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Black holes
01-14-2005, 07:49 PM
Post: #1
Black holes
Can any body define a black hole ????????????? I dont want you to copy and paste any material from any website. I want you current understanding about black holes........
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01-14-2005, 08:55 PM
Post: #2
 
might be an object form which light cannot pass...

Ace
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01-14-2005, 09:13 PM
Post: #3
 
Black hole is KALA SORAKH !! <img src=icon_smile_big.gif border=0 align=middle>

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01-14-2005, 09:56 PM
Post: #4
 
<BLOCKQUOTE id=quote><font size=1 face="Verdana, Tahoma, Arial" id=quote>quote<hr height=1 noshade id=quote>
Black hole is KALA SORAKH !! <img src=icon_smile_big.gif border=0 align=middle>

The difference between dreams and accomplishment is purly desire
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Tahoma, Arial" size=2 id=quote>


By definition a black hole is a region where matter collapses to infinite density, and where, as a result, the curvature of spacetime is extreme. Moreover, the intense gravitational field of the black hole prevents any light or other electromagnetic radiation from escaping. But where lies the "point of no return" at which any matter or energy is doomed to disappear from the visible universe?

Or in Simpler Words

A black hole is a region of spacetime from which nothing can escape, even light.


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01-15-2005, 09:15 AM
Post: #5
 
My my mobin... you actually did search the dictionary for that one ... dint you? <img src=icon_smile.gif border=0 align=middle>

Anyways, some have theorized that these black holes can be gateways to other universes or even shortcuts within our own. The problem is that nothing can survive travelling through such infinite gravitational fields.

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01-15-2005, 01:35 PM
Post: #6
 
Actually, a little light can escape the black hole. I read somewhere that Hawking has proved that light at the edge of a black hole can escape it, due to the uncertainity factors of quantum physics.



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01-17-2005, 12:59 PM
Post: #7
 
If i aint mistaken, the point of no return or as you like to call it the 'edge' of a black hole is called 'event horizon', moving beyond which nothing can come back.

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01-17-2005, 01:45 PM
Post: #8
 
Hmm... Seems like I misquoted. The thing I was talking about is called "Hawking Radiation" and refers to energy, not specifically light, being emitted by Black Holes. A quote from Wikipedia (arguably internet's most reliable source of information)

"Classically, the gravitation is so powerful that nothing, not even radiation, can escape from the black hole. However, by doing a calculation in the framework of quantum field theory in curved spacetimes, Hawking showed quantum effects allow black holes emitting in a thermal spectrum."

However, I'm just an accountant-to-be so my knowledge on the subject is limited <img src=icon_smile.gif border=0 align=middle>. Though I will be taking a theoretical physics class next year so I may learn more about this stuff.



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01-17-2005, 09:30 PM
Post: #9
 
Recently, a black hole has been discovered having mass 30,000 times of our sun having an area of just 20,000 square miles ........ Imagine how much gravitational pull is required to shrink mass to that level ..........
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01-18-2005, 09:01 AM
Post: #10
 
Hmm... hawking radiation, will have to read about it. Thanks Faraz

<BLOCKQUOTE id=quote><font size=1 face="Verdana, Tahoma, Arial" id=quote>quote<hr height=1 noshade id=quote>Imagine how much gravitational pull is required to shrink mass to that level<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Tahoma, Arial" size=2 id=quote>

shouldnt cause anything more than a slight headache to the ones being pulled by it, i presume. <img src=icon_smile.gif border=0 align=middle>

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01-18-2005, 11:10 AM
Post: #11
 
Well if we want to simply understand black hole, then consider this example.
Suppose we have a big blanket and it is held horizontally over the ground by four persons holding four corners. Now the blanket is the space-time continuum... remember x,y,z,t from high school.
Now if we put a heavy piece of stone in the centre of it, it will bend the blanket (space-time) around it and perhaps cause a little hump downward on the blanket. Now suppose this stone is of infinite or extremely high mass, so the hump created will be so deep that nothing could go out... this is the black hole...


NB. Stephen Hawking has some problems solving the dilemma of information issue with Hawkings radiation... remember his recent announcement 'I was wrong'. He lost the bet to his colleague John Preskill although he should be credited to come up with now the aparent right answer..
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01-18-2005, 04:47 PM
Post: #12
 
Beautiful Example CBpian .....<img src=icon_smile_kisses.gif border=0 align=middle><img src=icon_smile_kisses.gif border=0 align=middle><img src=icon_smile_kisses.gif border=0 align=middle><img src=icon_smile_kisses.gif border=0 align=middle><img src=icon_smile_kisses.gif border=0 align=middle><img src=icon_smile_kisses.gif border=0 align=middle> It was the same model that Einstein worked out for planets to travel in orbits around starts ..... a star has a gravity so great that it make curves in space time .... Now imagine if a tiny ball is rolled on the humped down blanket ..... what will happen ..... the ball will roll around the hump for a while ...... this is exactly how small abjects travel in orbits aroung large objects in space....
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01-22-2005, 04:26 AM
Post: #13
 
<BLOCKQUOTE id=quote><font size=1 face="Verdana, Tahoma, Arial" id=quote>quote<hr height=1 noshade id=quote>By definition a black hole is a region where matter collapses to infinite density, and where, as a result, the curvature of spacetime is extreme. Moreover, the intense gravitational field of the black hole prevents any light or other electromagnetic radiation from escaping. But where lies the "point of no return" at which any matter or energy is doomed to disappear from the visible universe?

Or in Simpler Words

A black hole is a region of spacetime from which nothing can escape, even light. <hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Tahoma, Arial" size=2 id=quote>


Its true that the above definition is qualified for the relevent meaning of BLACK HOLE. Recently i see the dictionary & this word is also giving some other aspects

1. Something that uses up a lot of money like

I'm worried that the project could become a financial black hole

2. Black Hole of CALCUTTA

A small room used as a prison in Calcutta, India. In 1756, 146 British prisoners were put into it, and most of them died in one night. People sometimes say that a small very crowded room or dark place is "like the Black Hole of Calcutta".





ASIF ALI
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