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Nov 27, 2020

Black Holes Could Be ‘Back Doors’ To Another Universe, Say Physicists


A physical object, such as a person or a spacecraft, could theoretically make it through a  wormhole in the center of a black hole, and perhaps even access another universe on the  other side, physicists have suggested. In what appears to be the logical extension of the Interstellar plot in which astronauts try to chase another universe after the catastrophic effects of climate change destroy Earth - physicists have modeled what would happen to a chair, a scientist and a vehicle spatial, if each ended up in the spherical wormhole of a black hole."What we did was to reconsider a fundamental question about the relationship between gravity and the underlying structure of space-time. In practical terms, we dropped a hypothesis that takes general relativity into consideration, but there is no reason a priori to support it in the extensions of this theory. ”said one of the members, Diego Rubiera-Garcia of the University of Lisbon in Portugal.So, let's take a step back and analyze some basics. According to Einstein's theory of general relativity, there is a singularity at the center of a black hole - the point where the forces of gravity are at their maximum intensity, and time and space actually end. If an object approaches the event horizon, it would be crushed in one direction and stretched in another, thanks to the extreme gravity forces of the tide that play inside a black hole. If the object remains ntact long enough to reach the center of a black hole, it will be infinitely long and thin: in practice, it has been spaghettified beyond recognition. Physicists have been playing for years with the hypothesis of a singularity in the center of a black hole, because until we can actually prove that it exists, there may be many possibilities that still work - in theory.Earlier this year, physicists from the University of Cambridge in the United Kingdom argued that there is no reason why a singularity should necessarily be inside a black hole. They suggest that in a universe with five or more dimensions - which for us is not out of the question - a "nude" may exist individually, which is not delimited by a horizon of events.Of course, that would mean big and huge things for our current understanding of how the laws of physics govern our Universe, because basically it needs Einstein's theory of general relativity to be wrong."If naked singularities exist, general relativity will fail," said one of the teams, Saran Tunyasuvunakool, in January. "And if general relativity fails, it would turn everything upside down, because it would no longer have any predictive power - it could no longer be considered an autonomous theory to explain the Universe."Even making mistakes Einstein is not to be excluded. Stephen Hawking has fought for decades with how general relativity seems to collide with quantum mechanics in black holes, a problem known as the information paradox. Assuming that the clauses of general relativity are not fixed in the stone, the new study  of the Rubiera-Garcia team argues that if you remove the singularity from a black hole, what you get in the center is a finite-sized wormhole instead. So, they understood what could happen if various objects - a chair, a scientist and a spacecraft - managed to overcome the event horizon and in the wormhole. These objects are  called "observers".They modeled these observers as an aggregation of points connected by physical or chemical interactions that hold everything together while the object travels along a geodesic line. A geodesic line is simply the path in space-time that follows an object in free fall."Each particle of the observer follows a geodesic line determined by the gravitational field," says Rubiera-Garcia. "Each geodesist feels a slightly different gravitational force, but interactions between body components may still support the body."By  publishing in the journal Classical and Quantum Gravity, the researchers demonstrate this by showing how the time spent by a ray of light on a circular journey between two parts of the body has always ended.This means that finite forces, no matter how strong, could compensate for the impact of the gravitational field near and inside the wormhole on a physical body that passes through it."Therefore, different parts of the body will still establish physical or chemical interactions and, consequently, cause and effect will still apply to the wormhole throat," they explain.So while general relativity theory predicts that an object approaching a black hole will be crushed in one direction and stretched in another infinitely, if we assume that the center of a black hole is a wormhole with a finite ray , the object can only be crushed as much as the size of the wormhole.This means that according to the Rubiera-Garcia hypothesis, an object could survive a journey through a wormhole and make it on the other side - and potentially in another universe - technically intact, but it would be crushed to the size of the finished wormhole.At least it's not completely destroyed, right?"For a theoretical physicist, the suffering of observers is admissible (one could even consider it part of an experimenter's work), but their total destruction is not," Rubiera-Garcia and his team cite a piece of opinion.Until we find out how to actually see a black hole, all of this will remain well and truly in the realm of pure hypotheses. But we are beginning to see how black holes might not be the horrible deadly traps that we erase the existence we thought they were.At a conference in August 2015 Hawking said of his solution to the information paradox: “The message of this lesson is that black holes are not as black as they are painted. They are not eternal prisons as they were once thought. If you feel like you're in a black hole, don't give up. There is a way out. "

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