| MadSci Network: Astronomy |
In short, yes!
There are some theories that have postulated the existence of other universes either connected to ours through wormholes or completely disconnected.
In answer to your question about missing mass though, this doesn't help. We know where the missing mass should be! The 'dark matter' problem was first theorised when it was noted that galaxies should not exist because there is not enough visible matter to keep them together. So, the missing matter should be in great halos around the galaxies.
It is possible that these other universes could collide with ours (if they are all expanding) and this might be observed as a black hole. This is highly speculative though and even the black holes that have been observed do not make up for the missing dark matter
[Moderator's note:
The multiple universes scenario will not explain the missing mass problem, because the missing mass is in our own universe. However, as I understand it, if parallel universes were to exist, they could not collide with ours because they have seperate spacetimes which do not interact with ours.
There are arguments, based on energy considerations, that suggest the multiple universe scenario is wrong.
For more information,you may want to look at another answer about multiple universes on the MadSci Network.
Jim O'Donnell, MadSci Admin]
Try the links in the MadSci Library for more information on Astronomy.