Marchimedes: "Infinite universes. Wrap your brain around that for a while and you kinda start to run outta room."

Some scientists insist that the 'multiverse' idea is not physics but 'metaphysics' - but then some very smart quantum physisists say there's no better explanation for superposition***. Whichever way you look at it, it's hard to grasp. The popular word is 'counter-intuitive'. What they really mean is, it's impossible to "wrap your brain around", as you say.

*** http://searchsmb.techtarget.com/sDefinition/0,,sid44_gci341263,00.html

"Time is what prevents everything from happening at once" - John Wheeler