Black Holes and Gravity

[sansavis]

Assumptions:

• Inside a black hole's event horizon light cones do not intersect the world lines of external objects.
• Gravity propagates as an event.

So a black hole's internal gravity doesn't affect external objects? What did I do wrong?

[csmyth3025]

Assumptions:

• Inside a black hole's event horizon light cones do not intersect the world lines of external objects.
• Gravity propagates as an event.

So a black hole's internal gravity doesn't affect external objects? What did I do wrong?

You'll have to be more specific with your links. Can you quote the Wikipedia links you provided in the context of the paragraph in which they appear?

 

In general, the gravity of the singularity inside the event horizon has the same effect as normal mass would have on objects outside the event horizon. A five solar mass black hole will have the same gravitational effect on planets and stars in its vicinity as a five solar mass normal star.

 

Chris

[sansavis]

You'll have to be more specific with your links. Can you quote the Wikipedia links you provided in the context of the paragraph in which they appear?

 

...as the horizon-crossing event's light cone never intersects the observer's world line...

 

Implying that light cones within the black hole's event horizon never intersect external world lines, or that internal events do not affect external ones.

 

In physics, gravitational waves are theoretical ripples in the curvature of spacetime which propagates as a wave, traveling outward from the source.

 

Implying that gravity has a light cone, or is an "event".

 

Hence, propagating gravitational waves within a black hole's event horizon never cross, and do not affect external events. Which I'm pretty sure is wrong.

Edited August 22, 2011 by sansavis

[csmyth3025]

Implying that light cones within the black hole's event horizon never intersect external world lines, or that internal events do not affect external ones.

 

 

 

Implying that gravity has a light cone, or is an "event".

 

Hence, propagating gravitational waves within a black hole's event horizon never cross, and do not affect external events. Which I'm pretty sure is wrong.

You may be confusing gravitational waves with gravity. The singularity inside the event horizon of a black hole is point-like and, by definition, symmetric.

 

In general terms, gravitational waves are radiated by objects whose motion involves acceleration, provided that the motion is not perfectly spherically symmetric (like a spinning, expanding or contracting sphere) or cylindrically symmetric (like a spinning disk).

(ref. http://en.wikipedia....itational_waves )

 

Chris

[sansavis]

You may be confusing gravitational waves with gravity. The singularity inside the event horizon of a black hole is point-like and, by definition, symmetric.

 

 

(ref. http://en.wikipedia....itational_waves )

 

Chris

 

What of gravitons then? They also constitute as particles with light cones (I think).

 

But yes, I was mistaken with gravitational waves.

[csmyth3025]

What of gravitons then? They also constitute as particles with light cones (I think).

 

But yes, I was mistaken with gravitational waves.

Gravitons are associated with the quantum theory of gravity - which is a theory that no one has yet been able to to devise:

 

...attempts to extend the Standard Model with gravitons have run into serious theoretical difficulties at high energies (processes with energies close to or above the Planck scale) because of infinities arising due to quantum effects (in technical terms, gravitation is nonrenormalizable). Since classical general relativity and quantum mechanics are incompatible at such energies, from a theoretical point of view the present situation is not tenable.^[9] Some proposed models of quantum gravity^[10] attempt to address these issues, but these are speculative theories.

(ref. http://en.wikipedia.org/wiki/Graviton )

 

For now, we're stuck with good old Albert Einstein's General Theory of Relativity - which is a geometric theory of gravity. That is to say, it describes gravity as being an effect of the curvature of space-time:

 

...Having formulated the relativistic, geometric version of the effects of gravity, the question of gravity's source remains. In Newtonian gravity, the source is mass. In special relativity, mass turns out to be part of a more general quantity called the energy-momentum tensor, which includes both energy and momentum densities as well as stress (that is, pressure and shear).^[28] Using the equivalence principle, this tensor is readily generalized to curved space-time...

(ref. http://en.wikipedia....n.27s_equations )

 

Chris