Ask Ethan: What happens when a black hole’s singularity evaporates?
If even black holes won’t last forever, what will happen when the last one goes?
“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
It’s hard to imagine, given the full diversity of forms that matter takes in this Universe, that for millions of years, there were only neutral atoms of hydrogen and helium gas. It’s perhaps equally hard to imagine that someday, quadrillions of years from now, all the stars will have gone dark. Only the remnants of our now-vibrant Universe will be left, including some of the most spectacular objects of all: black holes. But even they won’t last forever. David Weber wants to know how that happens for this week’s Ask Ethan, inquiring:
What happens when a black hole has lost enough energy due to hawking radiation that its energy density no longer supports a singularity with an event horizon? Put another way, what happens when a black hole ceases to be a black hole due to hawking radiation?
In order to answer this question, it’s important to understand what a black hole actually is.