Re: Do you believe in black holes?


"dlzc" <dlzc1@xxxxxxx> wrote in message
news:1190838331.936256.48420@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Dear George Dishman:

On Sep 26, 8:37 am, George Dishman <geo...@xxxxxxxxxxxxxxxxx> wrote:
On 26 Sep, 14:34, "N:dlzcD:aol T:com \(dlzc\)" <dl...@xxxxxxx> wrote:
"George Dishman" <geo...@xxxxxxxxxxxxxxxxx> wrote in message
news:1190792960.351724.200810@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On 25 Sep, 18:14,dlzc<dl...@xxxxxxx> wrote:

... we are going pretty far afield ...

I think some of this, particulary what is meant by
"information", is fundamental to our understanding
of the paper.

...
Unless I am mistaken, the photons in thermal radiation
carry no information.

"Black body radiation" is information.

Not in the QM sense AFAIK, the emission is random
and does not carry information about the source.

Heat transfer is to a body at its temperature. A real body is or is
not black, as far as absorption/emission. Is temperature
"information"?

No, in this context "information" is the quantum
numbers of the particles that entered the black
hole to provide it with its mass.

Absorption / emission
spectra is information. As to whether this
contributes to the "information loss paradox",
probably not. You lose this (in some sense)
when an emitter is eclipsed by, say, the Moon.

Whether the stuff from which it is emitted is ordered
or not makes no difference to the radiation, thus
thermal radiation from a black but highly ordered
crystal is indistiguishable from thermal radiation from
any other source.

You will have a characteristic emission when a
particular bond is formed. Note that diamond only
emits at a handful of wavelengths, so would be
quite distinguishable.

No, thermal black body radiation is described by
Planck's Law and is independent of the material.

Sorry, no.
http://links.jstor.org/sici?sici=0080-4630(19361202)157%3A892%3C579%3AFWOTTO%3E2.0.CO%3B2-B
http://www.freepatentsonline.com/5883388.html

Diamond also only emits light near its bond energies.

Yes, the paper describes the spectra spcific to the
material which is nothing to do with black body
radiation:

http://en.wikipedia.org/wiki/Black_body

Hawking radiation is black body and AIUI that
means it is generated randomly and doesn't
carry any information in the quantum sense.

But whether any
of this is part of "information loss" remains to be seen.

...
The concept of curvature comes fom GR and in
that theory what I said is (I believe) true, though my
knowledge is superficial.

And what I said is also true George.

I am not so sure, but you say a couple of different
things. GR says stuff goes in and has no alternative

... based on the known laws of physics (GR does not require that
something be stronger than neutron degeneracy pressure) ...

and that the effects of the stuff that went in affect
external stuff, but is that via 'FTL' virtual particles
from the stuff 'now' inside or normal causal effects
delayed from just before it went in?

I *want* to try a "speed of gravity experiment", to see when the
"distance differentiation" between a BH and a "large enough" mass that
is being swallowed is non-detect. Is the added mass instantly
available "at center" (or "on shell") or do we see it travel that "20
miles" at c? Certainly GR will expect c...

AIUI, the horizon expands as the mass enters in the
way that the contour lines on a map of your bedspread
would expand around one foot as you slid the other
(under the sheets) over to join it. The resulting
bulge radiates gravitational waves until the BH becomes
spherical again.

Einstein even mentions it
(along with Mach) as "reasons why". Doesn't mean,
that like aether in Maxwell's equations, it doesn't fall
out in the derivation as unnecessary. Meaning that
the question of whether or not true cannot be
answered by this particular "knowledge set".

That was what I meant regarding quantum
gravity, the new theory may replace the
concept of curvature rather than explaining
it other than as an approximation to the
new model.

In some other subsequent theory, the concept
of curvature may not even apply thus
hypothetically some quantum gravity model might
describe gravity as the exchange of virtual gravitons
in a perfectly flat Minkowski spacetime, who knows.
You cannot take a featue that is a hypothesis of one
theory and assume the feature is correct but the
theory that gives it its existence is false.

But you cannot assume an argument based on
no-aether, to make a proof against aether (as a
sylogism) using a theory that has no "grasp" on
either condition.

No, I'm not doing that, I am only giving a counter
example as proof that it is _possible_, I'm not
trying to prove that there _won't_ be curvature, we
simply don't know. It's like saying that since SR
doesn't have an aether and produces the same
conclusions as LET, it is possible that future
theories won't have an aether (and vice versa!).

We'll see what you said to my confusion about your position below...

GR starts with spacetime issuing
from mass/energy, and inertia being a property
of the Universe and expressed at each bit of
mass, but loses any sense of that in its
derivation. You apparently take that as meaning
that such has been disproven. What it really
means is that GR is entirely transparent to that
question.

GR says the metric is distorted by stress/energy, not
that it "issues from" it, but your are right about
inertia.

How are "the field" and "the Universe" different, in your opinion
George? Einstein said "the field" was responsible for curvature.

I would have to see the context to see which "field"
he meant, I don't know the quote. It may be just a
question of terminology, I might be using "metric"
or perhaps the means the "field equations".

And we will continue to disagree. And it cannot be
experimentally disproven, since there is no stretch
of space that does not have two bits of matter /
energy either propagating through it, or "staring" at
each other across it. Only in "models" is such
"pure" spacetime availaable.

The GR model is quite clear on the matter though,
ripples can progress through the metric without
the need for matter other than the source:

There you go again... "without the need". Maybe English is just too
imprecise.

I think it is quite precise, a single accelerating
mass can generate gravitational waves, a single test
mass at some distance will respond to those and there
is no _need_ for any other masses in between to
propagate the wave.

Too bad I don't know another! ;>P QM does it all without
any spacetime / metric / curvature... whatever it does.

Yes, it is couched in flat space but QED merges
QM with the weak field approximation of GR, in
other words it is asymptotically accurate for
small but non-zero curvatures.

http://lisa.nasa.gov/WHATIS/grav-wave.html

If LISA detects the waves then the model is as
well proven as you get in science, the ISM is
particles at a very low density so there is a
lot of empty space between them that those waves
must have crossed.

The volume is not empty. The volume only contains little if any
matter.

The waves would propagate equally well if it
contained no matter whatsoever.

It still serves the thermodynamic purpose of providing
"available states" between all the bits of matter around (not
necessarily near) it. As well as conveying light.

But gravitational waves are not light, nor are
they thermodynamic in nature.

And like the other dualities that theories have in
their formulations, the fact that neither "opposite"
viewpoint can be experimentally falsified, means
it is not a "good" question.

It isn't a question of falsification at this point.

Your argument (copied from above)...

No, the external gravitational effects are the
result of the curvature of the metric external
to the horizon, and of course that region is
always outside.

... is devoid of mention of the matter/energy that
the curvature issued from. As if *your
interpretation* were the only one that survives. I
don't agree, and I apologize for bringing it up.

GR is a set of equations, "interpretation" doesn't
come into it IMHO. It should be possible to look at
the model of a BH and say where an external
influence at some time originated, near but outside
the horizon or inside. My point is that the result of
that is only valid within GR, and GR only gives one
answer.

It give two different answers, apparently.One in terms of its
"founding principles", and (at least) one in terms of the formalisms
adopted to produce quantifiable predictions.

First I heard of that, what are these "two different
answers" and what was the question? AFAIK only the
equations make any predictions.

<snip - no argument>

Virtual exchange particles, responsible for
among other things the charge interaction, don't
care about c, distance, path or time. We don't
need to imagine that charge is somehow frozen
at the horizon, because Nature clearly does not
care even at energy levels we can easily
comprehend.

"Nature clearly does not care" ... can you justify
that observationally?

Quantum Mechanics (in which I am not an expert).
Virtual exchange particles travel all paths, and all
speeds to make a single exchange. These paths
are not exclusive of "going the wrong way", and
these speeds are not limited to c.

No, but can they cross the horizon? I don't know
what the theory says but you seem to imply that
there is already observational evidence that they
do, and I don't know what evidence you suggest
does that.

I will refer you to a post by Bilge, to dlzc, 2002Oct18:
<QUOTE>
... Look up "interaction free measurement". In effect, the idea is to
place an object in one path of a mach-zender interferometer and detect
the presence of the object without ever having a photon traverse the
path blocked by the object.
<END QUOTE>

Without observers on both side of a horizon, somehow communicating, we
cannot *know*.

I still don't get it David, sorry for being slow. You
said above "We don't need to imagine that charge is
somehow frozen at the horizon, because Nature clearly
does not care even at energy levels we can easily
comprehend.". How does a Mach-Zender Interferometer
demonstrate that nature doesn't care about the horizon?

...
That is the current thinking, yes. How does stuff
accrete? Jupiter shatters anything near it, that
does not orbit it...

That would happen, infalling material would be
"spaghettified" and disintegrate and the resulting
dust would go into orbit - angular momentum is
conserved.

How would dust "go into orbit"? Shoemaker Levy
did not go into orbit.

Shoemaker Levy _was_ in orbit, around the Sun. It
didn't reach perihelion because it hit Jupiter
first. Likewise the infalling material would be
on an elliptical (cometary) orbit but would be
intercepted by the existing accretion disc
material. We certainly know such discs exist
around many high mass candidates, it gets in
the way and is one of th main reasons why they
remain candidates!

We can't see them without the radiation, and we cannot imagine this
radiation without "accretion disc interactions".

Not quite - we can see radiation whose characteristics
suggest it comes from an accretion disc. The brightness
of that is vastly greater than the Hawking radiation
fom the black hole (if it exists). The comparison is
betwen thermal radiation from a source light years
across with a temperature of millions of degrees to an
object a few km in radius with a temperature of
millionths of a degree.

Pleh! (A sound of
general disgust.) The material being ingested, in many cases, was "in
orbit" around the BH's companion star. I feel the strong Irish farmer
lifting himself by his own bootstraps again...

Yes, it was part of the companion, got sucked off
(Roche limit), crossed to the surroundings of the
black hole where it merged with the accretion disc
at the outer edge. Over a long time, it spirals in
towards the central edge of the disc then falls off
and into the hole. It takes that time to get rid of
the angular momentum. What's your problem?

Not saying that you coudl not get a gravitational
boost, lose some momentum to the BH, and end
up with some sort of elliptical orbit. But in this
highly curved space, this is the same result as
being ingested directly.

No, it is a parking orbit where it waits to lose
angular momentum in some manner before it is able
to fall in. Within a certain radius, the path are
no longer orbits but spiral in towards the horizon,
beyond that however, almost normal orbits exist.

If 2M is the event horizon, 3M is the photon sphere, and 4M is the
lowest stable matter orbit. I think.

I believe it's 6M for the latter.

but generate "friction", to stop the bulk of
anything "infalling" from actually entering... ?

New material will experience friction in the form
of collisions with the disc material until it is
aggregated into it, the kinetic energy of the
differential speed being converted to heat.

*What* disc material George? The BH collapses
to either just outside the event horizon, or across
it. It swept that area clear. *What* disc mateial?

The accretion disc we see round most such objects
which hides our view of the BH.

"See" no. "Assume based on what we can imagine, based on what we can
measure" yes.

IMHO, ".. based on what we can measure" is "seeing"
in scientific parlance. In astronomy, that is closer
to the truth than many other disciplines.

....
It comes from the accretion disc, not the hole
itself.

Still unanswered.

Well see above, I see no problem at all in envisioning
a Saturn-like model with the ocassional comet being
ruptured by, and amalgamated into, a much denser and
hotter disc, AKA 'ring system'.

I am not convinced that you can get a disc from captured
material.

We see them round newly forming stars and other
systems so why not around black holes. Observations
suggest they are there.

Agreed. However, we do not see that in *this* solar system. Here we
see skies "swept clean" of most debris, with the notable exception of
the asteroid belt and planetary rings.

Sure, there is no more material left, but that doesn't
justify saying that you _cannot_ get a disc from captured
material where such material _is_ available.

...
I won't hazard a guess at figures but see if you
can find some 'typical' mass loss rates.

I am sure it is upwards of tens-of-Earths per
second, depending on "typical".

And at a significant fraction of the speed of
light, that's a lot of energy.

I don't have a problem with that. I have a problem
with it being trapped at an ever denser surface.

Saturn's rings don't sit on a surface!

Saturn's rings are quite far from the surface of the planet, such that
its atmosphere has negligible drag.

Radius 2M

The accretion disc is *all about*
drag, which is where the emissions are supposed to be coming from.

There is 'drag' betwen the particles _within_ the rings,
regular random impacts spread the momentum over all the
particles.

I have problems that they did
all this with a metric that is singular at the event
horizon, they get unexpected behavior at the
event horizon, and they had a choice of merics
that breeze past it with no issues. A polite wave
of the hand that "we don't have a problem with
the choice of metric" is not an answer.

Yes, that made me wonder too.

Well, then I guess they have a job for the future, figuring out how
"information" translates with Eddington or Kruskal as metrics. Maybe
you cut the trees down you can with the tools at hand, merely to
identify which trees you need different tools for?

I don't think the choice of metric matters, information
is quantum and attributed to particles themselves, not
their motions.

...
I think they are saying that as it falls in, they
have found a new quantum mechanism to generate
radiation which means sufficient energy gets
removed to prevent the horizon forming.

It has to be turned into rotational kinetic energy
George.

The material cannot spin faster than the speed of
light David. At the maximum stable speed, only a
small fraction of the energy is kinetic. Again
think of a fast particle of interstellar dust that
would pass throught the solar system hitting an
ice cube in Saturn's rings. There's a lot of
jostling for a while but eventually it all settles
down with the ring material a little hotter.

"Tens of Earth per second", George. Sorry, does
not compute.

Why not, bear in mind the size of the disc.

It had to start with *nothing*, because the area was swept clean.

Why do you think it is swept clean?

http://rsd-www.nrl.navy.mil/7213/lazio/GC/

Loads of stuff there!

Still does not compute.

Stuff arrives and it leaves and sometimes it
falls in, just the luck of the draw for a
passing star.

It is not
"disspating energy of collapse", but providing a
"force" to accelerate this mass, where neutron
degeneracy pressure is insufficient to do so.

Simple gravity accelerates the infalling material
up to more than disc speed and collisions capture
the material, what is the problem with that view?

What is stronger than neutron degeneracy pressure,
George?

Why do you think any strength is needed? At the
temperatures observed, it is all plasma.

Because according to them, mass, charge, spin, *everything* is
prevented from collapse. Neutron stars are not all cold, surface
interactions are quite easily detectable, even though the time
dilation on their surfaces is quite high. But our current BH
candidates *have no such surface interactions*. But they "must" have
this mysterious radiation that we cannot yet detect.

They have no surface David how can they have surface
interactions? If the material evaporates while falling
it never gets to a surface because there is no surface
to reach. The only thing that puzzlews me is what is
pulling the stuff in if nothing that went before
remains, but I'll have to read the paper in more
details for that, I've only had the most cursory of
reads so far.

Only that we never see it. It is an old lamp
with new polish, it seems to me.

I think the "pre-Hawking radiation" is the new
aspect. Whether that radiates enough to prevent
formation might need more careful modelling and
certainly they need to show that there remains a
threshold above which the observable radiation
falls as the mass rises.

It is insufficient to *maintain a surface* George.

Nobody is talking about *maintaining a surface* David.

Yes. That is what they are saying. This stuff all floats
outside the event horizon.

"Floats", like dust around Saturn, no surface.

Touched already. No orbit possible inside of 4M.

6M I think, so you have a ring with an outer edge at
say 100,000M and the inner edge near 6M.

And no initial
massive ring there because it went in with the rest of the BH, or it
also evaporated in a cloud of magic "pre-Hawking" fairy dust.

Think of methane raindrops on Titan - some
models say that as they fall, the temperature
rises and they evaporate before they rach the
ground.

Virga.

?

We had a word for what you are describing. Rain can be seen to fall
from a cloud, and evaporate before it makes it to the ground. Such is
called "virga".
http://en.wikipedia.org/wiki/Virga

Neat, thanks, not one I had heard before.


We can stop now, since the OP appears to be long gone. I understand
that you are simply responding with defense of this paper, and that
you have no particular axe to grind.

None at all, in fact I am sceptical too, but I am
hoping both of us will be able to have a better
understanding of the paper if we remove any
misconceptions by debating the various aspects.

George


.

Quantcast