New way find to detect ‘naked singularity’(22nd-April-2017)
Scientists have found a new way to detect a bare or naked singularity – the most extreme object in the universe where the usual laws of physics break down.
When the fuel of a very massive star is spent, it collapses due to its own gravitational pull and eventually becomes a very small region of arbitrarily high matter density, that is a ‘singularity’. If this singularity is hidden within an event horizon, which is an invisible closed surface from which nothing – not even light – can escape, the object is called a black hole. In such a case, we cannot see the singularity and we do not need to bother about its effects, researchers from the Tata Institute of Fundamental Research (TIFR) in Mumbai said.
- However, Einstein’s theory of general relativity predicts that the event horizon does not form when massive stars collapse at the end of their life-cycles.
- In this case, we are left with the tantalizing option of observing a ‘naked singularity’. Researchers, including those from the Institute of Mathematics of Polish Academy of Sciences in Poland, investigated how to observationally distinguish a naked singularity from a black hole.
- Einstein’s theory predicts an interesting effect – the fabric of spacetime in the vicinity of any rotating object gets ‘twisted’ due to this rotation.
- This effect causes a gyroscope spin and makes orbits of particles around these astrophysical objects precess (the axis on which the body rotates changes its orientation).
- The team argued that the rate at which a gyroscope precesses (the precession frequency), when placed around a rotating black hole or a naked singularity, could be used to identify this rotating object.
- In the first case, the rotating object is a black hole, while the second is a naked singularity.Researchers showed that the precession frequency of a gyroscope orbiting a black hole or a naked singularity is sensitive to the presence of an event horizon.
- A gyroscope circling and approaching the event horizon of a black hole from any direction behaves increasingly ‘wildly,’ that is, it precesses increasingly faster, without a bound. However, in the case of a naked singularity, the precession frequency becomes arbitrarily large only in the equatorial plane, but being regular in all other planes.