Royal Soldier Posted July 28, 2003 #1 Share Posted July 28, 2003 I was reading up on some theories about black holes earlier and I thought this might be an interesting topic for you guys to discuss. Okay, to get the ball rolling for people new to this concept: A black hole is a point, or a tear shall we say, in spacetime that has been cause by a giant-fast burning star collapsing on itself to form a super-dense area in the spacetime that has an infinite density in an extremely small volume (the black part of the hole is only around 15 miles in diameter on average). This object with so much density and with growing density all the time, warps time itself and with the extremly high gravity (of 10,000 million suns [or so I've read]) not even light can escape from a hole, giving it it's black "colour". So with the escape velocity higher than the speed of light, NOTHING will be escaping, since according to 'Einstein's Theory Of Relativity' nothing is faster than light. The balls rolling a little faster now, let's see where this goes: Black Holes; Unescapable Oblivions or...something else. Share your ideas! Link to comment Share on other sites More sharing options...
PurpleStuart Posted July 28, 2003 #2 Share Posted July 28, 2003 One, correct me if i'm wrong, but a black hole is not a tear. Two if i remember correct they have recently discovered that some matter or energy is infact expelled from black holes - will have to check that up again tho. Link to comment Share on other sites More sharing options...
Nethius Posted July 28, 2003 #3 Share Posted July 28, 2003 are you refering to this Purple? The material heats up due to this friction [this is the same effect as when you rub your hands together to warm them up]. When this happens around a black hole, X-rays are given off which we can detect. If the black hole is really large and has lots of debris in its disc, then it can reveal itself as one of the brightest objects in the Universe - a quasar. Link to comment Share on other sites More sharing options...
Sukato-San Posted July 28, 2003 #4 Share Posted July 28, 2003 I thought that black holes were collapsed stars? Link to comment Share on other sites More sharing options...
ShadyLady Posted July 28, 2003 #5 Share Posted July 28, 2003 They are, Sukato. Link to comment Share on other sites More sharing options...
Homer Posted July 28, 2003 #6 Share Posted July 28, 2003 PS, What you are referring to is called Hawking Radiation. This isn’t really matter escaping from a black hole, but it does appear that way. These are the result of virtual particles ‘popping up’ into existence near a black hole. VP’s always come in pairs, a positive and a negative, and the black hole typically absorbs the negative particle, while the positive ‘escapes’. So matter does not escape, or get expelled from, black holes. Link to comment Share on other sites More sharing options...
antares Posted July 29, 2003 #7 Share Posted July 29, 2003 What you are referring to is called Hawking Radiation. This isn’t really matter escaping from a black hole, but it does appear that way. These are the result of virtual particles ‘popping up’ into existence near a black hole. I read somewhere that these virtual particles represent the energy extracted from the gravitational field of a black hole. Does it mean that the Hawking Radiation cause black holes to change their mass? Link to comment Share on other sites More sharing options...
Homer Posted July 29, 2003 #8 Share Posted July 29, 2003 Yes. As the negative particle gets pulled into the black hole, it annihilates a positive particle that is already in the black hole mass. If you’ve read about the evaporation of black holes, this is what they are referring to. However, as black holes eat gases and other forms of matter, it more than replenishes the VP threat. Link to comment Share on other sites More sharing options...
antares Posted July 29, 2003 #9 Share Posted July 29, 2003 Aha, makes sense. Thanks, Homer! I glanced through some articles online and the amazing thing I learned was that for a massive black hole (30 solar mass) the evaporation time is extremely long - about 10^61 times the age of the Universe. Practicly they will last forever Link to comment Share on other sites More sharing options...
PurpleStuart Posted July 29, 2003 #10 Share Posted July 29, 2003 Yes thats probably what i was thinking about Homer, thanks, but i remember also seeing a diagram somewhere showing matter being expelled (possibly repelled?) from a black hole (in a thin 'beam'), but it is quite likely that it's my recollection thats at fault and it could of been a different object, not a black hole that was displaying this reaction. Any ideas what i'm thinking of? Link to comment Share on other sites More sharing options...
Homer Posted August 2, 2003 #11 Share Posted August 2, 2003 Unfortunately, I can't think of what it might be Link to comment Share on other sites More sharing options...
espdracomth Posted August 2, 2003 #12 Share Posted August 2, 2003 Hey PurpleStuart if I understand correctly you mean "jets" I've seen it too, you can barely see it on the link that Nethius gave, but it's there.Here's a couple links to the Blackhole jets. Blackholes #1 Blackholes #2 Link to comment Share on other sites More sharing options...
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