Long the stuff of fantasy, wormholes may be coming soon to a telescope near you
For decades now, black holes have been the rock stars of popular astrophysics, both fact and fiction. Physicists rely on them to explain all sorts of mysterious astrophenomena, and black holes have been essential plot devices in various films, from Star Trek (2009) to Galaxy Quest (1999) to (obviously) The Black Hole (1979).
But black holes are not the only famous members of the hole family. Their distorted spacetime cousins, wormholes, are also offspring of Einstein’s general theory of relativity. Black holes are regions of extreme gravity, crushing anything they swallow into subatomic smithereens. Wormholes are “bridges” connecting one region of spacetime to another. Black holes are the spacetime analog of bottomless pits; wormholes would be intergalactic (or interuniverse) superhighways. If they exist, wormholes could be the key to establishing theories that the universe occupied by humans is just one cosmic bubble in a vast multiverse. Wormholes could connect different times and places like Twitter connects tweeters.
The possibility of such spacetime tunnels was noticed shortly after Einstein published his general theory in 1916. Einstein and Nathan Rosen worked out the math for wormholes more thoroughly in a 1935 paper, so they are known technically as Einstein-Rosen bridges.
Unlike black holes, inhabitants of galaxies everywhere, wormholes are common only in fiction. You can see them in action in movies — Green Lantern (2011), Bill & Ted’s Excellent Adventure (1989), Carl Sagan’s Contact (1997) — but real space has not yet yielded any sightings of wormholes.