[Jarek Duda (OP)]

The hypothetical Hawking radiation means that a set of baryons can be finally transformed, "evaporate" into a massless radiation - that baryons can be destroyed. It requires that this matter was initially compressed into a black hole.
If baryons can be destroyed in such extreme conditions, the natural question is: what is the minimal density/heat/pressure required for such baryon number violation? (or while hypothetical baryogensis - creating more baryons than anti-baryons).
While neutron star collapses into a black hole, event horizon grows continuously from a point in the center, like it this picture from: http://mathpages.com/rr/s7-02/7-02.htm

As radius of event horizon is proportional to mass inside, the initial density of matter had to be infinity. So if baryons can be destroyed, it should happen before starting the formation of event horizon - releasing huge amounts of energy (complete mc^2) - pushing the core of collapsing star outward - preventing the collapse. And finally these enormous amounts of energy would leave the star, what could result in currently not understood gamma-ray bursts.

So isn't it true that if Hawking radiation is possible, then baryons can be destroyed and so black holes shouldn't form?

We usually consider black holes just through abstract stress-energy tensor, not asking what microscopically happens there - behind these enormous densities ... so in neutron star nuclei join into one huge nucleus, in hypothetical quark star nucleons join into one huge nucleon ... so what happens there when it collapses further? quarks join into one huge quark? and what then while going further toward infinite density in the central singularity of black hole, where light cones are directed toward the center?

The mainly considered baryon number violation is the proton decay, which is required by many particle models.
They cannot find it experimentally - in huge room temperature pools of water, but hypothetical baryogenesis and Hawking radiation suggest that maybe we should rather search for it in more extreme conditions?
While charge/spin conservation can be seen that surrounding EM field (in any distance) guards these numbers through e.g. Gauss theorem, what mechanism guards baryon number conservation? If just a potential barrier, they should be destroyed in high enough temperature ...

Is matter infinitely compressible? What happens with matter while compression into a black hole?
Is baryon number ultimately conserved? If yes, why the Universe has more baryons than anti-baryons? If not, where to search for it, expect such violation?
If proton decay is possible, maybe we could induce it by some resonance, like lighting the proper gammas into the proper nuclei? (getting ultimate energy source: complete mass->energy conversion)
Is/should be proton decay considered in neutron star models? Would it allow them to collapse to a black hole? Could it explain the not understood gamma-ray bursts?

[yor_on]

Isn't it two concepts?

One considering a compression, with the Hawking radiation being virtual pairs created at, or outside, a event horizon, annihilating mass inside the event horizon while its counterpart becoming 'mass' outside it?

So you get a balance, the universe keeping 'count'.

But I agree, it's a very tricky concept, and I'm not sure if I get it at all. It presumes something 'more' as it needs to keep 'count', inside as well as outside a event horizon. But the definition of a singularity should be that it exited all connections to the physics we know, as I get it?

[Jarek Duda (OP)]

Indeed this baryon destruction is spatially separated from production of Hawking radiation - as everything below horizon have to move toward the center and so all matter, or whatever have left from it, should be practically in the center.
So one puzzle is how their energy has traveled toward the horizon - it couldn't be done by photons, but let say it is done by gravitational field.

But the summary is: there were baryons ... pooof ... there are no baryons - they are not indestructible, baryon number conservation can be violated - like while baryogenesis.
If baryons can be destroyed, before getting to infinite density required to start formation of event horizon, neutron star should start burning its baryons in the center - there would be another stage of star evolution for massive neutron stars. Such explosion should temporary stop the collapse and (e.g. cyclically) release bursts of very high energetic radiation.

[yor_on]

Seen this Jarek?
http://dispatchesfromturtleisland.blogspot.se/2011/08/baryon-number-and-lepton-number-non.html

And just for curiosity, as it is discussing Feynman diagrams and the standard model.
https://www.simonsfoundation.org/quanta/20130917-a-jewel-at-the-heart-of-quantum-physics/

As for whether it has to move to a center I don't know, thought I did though

I mean, It's frame dependent, but I used to presume that in its own, local, definition it surely would find itself at a center in a measurable time. But then you have to question what other frames will define as being that time, relative their clocks. Doing so gives me a headache as we are discussing the inside of a event horizon, where the definition of that event horizon is that this is the place from where light and mass has only one path left, toward the center. That to me means that it cuts of from measurable physics into the unmeasurable, also relative a arrow. What will one kg:s acceleration be, relative passing some defined event horizon, one second (its local time) after it done so, sort of ? Is that dependent on the mass of that black hole as defined from a far observer? Or can I assume the same acceleration for all black holes, relative their event horizons, no matter what mass a far observer define? Especially if we to it add some descriptions in where everything inside a event horizon also becomes 'a center'. einsteinonline had a description of that, which I'm unable to find at the moment. I'll find a link to that later, I hope.
=

You could define it such as it is space that distorts though, 'c' being 'c', locally measured, in all circumstances, outside as well as inside a event horizon. Doing so, assuming a equivalence between a locally measured 'c' and ones local arrow, we come to a definition of a arrow continuing inside the event horizon, same as always, locally measured. But it neither solve what the path taken to that center would be, as measured from the outside, or inside, or where what that center 'is'.

[Jarek Duda (OP)]

Indeed, while Gauss law says that electric field on a closed surface (in any distance) determines charge inside - the whole EM field guards charge conservation (and analogously for spin), there are rather no similar, I would say topological, reasons for conservation of other numbers, like for leptons of baryons.
If so, what holds them together is a potential barrier of their structure - they are some local energy minimums. Energy barriers can be "tunneled" through due to thermodynamics in high enough temperatures, like maybe of the center of neutron star.

The main question is if black holes can even form, as before getting to infinite density required to start forming the event horizon, they should start burning baryons in the center?

[yor_on]

Wasn't there something about a gas cloud meeting a black hole, according to my somewhat faulty memory? Yes there was (had to google it though:) http://www.mpe.mpg.de/2189104/News_20130717

Don't know what data that may give, but we should get something from the 'collision'?
And I'll read your pdf, you're not that far from this 'jewel' if one think of that one as a topological representation of more dimensions than those we can measure, although I get the impression that your topological approach is contained in the 'four' we define as measurable?

[jeffreyH]

quantum loop gravity anyone?