I always liked the Narnia idea, that time went by at different intervals in different universes... but they didn't really say that, and it would kinda complicate things -- when altClark visits in L&Cs, he was in our world for two days or so -- would he go back to find that he'd missed 20 years?
Though that could be interesting... hmm... he'd have a chance at a secret identity again, and maybe even find the new incarnation of his soulmate...
And then, Paul kind of has a point, but if you go by Tempus Fugitive, going back in time has an amnesiac effect, so Lois shouldn't have remembered much <g>
In general, I try not to think too hard about the "scientific" details of things in the show, because they were often laughably wrong
PJ
