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Author Topic: How can black holes bend light?  (Read 10911 times)

Offline Seany

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How can black holes bend light?
« on: 11/04/2007 15:12:56 »
Apparently. Light bends towards a black hole. We've learnt that light always travel STRAIGHT. But this black hole.. The immense force of it, makes even light bend. What is a black hole? The purpose of it?

Comments please =)
« Last Edit: 03/10/2008 12:07:31 by chris »


 

Offline lightarrow

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Re: How can black holes bend light?
« Reply #1 on: 11/04/2007 19:54:56 »
Apparently. Light bends towards a black hole. We've learnt that light always travel STRAIGHT. But this black hole.. The immense force of it, makes even light bend. What is a black hole? The purpose of it?
Comments please =)

1. What does "The purpose of it?" mean?
2. Light is bent from every massive body. In 1917 Sir Eddington showed how light is bent from the sun exactly in the amount previously calculated from Einstein with GR (General Relativity).
3. Actually, light is not even bent, if we look at the real geometry of space-time; that is, it's space-time to be warped; light doesn't do anything than follow that geometry, so it actually goes straight (at least, all this is true according GR).
 

Offline Seany

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Re: How can black holes bend light?
« Reply #2 on: 11/04/2007 20:45:37 »
By "The Purpose of it".. I mean, why do blackholes exist? What is it for?
 

Offline Negin -(Universe)

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Re: How can black holes bend light?
« Reply #3 on: 11/04/2007 22:21:23 »
thats a very interesting question, it just occured to me that black holes could juct be there to get rid of space debris, i mean currently we're unable to actually see the inside of the hole due its very strong attractive forces, i mean where exactly does it lead to???? another universe??? the past, the future? we could always ASSUME that all the past moments of our lives are somehow saved in black holes?? its just an idea??
 

Offline Soul Surfer

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Re: How can black holes bend light?
« Reply #4 on: 11/04/2007 23:41:49 »
No thing exists for any specific purpose. Contrary to the thinking of some (religious) people, our universe does not come with a detailed instruction manual. It is up to us to find out how things work by careful scientific investigation.  Things only exist because they can!
« Last Edit: 11/04/2007 23:58:36 by Soul Surfer »
 

Offline Seany

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Re: How can black holes bend light?
« Reply #5 on: 12/04/2007 10:25:25 »
Hmm. Both your comments are contradictory.. But, thinking of Universe's point, I am quite tempted to think that black holes may just be there to clean up the space debris. Like a vacuum cleaner, and there is another world in that black hole, where it is full of debris and rock, as if we are trapped in a dust-bag in a vacuum cleaner. :P
 

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Re: How can black holes bend light?
« Reply #6 on: 12/04/2007 13:18:13 »
Hmm. Both your comments are contradictory.. But, thinking of Universe's point, I am quite tempted to think that black holes may just be there to clean up the space debris. Like a vacuum cleaner, and there is another world in that black hole, where it is full of debris and rock, as if we are trapped in a dust-bag in a vacuum cleaner. :P

Not sure where you see the contradictions.

There is a difference between your perspective and theirs, insofar as you are looking at a top down view, and suggesting there is some grand design that everything fits into; while the common scientific view is bottom up - it assumes simply that each component of the universe acts autonomously, without any grand plan, and the outcome we see is merely the accidental outcome of that autonomous action of the various component parts of the universe.

The other error is to assume that a black whole really has any more capacity to suck things up than any large object (e.g. an equally massive star).  The difference between a black hole and a star is that while both will suck things up, a star will also emit light, cosmic rays, and exhaust gasses back out to the surrounding universe, whereas a black hole sucks things up but sends nothing (except, possibly, a very small amount of Hawkins radiation) back out again (hence why it appears black).
 

Offline Seany

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Re: How can black holes bend light?
« Reply #7 on: 12/04/2007 13:20:35 »
Hmm. Both your comments are contradictory.. But, thinking of Universe's point, I am quite tempted to think that black holes may just be there to clean up the space debris. Like a vacuum cleaner, and there is another world in that black hole, where it is full of debris and rock, as if we are trapped in a dust-bag in a vacuum cleaner. :P

Not sure where you see the contradictions.

There is a difference between your perspective and theirs, insofar as you are looking at a top down view, and suggesting there is some grand design that everything fits into; while the common scientific view is bottom up - it assumes simply that each component of the universe acts autonomously, without any grand plan, and the outcome we see is merely the accidental outcome of that autonomous action of the various component parts of the universe.

The other error is to assume that a black whole really has any more capacity to suck things up than any large object (e.g. an equally massive star).  The difference between a black hole and a star is that while both will suck things up, a star will also emit light, cosmic rays, and exhaust gasses back out to the surrounding universe, whereas a black hole sucks things up but sends nothing (except, possibly, a very small amount of Hawkins radiation) back out again (hence why it appears black).

Yes. So the difference between a star and a black hole, is that one is black, one is light, and one only sucks, the other one lets out aswell?
 

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Re: How can black holes bend light?
« Reply #8 on: 12/04/2007 14:14:34 »
Yes. So the difference between a star and a black hole, is that one is black, one is light, and one only sucks, the other one lets out aswell?

In crude terms, that is about it.
 

Offline Seany

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Re: How can black holes bend light?
« Reply #9 on: 12/04/2007 14:17:45 »
In crude terms, that is about it.

Ah. But, if a star *sucks* a meteor or a comet, or a small planet. What happens to it? Doesn't it just attach itself or crash land of the star?

But, for a black hole. If a black hole and a star is exactly the same, apart from the fact that stars give out gases and burn hydrogen etc, shouldnt the debris/rocks/meteors which gets sucked into the blackhole, just be "stuck" to the black hole? Just like it would do to a star..
 

another_someone

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Re: How can black holes bend light?
« Reply #10 on: 12/04/2007 15:55:46 »
Ah. But, if a star *sucks* a meteor or a comet, or a small planet. What happens to it? Doesn't it just attach itself or crash land of the star?

But, for a black hole. If a black hole and a star is exactly the same, apart from the fact that stars give out gases and burn hydrogen etc, shouldnt the debris/rocks/meteors which gets sucked into the blackhole, just be "stuck" to the black hole? Just like it would do to a star..

When you get very close to the two, clearly there are differences; but what I was talking about was at a distance.

When you get close to a star, you just vaporise, and even closer yet, and you get turned to plasma, and finally (if you don't get blown away by the exhaust gasses of the star) you will just get sucked into the inferno of the star.

With a black hole, it is a lot more complex, because there is no heat, light, or gas, given off my the black hole (although there may be intense radiation given off by the swirling gasses around the edge of a black hole if the black hole has a nearby source of gas to suck up).  If there is no nearby source of gas, then what happens will depend to some extend on how heavy the black hole is, but ultimately the end result will always be that when you get close enough, you will be torn apart by the massive gravitation tidal forces (but by this time, because the black hole is much smaller than a star, you would be much closer to the centre of the black hole than you could ever have gotten to the centre of a star of the same mass), and ultimately then crushed by the gravity.  This final fate in a black hole may well be hidden from the outside world, because you will (unless the black hole is very light) be within the event horizon that cloaks the core of the black hole.
 

Offline Seany

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Re: How can black holes bend light?
« Reply #11 on: 12/04/2007 16:03:03 »
Ah. But, if a star *sucks* a meteor or a comet, or a small planet. What happens to it? Doesn't it just attach itself or crash land of the star?

But, for a black hole. If a black hole and a star is exactly the same, apart from the fact that stars give out gases and burn hydrogen etc, shouldnt the debris/rocks/meteors which gets sucked into the blackhole, just be "stuck" to the black hole? Just like it would do to a star..

When you get very close to the two, clearly there are differences; but what I was talking about was at a distance.

When you get close to a star, you just vaporise, and even closer yet, and you get turned to plasma, and finally (if you don't get blown away by the exhaust gasses of the star) you will just get sucked into the inferno of the star.

With a black hole, it is a lot more complex, because there is no heat, light, or gas, given off my the black hole (although there may be intense radiation given off by the swirling gasses around the edge of a black hole if the black hole has a nearby source of gas to suck up).  If there is no nearby source of gas, then what happens will depend to some extend on how heavy the black hole is, but ultimately the end result will always be that when you get close enough, you will be torn apart by the massive gravitation tidal forces (but by this time, because the black hole is much smaller than a star, you would be much closer to the centre of the black hole than you could ever have gotten to the centre of a star of the same mass), and ultimately then crushed by the gravity.  This final fate in a black hole may well be hidden from the outside world, because you will (unless the black hole is very light) be within the event horizon that cloaks the core of the black hole.

A Blackhole cannot be VERY LIGHT, because then it wouldn't have the intense gravity to suck it up. Also, a blackhole is a star which has burnt out, so it can't exactly be light.

And.. When I die, I want to die going in the blackhole :D.. Might be a tad bit painful though :D.. But you never know, I might live again and come out through the whitehole and live in heaven!
 

another_someone

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Re: How can black holes bend light?
« Reply #12 on: 12/04/2007 16:57:48 »
A Blackhole cannot be VERY LIGHT, because then it wouldn't have the intense gravity to suck it up. Also, a blackhole is a star which has burnt out, so it can't exactly be light.

Light and heavy are relative terms - it all depends upon what you consider the norm.

And.. When I die, I want to die going in the blackhole :D.. Might be a tad bit painful though :D.. But you never know, I might live again and come out through the whitehole and live in heaven!

Ian (SoulSurfer) will be able to tell you all about the nice complexities of rotating black holes, and all the possibilities they allo, but I shall not attempt to go down there - I shall leave it to Ian if he comes along.
 

Offline Seany

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Re: How can black holes bend light?
« Reply #13 on: 12/04/2007 17:00:36 »
Ah ok thanks alot though!


IIIIIIAAAAAAAAAAAAAANNNNNNNNNNNN!!!!!!!!! Could you come here please :D
 

Offline lightarrow

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Re: How can black holes bend light?
« Reply #14 on: 12/04/2007 20:53:56 »
And.. When I die, I want to die going in the blackhole :D.. Might be a tad bit painful though :D
I don't advise it to you.
George (another_someone) has tried to explain you that it wouldn't be exactly a tad bit painful; I explain you better: it would be one of the worse tortures you can imagine.
I would never like to see a person undergo something like that.
 

Offline Seany

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Re: How can black holes bend light?
« Reply #15 on: 12/04/2007 20:58:27 »
I realise why it would be torture, as you're body would be crumpled and pulled and everything. But wouldn't the whole thing be too fast and too agonising to feel anything at all?
 

Offline lightarrow

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Re: How can black holes bend light?
« Reply #16 on: 12/04/2007 21:07:37 »
I realise why it would be torture, as you're body would be crumpled and pulled and everything. But wouldn't the whole thing be too fast and too agonising to feel anything at all?
If I were you, I wouldn't make the experiment to know it.
I haven't made a calculation, but it could last longer than what you think.
 

Offline Seany

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Re: How can black holes bend light?
« Reply #17 on: 12/04/2007 21:09:47 »
Hmm. O.K. I'll think about what you said again, before swimming into one. :) It might be quite fun though? :P
 

Offline bilal

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Re: How can black holes bend light?
« Reply #18 on: 03/10/2008 06:14:06 »
I just read about bendind of light. i just think about gravity it is attractive and energy is repulsive.they both compete with each other.in holes attraction is far Much higher and light spill absorbed in it.why are there black holes.in my view they are anti light part of universe(just like matter antimatter)when light came to existence anti light also.
 

Offline Supercryptid

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How can black holes bend light?
« Reply #19 on: 03/10/2008 14:48:20 »
in my view they are anti light part of universe(just like matter antimatter)when light came to existence anti light also.
Light is made of photons. Photons are their own antiparticles. Therefore light is already its own antilight.
 

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How can black holes bend light?
« Reply #19 on: 03/10/2008 14:48:20 »

 

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