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If light cant escape from a gravity well, how can gravity escape? we see that gravity of one object attracts another, obviously attracts itself. Is there a point that there is so much gravity that it attracts itself so hard that it turns back on itself. Is it a time energy of zero, i.e. instaneous effect on all objects? or does it affect an object at $c$, time energy of 1. Then how can our galaxy stay together, as all the gravity we are currently wading through was 'emitted' tens of thousands of gravity years ago from a different relative position?

Qmechanic
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Tarkus
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    What do i read up on? Newtonian gravity. You don’t need General Relativity to understand what holds a galaxy together. I think you may be confusing gravitational waves with regular gravity. The former are tiny perturbations on the latter. – G. Smith Oct 07 '20 at 02:44
  • There is nothing in physics called a “time energy” (and if there were, it wouldn’t have values like 0 and 1) so your question is incomprehensible. – G. Smith Oct 07 '20 at 02:49
  • @G.Smith I think the OP is trying to ask this: If the gravity of a black hole is so strong that light cant escape and nothing can travel faster than light, how does gravity escape? – mmesser314 Oct 07 '20 at 03:32
  • @mmesser314 If that’s the question, then it’s a duplicate since that gets asked a lot on this site. – G. Smith Oct 07 '20 at 03:45
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    Does this answer your question? How does gravity escape a black hole? – Thorondor Oct 07 '20 at 04:12

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I will answer assuming this re- stating of the question is what the question is about.

If the gravity of a black hole is so strong that light cant escape and nothing can travel faster than light, how does gravity escape? – mmesser314

There are two theories of gravity , both valid in their respective realm of variables.

For masses of the size in our solar system Newtonian mechanics and gravity give a good fit to observations and are predictive, except in specific cases where General Relativity gives a better fit

Newton's classical theory of gravity offered no prospect of identifying any mediator of gravitational interaction. His theory assumed that gravitation acts instantaneously, regardless of distance

So your questions are valid within the Newtonian frame.

After the thinking out of the box by Einstein and the demonstration that General Relativity is the encompassing theory of gravity of which Newtonian gravitation is a limit for low masses, the instantaneous part is removed.

General Relativity, GR embeds Lorenz transformations. In Lorenz transformations nothing can travel faster than c, the velocity of light. Electromagnetism defines electromagnetic waves, and General Relativity defines gravitational waves. Both waves have velocity c. Gravitational waves have been seen experimentally in the LIGO experiment.

The effect of a change in a gravitational system cannot travel faster than the velocity of light.

If light cant escape from a gravity well, how can gravity escape?

If by "gravity well" you mean a black hole, that is a different story than the gravity wells that are the planets stars and galaxies. Light comes into our eyes from all those bodies.

No light or gravitational waves come out of a black hole.

we see that gravity of one object attracts another, obviously attracts itself.

There is no obviously about it, only in that the atoms and molecules that constitute an object also have a small gravitational attraction to each other.

Is there a point that there is so much gravity that it attracts itself so hard that it turns back on itself.

Gravity is an attribute of an object, is not an object in itself.

Is it a time energy of zero, i.e. instaneous effect on all objects?

If you mean the time it takes energy to be transmitted, as explained above, there is the maximum velocity c that does not allow instantaneous transmissions. General Relativity is the theory that describes gravitational attraction by distortions in space time , and , see above, nothing is instantaneous.

Then how can our galaxy stay together, as all the gravity we are currently wading through was 'emitted' tens of thousands of gravity years ago from a different relative position.

We are moving through space-time , (x,y,z,t) is a four vector . The GR equations give a mathematically consistent behavior/description of the universe.

anna v
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