It’s hard to skim through a day’s news feed or newspaper without seeing at least one story about wormholes. And of course, they often pop up in sci-fi novels, movies, and TV shows. Why is that? What’s so fascinating about something that’s purely theoretical? Unlike black holes, humans have yet to observe a wormhole. Since a wormhole plays a starring role in my first novel, The Lightning in the Collied Night, I thought I’d explore our fascination with wormholes.

The first question I should cover is, what is a wormhole? I think this article in Astronomy does a good job answering that question for people who aren’t quantum physicists. That article says a wormhole is like a tunnel between two distant points in our universe. Some of them could theoretically be traversable and drastically cut the travel time from one point to the other (more on that below). The article goes on to say that some wormholes could, again theoretically, act as “time machines” between those two points (more on that below, too). There’s many scholarly papers available online that go into much more detail about wormholes, if you’re interested in that kind of thing. This short blog post merely scratches the surface… if wormholes had a “surface” to scratch.

How long have humans been thinking about wormholes? The first hint about what would later be called “wormholes” came in 1916. While reviewing another physicist’s solution to the equations in Albert Einstein’s theory of general relativity, Austrian physicist Ludwig Flamm realized another solution was possible. He described a “white hole,” a theoretical time reversal of a black hole. Entrances to both black and white holes could be connected by a space-time conduit. Then in 1935, Einstein and physicist Nathan Rosen used the theory of general relativity to build on on that idea, proposing the existence of “bridges” that connect two different points in space-time. These shortcuts through space-time came to be called Einstein-Rosen bridges, and eventually by the friendlier term “wormholes.”

Unfortunately, those bridges are likely to be extremely unstable and short-lived, and thus they aren’t good candidates for sci-fi stories in which people travel through a wormhole. (Although in a short story from 1931, The Meteor Girl, the hero used something like an Einstein-Rosen bridge to rescue his fiancée from a shipwreck 4,000 miles away and 12 hours 40 minutes into the future. It was probably the first use of a “wormhole” in fiction—unless H.G. Wells’ time machine leveraged a wormhole.) Fortunately for us sci-fi wormhole fans, scientists theorize that more stable wormholes might be formed from spinning black holes. Then there’s the Randall-Sundrum II model for wormholes that form in five-dimensional spacetime. Importantly (and something to keep in mind if you read my book), such wormholes might be traversable by humans. That’s good news for all the sci-fi books, movies, and TV shows in which people zip through space (and maybe also time) using a wormhole.

As I mentioned earlier, no one’s seen a wormhole yet. But if we did see one, what would it look like? Many scientists believe that the “mouth” of a wormhole would look very similar to a black hole, but that entrance may or may not actually be a black hole. The traversable wormholes I mentioned earlier would supposedly look like intermediate-mass black holes to an untrained observer. Okay, then how would someone actually discover a wormhole, if they look like a black hole? Some good news there, too: researchers in Bulgaria theorized that it should be possible to tell wormholes and black holes apart by noting subtle differences between them, such as polarization patterns and intensities and also their radii. (Hmm… maybe in 25-30 years observers with powerful telescopes will be able to do that?) Other scientists believe that wormholes could magnify the light of distant objects by up to 100,000 times—an effect known as “microlensing.” That would make wormholes easier to spot, in theory. But black holes and other celestial objects such as stars produce a microlensing effect, too, and that might make it difficult to discern a wormhole from something else.

If it could be possible for a person to traverse a wormhole and exit in one piece, what about the time travel aspect? In sci-fi, people use wormholes to go forwards and backwards through time, all the time. Is that possible, even with hugely-stretched theory? We know it’s possible for humans to travel forward in time. At least one person, Russian cosmonaut Sergei Krikalev, has done it. He went forward 1/48 of a second during his 803 total days in Earth orbit. I know, not very exciting from a storytelling perspective, but it proves that time travel is possible. At least one astrophysicist believes that traversable wormholes could be used to go forwards or backwards in time—but only with a “Herculean” effort. Other scientists believe that it might be possible, although extremely difficult, to use a wormhole to travel to the past—but it’s not possible to travel to the future. And the furthest you could go back in time is the point when the wormhole was created. Then there are scientists who believe that time travel, especially going backwards in time, is impossible. And there’s also scientists who believe that wormholes are impossible. But that would ruin a lot of entertaining sci-fi, so I’ve chosen to ignore those scientists here. 😉

It should be clear why wormholes are so fascinating and popular in sci-fi: they allow—theoretically—almost instantaneous space travel across large distances. No need to mess with those inconvenient (and often boring) sleeper ships or something that’s probably more unrealistic than wormholes: faster-than-light propulsion à la “warp drive.” Plus wormholes offer the ability—maybe/sorta—to travel through time—forwards and/or backwards, depending on which scientists you agree with. Think of all the story possibilities! No wonder so many books, films and shows have included or even been based on the existence of wormholes. Without wormholes, there would’ve been no Stargate movie or series, no Sliders, no Doctor Who, no The Black Hole, no Contact, no Interstellar, no Star Trek: Deep Space Nine, no Babylon 5, and many more including several MCU movies. Plus too many novels and short stories to list. What a wonderful plot device! If there were no such thing as wormhole theory, sci-fi writers would’ve been forced to invent it.

As I mentioned, there’s a wormhole in my book that’s critical to the story. It’s one of those traversable wormholes that allows humans to travel through it and survive—or believe they can do that, at least—using technology that might be available 30 years from now. And it’s one of those wormholes that might be a gateway to another time. Big assumptions, yes—but necessary for my story. While I tried in my book to respect science and scientific predictions about the future, the wormhole is where I have to ask readers to “just go with it.” But lots of sci-fi novels, movies, and TV shows have done that. So as Captain Sisko of Deep Space Nine said, as he was looking out the window at a stable traversable wormhole: “I think I can live with it.”