# Thread: Does a black hole propogate gravity?

1. ## Does a black hole propogate gravity?

If nothing can escape the warping of space-time of a black hole AND gravity travels lazily at the speed of light. Then how could a black hole have a gravitational field?

2. Gravity IS the warping of space time. It is not something that has to be emitted by the black hole.

3. It's not gravity that travels at the speed of light, it's changes to the gravitational field. Say you have a large mass and move it suddenly. Someone feeling the gravity from that mass won't notice the change in its pull until the same time that they see the mass move, because the change takes the same amount of time to propogate as the photons take to reach him.

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Charge is transmitted by virtual photons. How can charge escape a black hole? At least we're still talking about photons.

5. Originally Posted by phunk
It's not gravity that travels at the speed of light, it's changes to the gravitational field. Say you have a large mass and move it suddenly. Someone feeling the gravity from that mass won't notice the change in its pull until the same time that they see the mass move, because the change takes the same amount of time to propogate as the photons take to reach him.
So ... near a black hole do you have that effect? Since they will never see the singularity ( which is the black hole )???

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The singularity + the event horizon = the black hole.

7. ## Gravity

Originally Posted by tommac
If nothing can escape the warping of space-time of a black hole AND gravity travels lazily at the speed of light, then how could a black hole have a gravitational field?
Because gravity is not something that is emitted. Gravity is the curvature of spacetime induced by mass. The black hole has mass, and therefore it has gravity. The gravity is outside the black hole, and does not propagate from inside the black hole.

Originally Posted by phunk
It's not gravity that travels at the speed of light, it's changes to the gravitational field. ...
Indeed so, and the changes propagate in the form of gravitational waves. Gravitational waves, predicted by general relativity, are a necessary consequence of the fact that changes in gravitational fields do not propagate instantaneously, but rather at a finite speed. Although we have not yet unambiguously observed gravitational waves, evidence from the orbital decay of binary pulsars is consistent with the predictions of general relativity (i.e., Bhat, Bailes & Verbiest, 2008; Bisnovatyi-Kogan, 2006; Weisberg & Taylor, 2005; van Straten, et al., 2001; Taylor & Weisberg, 1982). So there is plenty of observational evidence in favor of the proposition that general relativity, and the finite propagation speed of gravitational waves, are valid.

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Ask yourself if gravity attracts gravity? If yes, then a black hole wouldn't allow the outside to know its mass.

If no, we have the real world that we appear to be living in.

9. Originally Posted by alainprice
Ask yourself if gravity attracts gravity? If yes, then a black hole wouldn't allow the outside to know its mass.

If no, we have the real world that we appear to be living in.
Obviously I know the answer to the question ... but what I am hinting at is how does a gravitational wave escape a curvature of space so severe that space-time is warped back in on itself.

What you seem to be saying is that the warping itself of space time in the form of a gravitational wave is immune to space itself. Thus not effected by the curvature of space-time

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A gravitational wave IS the curvature of space.

Keep working on making the proper link between gravity, spacetime and matter-energy.

11. Originally Posted by alainprice
A gravitational wave IS the curvature of space.
Ok so ... relative to any point in the curved space, gravity can travel faster than the speed of light.

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No, that is the basis of GR. Gravity always travels at the speed of light, relative to the starting point.

Relative to a starting point, nothing can move faster than 'c' locally.

13. Originally Posted by alainprice
No, that is the basis of GR. Gravity always travels at the speed of light, relative to the starting point.

Relative to a starting point, nothing can move faster than 'c' locally.

If you have a place inside of the black hole's event horizon. If you shine a light in your duracell powered flashlight ourwards from inside the EH. Space-Time is curved in such a way that the light travels at the speed of light but will never get to the EH. However if you were standing the surface of a superdense star that just got eaten the gravity from that star would be felt outside of the EH. Therefor it can not travel along the same path as the light coming off of that star OR if it did it would need to travel faster than than the light from your flashlight to get to any point outside of the EH.

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That's akin to how it would work if gravity were subject to itself.

Gravity isn't composed of photons. Why would you expect it to behave as light would or be subject to the same influences and rules?

15. Originally Posted by seanhogge
That's akin to how it would work if gravity were subject to itself.

Gravity isn't composed of photons. Why would you expect it to behave as light would or be subject to the same influences and rules?
Ignoring how it works ... I am trying to make a statement here.

Gravitational waves move faster than the speed of light at least from the singularity of a black hole? ( true or false )

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False.

My attempts to assist you have been fruitless. I will cease to participate.

Best of luck in your endeavors.

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If you're going to ignore how it works, how can you make statements about how it works?

18. Originally Posted by alainprice
False.

My attempts to assist you have been fruitless. I will cease to participate.

Best of luck in your endeavors.
I am really sorry that you see it like that. How do you define fruitless? Meaning that I didnt totally and fully understand completely what you were saying?

19. Originally Posted by seanhogge
If you're going to ignore how it works, how can you make statements about how it works?
uggg ...

look ... space time is curved. Light travels based on that curature right? But since gravity causes the curvature it is does not follow the curve right?

Then how can one measure how fast gravity travels if not to compare it with the speed of light?

Is it safe to say that gravity travels at the speed of light in a perfect vacuum void of any gravitational forces?

Now if there was another BH in the way curing the space in front of the gravitational waves from our BH ... would something on the other side of our BH also experience the gravity from our BH ?

I mean i am trying to agree with all of you but there seems to be one missing piece.

20. Originally Posted by tommac
... space time is curved. Light travels based on that curature right? But since gravity causes the curvature it is does not follow the curve right?
I have always pictured that gravity IS the curvature. In other words, the detection of curvature is called gravity.

Originally Posted by tommac
I mean i am trying to agree with all of you but there seems to be one missing piece.
It seems like you keep equating gravity with an actual object. It's not.

You either need to take a leap to the abstract way of thinking, or need to understand the mathematical definition of it. It just doesn't match anything on the scale of everyday human experience.

21. Originally Posted by NEOWatcher
I have always pictured that gravity IS the curvature. In other words, the detection of curvature is called gravity.

It seems like you keep equating gravity with an actual object. It's not.

You either need to take a leap to the abstract way of thinking, or need to understand the mathematical definition of it. It just doesn't match anything on the scale of everyday human experience.
OK I dont need an actual object for gravity.
I am saying that gravity ( I dont like this term because I think of blue shift when I think of gravity ) ... lets call it anti-gravity ... although I am sure that someone will complain here ...

I am saying that anti-gravities ( again ... I am just using that word because I am forced to ) curvature of space time over long distances ( trillions of light years ) would cause a signifigant red shift ... much stronger than the blue shift ( or red shift if the observer was inside of it ) that occurns near a gravity well

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Originally Posted by tommac
look ... space time is curved. Light travels based on that curature right? But since gravity causes the curvature it is does not follow the curve right?
I'd be willing to go with that, yes.

Originally Posted by tommac
Then how can one measure how fast gravity travels if not to compare it with the speed of light?
We're not measuring the travel of gravity. Gravity as we know it can only be observed by its effect on matter. So we're measuring the speed of reaction by matter of distance to a gravitational source. For example; an object closer to a gravitational source "feels" that source more quickly than one farther away.

Originally Posted by tommac
Is it safe to say that gravity travels at the speed of light in a perfect vacuum void of any gravitational forces?
Gravity doesn't react to matter. It only acts upon it. So perfect vacuums are irrelevant.

Originally Posted by tommac
Now if there was another BH in the way curing the space in front of the gravitational waves from our BH ... would something on the other side of our BH also experience the gravity from our BH ?
Yes. It would feel the net force of both black holes. Gravity doesn't interact with itself. It concatenates such that the first black hole's gravitational attraction is added to the second from the perspective of an outside observer.

Originally Posted by tommac
I mean i am trying to agree with all of you but there seems to be one missing piece.
It rather seems that no matter how many times it's said by those who are far more qualified than we, your response is perpetually "but that can't be," instead of "I don't understand how that can be."

You and I both need to face facts that our limited expertise will require a certain amount of authoritative dicta. Only when we fully understand the underpinnings of the dicta may we begin to question it with any hope of progress.

It seems worthy of noting that most of the anti-mainstream discoveries have almost entirely been made by those intimately enmeshed with mainstream work.

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Originally Posted by seanhogge
It seems worthy of noting that most of the anti-mainstream discoveries have almost entirely been made by those intimately enmeshed with mainstream work.

Deep!

24. Originally Posted by seanhogge
I'd be willing to go with that, yes.

We're not measuring the travel of gravity. Gravity as we know it can only be observed by its effect on matter. So we're measuring the speed of reaction by matter of distance to a gravitational source. For example; an object closer to a gravitational source "feels" that source more quickly than one farther away.

Gravity doesn't react to matter. It only acts upon it. So perfect vacuums are irrelevant.

Yes. It would feel the net force of both black holes. Gravity doesn't interact with itself. It concatenates such that the first black hole's gravitational attraction is added to the second from the perspective of an outside observer.

It rather seems that no matter how many times it's said by those who are far more qualified than we, your response is perpetually "but that can't be," instead of "I don't understand how that can be."

You and I both need to face facts that our limited expertise will require a certain amount of authoritative dicta. Only when we fully understand the underpinnings of the dicta may we begin to question it with any hope of progress.

It seems worthy of noting that most of the anti-mainstream discoveries have almost entirely been made by those intimately enmeshed with mainstream work.

Ummm ... I am not sure that I am saying that they are wrong ... but more that I dont understand what they are saying ... when I say I dont agree ... it must be prefixed with the fact that I have only been thinking about this stuff for a month or so. I am sure even neverfly knows more than I do. I just dont agree with stuff until I understand it ... sorry if I sounded too confident in my statements.

25. OK all ... instead of starting a new thread ... which I think is needed for this ... per neverflys advice I will keep it here.

Is the speed of propogation of gravity constant? That is regardless of where you observe the effects of gravity does its speed of propogation appear constant?

26. Originally Posted by tommac
Ummm ... I am not sure that I am saying that they are wrong ... but more that I dont understand what they are saying ... when I say I dont agree ... it must be prefixed with the fact that I have only been thinking about this stuff for a month or so. I am sure even neverfly knows more than I do. I just dont agree with stuff until I understand it ... sorry if I sounded too confident in my statements.
Tommac, I was where you are now, a few years ago, but I learned that I have to walk before I can run, so I went back to basic principles and then decided to concentrate on one single aspect of the big picture until I understood it. The aspect I chose was the expansion of the universe. In looking into the expansion I found myself having to learn a whole lot of new concepts along the way, and I am only really starting to get to grips with the big picture of expansion now, although certain aspects still elude me.

You seem to have chosen a starting point where you want to understand cosmic expansion, the underlying nature of gravity, black holes and a whole gamut of cosmological subjects, all at the same time. You will find that as you truly understand one concept, others start to click into place (until you come across quantum physics, that is!) but if you risk thinking you understand something when you really don't, you end up heaping misconceptions upon yourself all the way down the line.

You have your whole life to come to a true understanding.

P.S. I know virtually nothing about black holes.

27. thanks ... but was there a need to post this in one of my threads rather than PMing me this? I was trying to keep to one thread but again it is filled with this stuff. So I will try to repost it again. Please if you have any of this heart to heart stuff you are sending please PM it to me or add it in your own thread. Please.

But thanks for the post. I see what you are saying.

Originally Posted by speedfreek
Tommac, I was where you are now, a few years ago, but I learned that I have to walk before I can run, so I went back to basic principles and then decided to concentrate on one single aspect of the big picture until I understood it. The aspect I chose was the expansion of the universe. In looking into the expansion I found myself having to learn a whole lot of new concepts along the way, and I am only really starting to get to grips with the big picture of expansion now, although certain aspects still elude me.

You seem to have chosen a starting point where you want to understand cosmic expansion, the underlying nature of gravity, black holes and a whole gamut of cosmological subjects, all at the same time. You will find that as you truly understand one concept, others start to click into place (until you come across quantum physics, that is!) but if you risk thinking you understand something when you really don't, you end up heaping misconceptions upon yourself all the way down the line.

You have your whole life to come to a true understanding.

P.S. I know virtually nothing about black holes.

28. Reposted as to not get lost in the Bull shorts above.

OK all ... instead of starting a new thread ... which I think is needed for this ... per neverflys advice I will keep it here.

Is the speed of propogation of gravity constant? That is regardless of where you observe the effects of gravity does its speed of propogation appear constant?

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Originally Posted by tommac
Reposted as to not get lost in the Bull shorts above.
That Does It!

Tommac, I appreciate your desire to learn.
But I'm Publicly announcing (and you are just going to have to learn to live with that) that you are the first BAUTer to ever make it onto my ignore list.

Goodbye Tommac...

30. OK all ... instead of starting a new thread ... which I think is needed for this ... per neverflys advice I will keep it here.

Is the speed of propogation of gravity constant? That is regardless of where you observe the effects of gravity does its speed of propogation appear constant?

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