Black holes are perhaps the strangest, least-understood objects in our universe. With so much potential — being linked to everything from wormholes to new baby universes — they have sucked in physicists for decades.
But as strange as these known objects are, even stranger types of black holes could be dreamed up. In one upside-down, hypothetical version of the universe, a bizarre type of black hole could exist that is stranger than an M.C. Escher sketch. Now, a team of researchers has plunged into the mathematical heart of so-called charged black holes and found a slew of surprises, including an inferno of space-time and an exotic fractal landscape … and potentially more.
Welcome to a holographic superconductor
There are all sorts of potential, hypothetical black holes: ones with or without electric charge, ones spinning or stationary, ones surrounded by matter or those floating in empty space. Some of these hypothetical black holes are known for certain to exist in our universe; for example, the rotating black hole surrounded by infalling matter is a pretty common presence. We’ve even taken a picture of one.
But some other kinds of black holes are purely theoretical. Even so, physicists are still interested in exploring them — by diving into their mathematical foundations, we can realize new relationships and implications of our physical theories, which can have real-world consequences.
One such theoretical black hole is an electrically charged black hole surrounded by a certain kind of space known as anti-de Sitter. Without getting into too much of the nitty-gritty, this kind of space has constant negative geometric curvature, like a horse saddle, which we know is not a good description of our universe. (A cosmos with anti-de Sitter space, all else being the same, would have a negative cosmological constant, which means that any matter would tend to condense into a black hole, versus the known accelerating expansion that is flinging the universe apart.
This horse-saddle space doesn’t exist in our universe, But that’s okay: It turns out that these exotic black holes still have surprisingly intricate structures worth exploring.
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One of the reasons it’s worth exploring is that charged black holes share a lot of similarities with rotating black holes, which certainly do exist in our universe, but charged black holes are mathematically simpler to grapple with. So by studying charged black holes we can gain some insights into real-world rotating black holes.
Also, physicists have found that when these black holes become relatively cool, they build up a “haze” of quantum fields around their surfaces. This haze sticks to the surface, pulled inward by the never-tiring gravity of the black hole itself, but pushed outward by the electric repulsion of the same black hole. A haze of quantum fields operating in stability on a surface is also known as a superconductor. Superconductors have real-world applications (namely, they can transmit electric current with