From Matt Strassler.
Did Hawking Say “There Are No Black Holes”?
This is one of the responses by scientists to that media story. It is the snarkiest I have seen so far 🙂
First, Hawking does not have a new theory… at least not one he’s presented. You can look at
his paper here — two pages (pdf), a short commentary that he gave to experts in August 2013 and wrote up as a little document — and you can see it has
no equations at all. That means it doesn’t qualify as a theory. “Theory”, in physics, means: a set of equations that can be used to make predictions
for physical processes in a real or imaginary world. When we talk about Einstein’s theory of relativity, we’re talking about equations.
This reminded me of a panel at Convergence back in 2010.
The word “theory” does not mean “speculations” or “ideas”, which is all that is contained in this little article. Maybe that’s what theory means at a cocktail party, but it’s not what “theory” means in physics.
I agree, although in non-technical conversation I fear it is a lost cause.
Second, what Hawking is addressing in this note is the precise level of blackness of a black hole… in short, whether the name “black hole” for the objects we call black holes is really appropriate.
But simply the fact that black holes aren’t quite black isn’t new. In fact it was Hawking himself who became famous in 1974-1975 for pointing out that in a world with quantum physics, typical black holes cannot be precisely
black — so it’s not true that nothing ever comes out of a black hole.
What he means [here] is that black holes are very, very slightly (though importantly) less black than he said in his 1974 paper…
“There are however apparent horizons which persist for a period of time.”
Translation: for an extremely long time,
what we call a black hole will behave in just the way we have long thought it does. In particular, there is no change in any of the astrophysics
of black holes that astronomers have been studying in recent decades. The only issue is what happens as a black hole begins to evaporate in a serious way,
and when you look very, very carefully at the details of the Hawking radiation, which is very difficult to do.
In astrophysics “extremely long time” means “much more than the present age of the Universe”, about 13.8 Billion year. This is in contrast to elementary particle
physics, where the muon’s half life of 2.2 microseconds is considered a very long time. Context is everything.
Meanwhile, the media takes the five words “There Are No Black Holes” and creates almost pure fiction, fiction that has almost nothing to do with the reality of the science. Well done, media, well done. Sometimes you’re just like a black hole: information comes in, and after being completely scrambled beyond recognition, comes back out again through a mysterious process that makes no sense to anyone. Except that in your case, it’s very clear that information is lost, and misinformation is created.