The End of Everything (Astrophysically Speaking)

by Katie Mack

Some theorists have tried to reassure me. Sean Carroll, a cosmologist at Caltech who’s interested these days in the underpinnings of quantum mechanics, thinks we are all being a little rash to dismiss spacetime as not strictly real. “It’s real but not fundamental,” he tells me. “Just like this table is real but not fundamental. It’s a higher level of emergent description. That doesn’t mean it’s not real.” Basically we shouldn’t get too hung up on this because it’s not like spacetime isn’t there, it’s just that if we really understood what it was made of, it would look, at a deeper level, like something else entirely. This does not, in fact, reassure me.VII As a physicist I always try to maintain some level of dispassionate reserve when it comes to my subject, but the notion that spacetime is only real in the sense that it is something we can talk about and sit on but not in the sense of being what the universe is actually made of still makes me feel like it might collapse underneath me at any moment.