: To whom, : I won't enter into a debate on how the : Universe was created other than to say that if : one accepts the theory that the Universe was : the result of a big bang, then is there any : logical reason that this couldn't have happened : more than once? That would assume that there was : enough mass to cause the Universe to eventually : collapse back into one point. Considering the vastness of space, is there any logical reason : that there couldn't be more than one Universe? : The reason that I question this, is the pictures : I have seen of two Galaxies colliding. If all : the galaxies in this Universe are moving away : from the single point of the origin of the "Big : Bang" and, consequently, moving away from each : other, then you should not be able to have two : galaxies on a collision course. The only way for : this to be possible, in my humble opinion, is to : have more than one point of origin which suggests : more than one galaxy and more than one "Big Bang". I would appreciate your thoughts concerning this idea. : Thank you, : : Galaxies can still collide in a single Big Bang model Universe. The reason is gravity. Two galaxies that are moving away from all the other galaxies may be in orbit arround each other. This is the case of the Milky Way and M31. In about 2 billion years These Two galaxies could collide. By looking at the spectra of the galaxy it is possible to determin it,s velocity. All other galaxies are moving away, they have a red shift. The andromeda galaxy has a blue shift which means that it is approaching or galaxy.Other galaxies that you have seen in photos or thru a telescope were also at one time in orbit arround each other. That orbit has decayed and resulted in a collision. Look for a photo of NGC4038-4039. Hubble has taken a wild photo of this colliding galaxy.