Spin State - Chris Moriarty [77]
“Meaning?”
“Ah!” He leaned forward, showing the kind of enthusiasm that usually meant he was about to talk math to her. “Interference patterns are the riddle that kicked off the whole enterprise of quantum physics. Basically, we’re talking about the two-slit experiment.”
“Oh,” Li said as her oracle summoned up a long-forgotten picture from an introductory physics textbook. “The thing where you put one photon through a screen and it interferes with itself, right? And then you get to watch the physicists jump up and down and argue about whether it’s a wave or a particle. Or both. Or neither. I never really saw what that had to do with Sharifi, though.”
“That’s where Coherence Theory comes in. How much do you know about it?”
Li shrugged. “You mean like the Everett-Sharifi Equations, the Coherent Worlds Theorem, that stuff?”
“Exactly. And like Sharifi said in her sales pitch, the answer was in our past, on Earth. It goes all the way back to the twentieth century in fact. To an American named Hugh Everett, who studied the wave theory of quantum mechanics and came up with this crazy idea that there was nothing theoretical about quantum mechanical wave functions at all. That they were actual manifestations of multiple worlds, multiple possible histories. In short, that the mathematical formalism of wave mechanics—and this is the part Hannah really loved, of course—that the mathematical form itself gave us the key to understanding the nature of the physical universe.
“According to Everett, each point on the Schrödinger wave function that you use to calculate the possible locations of an electron around the nucleus or the possible spin orientations of a photon has a real, physical existence. Just not in this world. In another world. One of an infinite number of worlds that branch off from each other every time a thermodynamically irreversible measurement event takes place.
“So—textbook example—you come to a crossroads, and you have to decide whether to turn left or right. Or so it seems. But actually you take both forks in the road. You just take them in different worlds. Or, depending on your terminology, in different constituent universes of the multiverse.”
“Then . . . what’s the point? I mean, everything happens no matter what you do, or what path you choose? It’s crazy.”
“Well, yes, that’s certainly the majority view of things. Or at least it was for several centuries. The Many-Worlds interpretation was one of those theories that was so absurd that Everett either had to be insane or right. And like a lot of crazy theories it took a long time to get off the ground. It got nowhere with most of Everett’s colleagues, in fact, and he left academia and eventually smoked himself to death, ignored and ridiculed.”
“What a surprise,” Li said caustically.
“Right. Well, Everett’s idea sat around gathering dust for the next few centuries while experimental physicists went on with their experiments. Experiments that over time, and without anyone really stopping to notice, gradually made the Many-Worlds theory look less and less crazy and more and more like it might just be a small but important piece of the truth.
“That’s where Hannah Sharifi comes into the story. Hannah was obsessed with Everett’s work. She basically spent two decades trying to prove that the Many-Worlds interpretation of quantum mechanics was right, and that Everett just hadn’t had the experimental data or the computational tools to prove it.”
“But she didn’t prove it, did she?” Li said. “She failed. The most famous failure in the history of physics, right? The biggest mistake since Columbus ran into America and called it India.”
“Yes. She failed. Which is to say that she didn’t prove the multiverse was physically real in the way she believed it was. But—and this is important—a theory doesn’t have to be experimentally verifiable to be valuable. And what she did with Coherence Theory was in some ways far more significant than pinning down an experimental result. She gave us a new theoretical framework for thinking about quantum-level events. In