It's easy to fold a piece of paper in half once, twice or even three or four times. But what's the highest number of times one piece of paper can be folded in half?
"De novo" genes may have paved the way for humans' big brains.
Modern humans have a youthful brain, and this "Peter Pan syndrome" is also seen in Neanderthals.
Black holes form natural time machines that allow travel to both the past and the future. But don't expect to be visiting dinosaurs any time soon.