Antimatter

There’s a time machine on the Stanford University campus, and it runs day and night. It won’t hurl anyone into the past or future, but it does something almost as audacious: It reenacts events that occurred just after the Big Bang, when some of the pure energy that filled the cosmos became all the matter that now exists. Inside an 18-foot-high, 1,200-ton particle detector, matter and antimatter moving at nearly the speed of light smash into each other billions of times a second, shattering into subatomic debris that hasn’t existed for about 14 billion years. “We have the gall to believe that we can prepare a situation that is very analogous to what you had at the beginning of time,” says physicist Jonathan Dorfan, director of the Stanford Linear Accelerator Center. “We’re trying to understand what happened during an extraordinarily energetic part of the birth of the universe—and we do ...