Bob600

The basic understanding of the actions of a Black Hole is that it draws everything into it and nothing can escape. Is it possible that if a black hole was massive enough and having sucked in all the matter and energy in its vicinity, could it also suck in its own gravity allowing none could escape? And if so would it simply cease to exist as there would be no longer an indication of its presence.

RelativityIsWrong

Actually, that's an interesting conundrum for my knowledge of quantum mechanics... in the relativistic definition, it won't suck in spacetime, but in terms of the quantum, a graviton wouldn't be able to escape.

topsquark

If a graviton couldn't escape then how does a black hole have a gravitational field?

j/k I couldn't resist that one. It's the wrong way to look at the problem.

Seriously now. Remember that space-time is curved near a black hole, which "funnels" everything falling in toward the center. Gravitons don't need to escape, they are there due to the space-time curvature.

Just to be clear about a black hole's strength. If the Sun suddenly turned into a black hole (without any other effects) the planets would continue on in their orbits just like they always have...they wouldn't get "sucked in." The special properties of a black hole only come into play when you are close to the center.

-Dan

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RelativityIsWrong

That doesn't really make sense based on my (limited) knowledge of physics. If I understand correctly, a graviton would be emitted from the object at the center of the black hole. But it would then need to travel away, fighting against the speed of light gravitational pull.

Assuming I understand correctly, this is why (gravitational) force carriers with energy don't work very well...

Speaking of which, does anyone know why gravity is actually considered a standard force? I mean, it acts more like a law of motion than the electromagnetic/weak/strong forces. More a property of spacetime than a property of a particle.

topsquark

Where there is an electric charge there is an electromagnetic field and thus photons.

Where there's a mass there's a gravitational field and thus there are gravitons.

They work, but the Math is much more complicated. There are fields where the mediating particles carry the "charge" of the field themselves. They are called "Yang-Mills" fields. (This is not true for EM...photons carry no electric charge. QED, the quantum version of EM, is relatively simple for that reason.)

(shrugs) It has a field, in quantum terms it is an interaction, so it's a force by definition.

-Dan

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Troll

Considering the concept of dark energy, I have come to think of gravity as a force working upon the universe rather than from within it.

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