[Eric A. Taylor (OP)]

according to Relativity the perception of time, how long it takes for a second to elapse, depends on the relative velocity of the observers. Two people travailing at different speeds will not agree on the amount of time that has passed. This is also true of gravity.  A person standing on the surface of the moon will not agree with a person standing on Earth as to how much time has passed. Though it will take a very long time for them to notice the difference, the event horizon of a black hole has a much more powerful gravity field. So powerful that an observer at the event horizon would never say "when", as viewed from Earth, to signal the elapse of his first second. From that idea there should be no observable spin from outside the black hole.

This is just my own theory, but I imagine that if we were able to see below the event horizon of the black hole we'd see the surface of the star that collapsed to form it, still slowly (to us) collapsing. Should you decide to try and find this star you won't though. Assuming you can get passed the stretch you'd cross the event horizon after the star's surface, so you won't see it. However your own time perception will be slowed down. If billions of years later someone comes along and looks in they'll see you, still there just above the surface of the star.

[yor_on]

well, I think I can say one thing. If we assume that at the 'heart' of a Black hole there is a non dimensional 'singularity', then I believe it can have any spin it wants. It should behave just a strange as a photon at least. Both are 'point less' in main stream theory, so to speak. What differs them is the 'gravity' expected to act in their vicinity and that is then a result of a 'mass' getting so compressed (BH) that it surpass any mathematical descriptions, just as a photon seems to do in other ways.

[Soul Surfer]

Please listen.   At the heart of any rotating black hole there is NOT a non dimensional singularity!  That has been proved and accepted by experts for many years, see my earlier post for details of the simplest model of its structure.  Also there is absolutely no such thing as a non rotating black hole. So all this talk about mysterious non dimensional singularities at the middle of black holes is just rubbish talked about by "gee whiz" scientists and publicity idiots who really do not understand the theory.   Scwartschild black holes are just so improbable that you might as well think that they don't exist.    I really do wish that the text books would get it right.

[DM613]

I like your idea in place, although the "expansion" still gives me a headache, it should speed up with larger "zones", and quickly became superluminous as defined by measuring the movements of the stars " on? I do not see why we expect to accelerate at a pace stately, like all new areas should be as ready for further expansion as any old "space"? If anyone has bothered me for some time.

[imatfaal]

DM613 Your post is a slight re-write of Yo-rons post above.

Please stop this immediately! It is against forum rules and will result in a ban

[syhprum]

All the mystery of Black holes stems from the belief that matter cannot be compressed to a higher density than that found in a Neutron star, what is the evidence for this ?
Neutron stars can have an escape velocity c/2 so why not beyond the EV a Neutron star like object but of higher density

[yor_on]

I'm trying to understand what  JP wrote there?

" Space itself is being "pulled" at faster than the speed of light, and no matter how fast you go, you can't escape.  The same thing is happening with rotating black holes."

would that be a 'force' acting on SpaceTime? If you have one that can 'propel' space ftl, doesn't that imply that what creates that 'force' acting on space would be of a even greater magnitude? A 'infinite Gravity' in this case?

[Halc]

I'll pick one of the posts and comment as best I understand things, but I'm not speaking from authority here.

Nothing will break the speed of light in a vacuum. We can only see to the Event Horizon though, so if you want you might assume that past that there can be some other region with different laws of physics.

Some laws are different beyond the event horizon, and some not.  I doubt that local light speed is different beyond the singularity.

As I've seen it described in multiple places, we can consider normal spacetime to be 4 dimensions w,x,y,z.  Let's assign time to w, in a frame where a black hole is stationary somewhere.  x is towards the black hole (down).  y is tangential in the direction of its rotation, and z is the remaining axis.
Beyond the event horizon (EV as you call it), time is suddenly assigned to the x axis and w becomes just another spatial dimension in which matter can move in either direction.  Objects within a black hole can travel back in our time, but cannot get out.  There is no 'down' anymore because that direction is now the future.  Matter cannot get out of the black hole any more than you can travel to your own past.  There is no rotation anymore since there is no radius.  Motion is linear, but space is quite bent.  What appeared to be angular momentum translates into linear momentum in the direction of y.  All stuff is moving that way, and if anything is to accelerate away from that trend, an equal and opposite reaction (Newton still lives in there) is required.

I think it was SoulSurfer(?) that gave a beautiful explanation of where the black hole is thought to get its 'rotational energy' from? It was the direct result of all objects 'spinning', with the angular momentum growing relative its 'size' as it compressed into a 'point'. As it becomes that 'point' all laws of physics breaks down, and its mass becomes 'infinite' as i understands it.

As matter gets closer to the singularity (the end of time in the description above), yes, its mass/energy becomes infinite, but its negative gravitational potential energy becomes negative-infinite, so conservation of energy is preserved.  Yes, that infinite mass multiplied by the infinitesimal proximity to the central singularity yields an angular momentum that is preserved.

The Event horizon is the last outpost for our laws of physics, at least as we can measure, so assuming this is right then it would surprise me if we ever found any black Holes that didn't spin relatively close to light.

Black holes have angular momentum, and that isn't measured in units of 'speed', so no, they don't spin at the speed of light.

It must have to do with what mass they had before they collapsed and their 'spin' at that time.

Yes.  Whatever the cumulative angular momentum of the stuff falling in, the black hole preserves that.  The Hawking radiation will actually dissipate some of that momentum, as will gravitational effects.

Wonder if there are Black Holes of opposite spins?

All different spins.  The axis can be oriented any-which-way, but something like Sagittarius-A has a spin orientation very close to that of Milky-Way at large.  Surely there are pairs that have nearly identical axes but opposite spins.  That would just mean that if they merged, the resulting object would have less overall spin.

And there's one more thing, to me it's the gravity that has 'directions', not space as such. And as 'gravity propagates' at 'c'?

Gravity does not propagate.  It is a static field distortion, else it would be a violation of energy conservation.  Gravitons and gravity waves do propagate at c.

Black holes have less gravity than the stars that originally formed them, since a good deal of the mass of those stars gets blown away in the supernova event that leaves the black hole behind.  So if you were a planet orbiting the star at radius X (and you survived being that close to a supernova), the effect would be orbiting at a new radius greater than X due to the lower gravity, and it going completely dark when your star flashes bright and then goes totally out, exactly like an incandescent light bulb in its final moment.

[yor_on]

Thanks for your thoughts Halc
Don't know

According to Einstein it's a 'field'. whether that field has a propagation (propagations) or not I'm not sure, you can use a clock to define events, and then order them in some 'higher dimension' but locally that order is observer dependent. And that's where we live. You can also create static events bound by time in that higher dimension. In such a case there is no propagation except a local clock ticking, presenting you local 'sheets' of 'events'

[yor_on]

 A 'force' is one way to describe it, as in a waterfall (gravity) driving a mill, or wind doing the same. But it seems a limited case to me. If one want a 'field' then forces disappear. You need to add time to make them appear.
=

Or if you like, a 'clock'. That's 'local'
Time is more of a property to me

[evan_au]

All the mystery of Black holes stems from the belief that matter cannot be compressed to a higher density than that found in a Neutron star, what is the evidence for this ?

The surface density of a neutron star is somewhere around the density of a Lead nucleus (just zillions of times bigger, physically).

If you want to see what happens under higher pressures (like the center of a neutron star), you have to do experiments like smash lead nuclei together in a particle accelerator, and just such experiments are done at the LHC. The problem is that with no gravity to confine the results, the lead nuclei shatter into a cloud of other particles, so physicists have to rely on theory.

One theory is that the "strange" quark might be stable under the immense pressure at the center of a neutron star. The strange quark has much higher mass than the more familiar light quarks making up protons and neutrons. So maybe a "strange star" could be denser than a "neutron star"?
See: https://en.wikipedia.org/wiki/Strange_star

There are a few experiments proposed or underway now that may be able to test these theories on neutron stars and pulsars:
LIGO has detected its first neutron star merger. In this case, the final product became a black hole, rather than a bigger neutron star. With increased sensitivity and more detections, astronomers should be able to place tighter bounds on the size of neutron stars before they collapse into black holes.
See: https://en.wikipedia.org/wiki/GW170817#Astrophysical_origin_and_products

I saw a proposed satellite-based experiment measuring the radius and density of neutron stars by studying the spectrum of light emitted by pulsars, with very high resolution in time. By monitoring the red and blue shift, the surface velocity can be measured, and the pulse rate gives the rotation speed. Together, it should be possible to work out the size of the neutron star.

Yet another method proposes to use neutron star seismology to study the interior of neutron stars.
See: https://en.wikipedia.org/wiki/Neutron-star_oscillation

But once the central density of a neutron/strange star reaches a critical value where the escape velocity exceeds the speed of light, current theory suggests that nothing can withstand the plunge into a singularity at the center of a black hole.