The Multiverse is having a moment. From “Rick and Morty” to Marvel movies, the idea that our Universe is just one of many has inspired countless storylines in recent popular culture.

Why is the Multiverse so compelling? To theoretical physicist and philosopher Sean Carroll, one reason is that we’re drawn to wondering how things might have turned out differently. What if you had chosen a different career path? Married someone else? Moved to a different city?

Of course, there’s obviously no guarantee that you’re living out those alternate timelines in a different universe. But there are real scientific reasons to think that the Multiverse exists. And as Carroll explains, that possibility comes with some fascinating philosophical implications.