Why does gravity not end at the event horizon?

In summary: Q12 "It is thought that the escape of mass from a Schwarzschild black hole is not possible, although some energy might be released in the form of gravitational waves."In summary, a question that's been bugging me is why gravity doesn't escape from a black hole abruptly. It is thought that the escape of mass from a Schwarzschild black hole is not possible, although some energy might be released in the form of gravitational waves.
  • #1
okkvlt
53
0
A question that's been bugging me:

Why doesn't the gravitational influence of a black hole end abruptly at the event horizon?

Supposedly nothing can escape a black hole, so how does gravity itself escape?

Light cannot escape a black hole, and gravity travels at the speed of light. Therefore both gravity and light travel below the escape velocity. Thus, gravity cannot escape the black hole.

I suppose you could bring up the fact that photons don't interact with other photons, and then extend that to gravity by declaring that gravitons don't interact with other gravitons. But this still leaves something to be desired: how can anything escape the curvature of space-time? If gravitons arent affected by the curvature of space, then what else is there other than space that gravitons can move through?

Furthermore, the existence of gravitational waves produced by binary star systems seems to imply to me that gravity does interact with itself.

In your explanation, please use math i can understand(no tensors).

thanks.

Also, another question: How does the inverse square law manifest itself in GR? In Newtonian mechanics, its so elegant that the inverse square law is a result of the equation for the surface area of a sphere. And the inverse square law also works for electromagnetism, so I am kind of skeptical of general relativity- it just seems to muddle things up.


And what happens when division by zero enters the laws of physics?(as in a black hole where distance=0) Does the force become infinite? or is zero distance impossible?
 
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  • #2
okkvlt said:
A question that's been bugging me:

Why doesn't the gravitational influence of a black hole end abruptly at the event horizon?

Supposedly nothing can escape a black hole, so how does gravity itself escape?

Light cannot escape a black hole, and gravity travels at the speed of light. Therefore both gravity and light travel below the escape velocity. Thus, gravity cannot escape the black hole.

I suppose you could bring up the fact that photons don't interact with other photons, and then extend that to gravity by declaring that gravitons don't interact with other gravitons.
Unlike classical electro-magnetism, GR is non-linear. So if a graviton description of gravity exists (that is still debatable), gravitons should interact with gravitons.

As for the "how does the force escape" type questions, I think you are taking the concept of a force mediated by particles too literally.

For example, virtual photons CAN escape a black hole. So if charges fall into the black hole, from the outside you can indeed tell that the black hole is charged. Similarly with gravity.

Does that help some?
It sounds like the main sticking point is the force mediated by particles description, so I'd suggest starting there if you wish to dig further.

okkvlt said:
And what happens when division by zero enters the laws of physics?(as in a black hole where distance=0) Does the force become infinite? or is zero distance impossible?
That usually indicates a failure of the theory (or choice of parameterization). We can't say what happens at the singularity using GR, because GR can't tell us.
 
  • #3
Supposedly nothing can escape a black hole, so how does gravity itself escape?
As I understand it, to the outside observer the black hole takes an infinite time to form, although in its own frame, the black hole forms right away. In any case, the gravity felt by the outside observer is that of the object becoming a black hole.
 
  • #4

1. Why does gravity not end at the event horizon?

Gravity is a fundamental force of nature that is caused by the bending of spacetime. The event horizon, which is the point of no return for objects entering a black hole, is where the gravitational pull becomes incredibly strong. However, gravity does not end at this point because the mass of the black hole continues to exert its gravitational force on objects outside of the event horizon.

2. Does the strength of gravity change at the event horizon?

No, the strength of gravity does not change at the event horizon. The gravitational pull at this point is already extremely strong, and it remains the same as objects get closer to the black hole. However, the effects of gravity may become more noticeable due to the intense curvature of spacetime near the event horizon.

3. Can anything escape the event horizon?

Once an object crosses the event horizon, it is impossible for it to escape the black hole's gravitational pull. This is because the escape velocity, which is the speed needed to overcome the gravitational force, is greater than the speed of light at this point. Therefore, even light cannot escape the event horizon.

4. How does the event horizon relate to the size of a black hole?

The size of a black hole is directly related to the size of its event horizon. The event horizon is determined by the mass of the black hole, with larger black holes having larger event horizons. This means that the closer an object gets to a black hole, the stronger the gravitational pull will be.

5. Is the event horizon a physical barrier?

No, the event horizon is not a physical barrier that prevents objects from entering a black hole. It is simply the point of no return, where the gravitational pull is so strong that even light cannot escape. Objects can still pass through the event horizon, but they will be pulled towards the center of the black hole and eventually be crushed by its immense gravity.

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