Re: CMBR and neutron stars

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

"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message news:dehcl1$vgt$1@xxxxxxxxxxxxxxxxxxxxxxx

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

If it happened *frequently*, I would wager that the deep
space Hubble shot, repeated annually, would show
something winking out or something winking in.  Of
course Hubble opens yet another can of worms...


It happened frequently enough that we see lots of
galaxies, but it mostly happened a very long time ago.

... as far as we can tell ...

It may still be happening somewhere fairly local but spotting it would not be easy unless we got very lucky. The best chance we stand is to look at very distant patches of younger universe.

Even geological timescales are relatively short compared
to stellar evolution and galaxy formation.


OK.  Thanks.

the event horizon-- on either side, or exactly on it--
would see nothing special there.


I can't agree with this.  The matter infalling into a BH
finds something "special", or we would not have
intense jets of energy (and yes before the event
horizon, George).  Since light emitted at the EH never
exits, we don't *know* what a physical entity would
see at/on/inside an EH.  Perhaps looking at the BB in
a new light will answer the "inside" part.


Why don't you read the references you have already
been given?

I have most of them. I have also read the references I provided. That is why I have the question.

Real black holes feeding in the universe are pretty brutal
things - fast spinning and with embedded magnetic fields,
combine that with inflowing material and you get accretion
disks with quite well understood mechanisms for
extracting rest mass energy from matter and generating relativistic jets. See for example:

http://www.aip.de/groups/MHD/publications/01/pp_slumi.pdf

No magic is required.

I'm am proposing neither "magic" nor "new physics", Martin. This is a question based on interpretation of GR models, with solutions by reputable sources. I may be misunderstanding their conclusions, but "it is only a mathematical wet dream" is not an answer.

Why not? Your argument here seems to be predicated on a misunderstanding of the properties of space-time at or near the event horizon.

And you are stuck with the very serious problem that inside a BH there are no stationary observers, or stable orbits and the trajectory of any test particle will reach the central singularity in finite time.

You also get the same mechanisms active to generate jets in some neutron star or white dwarf compact
object accretion disks like SS433 and various other
cataclysism variable stars.

BTW You might like to worry a bit more about the
dynamical situation inside a BH. There are no stationary
observers there unless you invent new physics. That
means you always fall into the central singularity.

How can you assert there is a "central singularity"? How can you extend your "flatlander logic" into a place that "common sense" cannot go? Otherwise, I don't disagree with anything you just said.

We hope that some new quantum physics kicks in before reaching the final central singularity, but using the existing GR spatial geometry models there is something very very nasty lurking at the centre of a BH.

The mathematics of GR is very clear cut R=0 is a very very bad place, but R=Rs is just the last place you can send a light message out from.

In looking around for accessible web references on this stuff I stumbled upon some modern GR coursework at Queen Mary University of London that may help - namely:

http://monopole.ph.qmul.ac.uk/~bill/stg/stg_chapter_8.doc
http://monopole.ph.qmul.ac.uk/~bill/stg/stg_chapter_9.doc

Both about 1.4MB

The URL Steve Carlip posted for Andrew Hamiltons website
contains some useful stuff on what it would be like inside the
event horizon.

http://casa.colorado.edu/%7Eajsh/schw.shtml

I had never really thought about it this way before, but at least
in the static Schwarzschild metric you never get to see the
singularity at the BH centre - there is always a surface just
ahead of you where the escape velocity exceeds the speed
of light (in the classical interpretation).

Yes, I've seen these simulations. The methods and assumptions are not well described, and I am uncomfortable with his description of "falling at c".

That is almost certainly loose use of words. I expect he means falling at c-epsilon in the limit as epsilon tends to zero.

Regards,
Martin Brown
.

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