For the record - I do! It just makes the show more realistic for me if the physical laws are the same, and has been observed by others there are plenty of methods to explain away inconsistencies.
There are more than enough reasons to think that it exists in an alternate history though. A history where the space age developed in the way we wanted it to...
Man, I don't even want to get into alternate universes/ timelines, et c. in this thread. I don't mind straying, but that's too far out of the box ( plus I hate anything alternate universy