That's an interesting observation! if they were crunched out of existence, a black hole would soon evaporate!
I have a similar question, still not really answered, about the big bang. At some point, only photons and elementary particles existed, so it seems to me the mass of the universe must have been very different. Theoretically, you should be able to raise the temperature to a point where only photons exist - and they do not have mass.
I have a similar question, still not really answered, about the big bang. At some point, only photons and elementary particles existed, so it seems to me the mass of the universe must have been very different. Theoretically, you should be able to raise the temperature to a point where only photons exist - and they do not have mass.
I see no suggestion that the ergosphere of Sgr A* contributes to the precession of S2's orbit. It appears to be just normal Schwarzschild precession.
Indeed, how large IS the supermassive black hole's ergosphere?
For future reference: S2's closest approach to Sgr A* is around 20 billion kilometres (120 times the distance between the Earth and the Sun).
https://www.mpg.de/14692117/detection-of-schwarzschild-precession-in-the-orbit-of-star-s2
Photons have no rest mass
However, they do have energy.
Spacetime is curved by both mass and energy.
I should clarify my previous statement.
The singularity is a place where matter is compressed down to an infinitely tiny point.
It is all our conceptions of time and space that completely break down, ie., no longer exist.
I guess the question is 'what is the difference between Schwarchild precession and frame-dragging?
So, if spacetime is curved by both mass and energy, and we know spacetime is perturbed by gravitational events eg neutron star mergers leading to 'ring down' events that can be picked up by LIGO, surely it follows that energy aka rest-massless particles can also perturb spacetime?
Ccirca 1 x 10^55 kg give or take 1 order of magnitude (I'm typing this from memory).
I'm thinking of Stephen Weinberg's 'The First Three Minutes' and the BB initial temperature of 100 million trillion trillion kelvins (now I did look that up, and have to confess I absolutely prefer scientific notation eg 10^30 rather than this 'trillion trillion' or whatever stuff.
I'm thinking of Stephen Weinberg's 'The First Three Minutes' and the BB initial temperature of 100 million trillion trillion kelvins (now I did look that up, and have to confess I absolutely prefer scientific notation eg 10^30 rather than this 'trillion trillion' or whatever stuff.
Is that 10^37 Kelvin? Not something that can be generated in the LHC, so we know the Higgs bosun must have come much, much later, relatively speaking. So, I'm wondering how much mass was added as the universe cooled during its initial phase.
Schwarchild precession is simply due to the presence of a 'central' mass.
Whereas frame-dragging is due to the rotation of the 'central' mass.
The total precession would be calculated by combining the Schwarchild precession with the frame-dragging precession.
However, given the distance scales involved, frame-dragging (which has a fluid-dragging analogy) would be more applicable to the accretion disc of a black hole.
You mean that the linear velocity (v) at the equator can approach the speed of light.
v = r ω (where r = the radius of the star and ω is its angular velocity).
I've seen one example of the linear velocity of a neutron star at its equator - 70,000 km per second or approximately 24% of the speed of light.
If you want some fun, and you've not come across it before, look up quantum field theory and the unruh effect...
The Unruh effect has never actually been observed, so it may be time for you to take an early (hot) shower! 
Many things - including a number that have been discussed here - have not yet been seen.. That doesn't make them uninteresting... QFT is interesting...
I certainly didn't say that QFT was "uninteresting".
Perhaps my brilliant play on words, replacing Wiki's "thermal bath" with "hot shower", went unnoticed! 🙂
https://en.wikipedia.org/wiki/Unruh_effect