A team of theoretical physicists has discovered a strange structure in space-time that to an outside observer might look just like a black hole, but upon closer inspection would be anything but: imperfections in the very fabric of the universe.
Einstein’s general theory of relativity predicts the existence of black holes, which are formed when giant stars collapse. But the same theory predicts that their centers are singulars, which are points of infinite density. Since we know that infinite densities cannot actually exist in the universe, we take this as a sign that Einstein’s theory is incomplete. But after nearly a century of searching for extensions, we have yet to confirm a better theory of gravity.
But we do have candidates, including string theory. In string theory, all particles in the universe are actually microscopic vibrating loops of strings. In order to support the variety of particles and forces we observe in the universe, these strings can’t just vibrate in our three spatial dimensions. Instead, there must be additional spatial dimensions that coil themselves into manifolds so small they escape everyday observation and experimentation.
This strange structure in space-time has given a team of researchers the tools they need to define a new class of objects, something they call topological soliton. In their analysis, they found that these topological solitons are stable defects in spacetime itself. They do not require the existence of any other matter or forces – they are as natural in the fabric of space-time as cracks in ice.
The researchers studied these solenoids by examining the behavior of light passing near them. Because they are objects with extreme space-time, they bend space and time around them, affecting the path of light. To a distant observer, these seltons would appear just as we would expect black holes to appear. They will have shadows and rings of light and works. The images derived from the Event Horizon Telescope and the detected gravitational wave signatures will all behave the same way.
Once you get close you will realize that you are not looking at a black hole. One of the main features of a black hole is its event horizon, an imaginary surface that if you crossed it you would find yourself unable to escape. Topological solitons, since they are not singularities, are not characterized by event horizons. So you could in principle just go up to the slithon and hold it in your hand, assuming you survived the encounter.
These topological solitons are an incredibly hypothetical object, based on our understanding of string theory, that has yet to prove to be a viable update to our understanding of physics. Nevertheless, these strange objects serve as important test studies. If researchers can spot an important observational difference between topological solitons and conventional black holes, it could pave the way for a way to test string theory itself.
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