Exploring Black Hole Anatomy: The Singularity, Event Horizon, and Photon Sphere

[Naty1]

"So when gravity is strong enough then matter turns into energy .."

That is speculation. Things start out that way and stars are born from clouds of gas, but then the nuclear processes run their course permitting further compression and greater density.

As stellar masses get more dense due to gravitational energy, things progress in density to electron degeneracy, then neutron, then quark, then apparently collapse to a black hole...by that time no one knows what happens to 'mass'...we believe the singularity is one of time, not space.

Regarding neutron stars:

Modern estimates range from approximately 1.5 to 3.0 solar masses. [before collapse to a black hole] [3] The uncertainty in the value reflects the fact that the equations of state for extremely dense matter are not well known.

In a neutron star less massive than the limit, the weight of the star is balanced by short-range repulsive neutron-neutron interactions mediated by the strong force and also by the quantum degeneracy pressure of neutrons, preventing collapse. If its mass is above the limit, the star will collapse to some denser form. It could form a black hole, or change composition and be supported in some other way (for example, by quark degeneracy pressure if it becomes a quark star). Because the properties of hypothetical more exotic forms of degenerate matter are even more poorly known than those of neutron-degenerate matter, most astrophysicists assume, in the absence of evidence to the contrary, that a neutron star above the limit collapses directly into a black hole.

Tolman–Oppenheimer–Volkoff limit
http://en.wikipedia.org/wiki/Tolman–Oppenheimer–Volkoff_limit

 

[Chalnoth]

"So when gravity is strong enough then matter turns into energy .."

That is speculation.

It's a bit worse than that. I didn't feel like pointing this out before, but I might as well now.

The statement that matter turns into energy doesn't even make sense. Energy is a property of matter. It doesn't have its own existence separate from matter (provided you have a broad definition of matter to include things like photons). Matter can turn into different forms. But it doesn't make any sense at all to say it turns into energy. Matter has energy, it doesn't turn into it.

 

[zhermes]

The statement that matter turns into energy doesn't even make sense. Energy is a property of matter. It doesn't have its own existence separate from matter (provided you have a broad definition of matter to include things like photons). Matter can turn into different forms. But it doesn't make any sense at all to say it turns into energy. Matter has energy, it doesn't turn into it.

Thats not correct use of the language. Matter specifically refers to things with rest-mass. Matter is a sub-type of energy---it must have rest-mass energy, and can possesses additional energy (i.e. kinetic, internal, etc). Photons are not matter, space(time) is not matter---both can have energy.
The statement that 'matter turns into energy' is not rigorously correct as matter is already energy. But colloquially, the 'energy' being referred to is energy in a more 'pure' form---e.g. radiation, or kinetic energy.

 

[Chalnoth]

Thats not correct use of the language. Matter specifically refers to things with rest-mass.

When the gluons in a proton/neutron make up most of their masses, this definition ceases to make sense. But whatever, that isn't important to my point. The next part is.

Matter is a sub-type of energy

No. This is completely wrong. Even if you don't call the gauge bosons matter, the fact is that they are not energy. They are particles that have energy. There is nothing more or less pure about a photon versus an electron.

 

[bill alsept]

Matter can turn into different forms. But it doesn't make any sense at all to say it turns into energy. Matter has energy, it doesn't turn into it.

Is energy just one form of motion or another as in momentum or angular momentum? I am confused as to what photons are . When mass gives off photons is it loosing anything or is it just radiating the extra energy that is being bottle necked into it? Is it like galaxies when too much matter is forced into the center at one time a quasar can form to relieve the excess? If E=Mc2 what are photons and what part do they play in GR? Is there an answer to the equation E/c2=?. Or can you do that?

 

[zhermes]

No. This is completely wrong. Even if you don't call the gauge bosons matter, the fact is that they are not energy. They are particles that have energy. There is nothing more or less pure about a photon versus an electron.

Matter has mass. Mass is a form of energy. Photons don't have mass, besides fractions the other gauge bosons do. The rest is a philosophical question of what is the intrinsic property of particles... I'm not sure that I disagree with you.

 

[Chalnoth]

Is energy just one form of motion or another as in momentum or angular momentum?

I'm not entirely sure of a colloquial way of explaining energy. Energy is a conserved quantity that arises because local laws of physics are invariant in time. Momentum, similarly, is a conserved quantity that arises because local laws of physics are invariant in with respect to location in space. Angular momentum is a conserved quantity that arises because the local laws of physics are invariant with respect to rotation.

All of these are properties of the fermions and bosons that inhabit space, whether you're talking about protons, electrons, photons, or whatever. They also contain other conserved quantities that are due to quantum-mechanical degrees of freedom, such as electric charge, weak hypercharge, and color (for the strong force interaction: not literal color, this is just what we call the strong charges).

I am confused as to what photons are . When mass gives off photons is it loosing anything or is it just radiating the extra energy that is being bottle necked into it?

A photon is a spin-1 particle with no rest mass that couples to electromagnetic charges. Because photons have no other quantum numbers, the only things that need to be conserved when a photon is emitted are momentum, angular momentum, and energy. Everything else is conserved automatically.

Is it like galaxies when too much matter is forced into the center at one time a quasar can form to relieve the excess? If E=Mc2 what are photons and what part do they play in GR? Is there an answer to the equation E/c2=?. Or can you do that?

This doesn't make any sense to me. A quasar doesn't form to relieve any sort of excess. A quasar forms because you have a lot of matter falling into the central black hole. When that matter is used up or blown away, the quasar turns off.

 

[Chalnoth]

Matter has mass. Mass is a form of energy.

Ergo matter has energy, but is not a form of it.