If the theory of the multiverse is correct, our universe is not alone: it’s just one in a sea of universes. If you could escape them all and look back at where you’d come from, you’d see an endless array of bubbles (or boxes or maybe doughnuts) stretching out in all directions, expanding and contracting, evolving and failing.

This is slightly different from the “many-worlds” theory of quantum physics, which believes that every decision we make shapes the universe we’re in. According to that hypothesis, every time we pull one book from the shelf instead of another, or select this brand of cereal instead of that one, we create a new universe. We live in an an overlapping network of parallel universes, universes that are constantly branching off in new directions, existing side-by-side but never touching. Timespace is like a hall of mirrors, only none of us can see our reflections.

If either of those theories is correct, then there are an infinite number of universes. And if both are correct, well, it’s hard to wrap my head around that.

But here’s the interesting part: if there are an infinite number of universes, then any scenario we can imagine is not only probable, but certain:

• In one universe, things are exactly as they are now, except I’m wearing a swimsuit instead of khakis.
• In another, my skin is green.
• In another, my dogs can talk.
• In another, I am straight, and Jonno is a leggy blond woman.
• In another, I am straight, and Jonno is a leggy redhead.
• In another, I never met Jonno at all.
• In another, I am very much alone.
• In another, I am already dead.

Religious leaders often talk about how precious life is, how lucky we are to be here. Physicists make the same point, but they do so much, much better.