Our views of a black hole

All About Space - - Black Holes Are Leaking! -

Tra­di­tional view

Orig­i­nally we thought noth­ing could es­cape from a black hole.

Then, in 1974, Stephen Hawk­ing ar­gued that a black hole should slowly evap­o­rate as pairs of par­ti­cles are cre­ated at the event hori­zon and one is swal­lowed and the other es­capes. How­ever, his cal­cu­la­tions showed that this Hawk­ing ra­di­a­tion de­pends only on the black hole's mass. Any other in­for­ma­tion about the ob­ject would be com­pletely lost to the void, in vi­o­la­tion of the rules of quan­tum the­ory.

Fire­wall view

Later, the­o­rists re­alised that this ‘in­for­ma­tion para­dox’ could be re­solved if the quan­tum link be­tween the two par­ti­cles – a prop­erty called en­tan­gle­ment – is sud­denly sev­ered.

How­ever, this would lead to a spike in en­ergy all along the event hori­zon. Any­thing cross­ing the line would be in­stantly in­cin­er­ated in a ‘fire­wall’. This is in di­rect con­tra­dic­tion to Ein­stein's gen­eral the­ory of rel­a­tiv­ity, which says an ob­server shouldn't notice any­thing spe­cial when cross­ing the line.

Par­al­lel uni­verses view

Some physi­cists ar­gue that both the in­for­ma­tion and fire­wall para­doxes go away if you think of black holes from the view­point of the Many Worlds in­ter­pre­ta­tion of quan­tum the­ory. It says that ev­ery quan­tum event (such as the cre­ation of a par­ti­cle pair at the event hori­zon) splin­ters the uni­verse into mul­ti­ple copies – or branches – where all pos­si­ble out­comes play out. In­for­ma­tion is pre­served across all branches and Ein­stein's rule about a smooth pas­sage over the event hori­zon only ap­plies to each in­di­vid­ual branch.

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