Sad about Hawking's passing but not really sure about his science?

[QED]

Here's a longish twitter thread that does a nice job of summarizing Hawking's work. I'm including a link to the original thread, a few of the tweets, and a link to an unrolled version that is much easier to read.

Original:

Link to tweet

Certainly his disease was part of why the public knew of Stephen Hawking. But his most famous result is important and amazing. Let me tell you about it. (note: this is all from before my time, so I'm telling the simplified story)

Well before Hawking, we understand the existence of black holes as a gravitational body. They are a solution to Einstein's General Relativity field equations; the unique solution for a point mass.

But there was a problem: black holes are the unique solution, so there appears to be only one state of "a black hole" for a given mass (and spin and charge). That means that a black hole should have zero entropy.

And that's a problem, because that means that you could reduce the entropy of the Universe by throwing a system with non-zero entropy into a black hole. And there's one law we don't want to break, its the 2nd Law of Thermodynamics: entropy always increases.

So, you can say "ok, we don't know how the entropy comes about, but let's just declare that black holes have entropy. Problem solved." (and we still don't know "where" the entropy of black holes is coming from). Hawking was part of formalizing this.

(Much more on twitter thread or see the unrolled version.)

Unrolled:

https://threadreaderapp.com/thread/973780532134858752.html

[Me.]

1. Will Be Missed

[RKP5637]

2. I just didn't expect him to be gone yet, it seemed he was perpetual. n/t

[PatentlyDemocratic]

3. Great ambassador for science too - nt

[QED]

4. Indeed he was.

I loved his appearances on The Big Bang theory.