Re: CMBR and neutron stars

Dear Martin Brown:

"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in
message news:dehcl1$vgt$1@xxxxxxxxxxxxxxxxxxxxxxx
> N:dlzc D:aol T:com (dlzc) wrote:
>
>> "Jeff Root" <jeff5@xxxxxxxxxxxx> wrote in message
>> news:1124834806.341043.78910@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>>
>>>David A. Smith wrote:
>>>
>>>>... we don't discover entirely new galaxies where none
>>>>existed before, say, 10 or 20 years ago. We are only
>>>>able to bring new more-distant ones into focus.
>>>
>>>Twenty years ago we couldn't even see new stars forming
>>>in our own galaxy. Only the introduction of infrared
>>>telescopes in Space made it possible.
>>>
>>>Perhaps someday we will gain access to astronomical
>>>records going back hundreds of millions of years, and
>>>they will show that we can see galaxies now that did
>>>not yet exist at that earlier time.
>>
>> 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 ...

> When we are able to see back far enough to the galaxy formation
> era and wait for a few
> billion years we may yet see galxies form. In the
> meantime we have to look out for galaxies at various
> stages of evolution and try to join the dots.
>
> Incidentally we have only just noticed some faint diffuse
> local group galaxies sat on our doorstep. eg
>
> http://www.seds.org/~spider/spider/LG/Add/cet_dw_d.html
> http://www.newscientist.com/article.ns?id=dn7056
>
> Even geological timescales are relatively short compared
> to stellar evolution and galaxy formation.

OK. Thanks.

>>>On another aspect of this topic: I *sort of* agree that
>>>a black hole's event horizon is a singularity. It is
>>>the limit beyond which light cannot reach distant parts
>>>of the Universe. As a "limit", it is a "boundary", and
>>>thus a sort of singularity. But an observer close to
>>>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.

> 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.

> 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".

Thanks.

David A. Smith


.

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    ... in our own galaxy. ... galaxies at various stages of evolution and try to join the dots. ... As a "limit", it is a "boundary", and thus a sort of singularity. ... something "special", or we would not have intense jets of energy (and yes before the event horizon, George). ...
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