It's one thing to make an object invisible, like Harry Potter's mythical cloak. But scientists have made an entire event impossible to see. They have invented a time masker. Think of it as an art heist that takes place before your eyes and surveillance cameras. You don't see the thief strolling into the museum, taking the painting down or walking away, but he did.
Senh: This is an interesting approach. Slowing down light, so something can happen before it reaches our eyes. This seems like the most elegant solution, but it's probably way too difficult to do practically.