This week, Stephen Hawking, the most famous living scientist, changed his mind about what black holes are. It wasn’t the first time. This timeline guides you through the most important shifts in our understanding of these curious cosmic objects.
1916: Original black hole
Black holes emerge from general relativity: nothing, not even light, escapes event horizon.
1974: Hawking radiation
Hawking shows that black holes emit radiation thanks to quantum mechanics.
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2004: Information escape
Hawking accepts that information escapes from black holes – forcing him to concede a seven-year-old wager with another physicist.
2012: Firewall paradox
Escaping information ignites firewall, which can’t be reconciled with general relativity.
2014: Apparent horizon
Event horizon replaced by apparent horizon that allows some light through – and kills firewall.
Read more: “What would it look like to fall into a black hole?“
