The human mind likes finite things. We like beginnings and endings. (Middles, less so.) You may tell someone that he’s your BFF, but neither of you truly believes the “forever” part.

It’s hard work, thinking about infinity–real infinity, real forever–but as a kid raised in the Southern Baptist church, I was obsessed with it. That’s what heaven is supposed to be, right? Infinity? Another day in paradise. And another. And another. Until you just want to kill yourself from boredom. But of course….

Anyway, I couldn’t. I couldn’t grasp the word “never-ending”. Then, I heard about the many-worlds interpretation, often referred to by non-sciencey people as the parallel universes theory.

The many-worlds interpretation is one of many theories that pops up when people discuss time travel. It’s the idea that every time we take an action–for example, making a decision–we create a new universe. In one universe, I chose to break with tradition and wear a pink shirt to work today. In another, I wore blue. In another, I wore my usual black.

In another universe, I went to work stark naked, and the cops were called. In another, I did the same, but nobody really cared. And in yet another, I went to work stark naked, and everyone else did, too, because clothing hadn’t been invented.

But even that isn’t technically “infinite”. Yes, I make a lot of decisions over the course of the day–so do you, so does everyone. If I make 1,080 decisions today–one every minute of the day, except for the six hours I sleep, I’ve created 1,080 parallel universes. If all 7,000,000,000 people on the planet do the same, we’ve created a 7.56 trillion parallel universes in a day, 2.76 quadrillion parallel universes each year, 276 quadrillion universes every century. Multiply that times the number of sentient species on this planet and every other planet that supports life throughout all of history, and wow.

And yet, that’s not infinite. It’s a lot, but it’s nowhere close to infinite.

To tackle infinity–real infinity–consider the multiverse theory. It suggests that ours is one of an infinite number of universes bumping up against one-another, like bubbles in a non-stop bubble bath.

In one of those universes, my genetic twin is sitting next to your genetic twin as he types this. In another, he’s just walked out on your twin after 20 years of living together. In another, he’s walked out after 19 years. And in yet another, he’s walked out after 19 years, and he’s taken the dog.

You’ve heard of rule #34, which says that if it exists, there’s porn of it? The multiverse theory is a little like that: if you can conceive of it, it’s happening somewhere in the multiverse. Even if you can’t conceive of it, it’s happening.

But wait, there’s more: if the multiverse theory is correct, all of that–the shirts we choose, the walking out, the dog–all of that is happening simultaneously. And it keeps happening simultaneously. Forever.

That’s infinity, dammit.