clipka escreveu:
> Darren New <dne### [at] sanrrcom> wrote:
>> It's possible I got that wrong.  Indeed, it's possible I don't know anything
>> at all about the subject that I think I do. :-)  Were this an actual
>> scientific forum, I'd have shut up a long time ago.
> 
> Well, same with me - but that's the fun part about it: Nobody *expects* us to
> know what we're talking about, so we can let our imagination run wild ;)

Don't worry, you guys!  Even scientists let their imaginations run wild 
too...

This was a very interesting thread, despite being a very difficult and 
misunderstood subject among laymen.  But I'm actually amazed by how few 
were drawn to it.  I thought most geeks love space talk and povray is 
full of geeks after all! :D

>>> AIUI the cosmological horizon is just the distance we can see *now*. Everything
>>> beyond will become visible to us over time. Theoretically speaking.
>> Oh, the event horizon. No, I think it's caused by space itself expanding,
>> due to the big bang sort of thing.  If it all collapses again, that's a
>> different question.
> 
> But if it all collapses again, then we couldn't have such an event horizon,
> right? After all, it would all "boil down" (literally ;)) to a single point
> again, where all the stuff will be able to interact once more...

Since we're speculating, if space is really expanding, do you think in 
absolute terms we're now much larger than dinosaurs back in their day? 
Of course, fossils won't tell, cause they expanded ever since too. ;)

> (Then again, currently scientists claim we'll all be ripped to pieces one day by
> the ever-faster expanding space within us all... hmmm... "the space within us" -
> sounds a bit hippie-ish ;)

I don't want to live to see proton decay!  well, not that I would 
anyway... :P

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Darren New <dne### [at] sanrrcom> wrote:
> Ha! You're teaching me as you go! :-)

Scratch that.  It could be  LOT worse.  I could be this guy (worth at listen at
about 31:00):

http://www.thisamericanlife.org/Radio_Episode.aspx?episode=293

Also interesting/entertaining:

http://insti.physics.sunysb.edu/~siegel/quack.html
http://math.ucr.edu/home/baez/crackpot.html

 - Ricky

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clipka escreveu:
> nemesis <nam### [at] gmailcom> wrote:
>> Darren New escreveu:
>>> nemesis wrote:
>>>> kind of after image that seems to ever approach the event horizon
>>>> without ever touching it, but in reality the crossing of the EH
>>>> already took place and nothing of what happens in the inside is seen...
>>> Hmmmm.... I'll have to think on it.
>> I think it has something to do with the last photons coming out of the
>> object entering the EH are severely slowed down by the massive gravity
>> and only reach you after much more time than normal has passed.
> 
> Yeah - interestingly, the distance between a point near the EH and a point far
> away is shorter when moving towards the EH than when moving away from it on the
> very same route...

So that's why light takes a lot more time to reach us and thus the after 
image just before the crossing is visible.  OTOH, time and space are two 
sides of the same coin, isn't it?

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nemesis wrote:
> "We start with effects actually seen in the lab, which I think gives it 
> more credibility than black holes"
> 
> evidence.

The effects of what appear to be black holes are seen in astronomy. Just not 
in the lab as such.

> If we assume blackholes exist, without much evidence so far,

A fair amount of evidence, actually.

> Perhaps the blackhole is then just a curve along 
> this surface and the poor fellow ends up in another region of 
> space-time.

Basically, yes. Some types of black hole structures are thought to work that 
way. Like, a rotating black hole can be traversed like that without hitting 
the singularity, supposedly.

It's all math, tho, with no actual physics evidence beyond what the math 
implies. If reality isn't isomorphic to the math after all, it won't work.

-- 
   Darren New, San Diego CA, USA (PST)
   "Ouch ouch ouch!"
   "What's wrong? Noodles too hot?"
   "No, I have Chopstick Tunnel Syndrome."

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Darren New <dne### [at] sanrrcom> wrote:
> nemesis wrote:
> > "We start with effects actually seen in the lab, which I think gives it
> > more credibility than black holes"
> >
> > evidence.
>
> The effects of what appear to be black holes are seen in astronomy. Just not
> in the lab as such.
>
> > If we assume blackholes exist, without much evidence so far,
>
> A fair amount of evidence, actually.

Yes, but according to the article you linked, QM physicists are giving another
explanation for the same effects without the paradoxes blackholes carry, the
same ones we were avidly discussing about previously:  the "lost information"
and the "after-image" effect of something crossing the EH as seen from an
external observer.  Of course, they are trying to explain it by relying on a
supposed dark matter star that has never been detected before either. :P

Surely the Dark side is very sneaky!

OTOH, will we ever witness such object, blackhole or dark matter star?  Such
humongous gravitational force surely has many objects orbiting it,
"overcrowded" as clipka mentioned, and most of it being gas and stars, so what
is the chance of seeing what isn't supposed to be seen except against a clear
starry background?

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Darren New <dne### [at] sanrrcom> wrote:
> A fair amount of evidence, actually.


Absolutely fascinating:

http://www.eso.org/public/outreach/press-rel/pr-2008/phot-46-08.html

 - Ricky

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triple_r wrote:
> http://www.eso.org/public/outreach/press-rel/pr-2008/phot-46-08.html

Kewl. I was thinking of this one.
http://en.wikipedia.org/wiki/Cygnus_X-1

-- 
   Darren New, San Diego CA, USA (PST)
   "Ouch ouch ouch!"
   "What's wrong? Noodles too hot?"
   "No, I have Chopstick Tunnel Syndrome."

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Darren New <dne### [at] sanrrcom> wrote:
> triple_r wrote:
> > http://www.eso.org/public/outreach/press-rel/pr-2008/phot-46-08.html
>
> Kewl. I was thinking of this one.
> http://en.wikipedia.org/wiki/Cygnus_X-1

Convincing evidence, but I'm a sucker for the visually spectacular ones:

http://en.wikipedia.org/wiki/Elliptical_Galaxy_M87

 - Ricky

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"triple_r" <nomail@nomail> wrote:
> Darren New <dne### [at] sanrrcom> wrote:
> > A fair amount of evidence, actually.
>
>
> Absolutely fascinating:
>
> http://www.eso.org/public/outreach/press-rel/pr-2008/phot-46-08.html

Yes.  Look the last video, it's a journey to the center of the galaxy through a
multilayered collection of ever zooming galaxy shots.  It ends with both the
collected frames aquired over 16 years and accelerated by a few million times
and a CG detailing what's going on.

Truth be told, I don't think the video gives the exact scale of the thing.  I
mean, I thought the central blackhole, or whatever it is those stars are
orbitting around, would be much bigger.  Yes, I know it's hyperdense, but even
still...

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> Depends on definition if speed, but as it is usually specified based on 
> the
> observer's timeframe: Yes. Gravitation near a black hole is so strong 
> that -
> from an observer's POV - through time delation and the warping of space it
> causes "that poor old sod over there" to slow to a halt.

I always thought that it could be possible to go forward in time by some 
arbitrary amount just by making a close orbit around a black hole.  The 
closer you go, the more time you can jump forward.  So just type in the year 
3050 to your ship, it fires you off towards the nearest black hole, and a 
few months later you return back towards Earth in the year 3050 +/- a few 
months ;-)

Or doesn't it work like that?

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