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Old 01-07-2012, 07:57 PM
 
Location: Fairfax
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Scientists talk about the rules of physics breaking down within the event horizon of a black hole.

The very fact that light cannot escape it is evidence of this. So does matter travel faster than c in its approach to the center? If it traveled slower, you could shine a flashlight behind you and the photons would move away from the singularity which obviously does not happen.

This is completely speculative, but what is the general consensus on this? I know the idea is that space is infinitely warped that just a function of the black hole's gravity?

While we're at it, if you can think of other instances of the laws of physics becoming irrelevant within the event horizon post them.
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Old 01-07-2012, 08:34 PM
 
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I've always been under the impression that once you hit the event horizon all the laws of the physical universe cease to exist not just one or two...
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Old 01-07-2012, 08:56 PM
 
Location: Fairfax
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Originally Posted by plwhit View Post
I've always been under the impression that once you hit the event horizon all the laws of the physical universe cease to exist not just one or two...
Well, the law of gravity seems intact or we'd see stuff spewing out.
Regardless, the concept is mind-blowing.
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Old 01-07-2012, 11:29 PM
 
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Quote:
Originally Posted by decafdave View Post
Well, the law of gravity seems intact or we'd see stuff spewing out.
Regardless, the concept is mind-blowing.
Some stuff does spew out, so to speak. Not everything is pulled in past the event horizon. A tremendous amount of radiation is emitted. Some particles can be hurled back out into space. It might even be that if a black hole pulls in too much in too short of a period of time, it may burp some of the excess out. Quasars are an extreme example. If there are periods when less material is available, black holes can become inactve or "quiet". When there's plenty of stuff, they become more active. That kind of behavior is probably related to activity at or near the event horizon though. It's also thought that while black holes rotate on their own axis, some are thought to be stationary. My guess is that the latter are wanderers drifting through space.

While the gravity is extreme, gravity is considered as one of the fundamental forces. Where physics starts getting weird is as you get closer to a black hole, not only is space compressed to extreme, but time itself slows down. Leonard Susskind pictures a strange phenomena that takes places as you get closer to a black hole. From the point of view of a distant observer, the view of an object falling in would appear to multiply. Imagine the propeller of an airplaine. Instead of seeing just one propeller, you'd start to seeing two propellers, then four, then eight, then sixteen, etc. And the closer it gets to the even horizon, the more propellers would seem to appear. It's a strange illusion that Susskind describes as holographic. Once past the event horizon it's presumed that time comes to a halt. It's at that point where physics breaks down. There might be some kind of physics taking place, but it'd be physics which are beyond our current understanding.



What Would Happen If You Fell into a Black Hole? - YouTube



Journey into a Schwarzschild black hole - YouTube



Neil DeGrasse Tyson - Death By Black Hole - YouTube


This isn't the same as what happens approaching a black hole, but it gives a good idea of an illusion. It looks like there are multiple blades which are bent, some appearing to detach, but it's just an illusion. If you were the blade, your view would be that everything beyond you would look like a distorted blur.


Airplane propeller optical illusion - YouTube
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Old 01-08-2012, 09:14 AM
 
Location: Westwood, MA
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Quote:
Originally Posted by plwhit View Post
I've always been under the impression that once you hit the event horizon all the laws of the physical universe cease to exist not just one or two...
In terms of physics, not that much interesting happens at the event horizon. It simply marks the boundary between bounded and unbounded light-like paths. The laws of physics are essentially the same on either side, though. The known laws of the physical universe break down at or near the gravitational singularity at the center of the black hole, where energy density become nearly infinite.

In other words, if you were in a windowless box falling toward a black hole, you wouldn't be able to detect anything particularly interesting happening as you crossed the event horizon. It's only outside observers who would notice anything remarkable about the event horizon.
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Old 01-08-2012, 09:41 AM
 
Location: Fairfax
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Originally Posted by NightBazaar View Post
Some stuff does spew out, so to speak. Not everything is pulled in past the event horizon. A tremendous amount of radiation is emitted. Some particles can be hurled back out into space. It might even be that if a black hole pulls in too much in too short of a period of time, it may burp some of the excess out. Quasars are an extreme example. If there are periods when less material is available, black holes can become inactve or "quiet". When there's plenty of stuff, they become more active. That kind of behavior is probably related to activity at or near the event horizon though. It's also thought that while black holes rotate on their own axis, some are thought to be stationary. My guess is that the latter are wanderers drifting through space.
Nothing spews out of black holes, although I can understand how quasars caused the confusion here. Anything that is "burped out" has not yet fallen into the event horizon. The tremendous radiation that is emitted comes from the accretion disk, which is a high pressure bottleneck of matter/energy competing to enter the event horizon.

However, none of these gamma rays or x-rays originated from within the black hole.
Quasar - Wikipedia, the free encyclopedia

Hawking radiation, is an entirely different matter, and if it exists is completely un-observable in an active black hole (the single quantum particle would be swamped by matter coming in the other way).

Quote:
Originally Posted by NightBazaar View Post
While the gravity is extreme, gravity is considered as one of the fundamental forces. Where physics starts getting weird is as you get closer to a black hole, not only is space compressed to extreme, but time itself slows down. Leonard Susskind pictures a strange phenomena that takes places as you get closer to a black hole. From the point of view of a distant observer, the view of an object falling in would appear to multiply. Imagine the propeller of an airplaine. Instead of seeing just one propeller, you'd start to seeing two propellers, then four, then eight, then sixteen, etc. And the closer it gets to the even horizon, the more propellers would seem to appear. It's a strange illusion that Susskind describes as holographic. Once past the event horizon it's presumed that time comes to a halt. It's at that point where physics breaks down. There might be some kind of physics taking place, but it'd be physics which are beyond our current understanding.
Time slows down even close to Earth. GPS satellites have to contend with extra micro seconds every day because of their speed and lower gravity due to distance.

Back to my original question, since we consider photons as timeless, and the matter/energy right AT the event horizon would look timeless to the outside observer, it must be traveling at exactly the speed of light. An observer in a spaceship passing through the event horizon would see the entire future history of the universe play out (as long as the black hole continues to exist).

But, the instance that matter/energy passes the event horizon it should be traveling faster than the speed of light towards the singularity. Craziness ensues:

1. Does time go in reverse? How would this play out for the "inside" observer?
2. Is this breach in the law of physics allowed because the event horizon "hides" it from the outside universe?
Cosmic censorship hypothesis - Wikipedia, the free encyclopedia
3. In a supermassive black hole, there is very little tidal force and a person could easily survive for hours beyond the event horizon. How is he going to observe time as a superluminal object?

I think these things give credence to the idea that anything inside black holes are in a separate universe given the different set of laws.
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Old 01-08-2012, 10:39 AM
 
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Originally Posted by decafdave View Post
Nothing spews out of black holes, although I can understand how quasars caused the confusion here. Anything that is "burped out" has not yet fallen into the event horizon. The tremendous radiation that is emitted comes from the accretion disk, which is a high pressure bottleneck of matter/energy competing to enter the event horizon.
We agree black holes suck everything around it into it.

How are you so sure nothing comes out of a black hole?

I didn't realize mankind had discovered everything there is to know about the Universe, when did that occur?
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Old 01-08-2012, 10:45 AM
 
Location: Westwood, MA
3,608 posts, read 4,779,236 times
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Quote:
Originally Posted by decafdave View Post
Nothing spews out of black holes, although I can understand how quasars caused the confusion here. Anything that is "burped out" has not yet fallen into the event horizon. The tremendous radiation that is emitted comes from the accretion disk, which is a high pressure bottleneck of matter/energy competing to enter the event horizon.

However, none of these gamma rays or x-rays originated from within the black hole.
Quasar - Wikipedia, the free encyclopedia

Hawking radiation, is an entirely different matter, and if it exists is completely un-observable in an active black hole (the single quantum particle would be swamped by matter coming in the other way).



Time slows down even close to Earth. GPS satellites have to contend with extra micro seconds every day because of their speed and lower gravity due to distance.

Back to my original question, since we consider photons as timeless, and the matter/energy right AT the event horizon would look timeless to the outside observer, it must be traveling at exactly the speed of light. An observer in a spaceship passing through the event horizon would see the entire future history of the universe play out (as long as the black hole continues to exist).

But, the instance that matter/energy passes the event horizon it should be traveling faster than the speed of light towards the singularity. Craziness ensues:

1. Does time go in reverse? How would this play out for the "inside" observer?
2. Is this breach in the law of physics allowed because the event horizon "hides" it from the outside universe?
Cosmic censorship hypothesis - Wikipedia, the free encyclopedia
3. In a supermassive black hole, there is very little tidal force and a person could easily survive for hours beyond the event horizon. How is he going to observe time as a superluminal object?

I think these things give credence to the idea that anything inside black holes are in a separate universe given the different set of laws.
I don't know where you've received your information about the event horizon, but many of the things you say are not true. Matter passing through the event horizon does not travel faster than the speed of light. I'm not sure why you have this idea, but the event horizon is simply where light can no longer propagate radially away from the black hole based on the geometry around the black hole. I think the rest of your statements come directly from this initial faulty assumption and so would also be either false or irrelevant.
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Old 01-08-2012, 11:13 AM
 
Location: Wilsonville, OR
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Quote:
Originally Posted by plwhit View Post
We agree black holes suck everything around it into it.

How are you so sure nothing comes out of a black hole?

I didn't realize mankind had discovered everything there is to know about the Universe, when did that occur?
It is impossible by definition. Once something crosses the event horizon, it literally has no possible futures that exist outside of it. All possible futures point directly to the singularity.
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Old 01-08-2012, 02:53 PM
 
Location: Fairfax
2,880 posts, read 6,228,199 times
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Originally Posted by jayrandom View Post
I don't know where you've received your information about the event horizon, but many of the things you say are not true. Matter passing through the event horizon does not travel faster than the speed of light. I'm not sure why you have this idea, but the event horizon is simply where light can no longer propagate radially away from the black hole based on the geometry around the black hole. I think the rest of your statements come directly from this initial faulty assumption and so would also be either false or irrelevant.
If you'll read the op, you'll see that my statements were really questions.

That said, doesn't the twisted geometry around a black hole necessitate that the escape velocity be higher than the speed of light? As far as I know, scientists haven't come to the conclusion that the escape velocity inside the event horizon is infinite. The escape velocity at the horizon is c. So you're saying that immediately inside it jumps to infinity?

So again, if matter is supposedly falling into the singularity at sub-light speed, then I don't understand why you couldn't shine a flashlight behind you as you fall.
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