Light inside a black hole?

If you move to the centre of a black hole, where gravitational forces sort
of cancel, can light and normal matter exist in some area there?

Or does the black hole simply get denser when you move towards it center,
as opposed to haveing a center with a dense shell around it (black egg)?


As a follow up question: Is what we see of the universe perhaps the inside of
a black hole?

Sorry, early morning question :-)

"Jan Panteltje" wrote in message ...
If you move to the centre of a black hole, where gravitational forces sort
of cancel, can light and normal matter exist in some area there?

Gravitational forces don't cancel because the mass of a
black hole (except for the infalling matter from its
"feeding") is located at a singlularity at the center.
Gravitational acceleration and tidal forces increase
without limit as you approach the center.


Or does the black hole simply get denser when you move towards it center,
as opposed to haveing a center with a dense shell around it (black egg)?

There's no shell. The event horizon is about as substantial
as a property line; it just demarkates the boundary beyond
which there's no escape.



As a follow up question: Is what we see of the universe perhaps the inside of
a black hole?

No, the physics isn't right. Inside the event horizon of
a black hole theory indicates that spacial coordinates
take on a timelike property. That is to say, all
trajectories (paths of particles) lead inexorably towards
the central singularity, much like time inexorably leads to
the future outside of the event horizon. In our space
environment we have freedom to move freely in all directions,
and we don't see any evidence of a single point of
convergence.


Sorry, early morning question :-)

On a sunny day (Fri, 5 Jan 2007 09:31:03 -0500) it happened "Greg Neill"
wrote in
:

"Jan Panteltje" wrote in message ...
If you move to the centre of a black hole, where gravitational forces sort
of cancel, can light and normal matter exist in some area there?

Gravitational forces don't cancel because the mass of a
black hole (except for the infalling matter from its
"feeding") is located at a singlularity at the center.

But why? image for a moment matter falling into a body.
As its mass increases, the escape speed from it will increase.
At some point the escape speed will be greater then C, so light cannot escape,
we no longer see any EM waves coming from it, we call it a black hole
(is this correct?).

There is nothing that says that the thing could not be a bit hollow, its being
black only depends on the escape speed.

(I could imagine somebody compressing an object, to comprss it all the
way to the center may be prevented by the outer layers becoming too strong).


Gravitational acceleration and tidal forces increase
without limit as you approach the center.

Nobody has been or even measured anything there via remote methods.
So that would be a postulate, creating nasty infinities.
Nature does not accommodate infinities :-)

Or does the black hole simply get denser when you move towards it center,
as opposed to haveing a center with a dense shell around it (black egg)?

There's no shell. The event horizon is about as substantial
as a property line; it just demarkates the boundary beyond
which there's no escape.

I agree with that (except for 'evaporation' of particles).

Dear Jan Panteltje:

Jan Panteltje wrote:
On a sunny day (Fri, 5 Jan 2007 09:31:03 -0500) it happened "Greg Neill"
wrote in
:

"Jan Panteltje" wrote in message ...
If you move to the centre of a black hole, where
gravitational forces sort of cancel, can light and
normal matter exist in some area there?

Gravitational forces don't cancel because the mass of a
black hole (except for the infalling matter from its
"feeding") is located at a singlularity at the center.

But why? image for a moment matter falling into a body.
As its mass increases,

The mass of infalling matter does not increase. Its "kinetic energy"
comes from the gestalt of the BH, so crossing the EH makes any change
in "system center of mass" problematic.

David A. Smith

On a sunny day (5 Jan 2007 07:45:35 -0800) it happened "dlzc"
wrote in . com:

Dear Jan Panteltje:

Jan Panteltje wrote:
On a sunny day (Fri, 5 Jan 2007 09:31:03 -0500) it happened "Greg Neill"
wrote in
:

"Jan Panteltje" wrote in message ...
If you move to the centre of a black hole, where
gravitational forces sort of cancel, can light and
normal matter exist in some area there?

Gravitational forces don't cancel because the mass of a
black hole (except for the infalling matter from its
"feeding") is located at a singlularity at the center.

But why? image for a moment matter falling into a body.
As its mass increases,

The mass of infalling matter does not increase.

I was trying to say that the mass of the body increaes.

Dear Jan Panteltje:

Jan Panteltje wrote:
On a sunny day (5 Jan 2007 07:45:35 -0800) it happened "dlzc"
wrote in . com:

Dear Jan Panteltje:

Jan Panteltje wrote:
On a sunny day (Fri, 5 Jan 2007 09:31:03 -0500) it happened "Greg Neill"
wrote in
:

"Jan Panteltje" wrote in message ...
If you move to the centre of a black hole, where
gravitational forces sort of cancel, can light and
normal matter exist in some area there?

Gravitational forces don't cancel because the mass of a
black hole (except for the infalling matter from its
"feeding") is located at a singlularity at the center.

But why? image for a moment matter falling into a body.
As its mass increases,

The mass of infalling matter does not increase.

I was trying to say that the mass of the body increaes.

That is what I am telling you is incorrect. The BH gains the mass of
the body, and vice versa. But not as a function of the body's speed.

We cannot pass by each other at large fractions of the speed of light,
and turn one another into black holes.

David A. Smith

Dear Jan Panteltje:

"Jan Panteltje" wrote in message
...
On a sunny day (5 Jan 2007 07:45:35 -0800) it happened "dlzc"

wrote in
. com:

Dear Jan Panteltje:

Jan Panteltje wrote:
On a sunny day (Fri, 5 Jan 2007 09:31:03 -0500) it happened
"Greg Neill"
wrote in
:

"Jan Panteltje" wrote in message
...
If you move to the centre of a black hole, where
gravitational forces sort of cancel, can light and
normal matter exist in some area there?

Gravitational forces don't cancel because the
mass of a black hole (except for the infalling
matter from its "feeding") is located at a
singlularity at the center.

But why? image for a moment matter falling
into a body. As its mass increases,

The mass of infalling matter does not increase.

I was trying to say that the mass of the body
increaes.

I finally got it. There is no black hole yet. The body you are
speaking of is at some threshold. It accumulates more mass.
Then you started talking about what happens next.

I need to practice "reading for comprehension". Sorry.

David A. Smith

"Jan Panteltje" wrote in message ...
On a sunny day (Fri, 5 Jan 2007 09:31:03 -0500) it happened "Greg Neill"
wrote in
:

"Jan Panteltje" wrote in message
...
If you move to the centre of a black hole, where gravitational forces sort
of cancel, can light and normal matter exist in some area there?

Gravitational forces don't cancel because the mass of a
black hole (except for the infalling matter from its
"feeding") is located at a singlularity at the center.

But why? image for a moment matter falling into a body.
As its mass increases, the escape speed from it will increase.
At some point the escape speed will be greater then C, so light cannot escape,
we no longer see any EM waves coming from it, we call it a black hole
(is this correct?).

There is nothing that says that the thing could not be a bit hollow, its being
black only depends on the escape speed.

(I could imagine somebody compressing an object, to comprss it all the
way to the center may be prevented by the outer layers becoming too strong).

A black hole forms when the pressure due to self-gravitation
of the constituents exceeds the support capability of these
constituents. That is, when the inward pressure exceeds the
electron degeneracy pressure of matter, there is nothing
that can prevent gravity from "winning" and collapsing the
matter to a singularity (nothing, that is, that we currently
know about). There is no known from or state of matter that
can withstand the pressures created by gravity at the extremes
of a black hole.



Gravitational acceleration and tidal forces increase
without limit as you approach the center.

Nobody has been or even measured anything there via remote methods.
So that would be a postulate, creating nasty infinities.
Nature does not accommodate infinities :-)

That, too, is a postulate! Since we haven't been there, we
cannot know. General Relativity, which should hold true until
very close to the purported singularity, indicates that the
end of all matter entering the black hole will be to end at
a singular point at its center.


Or does the black hole simply get denser when you move towards it center,
as opposed to haveing a center with a dense shell around it (black egg)?

There's no shell. The event horizon is about as substantial
as a property line; it just demarkates the boundary beyond
which there's no escape.

I agree with that (except for 'evaporation' of particles).

One could speculate that the same process that generates
the particle pairs for Hawking Radiation might increase
in effect as one approaches the singularity, so that rather
than being devoid of matter between the horizon and singularity,
the mass is spontaneously and continuously being recycled
close to the singularity as particle pairs. So the
space inside could be populated by a continuously annihilating
soup of particles which increases in density towards the
center.

On a sunny day (Fri, 5 Jan 2007 12:05:20 -0500) it happened "Greg Neill"
wrote in
:

Gravitational acceleration and tidal forces increase
without limit as you approach the center.

Nobody has been or even measured anything there via remote methods.
So that would be a postulate, creating nasty infinities.
Nature does not accommodate infinities :-)

That, too, is a postulate! Since we haven't been there, we
cannot know. General Relativity, which should hold true until
very close to the purported singularity, indicates that the
end of all matter entering the black hole will be to end at
a singular point at its center.

I do not know enough about particle physics to argue one way or the other here.
But 'singular point' is purely theory, and if I would bet, then I would bet
that it is of finite size.
If _anything_ in nature was infinite, then there would be no place for us to exist :-)'
A bit philosophical perhaps.

For example, we say the electron is a point charge, but at the same time they
are trying very hard to find out what its size is :-)

Assuming those exist, if you press hard enough and all the quarks become lose,
and a quark-soup, can these occupy zero space? Or even the same space?
If not, then we no longer have a point.
Perhaps long before that new structures form..... structures we do not even
now know about.

But _point_ no, no point :-)

"Jan Panteltje" wrote in message ...

For example, we say the electron is a point charge, but at the same time they
are trying very hard to find out what its size is :-)

True. All measurements to date are consistent with an electron
radius of zero.


Assuming those exist, if you press hard enough and all the quarks become lose,
and a quark-soup, can these occupy zero space? Or even the same space?
If not, then we no longer have a point.
Perhaps long before that new structures form..... structures we do not even
now know about.

There would needs be new forces that come into play for
any structure to exist that opposes the gravitational
pressure. So far there's no sign of any such thing.


But _point_ no, no point :-)