Most black holes are deadly singularities that will crush everything inside, even stopping time. But there's a special kind of black hole that will let you travel in time—or to another Universe. Esther Inglis-Arkell explains:
Want a trip through a black hole without having to experience that pesky death? You're in luck. There's a special kind of black hole that's not just survivable, but might get you to another time, or another universe.
Black holes are, traditionally, the scariest things in the universe. Huge, mysterious, inescapable, they wander through the universe and eat everything that gets too close. "Too close" is defined by their event horizon. This is the point at which they go dark, because it requires so much energy to escape them that not even light can get away. Since not even a photon can cross the barrier, no event that happens inside the horizon can ever have an effect on people outside.
Unless, something very odd was going on in the center of the black hole. Most black holes spin - this is something that was discovered way back in the 1960s by physicist Roy Kerr. It wasn't exactly a shock, because most of the material that collapses into a black hole was already spinning. Sometimes, however, the spin on Kerr black holes goes a little above and beyond. Ever spun a glass of water, or soda bottle, so that the liquid inside swirls? Sometimes, if you spin it enough, the liquid actually parts, leaving a clear center and a spinning ring of water around it. The same kind of thing can happen in Kerr black holes. Instead of a singularity at the center, there's a ring. And you can go through the open portion of that ring without touching the gravitational crush.
What's on the other side? A lot of people have wondered. Some people think that these kind of black holes might be our key to time travel. They might be wormholes that let us hop between different points of the universe. Or they might be portals to different universes entirely. First we'll have to find a few, and then we'll need a few volunteers to go through. Preferably ones that haven't seen Event Horizon.
Top Image: NASA/JPL-Caltech
Second Image: Dana Berry/NASA