[sjastro]

Originally Posted by rustigsmed

thanks steven, i'm still a bit confused i understand that energy can be converted into mass and vice versa. in BH am i right in saying that all mass is converted to energy? so that would mean energy would have to have an affect on gravity in 'energy form' (as opposed from mass)?

cheers

russ

Russ,

Since our knowledge of what happens inside the event horizon is limited we can only speculate on whether all mass is converted into energy.
We know in the case of x ray binary stars where one of the companions is a BH, a large percentage of in-falling mass is converted into energy before it passes through the horizon.

One of the fundamental differences between Newton's theory of gravity and GR is the role of energy.
Suppose you have a planet under the gravitational influence of a binary star. In Newton's theory the total gravitational force between the planet and binary star is simply the sum of the gravitational forces between each component star and planet.
In GR the total gravitational force is the sum of the gravitational force of each component star and planet plus the gravitational binding energy between the stars.
The gravitational binding energy is the amount of energy required to separate the binary star.

So in GR energy does contribute to gravity.

Regards

Steven