"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:LouPe.125018$E95.97822@fed1read01...
Dear Martin Brown:

"Martin Brown" wrote in message
...
N:dlzc D:aol T:com (dlzc) wrote:

Dear Martin Brown:

"Martin Brown" wrote in message
...
....
And he can still see the fixed stars outside the BH.

That is what Andrew's simulations show, yes. Yet the photon sphere will
be continually ingested/drained by an expanding hole, and the Einstein
rings will sucessively give up some of their contents. At least.

Sorry but I cannot make any sense of the last two sentences.
You won't be able to see anything out of an active feeding BH
since it will be surrounded by opaque dense relativistic plasma.

WE
ARE
TALKING
ABOUT
A
FALLING
PERSON
INSIDE.
How is the world is he supposed to see specular images through an opaque
dense relativistic plasma (shades of the CMBRM, Batman!), Martin? Can we
see through the CMBRM?

David, before shouting at people, remember you were talking
about a black hole, not the big bang at this point:

"And he can still see the fixed stars outside the BH."

There is no "opaque dense relativistic plasma" around
many black holes. At the event horizon, there is nothing
but vacuum so the person inside can look back and see the
external stars. Obviously this would be different for a
BH that has a disk fed from a companion but again you
can still see out to that disk and the bottom of any jets.

George

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:5JPOe.124798$E95.60198@fed1read01...
Dear George Dishman:

"George Dishman" wrote in message
...

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:yUwOe.124442$E95.97537@fed1read01...
Dear Geroge Dishman,
....
I understand what you are saying, George. Now try these:
URL:http://www.aleph.se/Trans/Global/Omega/baby.txt

David, is there a way to get rid of the "URL:" part,
it breaks the link in Outlook Express because the
text is no longer a URL if you put "URL" in front.

I intentionally add the URL:, so that Outlook Express and other readers
will correctly form long links. Oh well... FWIW the links work for me.

Sometimes it does for me too but the definition
of a URL starts with the protocol to be used
followed by a colon. You are telling the software
to use the "URL" protocol instead of "HTTP".

I'll trim a lot because we have really covered
it.

But nothing else did, nor did it it in any particular talk about the
production of an inner Universe due to a choice of metric. However, it is
not important. I think it is a good question if the event horizon is even
*in* this Universe.

If there is a wind blowing from your back at Mach2,
you cannot hear someone in front of you. They are
still "in this universe". The key pint is that
no physics changes at the horizon and there is no
discontinuity.

http://www.astronomycafe.net/qadir/ask/a11125.html


Note also Andrew's quiz question 5:

http://casa.colorado.edu/~ajsh/quiz.html#quiz

The answer is he

http://casa.colorado.edu/~ajsh/schwp.html#metricinside

Then he claims that we "fall at c". And yet, this seems to
be what is at hand.

Imagine a duck swimming up river at 5m/s in a
stream that narrows approaching a weir. As the
stream narrows, the water moves faster. If the
duck starts where the water flows at 4m/s it
will escape but if it starts where it is 6m/s
it will move towards the weir ever faster until
it goes over.

A singularity occurs if the width of the stream
gets to zero at the weir as the speed becomes
infinite, but nothing happens to the water (or
the duck) where the flow is 5m/s.

The analogies are fine George. Unfortunately, *to whom* does the
infalling person appear to fall at c? Presumably a stationary observer,
but there are on possible stationary observers inside the photon sphere,
much less inside the event horizon.

This I think is where I disagree with Martin (which
worries me somewhat). I believe the answer is "to
an observer at infinity not moving relative to the
location of the black hole.". Have a look at the
freefall diagram:

http://casa.colorado.edu/~ajsh/schwp.html#freefall

Note that the green lines fall to the centre in
finite time and the time coordinate which is the
Y axis is the same regardless of whether the green
line is inside or outside. The orange lines show
light emitted by an infalling object. As the green
lines approach the horizon, the orange lines get
nearer to vertical and take ever longer to reach
the right-hand edge of the chart where a 'distant'
observer might hover by continually firing a rocket.

Once the green line (the freefalling object) crosses
the horizon though, the orange lines fall inwards,
the water is moving too fast for the duck (neat,
I just found Andrew used the same idea but with
canoes).

So what use are the words, what meaning can they convey where the context
is not part of this Universe (except though total mass, total charge,
total angular moementum)?

It is still part of this universe, the other universe
idea comes in after the matter passes the r=0 point.

George

N:dlzc D:aol T:com (dlzc) wrote:

"Martin Brown" wrote in
message ...

N:dlzc D:aol T:com (dlzc) wrote:

Dear Martin Brown:

"Martin Brown" wrote in
message ...

N:dlzc D:aol T:com (dlzc) wrote:

Yes, trick needed. Schwarzchild is singular at the event
horizon, as we have covered ad nauseum. Yet he managed to
achieve a continuous presentation... maybe it is well behaved
on either side of the EH.

Schwarzschild coordinates are singular at the event horizon in
the same way that latitude and longitude are singular at the
Earth's North pole.

Which of those goes to infinity, Martin?

Neither. But some infinities can be dealt with safely.

Similar predictions are made in Kruskal and Eddington models, and
they are not singular at the EH. We simply don't know what he
used.

I don't believe the choice of coordinate systems makes any difference to
the physics - it is just more confusing and difficult to work out the
calculations in some than in others.

It doesn't have any real physical significance and can be
worked
around.

Kruskal, Eddington and others. Yes, I know.

Then why do you choose to ignore them?

Why do you assume that I did? They both fold outer space or
outer spacetime into a separate inner time axis. Why do you
posture, rather than read the references that have been cited?

I must have missed the references you cited in support of your position.
Please repost them...

I
understand this is uncomfortable, and I am sorry for that. It is
just a question. Teenagers ask about sex too...

You are begining to sound like Gerald Kelleher.

The singularity at the centre of a BH in the classical GR
geometric interpretation cannot be so easily dismissed.

Yes, it can. "Classical GR" provides that an entirely
separate Universe is formed inside the BH. And if this is
close to reality, the "central singularity" we are heading for
(but will never reach) is an infinitely diffuse, cold future.
"Newton" provides a "central infinitely dense lump at the
center."

I think you will find most practitioners expect infalling
material to find itself at the centre of a BH (even a large
one) in a relatively short time. ISTR an hour or so for a big
galactic centre BH.

Outer expectations of inner duration are simply the Newton in you
(and others). Once the object crosses the event horizon, it is
gestalt with the BH. If somone wanted a "speed of gravity"
experiment, that would be the place to run it. When would an
orbitting body cease to respond to two distinct bodies, and only
orbit the single fatter BH?

I am inclined to trust the dynamical equations YMMV.

The analogies are fine George. Unfortunately, *to whom* does
the infalling person appear to fall at c?

Himself.

That is going to take some explaining. Light can and will
pass him at c in both directions (towards and away from EH).
So which way does he get "infintely redshifted light", and
from which way does he get "infintely blueshifted light"?
Just because light does not exit the EH, doesn't mean that
light cannot be directed opposite his fall.

Lets try the more precise description for a massive test
particle falling under GR of "c-epsilon" as epsilon tends to
zero instead.

So he doesn't fall at c wrt himself, and you are busting my
chops. Great!

He can measure his own velocity wrt to the fixed stars located outside
the black hole and provided he chooses a nice massive queiecent BH to
jump into he might live long enough to complete the experiment before
being annihilated on reaching the centre.

And he can still see the fixed stars outside the BH.

That is what Andrew's simulations show, yes. Yet the photon
sphere will be continually ingested/drained by an expanding
hole, and the Einstein rings will sucessively give up some of
their contents. At least.

Sorry but I cannot make any sense of the last two sentences.
You won't be able to see anything out of an active feeding BH
since it will be surrounded by opaque dense relativistic
plasma.

WE
ARE
TALKING
ABOUT
A
FALLING
PERSON
INSIDE.

Definitely strong indications of NetKook here. Shouting incoherently.

How is the world is he supposed to see specular images through an
opaque dense relativistic plasma (shades of the CMBRM, Batman!),
Martin? Can we see through the CMBRM?

A BH in total isolation from all other matter is only detectable from
outside by watching how it distorts light passing near it. Only when it
is actively feeding is there an accretion disk, relativistic plasmas
etc. Light from outside can cross and enter freely through the EH, but
it can never leave (shades of Hotel California).

In practice I suspect there may be some opacity problems near real ones
that are not feeding because of rotating embedded magnetic fields and
electron positron pair production etc. Maybe someone has done the
calculation. But in a thought experiment the requirement is only to
decide whether the existing laws of physics can be applied to the
situation and yield a self consistent result.

The falling observer is entitled to enter the BH with a clock
and full knowledge of the laws of astronomy, physics and
GR. He can measure the mass/size of the BH and then
time how long it takes him to reach the singularity
(subject to some minor experimental difficulties).

Sure can. Apparently ~125 Gy give or take tens (or hundreds)
of Gy.

Is that an estimate of the time to reach our nearest BH ? Or
something else? Most estimates I have seen for observers time
to live after freefalling into even the most massive BH
observed in our universe are only a couple of hours.

That is the *internal* time it takes for us to reach the
"infinitely diffuse cold, future". People that think Newton,
standing on the outside, will see us "undifferentiate" the
instant they figure we cross the event horizon. The horizon is
the "singularity at the center" to those "outsiders".

Or not. That is what the question is about.

You are really going to have to define your terms more carefully and/or
draw what you mean or better still the equations. Once again your last
few sentences do not make any sense to me.

I don't think we are using much Newtonian dynamics here...

Regards,
Martin Brown

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:XQROe.124809$E95.70204@fed1read01...
Dear George Dishman:

"George Dishman" wrote in message
...


I had written a more extensive reply but it got trashed
when a virus checker update locked up and has mostly
been superseded so I'll trim this severely.



What is raising the question of a non-closed Universe?

Without dark energy, GR gives some simple
solutions for an expanding universe:

1) Density greater than the critical value
means spatially and temporally finite so
we have a closed universe and a big crunch.
Expansion slows and reverses. A photon
created at t=0 gets exactly half way across
the universe when the crunch arrives.

Which doesn't work too well, since we have photons
arriving in all directions from even ~300,000 y after
the Big Bang.

Why is that relevant, there wasn't a centre as
you know.

Let's see. We can determine the temperature of the CMBR
a "billion years ago" by observing processes in distant stars.
You have arrived at 4300

6300 LY actually but never mind.

I hope to hold that number.

light years for the thickness of the CMBR. Seems to me like
we are still receiving light that has travelled more than once
around the size of that early Universe,

Age now is 13.7 billion years. Hypothetically, if
we were in a closed universe currently at maximum
volume, the crunch would be at 27.4 billion years.
In that case GR said it would take a photon
precisely 54.8 billion years to get back to where
it was created after going "once round". The
cosmological constant changes all that though.

even though it may no longer be able to make it
around the size of the Universe now. So the stated
condition "A photon created at t=0 gets exactly
half way across the universe when the crunch
arrives." is obviously not met in this Universe.

Currently a closed universe seems highly unlikely
as we have discussed.

Agreed. You asked me "why" and I was answering that.

Then I still don't understand why you said "Which
doesn't work too well, since we have photons
arriving in all directions from even ~300,000 y
after the Big Bang". They were produced everywhere
so would be arriving from all directions even 1s
after the bang.

And how they could have NOT been aroud the early Universe *at least once*,
when it took ~300,000 years to get to a size of 6300 ly. Maybe I'm being
too Newtonian about it...

No, I think it's more basic. The size in such a
universe would not be static. The radius first
increases then decreases. slice through it and
stack different slices at different times and
you get a shape like an american football
standing on one end. The path of a photon would
be a variable radius helix starting at the base
and winding round to the top. Looking down from
the top it turns through only 180 degrees total.

My figure of 6300 LY would suggest it was opaque at
372,700 years and transparent at 379,000 years. "In
an instant" doesn't seem inappropriate in cosmological
terms.

... but it does to a mechanical engineer! Is the "thickness" being the
same order of magnitude as the global "quench" meaningful?

What do you mean by "global 'quench'"?

What was completed by "379,000 years". The plasma was quenched to a
normal matter state. If we were expanding compressed air as an analogy,
it the point at which water vapor (as opposed to steam) would form.

OK, but then 6300 years is two order smaller
than that, not the same order of magnitude.

The z of the CMBR can be thought of as produced
by motion of the source away from us but it can
also be considered as similar to gravitational
redshift or a stretching of the wavelength of
the photon while it was travelling through space
that was being stretched.

That sucked when Paul Lutus was feeding it to me.

It is a standard way of expressing it. I'm not
keen myself but I think the three descriptions
are effectively equivalent while appearing
different in the same sense as wave/particle
duality.

But it requires that the photon give up some of its energy, yet retain the
vector portion of its mometum entirely intact. We don't know how to do
that.

Both energy and momentum are proportional to
frequency, and both values are frame-dependent.

Ignoring my 'proper motion' part, the kinetic
motion and the "expansion velocity" are one and
the same.

I think that I will stick with Ned Wright's defintion, wherein
"kinetic motion" is kept separate form expansion. "Let
each man lay his dead according to his own fashion."

Can you give me a pointer to this in his tutorial,
I wasn't aware he used the terms. I'll search
later but if you have bookmarked the section it
would save me some time.

I swear it was there explicitly. Any way, as close I can find is Part 2:
http://www.astro.ucla.edu/~wright/cosmo_02.htm
(without the URL:...)

Works perfectly :-)

QUOTE
Note that the redshift-velocity law is not the special relativistic
Doppler shift law
1+z = sqrt[(1+v/c)/(1-v/c)]
which only applies to special relativistic coordinates, not to
cosmological coordinates.
END QUOTE
neither a search for "kinetic" nor "motion" yielded as clear a delineation
as I'd like.

I think we have lost the thread on this, that
is just "the velocity" and doesn't draw any
distinctions.

They keep talking about "recombination",

It is a misnomer, it should be just "combination",
it's a bit of an in-joke actually.

Perhaps. But many still believe that it started from some "central
singularity", some complex (perhaps) ordered (certainly bound) state, it
had to "de-order" to "get out", then *recombined* to simpler diffuse
forms.

I've never seen anything like that suggested.

Like a white hole (or evaporating black one), which is hotter than the
Universe that contains it.

It is, but being hotter means the contents are
ionised. "Recombination" implies something cold
has been ionised by heating and is now becoming
cold again.

Then that is 'new physics'

No, it isn't.

I'll continue to disagree on that.

I provided three links that indicate that it isn't "new physics", but a
prediction of GR, quantum mechanics, or some combination thereof. You may
continue to disagree.

I just think you are looking at those pages with
a preconceived notion and are seeing what you
expect. I respect Steve Carlip's knowledge on GR
so I'll read what he says with great interest.

Consider a young Universe, some 6300 ly "across", with
mass sufficient to achieve a "curvature coefficient" of 1079
(compared to today).

Lots of confusion there, the optical thickness
of the period of recombination was 6300 ly but
that happened at 380,000 years so the part of
the universe which is _currently_ observable
might have been 760,000 LY across and the
whole universe would have been billions of
light years across or perhaps infinite.

The plasma would be too thick to fill 760,000 ly,

I have no idea what that means!

and still generate the spectrum.

Or that!

Perhaps this is another lesson for another day...

The universe appears to be flat and would have
been then too. The figure of 1079 is the redshift
compared to today, not the curvature.

An indication of the curvature of the Universe that emitted the light, vs.
the Universe that detected it.

Again your words mean nothing to me. I believe z
is a measure of the angle between two normals to
a surface that has curvature between them, but I
also suspect that's too simplistic. However, I
don't see how you could compute the angle between
two points on curved surfaces in different
universes. How do you calculate across the
discontinuity?

That may be a small beginning, but it no less massive.

It still held only 4% of the required matter in
baryonic form.

Sufficient to produce a redshift many orders of magnitude greater than our
Sun does, and by similar means. Last I heard, there was no Dark Matter at
the time of the CMBRM. Where does this stand now?

Where did you hear that? I thought the WMAP results
supported dark matter.

For the CMBR, use this link

http://lambda.gsfc.nasa.gov/product/...prod_table.cfm

Yes. This would be good (as a start) for a free BH, or one near our
position in a "largely spiral" galaxy.

I intended that as a good start for the CMBR after
the removal of all stars. You need individual stellar
spectra separately. A free BH has no spectrum since
it is black !

The detector of a satellite can behave like a "differential area" on an
event horizon.

Again I have no idea what you mean. If we point a
satellite at a black hole, we don't see the hole,
only the universe behind distorted a bit.

You believe that the images will come in spectrally, I do not.

That would be inside, we are outside all the black
holes we can use for a reference.

Then I need to come up with a spectrum for a BH consuming
a companion,

Try Cyg X1

A good search ("Cygnus X1"). I'll see what I can find. Is it "close"
and/or is the line-of-sight pretty clear?

http://en.wikipedia.org/wiki/Cygnus_X-1

2500 parsecs.

and to somehow infer the influx to the BH at the center of
our own galaxy.

It appears to be in a relatively clear region so
is invisible.

Vaccum cleaners are like that! How about the center of Andromeda? Is it
pretty quiet there also?

These may be of more use

http://www.astr.ua.edu/keel/agn/

In particular

http://www.astr.ua.edu/keel/agn/spectra.html

http://heasarc.gsfc.nasa.gov/docs/ob...n/agntext.html

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

Thanks, it's nice to know you appreciate it. I could
tell you do the same and while we may disagree I hope
you feel you benefit as much as me from reading the
cited resources.

What fun would it be if everyone agreed with me? I wouldn't get to learn
anything. ;)

Now if I just can...

A few more links to keep you going ;-)

If only I had the time to study them all myself

George

Dear George Dishman:

"George Dishman" wrote in message
...

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox
wrote in message news:5JPOe.124798$E95.60198@fed1read01...
Dear George Dishman:

"George Dishman" wrote in message
...

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox
wrote in message news:yUwOe.124442$E95.97537@fed1read01...
Dear Geroge Dishman,
...
I understand what you are saying, George. Now try these:
URL:http://www.aleph.se/Trans/Global/Omega/baby.txt

David, is there a way to get rid of the "URL:" part,
it breaks the link in Outlook Express because the
text is no longer a URL if you put "URL" in front.

I intentionally add the URL:, so that Outlook Express and
other readers will correctly form long links. Oh well...
FWIW the links work for me.

Sometimes it does for me too but the definition
of a URL starts with the protocol to be used
followed by a colon. You are telling the software
to use the "URL" protocol instead of "HTTP".

OK.

I'll trim a lot because we have really covered
it.

But nothing else did, nor did it it in any particular talk
about the production of an inner Universe due to a choice of
metric. However, it is not important. I think it is a good
question if the event horizon is even *in* this Universe.

If there is a wind blowing from your back at Mach2,
you cannot hear someone in front of you. They are
still "in this universe". The key pint is that
no physics changes at the horizon and there is no
discontinuity.

http://www.astronomycafe.net/qadir/ask/a11125.html

This is the standard interpretation, yes. There are alternatives
to this interpretation, alternatives provided by GR experts, and
I am attempting to test what I see is a perhaps falsifiable part
of their solutions. Yet I keep getting this "but the standard
interpretation is..."

Note also Andrew's quiz question 5:

http://casa.colorado.edu/~ajsh/quiz.html#quiz

The answer is he

http://casa.colorado.edu/~ajsh/schwp.html#metricinside

I think we can stop talking about Andrew and his pages. His
methods are not revealed, his wording is (apparently) sloppy, so
I don't think I can learn anything further from his pages as they
stand.

Then he claims that we "fall at c". And yet, this seems to
be what is at hand.

Imagine a duck swimming up river at 5m/s in a
stream that narrows approaching a weir. As the
stream narrows, the water moves faster. If the
duck starts where the water flows at 4m/s it
will escape but if it starts where it is 6m/s
it will move towards the weir ever faster until
it goes over.

A singularity occurs if the width of the stream
gets to zero at the weir as the speed becomes
infinite, but nothing happens to the water (or
the duck) where the flow is 5m/s.

The analogies are fine George. Unfortunately, *to whom*
does the infalling person appear to fall at c? Presumably
a stationary observer, but there are on possible stationary
observers inside the photon sphere, much less inside the
event horizon.

This I think is where I disagree with Martin (which
worries me somewhat). I believe the answer is "to
an observer at infinity not moving relative to the
location of the black hole.". Have a look at the
freefall diagram:

http://casa.colorado.edu/~ajsh/schwp.html#freefall

Note that the green lines fall to the centre in
finite time and the time coordinate which is the
Y axis is the same regardless of whether the green
line is inside or outside. The orange lines show
light emitted by an infalling object. As the green
lines approach the horizon, the orange lines get
nearer to vertical and take ever longer to reach
the right-hand edge of the chart where a 'distant'
observer might hover by continually firing a rocket.

Once the green line (the freefalling object) crosses
the horizon though, the orange lines fall inwards,
the water is moving too fast for the duck (neat,
I just found Andrew used the same idea but with
canoes).

I have discussed path_average_speed with you in relation to
Shapiro time delay. Any usage of "falling at c" for any observer
outside the BH is meaningless, even if you don't "buy" the "new
internal Universe" interpretation. Because the
path_average_speed for light at the horizon now has a 0 value
towards anyone outside the BH. So such claims would be
non-sequitur.

So what use are the words, what meaning can they convey
where the context is not part of this Universe (except though
total mass, total charge, total angular moementum)?

It is still part of this universe, the other universe
idea comes in after the matter passes the r=0 point.

No. I provided citations, George, but I cannot make you read
them. The other Universe starts at (some function of) r_S.

David A. Smith

Dear George Disman:

"George Dishman" wrote in message
...

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox
wrote in message news:LouPe.125018$E95.97822@fed1read01...
Dear Martin Brown:

"Martin Brown" wrote in
message ...
N:dlzc D:aol T:com (dlzc) wrote:

Dear Martin Brown:

"Martin Brown" wrote in
message ...
...
And he can still see the fixed stars outside the BH.

That is what Andrew's simulations show, yes. Yet the photon
sphere will be continually ingested/drained by an expanding
hole, and the Einstein rings will sucessively give up some
of their contents. At least.

Sorry but I cannot make any sense of the last two sentences.
You won't be able to see anything out of an active feeding BH
since it will be surrounded by opaque dense relativistic
plasma.

WE
ARE
TALKING
ABOUT
A
FALLING
PERSON
INSIDE.
How is the world is he supposed to see specular images through
an opaque dense relativistic plasma (shades of the CMBRM,
Batman!), Martin? Can we see through the CMBRM?

David, before shouting at people, remember you were talking
about a black hole, not the big bang at this point:

"And he can still see the fixed stars outside the BH."

That is not what *I* said George. It was to what I was
responding. I will apologize to Martin under separate cover.

There is no "opaque dense relativistic plasma" around
many black holes. At the event horizon, there is nothing
but vacuum so the person inside can look back and see the
external stars. Obviously this would be different for a
BH that has a disk fed from a companion but again you
can still see out to that disk and the bottom of any jets.

I find it fascinating that such a plasma might also fulfill the
needs of a CMBRM. But I don't find it compelling, only
"convenient".

I think the intergrated light history, on its own, will be
sufficient. I wonder if they got any sort of spectral
information on the "dual to a black hole" experiments...

David A. Smith

Dear Martin Brown:

"Martin Brown" wrote in
message ...
N:dlzc D:aol T:com (dlzc) wrote:

"Martin Brown" wrote in
message ...

N:dlzc D:aol T:com (dlzc) wrote:

Dear Martin Brown:

"Martin Brown" wrote in
message ...
....
And he can still see the fixed stars outside the BH.

That is what Andrew's simulations show, yes. Yet the photon
sphere will be continually ingested/drained by an expanding
hole, and the Einstein rings will sucessively give up some of
their contents. At least.

Sorry but I cannot make any sense of the last two sentences.
You won't be able to see anything out of an active feeding BH
since it will be surrounded by opaque dense relativistic
plasma.

WE
ARE
TALKING
ABOUT
A
FALLING
PERSON
INSIDE.

Definitely strong indications of NetKook here. Shouting
incoherently.

I need to apologize to you Martin. You had kept a level tone
until you claimed that the infaller could see external stars, and
then said that he could not see external stars. I lost it. I
apologize.

Now as far as "NetKook" goes...
It is evident that you wish to do anything but discuss this.
Goodbye.
plonk

David A. Smith

Dear George Dishman,

"George Dishman" wrote in message
...

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox
wrote in message news:XQROe.124809$E95.70204@fed1read01...
Dear George Dishman:

"George Dishman" wrote in message
...


I had written a more extensive reply but it got trashed
when a virus checker update locked up and has mostly
been superseded so I'll trim this severely.

OK.

....
even though it may no longer be able to make it
around the size of the Universe now. So the stated
condition "A photon created at t=0 gets exactly
half way across the universe when the crunch
arrives." is obviously not met in this Universe.

Currently a closed universe seems highly unlikely
as we have discussed.

Agreed. You asked me "why" and I was answering that.

Then I still don't understand why you said "Which
doesn't work too well, since we have photons
arriving in all directions from even ~300,000 y
after the Big Bang". They were produced everywhere
so would be arriving from all directions even 1s
after the bang.

And how they could have NOT been aroud the early
Universe *at least once*, when it took ~300,000 years
to get to a size of 6300 ly. Maybe I'm being too
Newtonian about it...

No, I think it's more basic. The size in such a
universe would not be static. The radius first
increases then decreases. slice through it and
stack different slices at different times and
you get a shape like an american football
standing on one end. The path of a photon would
be a variable radius helix starting at the base
and winding round to the top. Looking down from
the top it turns through only 180 degrees total.

*That* went right over my head! I know the light cone, which
could remotely be called one end of a football (Amercian
football, yes?), and the expansion of the Universe could be
called the other end... but the spiral?

My figure of 6300 LY would suggest it was opaque at
372,700 years and transparent at 379,000 years. "In
an instant" doesn't seem inappropriate in cosmological
terms.

... but it does to a mechanical engineer! Is the
"thickness" being the same order of magnitude as the global
"quench" meaningful?

What do you mean by "global 'quench'"?

What was completed by "379,000 years". The plasma was
quenched to a normal matter state. If we were expanding
compressed air as an analogy, it the point at which water
vapor (as opposed to steam) would form.

OK, but then 6300 years is two order smaller
than that, not the same order of magnitude.

379,000 - 372,700 = 6,300
.... looks like the same order of magnitude.

The z of the CMBR can be thought of as produced
by motion of the source away from us but it can
also be considered as similar to gravitational
redshift or a stretching of the wavelength of
the photon while it was travelling through space
that was being stretched.

That sucked when Paul Lutus was feeding it to me.

It is a standard way of expressing it. I'm not
keen myself but I think the three descriptions
are effectively equivalent while appearing
different in the same sense as wave/particle
duality.

But it requires that the photon give up some of its
energy, yet retain the vector portion of its mometum
entirely intact. We don't know how to do that.

Both energy and momentum are proportional to
frequency, and both values are frame-dependent.

"We don't know how to do that."
Stretching is what we don't know how to do. What we do see right
here/now is gravitational time dilation, which is sufficient also
to describe the redshift of ancient light.

Ignoring my 'proper motion' part, the kinetic
motion and the "expansion velocity" are one and
the same.

I think that I will stick with Ned Wright's defintion,
wherein
"kinetic motion" is kept separate form expansion. "Let
each man lay his dead according to his own fashion."

Can you give me a pointer to this in his tutorial,
I wasn't aware he used the terms. I'll search
later but if you have bookmarked the section it
would save me some time.

I swear it was there explicitly. Any way, as close I can find
is Part 2:
http://www.astro.ucla.edu/~wright/cosmo_02.htm
(without the URL:...)

Works perfectly :-)

QUOTE
Note that the redshift-velocity law is not the special
relativistic Doppler shift law
1+z = sqrt[(1+v/c)/(1-v/c)]
which only applies to special relativistic coordinates, not to
cosmological coordinates.
END QUOTE
neither a search for "kinetic" nor "motion" yielded as clear a
delineation as I'd like.

I think we have lost the thread on this, that
is just "the velocity" and doesn't draw any
distinctions.

It does, George. It delineates between velocity in Minkowski
spacetime, and expansion velocity. And the point is moot, since
it wasn't as clearly phrased on his pages as I "remembered".

They keep talking about "recombination",

It is a misnomer, it should be just "combination",
it's a bit of an in-joke actually.

Perhaps. But many still believe that it started from some
"central singularity", some complex (perhaps) ordered
(certainly bound) state, it had to "de-order" to "get out",
then *recombined* to simpler diffuse forms.

I've never seen anything like that suggested.

Like a white hole (or evaporating black one), which is hotter
than the Universe that contains it.

It is, but being hotter means the contents are
ionised. "Recombination" implies something cold
has been ionised by heating and is now becoming
cold again.

OK.

Then that is 'new physics'

No, it isn't.

I'll continue to disagree on that.

I provided three links that indicate that it isn't "new
physics",
but a prediction of GR, quantum mechanics, or some
combination thereof. You may continue to disagree.

I just think you are looking at those pages with
a preconceived notion and are seeing what you
expect. I respect Steve Carlip's knowledge on GR
so I'll read what he says with great interest.

You indicated that you felt the same way about John Baez. Two of
the citations I provided were his, and the third was Chris
Hillman. Steve Carlip is also a very smart cookie.

Consider a young Universe, some 6300 ly "across", with
mass sufficient to achieve a "curvature coefficient" of 1079
(compared to today).

Lots of confusion there, the optical thickness
of the period of recombination was 6300 ly but
that happened at 380,000 years so the part of
the universe which is _currently_ observable
might have been 760,000 LY across and the
whole universe would have been billions of
light years across or perhaps infinite.

The plasma would be too thick to fill 760,000 ly,

I have no idea what that means!

and still generate the spectrum.

Or that!

It is based on the words you provided, which came from your
understanding of the topic when you said it. So maybe a timeline
will reveal my confusion:
BB - 366,000 - 372,300 - 379,000 - 14 Gy
.... you say the CMBRM is 6300 ly thick, so I assumed 366,000 is
the start of it (or the beginning of the end).

Perhaps this is another lesson for another day...

The universe appears to be flat and would have
been then too. The figure of 1079 is the redshift
compared to today, not the curvature.

An indication of the curvature of the Universe that
emitted the light, vs. the Universe that detected it.

Again your words mean nothing to me. I believe z
is a measure of the angle between two normals to
a surface that has curvature between them, but I
also suspect that's too simplistic. However, I
don't see how you could compute the angle between
two points on curved surfaces in different
universes. How do you calculate across the
discontinuity?

It is continuous between them, isn;t it?

That may be a small beginning, but it no less massive.

It still held only 4% of the required matter in
baryonic form.

Sufficient to produce a redshift many orders of magnitude
greater than our Sun does, and by similar means. Last I
heard, there was no Dark Matter at the time of the CMBRM.
Where does this stand now?

Where did you hear that? I thought the WMAP results
supported dark matter.

I "heard that" here on sci.astro. Since I don't catch every bit
of late breaking news, and since I frequently get my memories
rearranged, I was asking you. So Dark Matter is evident in the
CMBRM?

For the CMBR, use this link

http://lambda.gsfc.nasa.gov/product/...prod_table.cfm

Yes. This would be good (as a start) for a free BH, or one
near our position in a "largely spiral" galaxy.

I intended that as a good start for the CMBR after
the removal of all stars. You need individual stellar
spectra separately. A free BH has no spectrum since
it is black !

The detector of a satellite can behave like a "differential
area" on an event horizon.

Again I have no idea what you mean. If we point a
satellite at a black hole, we don't see the hole,
only the universe behind distorted a bit.

Sigh...
George, I am going to use the recorded spectra, as detected by
"detectors", and infer from that via the magic of integration,
what the EH of a black hole would ingest over its surface, over
its lifetime. I thought I said this more than once.

You believe that the images will come in spectrally, I do not.

That would be inside, we are outside all the black
holes we can use for a reference.

This is what you are comfortable in believing, yes George. I
have seen "non-beginner" solutions to GR that indicate that
perhaps our Big Bang is the inside of an event horizon of a black
hole that contains our Universe. I propose to test this by the
above mentioned integration.

Then I need to come up with a spectrum for a BH consuming
a companion,

Try Cyg X1

A good search ("Cygnus X1"). I'll see what I can find. Is it
"close" and/or is the line-of-sight pretty clear?

http://en.wikipedia.org/wiki/Cygnus_X-1

2500 parsecs.

http://www.oa.uj.edu.pl/research/cygx1.html
.... spectral references. Much more suitable.
http://astrophysics.sr.unh.edu/mccon...26_v4_p119.pdf
.... and graphs!
line-of-sight is clear. So I will assume the spectrum ingested
is pretty close to the same, adjusting for the difference in
distance and angular size (using Einstein ring #1 as the outer
boundary).

and to somehow infer the influx to the BH at the center of
our own galaxy.

It appears to be in a relatively clear region so
is invisible.

Vaccum cleaners are like that! How about the center of
Andromeda? Is it pretty quiet there also?

These may be of more use

http://www.astr.ua.edu/keel/agn/

In particular

http://www.astr.ua.edu/keel/agn/spectra.html

http://heasarc.gsfc.nasa.gov/docs/ob...n/agntext.html

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

Here is a problem in modelling. Would you say that the
percentage of active galactic nucleii vs. non-active (Milky Way
and Andromeda) would be and indication that this behavior might
be periodic. In other words, my black-hole-in-galactic-center
model should be sometimes active, and sometimes not, roughly like
the percentage above?

Thanks, it's nice to know you appreciate it. I could
tell you do the same and while we may disagree I hope
you feel you benefit as much as me from reading the
cited resources.

What fun would it be if everyone agreed with me? I wouldn't
get to learn anything. ;)

Now if I just can...

A few more links to keep you going ;-)

If only I had the time to study them all myself

I won't blindside anybody. Anything I find will be on the
internet.

Thanks to all.

David A. Smith

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:qoOPe.129290$E95.2723@fed1read01...
Dear George Dishman:

"George Dishman" wrote in message
...

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:5JPOe.124798$E95.60198@fed1read01...
Dear George Dishman:

.... The key p[o]int is that
no physics changes at the horizon and there is no
discontinuity.

http://www.astronomycafe.net/qadir/ask/a11125.html

This is the standard interpretation, yes. There are alternatives to this
interpretation, alternatives provided by GR experts,

That is where you disagree with myself and both
Martin and Steve Carlip. I consider Steve to be
a "GR expert" having read his posts for many
years though he would no doubt disagree. Andrew
Hamilton is A professor lecturing on the subject
and is saying the same thing, there is only one
interpretation at the event horizon for a non-
rotating, non-charged black hole and it doesn't
have a singularity.

and I am attempting to test what I see is a perhaps falsifiable part of
their solutions. Yet I keep getting this "but the standard interpretation
is..."

No, what you keep getting is "There is only one
model provided by GR but it can be described in
a variety of coordinate schemes, some of which
don't work at the horizon.". What is annoying
people who have been "experts" in GR by any
normal standard is that you refuse to listen.
It is what happens at r=0 where there is a real
singularity and GR fails that is open to
interpretation.

Note also Andrew's quiz question 5:

http://casa.colorado.edu/~ajsh/quiz.html#quiz

The answer is he

http://casa.colorado.edu/~ajsh/schwp.html#metricinside

I think we can stop talking about Andrew and his pages. His methods are
not revealed, his wording is (apparently) sloppy,

"Answer to the quiz question 5: False."

That seems pretty unamibguous to me.

so I don't think I can learn anything further from his pages as they
stand.


"The Schwarzschild metric remains valid
inside the Schwarzschild radius. It is
fine to perform mathematical calculations
using the Schwarzschild metric."

Have you learnt that?

This I think is where I disagree with Martin (which
worries me somewhat). I believe the answer is "to
an observer at infinity not moving relative to the
location of the black hole.". Have a look at the
freefall diagram:

http://casa.colorado.edu/~ajsh/schwp.html#freefall

Note that the green lines fall to the centre in
finite time and the time coordinate which is the
Y axis is the same regardless of whether the green
line is inside or outside. The orange lines show
light emitted by an infalling object. As the green
lines approach the horizon, the orange lines get
nearer to vertical and take ever longer to reach
the right-hand edge of the chart where a 'distant'
observer might hover by continually firing a rocket.

Once the green line (the freefalling object) crosses
the horizon though, the orange lines fall inwards,
the water is moving too fast for the duck (neat,
I just found Andrew used the same idea but with
canoes).

I have discussed path_average_speed with you in relation to Shapiro time
delay.

Note the the freefall lines are curved. The path
average over any section would be a chord between
two points. The horizon is where the slope of the
line is c.

Any usage of "falling at c" for any observer outside the BH is
meaningless,

"Falling at", implies to me the instantaneous speed
rather than an average. Outside the horizon it is
less than c, at the horizon is is equal to c while
inside it is greater. This is valid all the way to
the central singularity where the lines become
horizontal and speed becomes infinite.

even if you don't "buy" the "new internal Universe" interpretation.

I'm not saying I am not prepared to consider it
but according to GR the entry to that universe
would be through the singularity at r=0 or at the
Cauchy horizon in the more general case I think.
This may be of interest, I ihaven't had a chance
to look through it myself yet though:

http://www.absoluteastronomy.com/enc...hy_horizon.htm

Because the path_average_speed for light at the horizon now has a 0 value
towards anyone outside the BH.

Not true, look at the freefall diagram again

http://casa.colorado.edu/~ajsh/stffbig_gif.html

You are talking about light this time rather than a
freefalling object so draw a chord between any two
points on a _yellow_ line. It has a finite non-zero
value. Infinitely far from the black hole the slope
of the line will be asymptotic to 45 degrees, the
speed of light. A path-average speed of zero would
require a chord to a yellow line which was vertical
on the diagram.

So such claims would be non-sequitur.

So what use are the words, what meaning can they convey
where the context is not part of this Universe (except though
total mass, total charge, total angular moementum)?

It is still part of this universe, the other universe
idea comes in after the matter passes the r=0 point.

No. I provided citations, George, but I cannot make you read them. The
other Universe starts at (some function of) r_S.

I read most of the pages. John Baez page was the first
of a series and I read the first three pages but his
maths is somewhat beyond my level. However, there seemed
to be only one paragraph that directly addressed this
point and subsequent pages were getting further from the
subject. I quoted that to you, here is the section in
whole (if you were refering to some other paragraph
please point me at it):

| To begin with, Lee Smolin, one of the originators of the loop
representation
| of quantum gravity, has been spending the last year or so writing a book
| in a popular style, to be entitled "Life and Light," which tours the
| cosmos and makes some interesting speculations on "evolutionary
| cosmology." These speculations are based on 2 hypotheses.
|
| A. The formation of a black hole creates "baby universe," the final
| singularity of the black hole tunnelling right on through to the initial
| "big bang" singularity of the new universe thanks to quantum effects.
| While this must undoubtedly seem outre to anyone unfamiliar with the
| sort of thing theoretical physicists amuse themselves with these days,
| in a recent review article by John Preskill on the information loss
| paradox for black holes, he reluctantly concluded that this was the
| *most conservative* solution of that famous problem!

and the relevant part again:

"the final singularity of the black hole tunnelling
right on through to the initial 'big bang' singularity
of the new universe"

Now I read "the final singularity" to mean r=0 where
there undoubtedly is a singularity. I guess you might
read it as meaning at the horizon, but at best it
doesn't resolve the question and IMHO it supports what
I and everyone else has been telling you.

If you can find something clear and unambiguous that
supports what you are saying about GR then I will
happily listen, I am here to learn, but so far you
have just been contradicting everything I have ever
read about the event horizon.

I think that's why Martin got the impression you are
taking a netkook attitude to this, though from past
discussions I'm somewhat surprised at your response.

George

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:YyRPe.129306$E95.57191@fed1read01...
Dear George Dishman,

"George Dishman" wrote in message
...

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:XQROe.124809$E95.70204@fed1read01...
....
And how they could have NOT been aroud the early
Universe *at least once*, when it took ~300,000 years
to get to a size of 6300 ly. Maybe I'm being too
Newtonian about it...

No, I think it's more basic. The size in such a
universe would not be static. The radius first
increases then decreases. slice through it and
stack different slices at different times and
you get a shape like an american football
standing on one end. The path of a photon would
be a variable radius helix starting at the base
and winding round to the top. Looking down from
the top it turns through only 180 degrees total.

*That* went right over my head! I know the light cone, which could
remotely be called one end of a football (Amercian football, yes?), and
the expansion of the Universe could be called the other end... but the
spiral?

OK I'll try again. This must have been a post I saw
some years ago in s.p.r but I can't find it ATM.

ASCII is a problem my football looks like this:

^
/ \
( )
\ /
V

The big bang is at the bottom, the crunch is at
the top and now is somewhere below the middle
as space is still expanding. I'll show us as a
dot in the middle:

_____ crunch
^
/ \
( . ) ___ now
\ /
V _____ bang


A photon from the bang would pass us at
45 degrees to a horizontal on that diagram

_____ crunch
^
/ \
( / ) ___ photon
\ /
V _____ bang


Now extend that line in both directions always
keeping it at 45 degrees to a horizontal until
it reaches all the way from the bang to the
crunch. If you now look down from the top and
assuming the football is transparent, the line
is a curve that goes 180 degrees round the
football. If the maximum extent looking down
is a circle, then the path of the light I think
would be a smaller circle drawn between the
centre of the larger circle and the
circumference. Hence in this closed universe a
photon only gets half way round the universe
between bang and crunch, you couldn't see the
back of your head even with a big enough
telescope.

I will again emphasise this is an obsolete
model which has greater than critical density
and no cosmological constant.

My figure of 6300 LY would suggest it was opaque at
372,700 years and transparent at 379,000 years. "In
an instant" doesn't seem inappropriate in cosmological
terms.

... but it does to a mechanical engineer! Is the "thickness" being
the same order of magnitude as the global "quench" meaningful?

What do you mean by "global 'quench'"?

What was completed by "379,000 years". The plasma was quenched to a
normal matter state. If we were expanding compressed air as an analogy,
it the point at which water vapor (as opposed to steam) would form.

OK, but then 6300 years is two order smaller
than that, not the same order of magnitude.

379,000 - 372,700 = 6,300

WMAP says recombination was about 380,000 years
after the bang, I subtracted 6300 to get 372,700.

... looks like the same order of magnitude.

378,000 is about two orders greater than 6300.

The z of the CMBR can be thought of as produced
by motion of the source away from us but it can
also be considered as similar to gravitational
redshift or a stretching of the wavelength of
the photon while it was travelling through space
that was being stretched.

That sucked when Paul Lutus was feeding it to me.

It is a standard way of expressing it. I'm not
keen myself but I think the three descriptions
are effectively equivalent while appearing
different in the same sense as wave/particle
duality.

But it requires that the photon give up some of its
energy, yet retain the vector portion of its mometum
entirely intact. We don't know how to do that.

Both energy and momentum are proportional to
frequency, and both values are frame-dependent.

"We don't know how to do that."
Stretching is what we don't know how to do.

I thought you said we didn't know how to reduce the
energy without reducing the momentum which is true.

What we do see right here/now is gravitational time dilation, which is
sufficient also to describe the redshift of ancient light.

Gravitational time dilation, Doppler shift and
stretching are all ways of describing the effect
that reduces the frequency. Reducing the frequency
affects both energy and momentum. You said "But it
requires that the photon give up some of its energy,
yet retain the vector portion of its mometum entirely
intact" which isn't correct.


QUOTE
Note that the redshift-velocity law is not the special relativistic
Doppler shift law
1+z = sqrt[(1+v/c)/(1-v/c)]
which only applies to special relativistic coordinates, not to
cosmological coordinates.
END QUOTE
neither a search for "kinetic" nor "motion" yielded as clear a
delineation as I'd like.

I think we have lost the thread on this, that
is just "the velocity" and doesn't draw any
distinctions.

It does, George. It delineates between velocity in Minkowski spacetime,