We've seen time travel so often in the movies you have
to wonder why nobody's figured out how to do it in real life. Certainly if the
amiable dunces (Keanu Reeves and Alex Winter) in Stephen Herek's Bill
and Ted's Excellent Adventure
(1989) can visit past luminaries like Napoleon and "So-crates" via George
Carlin and a phone booth, some actual scientist should have cracked the puzzle by now.