Swartzchild Radius

[BobbyJoeCool]

Ok... if you have a completely static black hole (as in not moving, not rotating, etc.), is the Swartzchild Radius the event horizon radius? Wikipedia seemed to imply that but didn't really say it.

[timo]

Yes. Except perhaps for the fact that the schwarzschild-radius is a "distance" while the event horizont is the "sphere" created by that radius.

[[Tycho?]]

Yeah they're the same thing.

[RoyLennigan]

there's a little bit more to it than that, though.

 

every celestial body has a schwarzschild radius, hypothetically. it is the size (proportional to its mass) at which that body becomes a black hole. for instance, the sun has a schwarzschild radius of about 3 km.

[Martin]

Ok... if you have a completely static black hole (as in not moving, not rotating, etc.), is the Swartzchild Radius the event horizon radius? Wikipedia seemed to imply that but didn't really say it.

 

BobbyJoe now everything seems thoroughly answered, can I add an irrelevant observation (comes of liking the English language and its relatives)

 

SCHILD means SHIELD (thanks to Atheist for correction!)

 

It could be the sign for an inn or shopkeeper, hung out LIKE a shield.

 

Anyway the German word is pronounced rather like "shield" or more exactly SHILD, as we might spell it.

 

And in English we have this word SWARTHY which is related to the german word for BLACK which is schwarz

 

So if you want to say "BLACK SHIELD" you might say

 

schwarz schild

 

 

Odd coincidence that this image should be connected with the mathematical model of a black hole with its round event horizon---itself a kind of dark impenetrable shield (but shielding from passage outwards, not inwards)

 

EDIT: THANKS AGAIN TO ATHEIST FOR CORRECTING DUMB WORD ERROR that I made earlier!

[timo]

Martin, I´m afraid I have to disapoint you at least once (maybe twice, dunno if you were just making fun or if you really don´t know what the Schwarzschild radius is named after):

 

Nr.1)

SCHILD means FOREHEAD

No. "Schild" means either "shield" ("der Schild") od "sign" ("das Schild"). "Forehead" is "Stirn" in german. You point about "Schwarz" is correct but it´s rather a coincidence because:

 

Possible Nr.2)

The whole thing is named after this guy: http://en.wikipedia.org/wiki/Schwarzschild

[Martin]

...

 

Possible Nr.2)

The whole thing is named after this guy: http://en.wikipedia.org/wiki/Schwarzschild

 

I am not disappointed a bit! very glad you corrected me about that German word, Atheist.

 

I did already know a little about Karl Schwarz Schild, but was glad to see the Wiki article about him.

 

Actually a UK site of mathematician biographies may be better than Wiki in this case:

http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Schwarzschild.html

 

From this page one sees that he had a huge moustache, and was already partly bald in this picture and so a forehead looking like a lightbulb.

 

One of my favorites of that period is Alex Friedmann of Saint Petersburg. An intellectual (we still use his cosmological model---the Friedmann equations) but also a daring baloonist!

 

Please take a moment to look at Friedmann's page

http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Friedmann.html