Researchers have discovered an unpublished theory of Albert Einstein’s—and it's completely off the mark. Physicist Cormac O’Raifeartaigh was going through the Einstein manuscripts at Hebrew University in Jerusalem when he discovered a draft paper attempting to explain why the universe was expanding but wasn’t filling up with empty space. This was before the Big Bang theory, and Einstein proposed that new matter showed up to fill in the gaps. We know today that this is clearly wrong, and Einstein eventually did, too. Still, O'Raifeartaigh said it was still a surprise to see the genius' mistake. “It's a bit like finding a play; you're looking through a draft version of Beckett's play Waiting for Godot, and then you suddenly realize halfway through, 'Wait a minute, there's no Godot in this play at all.'"