What if we could take a shortcut through spacetime and visit another galaxy? Sci fi movies have imagined the possibility for years, but are wormholes real? Ask Science explores the far reaches of our universe (and beyond).
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.
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 email@example.com.