# How does gravity get out of a black hole?

1. Feb 11, 2016

### black hole 123

And how does graviton escape the event horizon? People say it's because those gravitons are "virtual particles" and can travel faster than light, yet many of the posts i read on here say virtual particles dont even exist. Also, gravity TRAVELS at the speed of light, if the sun is suddenly gone we'll still feel its gravity, so please don't tell me somehow the gravity from a black hole manages to travel faster than light. Doesn't this prove gravitons are wrong, and gravity really is curved spacetime? Or uses some other mechanism not the same as the other 3 forces?

Last edited by a moderator: Feb 11, 2016
2. Feb 11, 2016

### jerromyjon

Gravity doesn't have to "fight the black hole" it IS the black hole.

3. Feb 11, 2016

### phinds

This is a common point of misunderstanding. Gravity is a field. The gravitational field of a black hole forms as the black hole is forming, so there IS no "getting out of" the black hole, it's just an existing field.

4. Feb 11, 2016

### Staff: Mentor

5. Feb 11, 2016

### Staff: Mentor

To add to what the others are saying:

The gravitational force between two objects is not caused by gravitons (assuming that there is such a thing as a graviton) moving from one to the other, so a black hole's gravitational effects do not depend on gravitons getting out of it.

Gravitons are a hypothetical concept that appears in some theories of quantum gravity, but they are no part of general relativity because it's not a quantum theory. If gravitons do exist, they will show up in the quantum mechanical description of how an object interacts with the local gravitational field in it's immediate vicinity.

6. Feb 11, 2016

### Staff: Mentor

This can't happen; it would violate local energy conservation. It is actually not trivial to formulate a thought experiment that can test the "speed of gravity" by changing gravitational sources, because of the requirement of local energy conservation, which means that sources of gravity can't be created or destroyed.