Oh no wait, erasers.
It’s at around this point that I start thinking “Why on earth did I decide to write something about the quantum eraser?” As if wavefunction collapse and wave-particle duality weren’t hard enough concepts to get your head around at the best of times, introducing the quantum eraser and quantum entanglement will probably make your brain implode completely. I know mine did, and still does every time I read about it. I make a lot of sacrifices for you guys, okay?