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Astrophysicists, particle physicists and other sundry researchers had for long believed that a black hole was a star that collapsed onto itself. It has been theorised that a collapse of the star created such a region in space-time where gravity is so high that even light cannot escape. Once particles of light cross the point of no return – or event horizon – they disappear into the darkness. Black holes are thus believed to be star-eaters.

In 1974, however, Nobel prize-winning physicist Stephen Hawking theorised that black holes are indeed not as dark as imagined but instead emitted a soft light that was constant and had no other source. Hawking theorised that at the event horizon, the black hole itself kept emitting a constant stream of photons, known as virtual particles, thus creating a soft yet steady stream of light, much like a star. These particles are created as s result of transient quantum fluctuations, which means they exist but keep popping in and out of existence.

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'migration rates' are measurements of how many people entering or leaving a country. and if more people are leaving, this could cause a population to change.