In science fiction, space explorers regularly pass through wormholes in spacetime that are connected by two black holes – celestial objects so dense that not even light can escape their clutches.
But are black holes really doors to wormholes? And would these wormholes look like their “Star Trek” counterparts?
The short answer is probably no, although the math of the universe doesn’t rule it out altogether.
By themselves, the only thing in the center of a black hole is a singularity — a point of infinite density.
In theory, however, a black hole can be paired with a mirror twin, called a white hole, to form a wormhole. Yet these theoretical wormholes would be nothing like those portrayed in science fiction – traditional wormholes are said to be incredibly unstable, meaning they would collapse the moment a single particle of matter entered them. .
Some physicists predict that a wormhole could become more stable if it were formed from a spinning black hole, but our understanding of what happens in this scenario is murky at best.
Scientists first discovered black holes not by observations in the universe, but by the mathematics of Einsteinthe theory of general relativity. These equations showed that if you shrink enough matter into a small enough volume, then gravity overwhelms all other forces and shrinks matter to an infinitely small point, known as the singularity.
Black holes are one-way trips. Once someone crosses their boundaries, called event horizons, they can never escape again. While black holes were once thought of as just a trick of einstein equationsastronomical observations finally revealed the existence of black holes in the universe.
But that same math also allows for the exact opposite of a black hole: a white hole. A white hole always has a singularity at its center and an event horizon surrounding it. But instead of falling into it and finding it impossible to escape, with a white hole a person could never reach the event horizon from the outside, because it constantly shoots its contents out into the universe faster than the speed of light.
The connection of paired singularities of a black hole and a white hole forms the simplest type of wormhole, also known as an Einstein-Rosen bridge.
Not very useful
Unfortunately, the Einstein-Rosen bridges aren’t very useful for crossing the cosmos. For one thing, the entrance to the wormhole is behind the event horizon. Since a person cannot enter from the side of the white hole, he would have to fall into a black hole to enter. But once someone crosses an event horizon, they can never escape again. This means that if you enter the wormhole, you are stuck inside for eternity.
The other problem with Einstein-Rosen bridges is their stability. “This bridge is a kind of wormhole, but it’s transitory: it pinches before any object can use it to get from one side to the other. So in that sense we don’t really have wormhole, since you can’t walk through it,” Samir Mathur, a physicist at Ohio State University, told Live Science in an email.
This instability exists because creating a wormhole requires a very precise and careful arrangement of matter. Anything that upsets this delicate balance – even a single packet of light, or photon – would trigger the wormhole to collapse instantly. The wormhole would tear like an overstretched rubber band faster than the speed of light, preventing anything from spreading through it.
Moreover, physicists largely believe that white holes do not exist in our universe. Unlike their siblings, white holes are incredibly unstable. According to the calculations, once a single piece of matter falls towards them, they instantly explode. So even if white holes formed naturally, they wouldn’t last very long.
The combination of the uncertainty of the existence of white holes, the instability of Einstein-Rosen bridges, and their relative uselessness means that if wormholes exist, they are probably not Einstein-Rosen bridges.
A rotating singularity
There may be a way to build a wormhole out of a more complicated type of black hole: consider their rotation. All black holes rotate, but New Zealand mathematician Roy Kerr was the first to solve the calculations for rotating black holes.
At the center of a spinning black hole, the extreme centrifugal forces spread the singularity point into a ring. It is possible that this “ring singularity” becomes an entrance to a wormhole, but again the problem of stability arises.
“The singularity of a Kerr hole is surrounded by an ‘inner horizon’, which in turn is surrounded by the ‘outer horizon’. People believe that the inner horizon is not a stable concept, and that small amounts of falling material will completely change the region inside that horizon, and therefore also change the singularity,” Mathur said. “The end result of this instability is unclear.” The problem is that if matter falls toward the ring singularity, it encounters two competing effects: the immense gravitational pull of the singularity itself, and the extreme centrifugal force of spin at the center of the black hole, which would act in the opposite direction. .
As you can imagine, this is not a very comfortable situation and things could go haywire very quickly. The situation is so unstable that it may even completely prevent the formation of the singularity. In this case, many physicists believe that the “ring singularity” concept of a rotating black hole will be replaced by a more concrete idea once we gain a better understanding of these objects.
Originally posted on Live Science.
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