Sometimes science fiction tells us stories of technology we can almost grasp already, like traveling to Mars. Other times it’s much more far-fetched and outrageous stuff, like wormholes. Since general relativity doesn’t explicitly, entirely forbid them, they have fascinated scientists and authors alike.
A wormhole is a tunnel, a shortcut between two far-apart regions in spacetime. The movie Interstellar had many flaws, but at least plausible science (thanks to the supervision of star physicist Kip Thorne). They also explain quite effectively the idea of wormholes: take a sheet of paper and fold it in half, then punch a hole through it. You just created a wormhole in your paper universe.
The entrance should look like a black hole, an inescapable sink where light and matter disappear forever. The exist should be the opposite: a source from which matter and light spring eternal—a white hole. Through a wormhole, you’d be able to cross immense distances in relatively short times. But, probably, not travel in time*.
So do they exist?
For sure we can’t make them. Making wormholes with paper is cute, but it only works because the sheet is two-dimensional and we are comfortable handling three. To create a real wormhole we’d need to work in four dimensions which is a non-starter for now.
It’s also unlikely that naturally-occurring, large wormholes exist. First, at least observing a white hole would give some indication of the existence of wormholes, but we’ve never seen them. Secondly, keeping a macroscopic wormhole open requires something that turns gravity from a force that pulls things together to one that pushes them apart. And we’ve never seen that either.
Still, I find really cool that we can imagine such an outlandish thing and actually reason about them, make sound arguments on how it could or could not work.
If you want more
- There’s plenty of semi-accurate explanations around about wormholes. But I liked this more serious one on Chalkdust
- NASA does a great job seriously answering all sorts of wormhole questions on this page
- Some say black holes are actually entrances of wormholes to other universes. Maybe, maybe not. Black holes are freakin’ weird.
* MINOR SPOILER: In Interstellar, Cooper does sort of travel in time, too. But that only happens after stepping into other dimensions: we’ve already crossed into magic.