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jnorman
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since energy absorbed by a BH is no longer available to the universe, why is that not a violation of the principle of conservation of energy?
jnorman said:since energy absorbed by a BH is no longer available to the universe
mathman said:The conservation law applies to the total of mass plus energy. This total includes the dark energy. The dark energy density (according to current theory) is constant as a function of time. Since the universe is expanding, the total energy in the universe is increasing, rather than constant.
bcrowell said:There is no conservation law for a scalar mass-energy in GR that applies globally in all spacetimes. However, there are measures of mass such as the Komar mass that apply in special cases. The Komar mass is defined and conserved in asymptotically flat spacetimes. If you have a black hole in an asymptotically flat spacetime and drop some mass into it, the total Komar mass is conserved. As PeterDonis pointed out, conservation of mass-energy doesn't have anything to do with whether the mass-energy is "available."
bcrowell said:It's not increasing, just undefined. We have a FAQ about this: https://www.physicsforums.com/showthread.php?t=506985
PAllen said:Are you sure you mean Komar mass? That is only defined for stationary spacetimes, which technically cannot accommodate matter falling into a black hole. What is conserved in an asymptotically flat spacetime is ADM mass.
since energy absorbed by a BH is no longer available to the universe, why is that not a violation of the principle of conservation of energy?
pervect said:As far as I know, the observer outside the event horizon doesn't see any energy, clasically.
pervect said:And non-clasically he just sees Unruh radiation, which he would see if he were accelerating at the same rate as he needed to be accelerating in flat space-time.
pervect said:As far as I know, the observer outside the event horizon doesn't see any energy, clasically. And non-clasically he just sees Unruh radiation, which he would see if he were accelerating at the same rate as he needed to be accelerating in flat space-time.
I might have gotten the later part slightly wrong, I'm not as familar with the QM aspects as I wish I was - but i think it's close.
There is a place where observers are expected to be fried when falling into relaitic rotating or charged black holes, but that's due to the effect called "mass inflation" and it occurs inside the event horizon. http://casa.colorado.edu/~ajsh/bhtalk_07/inflation.html has a short note, the same author has some more detailed papers.
A black hole is a region in space where the gravitational pull is so strong that nothing, including light, can escape from it. This happens when a massive star collapses under its own gravity.
Conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another. In the case of black holes, the energy of a collapsing star is transformed into gravitational potential energy, which is then stored within the black hole.
No, black holes do not violate the law of conservation of energy. While it may seem that energy is disappearing into the black hole, it is actually being transformed into a different form, as explained by Einstein's theory of general relativity.
Hawking radiation is a theoretical form of radiation that is believed to be emitted by black holes. This radiation carries away a small amount of energy from the black hole, causing it to slowly lose mass. However, this does not violate the law of conservation of energy as the lost energy is balanced out by the gain in energy of the emitted radiation.
No, conservation of energy is just one of the many laws of physics that apply to black holes. Other laws, such as conservation of momentum and angular momentum, also play a role in understanding the behavior of black holes.