#10. Evidence for Cosmic Inflation: Yes? No!
What would have ended up being one of the biggest findings of the year -- perhaps of the decade -- has turned out to be wrong. Early in the year, astrophysicists announced that they had detected gravitational waves, a telltale sign indicating a period of cosmic inflation immediately prior to the Big Bang. (Yes, cosmic inflation occurred before the Big Bang.) Alas, what they actually detected was dust. But fear not: Cosmic inflation is almost certainly still true, but this finding just wasn't the smoking gun.