"clipka" <nomail@nomail> wrote:

> Given that spacetime is notoriously distorted at the EH, this makes *no*
> statement whatsoever about its radial distance from the singularity. It could
> be - ta-ding! - zero after all...
>
>
> (Again, I find my theory of "EH=singularity" supported - it will mark a paradigm
> shift in the understanding of black holes, and I'm going to be a world-famous
> nobel prize winner, named along with Einstein, Hawking and Feinman! GR and QM
> will at last be proven false, and MY theory will TAKE OVER THE WORLD... no, THE
> *UNIVERSE*! *MUAHAHAHAHA*!)

Then why are the problems with the metric at the Schwarzschild radius removable
with a coordinate substitution, e.g. Eddington-Finklestein coordinates?  If

r* = r+2m ln( r/2m - 1 ),
u = t-r*,
v = t+r*

Then you work out the details, and - voila - the problems disappear, except at
the center.  Just sayin' is all...  Oh, but don't let that stop your plans for
universe domination.

 - Ricky

Post a reply to this message

clipka <nomail@nomail> wrote:
> Warp <war### [at] tagpovrayorg> wrote:
> >   So if he isn't inside the EH, that means that actually *nothing* can
> > ever cross the EH, which means that nothing goes inside a BH, and thus
> > nothing is "lost" there.

> That's basically what I think it says, yes.

  Well, I think you are wrong.

-- 
                                                          - Warp

Post a reply to this message

"clipka" <nomail@nomail> wrote:
> (Unfortunately, nothing so clear though as to identify the milky way as a mass
> of stars. Or maybe my glasses just aren't good enough for that.)

It's like this: even in the big city, if you look up the sky and begin counting
the stars nearby you soon realize you can't, because looking further next to
the bright ones you can also see lots of smaller, faint flickering dots.  They
are everywhere even though when you first felt venturous enough to try to count
the stars, they didn't seem too many.

I don't know if people on glasses have difficult to distinguish the smaller
stars, but once you start counting by the brightest ones, you inevitably become
more aware of the area closer to it and can distinguish a myriad of smaller
stars next to it...

Post a reply to this message

"clipka" <nomail@nomail> wrote:
> "clipka" <nomail@nomail> wrote:
> > Another BTW: With contemporary German orthography, "Schwartzschild" would lose
> > the "t" in his name... like "Rothschild" (which is "Redshield") would lose the
> > "h"...
>
> Duh... sorry folks for misinforming you on this important subject: Looks like
> Schwarzschild's "t" *already* got lost in some black hole... must have been
> redundant information after all...

Thanks.  I'm getting many useful tips in this thread, even though might some
conflict like either accelerating towards a blackhole or keeping where you are
curled up in fetal position... :D

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> > Thus, in the observer's reference frame (I'm deliberately avoiding the phrase
> > "as seen from the observer", because the formula doesn't say anything about
> > perception, but plain hard facts), as soon as the "victim" would hit the EH,
> > its time would come to a standstill, so it couldn't move *any* distance in
> > finite time.
>
> I'm not sure that follows. Photons move as fast as possible, and in their
> own reference frame, time has come to a standstill. Why does the victim's
> clock influence the velocity of the victim in the observer's timeframe?

That's a misconception here: Time for photons has not come to a standstill in
their *own* frame of reference, but at their location in the *observer's* frame
of reference (i.e. in the spacetime co-ordinate system where the observer is not
moving in space, and time flows at "normal speed" at his location).

Time is not universal, even in a single frame of reference.

> This is like saying I stick a giant engine on a spaceship, turn it on, and
> just go, and after a while you see me slowing down, because my clock is
> getting asymptotically close to stopped from your reference frame.

It's a bit different here I guess, because this is not about GR, but just about
SR, with a different underlying mechanism for time dilation.

In SR, which ignores gravitation and acceleration and just deals with constant
relative motion, all time dilation effects are just due to a change in frame of
reference, and can in fact be applied *mutually*: If you zoom by me at near
lightspeed, it seems to me that *your* clock is slower, while at the same time
it seems to you that *my* clock is slower. These are really just illusions due
to the peculiar nature of the question what "now" and "here" actually is.

This apparent paradoxon, however, only leads to problems when we meet once
again, which can only happen if at least one of us accelerates. Enter GR, which
deals with accelerated motion and gravitation; here, *real* time delation
effects happen, that are independent of the frame of reference, with the only
difference that in the "here" frame of reference, time "over there" slows down,
while in the "over there" frame of reference, it is time "here" that speeds up.
The relative effect is the same: Time "over there" runs slower than "here"

> > (Note however that time slows down so dramatically already very
> > close to the EH that the "victim" will not even *reach* EH in finite time.)
>
> *That* is why I think the victim will not find himself inside the EH - the
> universe (including himself) will have decayed to nothingness or some such
> before he gets there.

Yesss!

> > So, the equation does *not* state that the EH has a radius of r[s] = 2GM/c^2
> > after all. Instead, it states that it has a *surface* of 4 pi (2GM/c^2)^2.
>
> That difference is exactly the warped space. It happens with the sun and the
> earth, too, because of their gravity.
>
> IIRC, I read where the circumference of the (ideal) earth is something like
> a cm shorter than what it should be given the radius, and the sun is a
> kilometer or ten kilometers or some such different.

The order of magnitude is right, but someone messed up the sign; see
http://www.johnstonsarchive.net/relativity/stcurve.pdf (emphasis added):

"The true diameters of the Sun and Earth are 4.1 km and 4.4 mm GREATER,
respectively, than one would expect from applying Euclidean geometry (C = pi d)
to the observed surface of these bodies"

(Duh - took quite a while to google that one up. Looks like this is a topic not
so frequently tackled.)


> > Given that spacetime is notoriously distorted at the EH, this makes *no*
> > statement whatsoever about its radial distance from the singularity. It could
> > be - ta-ding! - zero after all...
>
> More like infinity, methinks.

(*scratches head*)
Doesn't make sense to me: We get closer to the black hole's center, and when we
have reached the EH this distance becomes *infinite*?

Now *that* would be *really* warped spacetime! :)


> > (Good enough to quality for a world-class crackpot this time, huh? =B))
>
> I don't think real crackpots go "Mwa ha ha ha!"

Darn. Lost again, hm?

Post a reply to this message

"triple_r" <nomail@nomail> wrote:
> Then why are the problems with the metric at the Schwarzschild radius removable
> with a coordinate substitution, e.g. Eddington-Finklestein coordinates?  If
>
> r* = r+2m ln( r/2m - 1 ),
> u = t-r*,
> v = t+r*
>
> Then you work out the details, and - voila - the problems disappear, except at
> the center.  Just sayin' is all...  Oh, but don't let that stop your plans for
> universe domination.

Spoil-sport :P

Don't know, haven't looked at these. At the moment I fancy the're... well,
dunno, maybe just plain wrong? =B)

They look a bit... weird to me in any case. I know UV co-ordinates, but these
don't seem to fit any mesh :P

(Hey, nothing like a bit of ridiculing some (probably) well-established formulae
that can't seem to be argued against; gotta make a few crackpot points after
all...)

Post a reply to this message

Warp <war### [at] tagpovrayorg> wrote:
> > >   So if he isn't inside the EH, that means that actually *nothing* can
> > > ever cross the EH, which means that nothing goes inside a BH, and thus
> > > nothing is "lost" there.
>
> > That's basically what I think it says, yes.
>
>   Well, I think you are wrong.

Reminds me of that Monty Python sketch:

"This is not argument, this is just plain contradiction"
"No, it isn't"
"Yes, it is!"
"No, it isn't"
"..."

Post a reply to this message

"nemesis" <nam### [at] gmailcom> wrote:
> Thanks.  I'm getting many useful tips in this thread, even though might some
> conflict like either accelerating towards a blackhole or keeping where you are
> curled up in fetal position... :D

Practical applied science, yes :)

Post a reply to this message

clipka wrote:
> That's a misconception here: Time for photons has not come to a standstill in
> their *own* frame of reference,

How do you know? They're moving at c, where relativity divides by zero. :-)

>> IIRC, I read where the circumference of the (ideal) earth is something like
>> a cm shorter than what it should be given the radius, and the sun is a
>> kilometer or ten kilometers or some such different.
> 
> The order of magnitude is right, but someone messed up the sign; see
> http://www.johnstonsarchive.net/relativity/stcurve.pdf (emphasis added):
> 
> "The true diameters of the Sun and Earth are 4.1 km and 4.4 mm GREATER,
> respectively, than one would expect from applying Euclidean geometry (C = pi d)
> to the observed surface of these bodies"

Diameters are greater than they should be, circumference is shorter than it 
should be. Yes?

>>> Given that spacetime is notoriously distorted at the EH, this makes *no*
>>> statement whatsoever about its radial distance from the singularity. It could
>>> be - ta-ding! - zero after all...
>> More like infinity, methinks.
> 
> (*scratches head*)
> Doesn't make sense to me: We get closer to the black hole's center, and when we
> have reached the EH this distance becomes *infinite*?

Yes. for the same reason that the diameter of the earth is *greater* than it 
should be given its circumference.

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

Post a reply to this message

"clipka" <nomail@nomail> wrote:
> Warp <war### [at] tagpovrayorg> wrote:
> > > >   So if he isn't inside the EH, that means that actually *nothing* can
> > > > ever cross the EH, which means that nothing goes inside a BH, and thus
> > > > nothing is "lost" there.
> >
> > > That's basically what I think it says, yes.
> >
> >   Well, I think you are wrong.
>
> Reminds me of that Monty Python sketch:
>
> "This is not argument, this is just plain contradiction"
> "No, it isn't"
> "Yes, it is!"
> "No, it isn't"
> "..."

No, it doesn't! :D

Post a reply to this message