Stephen Hawking

Serious discussion of science, skepticism, and evolution
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MattShizzle
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Stephen Hawking

Post by MattShizzle » Thu Mar 15, 2018 6:00 pm

If anyone doesn't know by now, he died 2 nights ago. So here's him singing the Monty Python Galaxy Song.

https://www.youtube.com/watch?v=XfcC6FYyL4U

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Minnemooseus
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On a related note

Post by Minnemooseus » Fri Mar 16, 2018 8:48 am

You might want to check out the mp3's on this page:

http://www.easylife.org/386dx/

Moose
"I know a little about a lot of things, and a lot about a few things, but I'm highly ignorant about everything." - Moose

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lpetrich
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Post by lpetrich » Sun Mar 18, 2018 11:23 am

It seems to me that he owed much of his fame to his disability, and how he nevertheless was as productive and successful as he was. But given what he had to go through, that was a great triumph for him.

He did some important scientific work.

His first big success was on general-relativity singularity theories. He showed that singularities, regions with infinite curvature, would form under a variety of circumstances, and he did so with techniques that were not restricted to special cases like spherical symmetry.

He then worked out the thermodynamics of black holes. Applying quantum mechanics to them, he showed that they have well-defined temperatures, and that they emit particles -- "Hawking radiation". A colleague of his, Jacob Bekenstein, showed that black holes have some thermodynamics-like properties, and SH's work confirmed this analogy.

Essentially,
  • Black-hole temperature ~ its surface gravity at its event horizon
  • Black-hole entropy ~ its event horizon's area
where the proportionality constants are quantum-mechanical factors.

He also got into popularization, writing books like "A Brief History of Time".

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Aupmanyav
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Post by Aupmanyav » Sun Mar 18, 2018 1:54 pm

[quote=""lpetrich""]Black-hole temperature ~ its surface gravity at its event horizon
Black-hole entropy ~ its event horizon's area[/quote]Could you expand it a little non-mathematically when you have time?
'Sarve khalu idam Brahma'
All things here are Brahman (physical energy).

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lpetrich
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Post by lpetrich » Mon Mar 19, 2018 7:34 pm

Temperature = that's essentially the random energy per bit of a system.

Entropy = that's the number of bits of description for going from a full microscopic description from a macroscopic description. Consider throwing a pair of six-sided dice. There are six ways of rolling a seven, but only one way of rolling a two or a twelve. That means that one needs about 2.5 bits of description to get from a seven to which numbers were on each die, and 0 bits for a two or a twelve.

Event horizon = that's the point of no return for a black hole, or more precisely, the surface formed by all such points.

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Aupmanyav
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Post by Aupmanyav » Tue Mar 20, 2018 6:51 am

Thanks, lpetrich. That is nice. Now, I cannot ask you to teach me the whole of modern Physics by forum posts. ;)
'Sarve khalu idam Brahma'
All things here are Brahman (physical energy).

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