy can give it a direction that happens to graze or collide with another galaxy.

Answer 3

They are moving away from each other for the most part; but there are areas where galaxies are close enough to each other where gravity overcomes this motion and start moving toward each other.
As for a common center, well there really *isn't* one, because the center is the WHOLE universe.

Answer 4

They are both moving in random directions and sharing a larger overall expansion. Basically, neglecting local swirling motions, they are all moving away from each other. The usual analogy is a spotted balloon being blown up. As the balloon expands, the spots all get farther apart, but there is no real center of expansion, except the center of the balloon, which is not part of the surface which is expanding.

Answer 5

Because we cant understand infinity, There are probably much more than one "big bang." If they do not interact with each other, then common center thinking will apply.