“A black-hole is a region in space where matter is infinitely condensed – it’s a singularlity in space-time.” “They become so compact that light rays basically or not any form of energy, can escape them because it’s all bent backwards and falls back into the horizon of this object.” “If you’re closer to the black hole than a certain distance, you will not be able to escape anymore. And this distance is called the Schwarzschild radius and is also referred to as the event horizon. So if you’re inside the event horizon, you will never be able to get out anymore.” The first black hole to be positively detected was named Cygnus X-1 And the first astronomer to observe this - by definition unobservable object - was Tom Bolton: Well, you can’t observe a black hole because, as you point out, nothing can escape from a black hole. What you do is observe the surroundings of the black hole for indications.” “If material actually falls into a black hole, it gets shredded apart and heats up. And as it heats up it starts emitting radiation.” “We can see evidence that matter is being thrown into the black hole because we can see evidence of fast rotation around the black hole, and matter getting very hot, and emitting, for example, lines from ionized iron, moving at fast speeds.” “Because a black hole is quite massive, any material – for example stars - that move close to it will feel a lot of gravity. And as a result these stars will move quite fast.” “In the case of the star that I worked on, Cygnus X-1, it’s a binary star system in which it was possible to determine the orbit of the visible star. And from that orbit we were able to infer the mass of the black hole. “ “To convince yourself that it’s a black hole you have to know what it’s size is and what the mass is and that the matter is all contained within a sufficiently small space.” “In the case of Cygnus X-1, the mass of the object, the invisible object, appears to be at least 10 solar masses, maybe as much as 15.”

When a super-massive star dies, it's corpse collapses into a knot so tight not even light can escape. And this drain on the fabric of the Universe can alter the very shape of space and shift the flow of time. World-recognized experts explain.

Credit: Dave Brody / SPACE.com

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