<p>Scientists have shown how a ring-shaped black hole could cause Einstein's general theory of relativity, a foundation of modern physics, to break down - assuming the universe contains at least five dimensions.<br /><br /></p>.<p>The researchers, from the University of Cambridge and Queen Mary University of London, have successfully simulated a black hole shaped like a very thin ring, which gives rise to a series of 'bulges' connected by strings that become thinner over time.<br /><br />These strings eventually become so thin that they pinch off into a series of miniature black holes, similar to how a thin stream of water from a tap breaks up into droplets.<br /><br />Ring-shaped black holes were 'discovered' by theoretical physicists in 2002, but this is the first time that their dynamics have been simulated using supercomputers.<br /><br />Should this type of black hole form, it would lead to the appearance of a 'naked singularity', which would cause the equations behind general relativity to break down.<br /><br />General relativity theory tells us that matter warps its surrounding space-time, and what we call gravity is the effect of that warp.<br /><br />In the 100 years since it was published, general relativity has passed every test that has been thrown at it, but one of its limitations is the existence of singularities.<br /><br />A singularity is a point where gravity is so intense that space, time, and the laws of physics, break down.<br /><br />General relativity predicts that singularities exist at the centre of black holes, and that they are surrounded by an event horizon - the 'point of no return', where the gravitational pull becomes so strong that escape is impossible, meaning that they cannot be observed from the outside.<br /><br />"As long as singularities stay hidden behind an event horizon, they do not cause trouble and general relativity holds - the 'cosmic censorship conjecture' says that this is always the case," said study co-author Markus Kunesch, a PhD student at Cambridge's Department of Applied Mathematics and Theoretical Physics (DAMTP).<br /><br />In case a singularity existed outside of an event horizon, not only would it be visible from the outside, but it would represent an object that has collapsed to an infinite density, a state which causes the laws of physics to break down, researchers said.<br /><br />Theoretical physicists have hypothesised that such a thing, called a naked singularity, might exist in higher dimensions.<br /><br />"If naked singularities exist, general relativity breaks down," said co-author Saran Tunyasuvunakool, also a PhD student from DAMTP.<br /><br />"And if general relativity breaks down, it would throw everything upside down, because it would no longer have any predictive power – it could no longer be considered as a standalone theory to explain the universe," said Tunyasuvunakool.<br /><br />The research was published in the journal Physical Review Letters.</p>
<p>Scientists have shown how a ring-shaped black hole could cause Einstein's general theory of relativity, a foundation of modern physics, to break down - assuming the universe contains at least five dimensions.<br /><br /></p>.<p>The researchers, from the University of Cambridge and Queen Mary University of London, have successfully simulated a black hole shaped like a very thin ring, which gives rise to a series of 'bulges' connected by strings that become thinner over time.<br /><br />These strings eventually become so thin that they pinch off into a series of miniature black holes, similar to how a thin stream of water from a tap breaks up into droplets.<br /><br />Ring-shaped black holes were 'discovered' by theoretical physicists in 2002, but this is the first time that their dynamics have been simulated using supercomputers.<br /><br />Should this type of black hole form, it would lead to the appearance of a 'naked singularity', which would cause the equations behind general relativity to break down.<br /><br />General relativity theory tells us that matter warps its surrounding space-time, and what we call gravity is the effect of that warp.<br /><br />In the 100 years since it was published, general relativity has passed every test that has been thrown at it, but one of its limitations is the existence of singularities.<br /><br />A singularity is a point where gravity is so intense that space, time, and the laws of physics, break down.<br /><br />General relativity predicts that singularities exist at the centre of black holes, and that they are surrounded by an event horizon - the 'point of no return', where the gravitational pull becomes so strong that escape is impossible, meaning that they cannot be observed from the outside.<br /><br />"As long as singularities stay hidden behind an event horizon, they do not cause trouble and general relativity holds - the 'cosmic censorship conjecture' says that this is always the case," said study co-author Markus Kunesch, a PhD student at Cambridge's Department of Applied Mathematics and Theoretical Physics (DAMTP).<br /><br />In case a singularity existed outside of an event horizon, not only would it be visible from the outside, but it would represent an object that has collapsed to an infinite density, a state which causes the laws of physics to break down, researchers said.<br /><br />Theoretical physicists have hypothesised that such a thing, called a naked singularity, might exist in higher dimensions.<br /><br />"If naked singularities exist, general relativity breaks down," said co-author Saran Tunyasuvunakool, also a PhD student from DAMTP.<br /><br />"And if general relativity breaks down, it would throw everything upside down, because it would no longer have any predictive power – it could no longer be considered as a standalone theory to explain the universe," said Tunyasuvunakool.<br /><br />The research was published in the journal Physical Review Letters.</p>