Are Wormholes Real?

Imagine if we could hop over to our nearest massive galaxy neighbor Andromeda and check out what our Milky Way looks like from the outside.

Or, want to know if the recently discovered Earth-like exoplanet is habitable? Send a probe over to check! The main challenge to space exploration has never been our imagination, or even our ability to come up with new technologies to make space flight possible, but the vastness of space.

It took 9.5 years for the New Horizons spacecraft just to get to Pluto which is still within our solar system. The nearest star (after our Sun) is more than 26 trillion miles away! Wouldn’t it be convenient if the universe offered us a shortcut?

What Is a Wormhole?

Theoretical physicists have hypothesized the existence of such shortcuts through spacetime since the 1930s, originally calling them white holes and eventually Einstein-Rosen bridges. A white hole acts like the reverse of a black hole by emitting energy while not allowing anything to enter. (Black holes, of course, allow matter and energy to enter but, much like the Hotel California, once you enter, you can never leave.) Since the name “Einstein-Rosen bridges” is a bit dry, they became more commonly known as wormholes.

You can picture a wormhole as a kind of tunnel that connects two points in spacetime. That tunnel could be a straight chute or take a more winding path. If the wormhole is “traversable” it acts as a shortcut through spacetime, connecting two points that would otherwise be far apart. Wormholes could connect different spots within a single universe or they can connect different universes.

The most common way wormholes are depicted is to imagine you are holding a piece of paper that represents normal space. Think of traveling through space as traveling along the sheet of paper. Now mark a point at each end and bend the piece of paper in half, bringing those two points together but without letting them touch. If you were to travel in normal space (i.e. along the sheet of paper) the trip from one of your marks to the other would be longer than if there were a tunnel or a “wormhole” connecting the two points on the paper through the empty space between them.

Now the big question—do wormholes really exist?

Do Wormholes Really Exist?

A wormhole has never been observed either directly or indirectly, but wormholes do exist in the sense that they arise in solutions to Einstein’s general relativity field equations. What that means for those of us who don’t deal in Jacobian matrices every day is that we can break down the universe into its many different parts and then use mathematical equations to describe how those pieces fit together.

Those field equations are like the scaffolding or that the universe is built upon. The equations that describe how general relativity or gravity works don’t require that wormholes exist but they do allow for their existence. In other words, one possible solution to the general relativity field equations is a wormhole connecting two points in spacetime.

Not only are wormholes purely theoretical, there are a few known issues with making them a reality even in mathematics outside of Einstein’s field equations. For starters, they are unstable meaning they collapse quickly. So any would-be spacetime travelers could never make it to the other end of the tunnel if the tunnel keeps collapsing around them. All is not lost, however, because physicists have discovered that invoking the presence of exotic matter can hold a wormhole open. Exotic matter, not to be confused with dark matter, is a form of matter that has negative energy density and negative pressure and is repelled rather than attracted by gravity. So far exotic matter usually comes in the form of particles in quantum experiments so no one knows if enough exotic matter to build a wormhole can exist all in one place.

And even if we could prop a wormhole tunnel open with the gravity repelling abilities of exotic matter, other theorists, like Stephen Hawking, have suggested that once anything, even a single particle, enters a wormhole, the mathematics require that the wormhole collapses. That does not bode well at all for intergalactic space and time travel.

Wormhole Potential

Wormholes are a popular subject among science fiction enthusiasts (think Contact or Donnie Darko) and theoretical physicists alike because such shortcuts would open up a universe of possibilities. We could travel to another galaxy in a human lifetime or explore the existence of parallel universes. And wormholes don’t just allow the possibility of space travel but also travel through time. We could go back to the early days of our solar system’s formation and settle the debate over how our moon formed or solve the mystery of how the supermassive black hole at the center of the Milky Way came to be, just for starters.

What would you do with a wormhole?

Until next time, this is Sabrina Stierwalt with Ask Science’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Ask Science on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com.

Wormhole image courtesy of Shutterstock.