Big Bang Theory Quote
Howard: Hold on. Pause. Something doesn't make sense.
(drawing on the whiteboard)
Howard: Look, in 2015, Biff steals the sports almanac and takes the time machine back to 1955, to give it to his younger self. But as soon as he does that, he changes the future, so the 2015 he returns to would be a different 2015, not the 2015 that Marty and Doc were in.
Leonard: This is Hot Tub Time Machine all over again. If future Biff goes back to 2015 right after he gives young Biff the almanac, he could get back to the 2015 with Marty and Doc in it. Because it wasn't until his 21st birthday that 1955 Biff placed his first bet.
Sheldon: Wait. Whoa, whoa. Is "placed" right?
Leonard: What do you mean?
Sheldon: Is "placed" the right tense for something that would have happened in the future of a past that was affected by something from the future?
Leonard: (thinking) Had will have placed?
Sheldon: That's my boy.
Quote from S08E05 - The Focus Attenuation