The idea that there isn't some alternate dimension that has been exactly the same as our dimension up to this moment doesn't make sense to me.
The sheer scale of alternate possibilities from the beginning of our universe is staggeringly infinite with every microsecond, but I have no doubts they exist in some way. This universe isn't the only physical materialistic one.
There was an actiony kind of movie called Source Code that falls in line with pretty much exactly how I feel about alternate universes in relation to time, that if we could pinpoint the exact parallel of our universe at a particular moment in time and enter it, we could use it to predict something in our current universe, and just flip over to the closest parallel universe each time we fail.