SEASON PREMIERE: Because of CBS’s Thursday Night Football, TV’s most popular sitcom is being moved back to Mondays to begin Season 8, if only until football season is over. And tonight, CBS presents a double dose of fresh Big Bang episodes – to give the best possible lead-in, and traction, to the new CBS series Scorpion, which is about a group of brilliant geeks who form a team to solve crimes and help those in need. But for now, against Gotham, the geeks of Big Bang Theory may be facing their own archnemesis.