Define Infinite in respect to the Universe?
Do you mean it won't end, it will expnad forever, then you're on pretty solid ground there, I suppose, but I see no reason that would lead to us being a dream.
If you mean the Universe is infinite in size, then that's pretty much the opposite of the current understanding of the Universe as being finite but unbounded. That very idea spawned a convoluted thred called "Spherical Issues," if you have the time and the stomach, you may find that topic interesting.
Edited by Adminnemooseus, : Off-topic banner.