The mere suggestion that stars could gravitationally collapse triggered one of the most bitter physics feuds of the last century. Eventual Nobel-Prize winner Subrahmanyan Chandrasekhar held that they could, but the United Kingdom's then-eminent Arthur Eddington so strongly disagreed that Chandrasekhar changed his area of research to escape the dispute.

And disagreements really haven't stopped since.

An upcoming study adds to this long history, suggesting black holes, now almost taken for granted, never actually come fully into existence, and that the solution to a decades-old black hole paradox may be simpler than supposed.

Respectability came for black holes only in 1967, when University of Cambridge astronomers spotted the first pulsar, a rotating, collapsed star not quite as dense as a black hole, which emits radiation at regular intervals.

Your garden-variety stellar black hole implodes into existence when a star exhausts its fuel, and the weight of its own gravity pulls the burnt-out remains down to a tiny core. This act is often accompanied by an explosion called a supernova. Einstein's theory shows that gravity bends light and if the collapsed supernova core is heavy enough (at least about three times heftier than the sun), the result would be a black hole with gravity so strong that light could never escape from its grasp, at least out to a distance called an "event horizon." Natch, the heavier the black hole, the farther out this event horizon extends.

 Source : USA Today

But in 1975, Stephen Hawking and another physicist, Jacob Bekenstein, handed physicists a new black hole headache, concluding these collapsed stars evaporate over time, with the steady release of particles in a featureless release of "Hawking radiation." The result famously combined Einstein's theory of gravity with quantum mechanics, which explains the behavior of sub-atomic particles.

Why is this a headache? Because of the famous "information paradox" of black holes. Basically, once something disappears into a black hole, it is irretrievably gone. Hawking's best-known example involves tossing an encyclopedia into a black hole. Once it passes the event horizon of a black hole, all the encyclopedia's "information" — all indication of its physical characterics — is gone forever. And unfortunately for the encyclopedia, Hawking radiation from a black hole would carry back no information from any volumes gobbled up by the black hole, by definition. So, in this sense, the information (i.e. the location of all the ink and paper molecules within the volume) has been destroyed.

However this violates another tenet of quantum mechanics which holds that "information" inside systems can't be utterly destroyed. Thus, the paradox.

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