“My discovery that black holes emit radiation raised serious problems of consistency with the rest of physics. I have now resolved these problems, but the answer turned out to be not what I expected.” -Stephen Hawking

One of the most puzzling things about Black Holes is that if you wait around long enough, they’ll evaporate completely. The curved spacetime outside of the event horizon still undergoes quantum effects, and when you combine General Relativity and quantum field theory in exactly that fashion, you get a blackbody spectrum of thermal radiation out.

Hawking radiation is what inevitably results from the predictions of quantum physics in the curved spacetime surrounding a black hole’s event horizon. Image credit: E. Siegel.

Given enough time, a black hole will decay away completely. But what will that entail? Will an event horizon cease to exist, exposing a former black hole’s core? Will it persist right until the final moment, indicative of a true singularity? And how hot and energetic will that final evaporative state be?

Against a seemingly eternal backdrop of everlasting darkness, a single flash of light will emerge: the evaporation of the final black hole in the Universe. Image credit: ortega-pictures / Pixabay.

Incredibly, even without a quantum theory of gravity, we can predict the answers! Find out on this week’s Ask Ethan.

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