Amanda Gefter

“Wheeler wasn’t the first to point out that quantum mechanics slips into paradox the minute you introduce a second observer. The Nobel Prize–winning physicist Eugene Wigner, for one, had emphasized it with a Schrödinger’s-cat-style thought experiment that became known as “Wigner’s friend.” It went something like this: Inside a lab, Wigner’s friend sets up an experiment in which an atom will randomly emit a photon, producing a flash of light that leaves a spot on a photographic plate. Before Wigner’s friend checks the plate for signs of a flash, quantum mechanics shows that the atom is in a superposition of having emitted a photon and not having emitted a photon. Once the friend looks at the plate, however, he sees a single outcome—the atom flashed or it didn’t. Somehow his looking collapses the atom’s wavefunction, transforming two possibilities into a single reality. Wigner, meanwhile, is standing outside the lab. From his point of view, quantum mechanics shows that until his friend tells him the outcome of the experiment, the atom remains in a superposition of having emitted a photon and not having emitted a photon. What’s more, his friend is now in a superposition of having seen a spot of light on the plate and not having seen a spot of light on the plate. Only Wigner, quantum theory says, can collapse the wavefunction by asking his friend what happened in there. The two stories are contradictory. According to Wigner’s friend, the atom’s wavefunction collapsed when he looked at the plate. According to Wigner, it didn’t. Instead, his friend entered a superposition correlated with the superposition of the atom, and it wasn’t until Wigner spoke to his friend that both superpositions collapsed. Which story is right? Who is the true creator of reality, Wigner or his friend?”
― Amanda Gefter, Trespassing on Einstein's Lawn: A Father, a Daughter, the Meaning of Nothing, and the Beginning of Everything

“Einstein said, “This huge world stands before us like a great eternal riddle.” Why couldn’t any of my teachers have told me that? “Listen,” they could have said, “no one has any idea what the hell is going on. We wake up in this world and we don’t know why we’re here or how anything works. I mean, look around. Look how bizarre it all is! What the hell is all this stuff? Reality is a huge mystery, and you have a choice to make. You can run from it, you can placate yourself with fairy tales, you can just pretend everything’s normal, or you can stare that mystery in the eye and try to solve it. If you are one of the brave ones to choose the latter, welcome to science. Science is the quest to solve the eternal riddle. We haven’t done it yet, but we’ve uncovered some pretty cool clues. The purpose of this class is for you to learn what clues we’ve already got, so that you can take those and head out into the world to find more. And who knows? Maybe you’ll be the one who finally solves the riddle.” If just one of my teachers had said that, I wouldn’t have taken meteorology.”
― Amanda Gefter, Trespassing on Einstein's Lawn: A Father, a Daughter, the Meaning of Nothing, and the Beginning of Everything