In other words, The Big Bang Theory is (https://www.reddit.com/r/bigbangtheory/comments/o7yec/tbbt_vs_that_70s_show/) That '70s Show set in present day.

Why The Big Bang Theory and That 70's Show are Basically the Same Show (http://roxiedust.blogspot.com/2014/12/why-big-bang-theory-and-that-70s-show.html)