clipka wrote:
> Talk about atoms - the ancient greeks "invented" them. 

Yes, and they also didn't believe in irrational numbers even after they were 
proved to exist. So I don't think you can pick one success out of history 
and call it a "prediction".

I mean, there's really only two or three possibilities: Stuff is atoms, 
stuff is continuous, stuff is a mixture. :-)

The greeks had no evidence of atoms, as far as I know. It was just a guess. 
It wasn't until Mendeleev (or the work that lead up to the periodic table) 
or so that people actually had evidence that atoms were the right answer.

-- 
   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:
> >   With this taken into account, can you just go from Earth to the nearest
> > black hole, get an enormous speedup and come back at 100x the speed and
> > slam onto Earth at that speed? From a gravity assist only, I don't think so.
> > I think it would be against conservation of energy. If you were travelling
> > from Earth to another star system, then maybe, but I don't think it works
> > in the closed case.

> It does.

> The trick is that the slingshot affects both bodies: That Huge Planet Over There
> and yout Teeny Weeny Space Machiney.

> Guess which one *seems* to be affected most...

> So if you use a black hole to slingshot you around back home, at the same time
> you sort of slingshot the black hole around your spacecraft into the opposite
> direction... it's just that the black hole won't bother *much*, being the fat
> lazy sucker it is.

  Actually it would work if the black hole was moving towards us. Then
the spacecraft could go there and rob part of this momentum and get a
speed boost back towards Earth.

  If the black hole was moving away from us then it would certainly not
work.

  Think about it as an elastic collision. It's a pretty accurate way of
thinking about it.

> > - If you go so close to a black hole that it will give you a stronger
> > slingshot effect than a regular star would, the tidal forces would
> > probably rip you apart. Not very practical.

> Nah, I don't think so. Would tidal forces rip you apart at the surface of the
> sun? I doubt.

  Remember: When the Shoemaker-Levy was on collision course against Jupiter,
tidal forces broke it in 9 parts well before it reached the surface. And
Jupiter is a lot less massive than the Sun.

  Ok, maybe if your spacecraft is sturdy enough, it might survive a
slingshot from the Sun. However, we are talking about black holes here,
and black holes have several times the mass of the Sun (because stars
as small as the Sun cannot collapse to black holes), and getting very
close to the event horizon (for it to make a difference compared to a
regular star).

> > - The humongous amounts of radiation around a black hole would probably
> > be enough to fry you to ashes in a fraction of a second, no matter what
> > kind of shielding you use, especially if you go so close that you would
> > get a larger speed boost than from a regular star.

> Again, only if there's an accretion disk. Remember: Black holes don't emit
> anything - only their surroundings may ;)

  They don't emit anything, but by their nature as being really massive
objects they surely tend to aggregate lots of nasty stuff orbiting around
them, and this stuff often emits large amounts of radiation by several
means.

  For example one concern about sending probes to orbit Jupiter is the
large amount of radiation there (which could break electronics if not
shielded properly). Jupiter, as a very massive object, gathers tons of it.
And Jupiter is a lot less massive than a normal black hole.

> However, maybe you also want to check the magnetic field of the black hole - I'm
> not sure about the orders of magnitude, but I wouldn't want all my electrons go
> spinning off to the left while the protons go off to the right - not to speak
> of the resulting synchroton radiation ;)

  Yeah, that too.

-- 
                                                          - Warp

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Warp wrote:
>   The major objections against singularities are more or less philosophical,
> rather than based on hard science. It's "hard to believe" that mass could
> be compressed into a point of zero volume.

I think that maybe used to be the case, but I think the objections are also 
that it's in conflict with QM right now.

>   If someone objects to the notion of a singularity, he would have to show
> some evidence that GR doesn't work as predicted in this case.

I thought that's why it's called a singularity? :-)

 > There must be
> some property of the Universe which makes GR not work in this situation,
> something which actually stops the singularity from forming. What could this
> phenomenon be? Has anyone ever measured such phenomenon to exist?

QM uncertainty, and symmetry rules that indicate you can't lose information 
about individual particles. You *can't* compress something down to zero size 
and not know both where it is and how fast it's moving, for example. QM also 
says you can't have two fermions in the same quantum state in the same 
place. (More precisely, the probability that it happens is zero, once you 
add up all the possible virtual paths.) Hence, you can't collapse an entire 
star into a single point.

I don't think the objects are just "it's hard to believe". It's just that 
nobody knows how to resolve the problem, since the incompatible theories 
both satisfy all the experimental evidence gathered so far.

>   The thing is, if GR equations are right, and there is a lot of evidence
> suggesting that they are,

... at the macroscopic level ...

But a singularity is, by definition, microscopic. :-)

> There's no known way for matter/energy to stop going towards this center. 

You wouldn't think a single electron could be larger than a house, either, 
but they've done that in a laboratory.

I think the real answer is that people just don't know yet. GR says one 
thing, and every experimental investigation we can do matches GR. QM says 
another thing, and every experimental investigation we can do matches QM. 
However, we don't have the capability (yet) of doing any experiment that 
would encompass both GR and QM in the same experiment that would give 
different answers in the area where they conflict.

Now, what would be fascinating would be for someone to come up with an 
experiment that proves you can't measure things in a way that would make QM 
and GR conflict. :-)

-- 
   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

Darren New <dne### [at] sanrrcom> wrote:
> You'd wind up changing the course of the black hole much less than you'd 
> change the course of your spaceship, is all.

  The black hole would have to be moving towards the general direction
of Earth, in that case.

> I also think the black hole would be better, because you can get closer and 
> get a bigger time dilation from the gravity also.

  But you get tons of other problems, as I described in my post. :P

> > - The humongous amounts of radiation around a black hole would probably
> > be enough to fry you to ashes in a fraction of a second, 

> FWIW, it's the accretion disk that generates the radiation, so you could 
> kill two birds with one stone by finding one without.

  As very massive objects, and ones usually formed from collapsing stars
(the collapse leaving behind tons of stuff), I think it would be rather
difficult to find "naked" black holes, without the accompanying stuff.

-- 
                                                          - Warp

Post a reply to this message

Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> You give one particle that is constantly emitting photons in all directions 
>> a push due south towards the singularity. You have an observer due north of 
>> the singularity looking south.  The observer due north will continue to see 
>> photons coming off the particle indefinitely?
> 
>   You can distribute a finite amount of photons over an infinite amount
> of time with a simple 1/x formula.

And therefore, yes, you would see photons coming off the particle 
indefinitely. :-) That's kind of what I was asking. If you see photons 
coming off forever, then you know that shortly before the most recently 
observed photon, the object still hasn't crossed the EH.

So since the person falling in will never see himself cross the EH (because 
his time slows), and the person outside will never see him cross, then stuff 
falling into a black hole does *not* fall into the singularity. Nothing 
crosses the EH, so nothing gets compressed into the singularity, yes?

(Discounting the black holes that have paths to the singularity that don't 
cross an EH, of course.)

-- 
   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

Darren New <dne### [at] sanrrcom> wrote:
> QM also 
> says you can't have two fermions in the same quantum state in the same 
> place.

  At least not in normal, almost-cartesian space, with extremely weak
gravity.

  How about inside space which is so curved that it forms an event
horizon because of a practically infinite gravity?-)

  Gravity is such a weak force in normal situations that you usually don't
have to even take it into account when making QM calculations. However,
inside a black hole gravity, rather obviously, overwhelms all other
forces and becomes absolutely dominant. What happens to eg. fermions
when gravity is immensely stronger than eg. the strong nuclear force?

  Under such pressures matter degenerates. Do fermions even stay as
fermions, or do they degenerate to something more elemental? Something
which might not be bound to QM laws?

> >   The thing is, if GR equations are right, and there is a lot of evidence
> > suggesting that they are,

> ... at the macroscopic level ...

> But a singularity is, by definition, microscopic. :-)

  Gravity is in effect also at subatomic levels, even though it's often
ignored because it's so weak in normal circumstances.

> > There's no known way for matter/energy to stop going towards this center. 

> You wouldn't think a single electron could be larger than a house, either, 
> but they've done that in a laboratory.

  "You wouldn't think" is different from "there's no known way". The
former is something related to my intuition. The latter is related to
current scientifical global knowledge.

  (Well, always with a big "AFAIK". I'm *not* a scientist.)

-- 
                                                          - Warp

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clipka escreveu:
> "nemesis" <nam### [at] gmailcom> wrote:
> Interestingly though, the real-existing phenomenon of "black holes" was
> originally a purely hypothetical prediction of GR - not some already known
> effect that needed to be explained. And it did predict their properties quite
> well as it seems. So this is strong evidence that the GR is a very good tool to
> make predictions.

It is, no doubt.  A very solid model, which QM enthusiasts are still 
plotting to supplant. :)

Evidence was found of objects with imense gravitational fields occupying 
relatively tiny areas in space and this matches with GR's predictions. 
But there's as of yet no evidence that singularities physically exist or 
that matter entering a blackhole is forever lost, except as a somewhat 
vague Hawking radiation...

So, the QM guys thought it would be a good idea to imagine an alternate 
model to explain such objects without relying on singularities and lost 
information.  And it's testable in lab, right here on Earth.  Of course, 
they are trying to somehow fit the lab effect to the observable 
phenomena, but without explaining why such effect would occur in the 
surface of stars...

> So in order to show that *their* theory is at least an equally good tool, they
> would actually have to demonstrate how their own theory explains not only the
> same *phenomenons* as GR, but *postulates GR itself* - or demonstrate how their
> theory is just a different way of looking at GR.

QM so far has made good predictions is the small, very small. :)

> BTW, speaking of it: When falling into a black hole I guess it may be best not
> to try to fight the inevitable... suppose you manage to stay at a fixed
> distance from the center - with all the blueshift of the photons falling in,
> you're gonna get your daily maximum dose of gamma rays in a few split
> seconds... so better fall in to experience the same blue shift (effectively
> leaving the shift unchanged from your perspective) and hope that the
> singularity is just a transition to a better life somewhere - um, I mean
> someWHEN - else...

a very good suggestion too. :)

Perhaps it's like passing through a corridor in flames:  you should run 
towards the end of it... :P

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> So since the person falling in will never see himself cross the EH

  I'm not sure where you are getting this one. I have not heard of it.
The only thing I have heard is that an *external* observer never sees
anything "touch" the event horizon.

  Time for an observer itself is always the same, regardless of where
he is.

-- 
                                                          - Warp

Post a reply to this message

Warp escreveu:
> point towards the center. There's no known way for matter/energy to stop
> going towards this center. Just advancing in time makes it advance towards
> this center.

I like how Hawking puts it:  "The singularity is the future:  as you 
advance towards it, you also moves towards the future" or something to 
that effect...

>   The only possible conclusion is that all the matter and energy compresses
> into a point of zero volume. If the singularity does not form in reality,
> then something must explain why. Something more than philosophical objections.

Well, if it was like that in the beginning, why couldn't it be possible 
now, huh?  Which also begs the philosophical question of whether passing 
through the EH leads to a whole new universe beginning from yet another 
big bang...

Post a reply to this message

nemesis <nam### [at] gmailcom> wrote:
> Which also begs the philosophical question of whether passing 
> through the EH leads to a whole new universe beginning from yet another 
> big bang...

  I don't think the spacetime geometry inside the event horizon of a
black hole would allow for a universe to exist in there.

-- 
                                                          - Warp

Post a reply to this message

Warp escreveu:
> nemesis <nam### [at] gmailcom> wrote:
>> We're actually cruising unknown frontiers at speeds vastly superior to 
>> 200km/sec
> 
>   With respect to what?
> 
>   Motion is always relative.
> 
to the center of the galaxy?

Post a reply to this message

Warp escreveu:
> nemesis <nam### [at] gmailcom> wrote:
>> Which also begs the philosophical question of whether passing 
>> through the EH leads to a whole new universe beginning from yet another 
>> big bang...
> 
>   I don't think the spacetime geometry inside the event horizon of a
> black hole would allow for a universe to exist in there.

In there or out there? ;)

Post a reply to this message

nemesis escreveu:
> Warp escreveu:
>> nemesis <nam### [at] gmailcom> wrote:
>>> Which also begs the philosophical question of whether passing through 
>>> the EH leads to a whole new universe beginning from yet another big 
>>> bang...
>>
>>   I don't think the spacetime geometry inside the event horizon of a
>> black hole would allow for a universe to exist in there.
> 
> In there or out there? ;)

I believe the singularity could only get a proper artistic rendering 
from Escher. :)

Post a reply to this message

nemesis <nam### [at] gmailcom> wrote:
> Warp escreveu:
> > nemesis <nam### [at] gmailcom> wrote:
> >> We're actually cruising unknown frontiers at speeds vastly superior to 
> >> 200km/sec
> > 
> >   With respect to what?
> > 
> >   Motion is always relative.
> > 
> to the center of the galaxy?

  Well, I suppose that since we are in a rotating frame of reference, and
given that it's physically possible (at least in theory) to determine an
inertial frame of reference centered at the center of our galaxy, we could
be moving at that speed with respect to this inertial frame of reference.

-- 
                                                          - Warp

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Darren New escreveu:
> clipka wrote:
>> Talk about atoms - the ancient greeks "invented" them. 
> 
> Yes, and they also didn't believe in irrational numbers even after they 
> were proved to exist. So I don't think you can pick one success out of 
> history and call it a "prediction".
> 
> I mean, there's really only two or three possibilities: Stuff is atoms, 
> stuff is continuous, stuff is a mixture. :-)
> 
> The greeks had no evidence of atoms, as far as I know. It was just a 
> guess. It wasn't until Mendeleev (or the work that lead up to the 
> periodic table) or so that people actually had evidence that atoms were 
> the right answer.

Indeed.  And atoms are not even atomic in the original sense of the 
greek word... ;)

Post a reply to this message

nemesis wrote:
>  holding your cup of coffee with a steady hand... :P

... which only means you need more coffee.

-- 
   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

Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> You'd wind up changing the course of the black hole much less than you'd 
>> change the course of your spaceship, is all.
> 
>   The black hole would have to be moving towards the general direction
> of Earth, in that case.

I don't have the math to be sure that's true.  Wouldn't it be possible to 
make it moving away less quickly?

I mean, certainly if there's a solid object moving away from you, you can 
land on it and jump off and go up. Stand on a trampoline going 1 MPH 
downwards - can you jump up?

You might be right, tho, if there's no physical contact, but as I say I 
don't want to learn the math to figure it out. :-)

>   But you get tons of other problems, as I described in my post. :P

Yah. I posted before I read that, methinks.

>   As very massive objects, and ones usually formed from collapsing stars
> (the collapse leaving behind tons of stuff), I think it would be rather
> difficult to find "naked" black holes, without the accompanying stuff.

Unless you manufactured it yourself, yes. :-)

-- 
   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

Warp <war### [at] tagpovrayorg> wrote:
>   If someone objects to the notion of a singularity, he would have to show
> some evidence that GR doesn't work as predicted in this case. There must be
> some property of the Universe which makes GR not work in this situation,
> something which actually stops the singularity from forming. What could this
> phenomenon be? Has anyone ever measured such phenomenon to exist?
>
>   If not, then any objection against singularities is more or less
> philosophical. "It doesn't sound right" is not hard science.

I'm not saying "it doesn't sound right" - I'm saying I *believe* something else
;)

It wasn't meant to be a scientific statement or any other claim of truth in the
first place. Just a purely philosophical statement amidst an otherwise
dominated by science and wild thoughts...


I believe science will find that GR is wrong close to its singularities,
because... well, because I love the idea that there might be some
mind-bogglingly simple way of looking at both GR and QM, which science just
hasn't been imaginative enough to discover ;)


>   The thing is, if GR equations are right, and there is a lot of evidence
> suggesting that they are, then there simply is no way for a singularity
> to not to form when a mass collapses to be smaller than its Schwarzschild
> radius. All geodesics inside the event horizon, including time geodesics,
> point towards the center. There's no known way for matter/energy to stop
> going towards this center. Just advancing in time makes it advance towards
> this center. Even if you tried to apply some force to a particle to stop
> it from getting closer to the center, you couldn't, not even if you applied
> an infinite force.

Hm - let's take this a step further, and salt it with a bit of quantum thinking
(which has successes of its own):

- If the equations say that inside the EH you can't do anyhing to a particle to
prevent it from going straight towards the center, then this might be a hint
that particles there can't *interact* in the first palce.

- If particles can't *interact*, there is no way to measure time; so the time a
particle would take from entering the EH until it reaches the center would be
"mu" (in the Zen sense, not some greek-lettered constant).

- If the equations say that as soon as a particle crosses the EH it will head
straight towards the center within a time of "mu", then it *might* be a hint
that the EH is *identical* with the center after all...


>   The only possible conclusion is that all the matter and energy compresses
> into a point of zero volume.

No - this is the most *straightforward* conclusion. But being straightforward,
it may hinder thinking along other lines, so I choose to discard it and let my
imagination run wild.

Occam's razor is a good tool, but applying it to some "brainstorming" will just
kill inspiration.

It's also a good thing to occasionally check whether the concept once regarded
as "most simple" actually still *is* the most simple.


> If the singularity does not form in reality,
> then something must explain why. Something more than philosophical
> objections.

Fine. So? I *love* some good crazy mix of science, philosophy and wild
speculations, nothing wrong there for me ;)


Then again, I could turn my speculation indeed into an objection: As of now, no
singularity (i.e. a condition where a formula gives "infinity" as an answer)
predicted by any scientific theory has ever been observed in true life. In
fact, various theories that predicted singularities have been *proven* to be
inconsistent with reality exactly at or close to these conditions. Therefore,
it is reasonable to assume that singularities predicted by scientific theories
actually indicate that the theory *fails* at these conditions.

This resoning is actually not philosophical in nature, but rather very
scientific, and may qualify for a theory in its own right. The statement is
clear: "If the formulae derived from a theory in the domain of natural science
result in "infinity" values for certain conditions, then it is invalid for
these conditions." Predictions can be easily derived from it, e.g. "The GR does
not accurately describe the conditions within the EH of a black hole". In this
case, putting the predictions to the test might be problematic, but I guess
other theories can be found.

Of course one must be careful with this reasoning. Finding that a theory
predicts singularities doesn't mean the theory as a whole msut be at fault - it
just should be taken as a warning to be careful about predictions made by the
theory close to these conditions. In fact, a theory may be perfectly fine
except *exactly* at these conditions. And, after all, this reasoning is just
another theory, so it *may* be wrong after all. But from evidence seen so far,
I guess it can be considered quite robust.

Post a reply to this message

Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> QM also 
>> says you can't have two fermions in the same quantum state in the same 
>> place.
> 
>   At least not in normal, almost-cartesian space, with extremely weak
> gravity.
> 
>   How about inside space which is so curved that it forms an event
> horizon because of a practically infinite gravity?-)

AFIAK, gravity's effect is so weak in QED at least that nobody knows how it 
affects things.

Note that I'm not saying "you can't have two fermions in the same state." 
I'm saying that's what QM says. And since it conflicts with GR's 
predictions, one of the other needs to be adjusted, unless you can prove 
that you can't prove either one is right.

Sure, it's possible that QM breaks down in extremes of GR, just like it's 
possible GR breaks down at extremes of QM.  I'm not saying one is right or 
the other. I'm saying it's not just "philosophical objections" to 
singularities, but actual mathematics that matches experimental measurements 
to 15 decimal places.

(I think gravity is something like 40 decimal places out, tho, so it's 
certainly possible QM isn't taking account of it properly.)

>   Under such pressures matter degenerates. Do fermions even stay as
> fermions, or do they degenerate to something more elemental? Something
> which might not be bound to QM laws?

It's entirely possible that's what happens.

>   Gravity is in effect also at subatomic levels, even though it's often
> ignored because it's so weak in normal circumstances.

Yep. And QM is in effect at levels the size of a star, similarly. :-)

>>> There's no known way for matter/energy to stop going towards this center. 
> 
>> You wouldn't think a single electron could be larger than a house, either, 
>> but they've done that in a laboratory.
> 
>   "You wouldn't think" is different from "there's no known way". The
> former is something related to my intuition. The latter is related to
> current scientifical global knowledge.

Sure. I was simply addressing your "philosophical objection" bit. :)

And there *is* a known way for it to stop going towards the center: QM.

If either of us knew whether GR or QM was more right in this situation, we'd 
already been in Stockholm picking up our prize. :-)

-- 
   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

Warp <war### [at] tagpovrayorg> wrote:
>   Just because you can't tell appart gravity from acceleration doesn't
> mean that all accelerations are caused by the same phenomenon as gravity.

No, but they both cause exactly the same effects...

Post a reply to this message

Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> So since the person falling in will never see himself cross the EH
> 
>   I'm not sure where you are getting this one. I have not heard of it.

Hmmm.... Maybe my bad, I think.  GR isn't easy for my brain.

If his clock slows to zero on the outside and he never crosses the event 
horizon, then the next tick of the clock is infinitely far in the future of 
the universe, yes?  So he never experiences crossing the EH because it takes 
forever for his clock to tick.  Say the black hole evaporates after a 
billion years - does the space ship ever hit the singularity?

-- 
   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

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

"That's what they told Galileo."
I know Galileo, and you're no Galileo. On the contrary, you're one of "they"


Heh heh heh.
-- 
   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

Warp <war### [at] tagpovrayorg> wrote:
>   The foundation of GR is that gravity does not, in fact, cause
> acceleration at all. An object in "free wall" is all about inertia
> and nothing about acceleration (even though it may not look like it
> to us).

From the viewpoint of a free-falling(!) "actor", gravity is actually absent,
yes. It has no effect whatsoever - it's just that That Big Black Hole Over
There keeps accelerating towards *him*, badly mangling spacetime as it does.

Post a reply to this message

Darren New escreveu:
> nemesis wrote:
>>  holding your cup of coffee with a steady hand... :P
> 
> ... which only means you need more coffee.

LOL

Post a reply to this message

clipka wrote:
> - If the equations say that inside the EH you can't do anyhing to a particle to
> prevent it from going straight towards the center, then this might be a hint
> that particles there can't *interact* in the first palce.

It doesn't. It says no particle going at or slower than c can avoid going 
towards the center. But QM doesn't restrict particles from going FTL, either.

> Fine. So? I *love* some good crazy mix of science, philosophy and wild
> speculations, nothing wrong there for me ;)

Welcome to p.o-t!  :-)   How about some Java/C++ flames now? ;-)

> it is reasonable to assume that singularities predicted by scientific theories
> actually indicate that the theory *fails* at these conditions.

Again, I think that's what's meant by the term "singularity". Isn't that why 
they name it after that word? The formulas fall down?

QM has its own singularities: if you take it all the way down to size zero, 
you get infinities in the sums. Feynman got his Nobel for proving you don't 
have to go down to zero, and regardless of where you stop approaching the 
limit of zero, you get the same answer (within tolerance of course).

So there's a singularity in QM in the same place there is in GR, in some 
sense - you can't do the QM formulas without freedom of motion, which 
doesn't happen at the singularity in a black hole.

-- 
   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

Warp <war### [at] tagpovrayorg> wrote:
>   Actually it would work if the black hole was moving towards us. Then
> the spacecraft could go there and rob part of this momentum and get a
> speed boost back towards Earth.

Well, for the sake of the original argument, I think you're wrong here: It
wasn't about a speed *boost*, but just using the black hole to "swing around"
and not lose any of the momentum that got us there in the first place.

Though you may be right that for the sake of this maneuver, *any* black hole not
sufficiently "static" with respect to us would be a bad choice. I didn't check
the math.

Then again, I think yours is wrong as well: With that black hole being
sufficiently heavy and having a speed of V, if we head there with a speed v, we
should be bouncing back at a speed of (roughly) v' = V-v (with no significant
influence of the hole's mass remaining), as long as neither of us is going
relativistic.

So it should suffice to find a black hole significantly slower than our
spacecraft.


>   Remember: When the Shoemaker-Levy was on collision course against Jupiter,
> tidal forces broke it in 9 parts well before it reached the surface. And
> Jupiter is a lot less massive than the Sun.

I'd expect it to depend a good deal on (a) how elastic the thing is, and (b) how
fast the thing is rotating around itself: When rotating fast, the tidal forces
not only tear at the electromagnitic "links" between the molecules and atomic
particles, but keep distorting the shape of the object, and I guess an overdose
of squishing and squashing kills an object a lot faster than the tidal forces
themselves.

It's similar to a tyre with not enough air pressure: As long as you don't move
your car, nothing bad will happen to it. But if you drive around with it too
fast, the squishing and squashing will heat it up, so it may ultimately break
up like that comet...

So, in this sense, the Shoemaker-Levy comet wasn't torn apart by tidal forces,
but was killed by RSI :)


>   They don't emit anything, but by their nature as being really massive
> objects they surely tend to aggregate lots of nasty stuff orbiting around
> them, and this stuff often emits large amounts of radiation by several
> means.

Well, would they aggregate more stuff than a massive star? (Assuming we're
talking about "star-sized" holes here)


>   For example one concern about sending probes to orbit Jupiter is the
> large amount of radiation there (which could break electronics if not
> shielded properly). Jupiter, as a very massive object, gathers tons of it.
> And Jupiter is a lot less massive than a normal black hole.

Maybe that's due to a magnetic field of Jupiter? Sort of a "Van Allen Belt,
XXL-size"?

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> So since the person falling in will never see himself cross the EH (because
> his time slows), and the person outside will never see him cross, then stuff
> falling into a black hole does *not* fall into the singularity. Nothing
> crosses the EH, so nothing gets compressed into the singularity, yes?

The problem here is the frame-of-reference thing.

An outside observer will see the "victim's" clock slow down.

The "victim" will not notice, so what will he see? From his point of view, he'll
reach the EH in finite time, so depending on what happens then, he *may* see
himself falling in.


> (Discounting the black holes that have paths to the singularity that don't
> cross an EH, of course.)

How could that be?

Post a reply to this message

clipka wrote:
> The "victim" will not notice, so what will he see? From his point of view, he'll
> reach the EH in finite time,

Let's say the outside observer measures the slow-down of the clock and 
calculates that the victim's clock will read 1PM at the moment the victim 
crosses the EH.  Will the victim ever experience 1:01PM?  What will the rest 
of the universe look like when the victim experiences 1:01PM? If the 
victim's clock actually stops with respect to the outside universe, the 
entire universe will age and disappear (or big crunch) before the clock 
reads 1:01PM, yes?

>> (Discounting the black holes that have paths to the singularity that don't
>> cross an EH, of course.)
> 
> How could that be?

Rotating highly charged black holes that don't have the same Schwartzchild 
equations. (The Schwartzchild equations only work for non-rotating 
non-charged black holes, methinks.) If you spin the black hole fast enough, 
the equator doesn't have an EH, or the pole doesn't, or something. (I've 
heard speculation that the equations must therefore be wrong.)

-- 
   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

Darren New <dne### [at] sanrrcom> wrote:
> If his clock slows to zero on the outside and he never crosses the event
> horizon, then the next tick of the clock is infinitely far in the future of
> the universe, yes?  So he never experiences crossing the EH because it takes
> forever for his clock to tick.  Say the black hole evaporates after a
> billion years - does the space ship ever hit the singularity?

Remember Achilleus and the turtle!

Post a reply to this message

clipka wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> If his clock slows to zero on the outside and he never crosses the event
>> horizon, then the next tick of the clock is infinitely far in the future of
>> the universe, yes?  So he never experiences crossing the EH because it takes
>> forever for his clock to tick.  Say the black hole evaporates after a
>> billion years - does the space ship ever hit the singularity?
> 
> Remember Achilleus and the turtle!

But the universe is still around when Achilleus passes the turtle. :-)

-- 
   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:
> Then again, I could turn my speculation indeed into an objection: As of now, no
> singularity (i.e. a condition where a formula gives "infinity" as an answer)
> predicted by any scientific theory has ever been observed in true life.

  Lack of evidence is not evidence of the contrary. Just because a
singularity has not been observed and measured doesn't necessarily mean
that singularities cannot exist.

  There are basically two choices:

1) Assume that GR equations are correct in all situations, including
   the extreme ones. There's little evidence to show that this wouldn't
   be so. One consequence of this is accepting singularities, at least
   until better evidence shows up.

2) Object to the notion of a singularity to be possible. This implies that
   GR equations do *not* work in all possible situations, and that they
   start to deviate in extreme conditions. However, no concrete evidence
   of this exists, nor widely accepted alternative theories.

  It may well be that singularities can not exist in this Universe, and
that something else is happening with collapsing stars (stars do collapse
due to gravity, which is something basically nobody doubts). However, as
long as viable theories or, better yet, evidence of alternatives are not
presented, science in general has to take choice #1.

  As far as I understand it, science is not about the Truth. The Truth may
be impossible to achieve. Science is about the best we know so far. About
getting as close to the truth as we can, by observing and measuring.

-- 
                                                          - Warp

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> If his clock slows to zero on the outside

  "On the outside" means "from the point of view of an external observer".
In other words, someone far away from the influence of the black hole,
looking at the falling clock.

  The observer who falls into the black hole *with* the clock will
perceive it normally. (Well, relatively speaking. Let's forget for
a moment the space-warping.)

> and he never crosses the event 
> horizon, then the next tick of the clock is infinitely far in the future of 
> the universe, yes?

  From the outside perspective.

>  So he never experiences crossing the EH

  The observer who is falling into the black hole does experience the
crossing.

-- 
                                                          - Warp

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> Rotating highly charged black holes that don't have the same Schwartzchild 
> equations. (The Schwartzchild equations only work for non-rotating 
> non-charged black holes, methinks.) If you spin the black hole fast enough, 
> the equator doesn't have an EH, or the pole doesn't, or something. (I've 
> heard speculation that the equations must therefore be wrong.)

  If I remember correctly, for a rotating black hole the singularity
will have a torus shape (with a minor radius of zero). The faster it
rotates, the larger the torus. I might remember this wrongly, though.

  Likewise the event horizon elongates, and if it rotates fast enough,
might even get some kind of torus shape itself as well, or something
like that.

-- 
                                                          - Warp

Post a reply to this message

Warp wrote:
> clipka <nomail@nomail> wrote:
>> Then again, I could turn my speculation indeed into an objection: As of now, no
>> singularity (i.e. a condition where a formula gives "infinity" as an answer)
>> predicted by any scientific theory has ever been observed in true life.
> 
>   Lack of evidence is not evidence of the contrary. 

If course it is.  It's not *proof*, but it's certainly evidence.

Do you go to the doctor to check if you have the flu, even if you have no 
symptoms? No, because lack of evidence is evidence to the contrary. :-)

> 1) Assume that GR equations are correct in all situations, including
>    the extreme ones. There's little evidence to show that this wouldn't
>    be so. One consequence of this is accepting singularities, at least
>    until better evidence shows up.

That would assume that QM is broken, and there's little evidence to show 
*that* would be so. :-)

> 2) Object to the notion of a singularity to be possible. This implies that
>    GR equations do *not* work in all possible situations, and that they
>    start to deviate in extreme conditions. However, no concrete evidence
>    of this exists,

Except fermions.

I don't think anyone on p.o-t knows whether GR or QM is wrong for sure.

But it has been fun talking about it, because I think I understand better 
what the problem is.

> long as viable theories

... which is where we came into the thread. :-)

-- 
   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

Warp wrote:
>   The observer who is falling into the black hole does experience the
> crossing.

OK. Maybe I'm just incapable of understanding this. :-)  But yes, I get a 
glimmering of what you're saying. That whole lack of simultaneity.

But if he's still emitting photons when the black hole evaporates, it would 
seem to be rather paradoxical even for GR.

If he never crosses the EH as seen from outside, and the black hole is (say) 
only one stellar mass, then the outside observer will see the hole evaporate 
(thus eliminating the EH) before the spaceship actually crosses the EH.

It would seem the occupant would think he *did* cross the EH, while those 
outside would have a constant view of the occupant outside the EH.

Plus, the occupant *can* look out and conceivably see what the universe 
looks like even after he's past the event horizon, which would imply the 
universe hasn't ended for *him*?

(Modulo the space ship being bigger than the black hole physically, if it 
is, and that "constant view" would be very intermittent, and I may be 
misremembering how big a hole needs to be to be stable. Ignore that bit for 
now. :-)

-- 
   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

Darren New <dne### [at] sanrrcom> wrote:
> But if he's still emitting photons when the black hole evaporates, it would 
> seem to be rather paradoxical even for GR.

  GR doesn't predict black hole evaporation. It's those quantum mechanists
messing around.

> If he never crosses the EH as seen from outside, and the black hole is (say) 
> only one stellar mass, then the outside observer will see the hole evaporate 
> (thus eliminating the EH) before the spaceship actually crosses the EH.

  Thinking about it, this is probably what would happen:

  If we assume the mass of the black hole would decrease, then the EH would
recess. The photons which were emitted extremely close to the EH will get
a speedup when the EH recesses. Basically the "point of entry" will stop
being *at* the EH and becomes being *above* it. Thus all the photons will
reach the external observer in finite time. The external observer will
end up actually "seeing" the falling object cross the EH.

  After all, how would the external observer actually see the black hole
getting smaller?

> Plus, the occupant *can* look out and conceivably see what the universe 
> looks like even after he's past the event horizon, which would imply the 
> universe hasn't ended for *him*?

  I don't think that's possible. When he is exactly at the EH, the entire
EH engulfs the entire view on all sides. He doesn't see anything else
than the EH. What he "sees" inside... I don't know.

-- 
                                                          - Warp

Post a reply to this message

Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> But if he's still emitting photons when the black hole evaporates, it would 
>> seem to be rather paradoxical even for GR.
> 
>   GR doesn't predict black hole evaporation. It's those quantum mechanists
> messing around.

Good point. :-)

> reach the external observer in finite time. The external observer will
> end up actually "seeing" the falling object cross the EH.

Hmmm... Yes, that's possible.

>   I don't think that's possible. When he is exactly at the EH, the entire
> EH engulfs the entire view on all sides.

Even straight up?   And again, QM comes in there, as there might be 
uncertainty in the sense of what is it that's "straight up"?

I don't know either. By now, I'm entirely in BS mode. :-)

-- 
   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

Darren New <dne### [at] sanrrcom> wrote:
> >   I don't think that's possible. When he is exactly at the EH, the entire
> > EH engulfs the entire view on all sides.

> Even straight up?

  Perhaps you see an infinitely small, very blue-shifted point.

>   And again, QM comes in there, as there might be 
> uncertainty in the sense of what is it that's "straight up"?

  The opposite direction of where gravity is pulling you. :)

-- 
                                                          - Warp

Post a reply to this message

Warp escreveu:
> Darren New <dne### [at] sanrrcom> wrote:
>> Plus, the occupant *can* look out and conceivably see what the universe 
>> looks like even after he's past the event horizon, which would imply the 
>> universe hasn't ended for *him*?
> 
>   I don't think that's possible. When he is exactly at the EH, the entire
> EH engulfs the entire view on all sides. He doesn't see anything else
> than the EH. What he "sees" inside... I don't know.

I think I'm finally understanding what Darren means.

If time slows down nearing a massive graviational field and an external 
observer sees the voyager freezing as he aproaches the EH, but still for 
him time would be the same as always, except perhaps he would see the 
external observer and the rest of the universe behind going by extremely 
faster as ages go by until eventually getting out of view once passing 
the EH.

The question Darren seems to pose is:  does it get an eternity for the 
voyager to get through the EH?  I believe not, even in the so called 
supermassive blackholes supposedly in the center of galaxies.  Spacetime 
dilatates near the EH, but don't become infinite (except in the 
singularity).  So, if we think otherwise we come to the turtle and 
Achilleus tale.

It's also interesting that a blackhole is as obscure as the future and 
the objects farther away we can get a glimpse of are from a bright 
distant past that gets away from us under heavy acceleration...

Post a reply to this message

nemesis wrote:
> The question Darren seems to pose is:  does it get an eternity for the 
> voyager to get through the EH?  

Something like that. Complicated by the question "who is asking?" :-)

Another interesting thought I saw somewhere:

The cosmological horizon is not unlike an event horizon - things moving 
towards it are going faster and faster relative to us, and hence are slowing 
down time-wise[1].  Perhaps the background microwave radiation is really 
just all the galaxies that used to be close red-shifted waaaaay down as they 
pile up near the border of the observable universe.



[1] Do they really slow down (for us) if their speed is caused by new space 
being created?  I have no idea, but from what I know of it, I think the 
answer is "yes".

-- 
   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

Darren New <dne### [at] sanrrcom> wrote:
> Let's say the outside observer measures the slow-down of the clock and
> calculates that the victim's clock will read 1PM at the moment the victim
> crosses the EH.  Will the victim ever experience 1:01PM?  What will the rest
> of the universe look like when the victim experiences 1:01PM? If the
> victim's clock actually stops with respect to the outside universe, the
> entire universe will age and disappear (or big crunch) before the clock
> reads 1:01PM, yes?

It seems to boil down to that, yes.


> >> (Discounting the black holes that have paths to the singularity that don't
> >> cross an EH, of course.)
> >
> > How could that be?
>
> Rotating highly charged black holes that don't have the same Schwartzchild
> equations. (The Schwartzchild equations only work for non-rotating
> non-charged black holes, methinks.) If you spin the black hole fast enough,
> the equator doesn't have an EH, or the pole doesn't, or something. (I've
> heard speculation that the equations must therefore be wrong.)

Yes, Schwartzschild (an interesting name coincidence, by the way, that someone
whose name translates to "Blackshield" should be the first to discover the
formula for a black hole's event horizon) did his calculations for the most
simple of black holes.

So if there's no EH, you can just zip straight through the singularity? And
actually decide to turn around any time? Speaking of which, how will time be
affected near the singularity?

I think I recall remember having heard that spinning black holes would actually
not have a point-shaped singularity at all, but a loop, because their drag on
spacetime is that extreme.

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> > Remember Achilleus and the turtle!
>
> But the universe is still around when Achilleus passes the turtle. :-)

Yeah, that's the weird part about black holes... but otherwise I find the
Achilleus-and-the-turtle image very helpful with them.

Post a reply to this message

Warp <war### [at] tagpovrayorg> wrote:
>   Lack of evidence is not evidence of the contrary. Just because a
> singularity has not been observed and measured doesn't necessarily mean
> that singularities cannot exist.

You would be right if you said that lack of *proof* is not *proof* if the
contrary. But lack of evidence (i.e. an observation that does not prove
something but still seems to support it) still is *evidence* (although maybe
not as strongly) to the contrary.

Lack of evidence that the invisible pink unicorn exists is some evidence that it
doesn't.

>   There are basically two choices:

I have made the experience that when someone presents just two choices, he's
typically overlooking something ;)

> 1) Assume that GR equations are correct in all situations, including
>    the extreme ones. There's little evidence to show that this wouldn't
>    be so. One consequence of this is accepting singularities, at least
>    until better evidence shows up.
>
> 2) Object to the notion of a singularity to be possible. This implies that
>    GR equations do *not* work in all possible situations, and that they
>    start to deviate in extreme conditions. However, no concrete evidence
>    of this exists, nor widely accepted alternative theories.

Or 3) Merely *question* the notion of a singularity being possible, drawing the
following conclusions:

* Assume that GR equations *may* be wrong in extreme situations like a
singularity, or even close to it; note that this may actually help *defend* GR
- because if we find that the singularity predicted by GR doesn't exist, we can
just interpret the singularity in the equations as saying that GR never
predicted anything (sensible) at all for these conditions in the first place.

* Take it as an incentive to search for other ways of seeing things, hoping to
come up with something that does the same job as GR (in all non-extreme
situations) but gives a non-singularity answer for the extreme situations. It
may actually be that we find a theory that has singularities somewhere else,
like - say - a point where there is no gravity (just a *very* wild speculation,
please don't jump on *this* one ;)), but otherwise gives sufficiently similar
results as GR does.

* Still, at the same time, without a tested superior theory, continue to use GR.


>   It may well be that singularities can not exist in this Universe, and
> that something else is happening with collapsing stars (stars do collapse
> due to gravity, which is something basically nobody doubts). However, as
> long as viable theories or, better yet, evidence of alternatives are not
> presented, science in general has to take choice #1.

No, science *must* take choice #3.


>   As far as I understand it, science is not about the Truth. The Truth may
> be impossible to achieve. Science is about the best we know so far. About
> getting as close to the truth as we can, by observing and measuring.

That's why #1 is stupid. The singularity problem is already an indicator that GR
*may* be wrong there, so why wait until this indicator turns to hard evidence
before starting to look for alternatives, when all experience suggests that
this indicator *will* turn to hard evidence (if the question can ever be
decided, that is)?

I'm not saying "trash GR, because it gives wrong answers for the center of a
black hole" - all I'm saying is "don't be *too* dogmatic about GR, and instead
keep your eyes peeled for fresh ideas, because GR gives *questionable* answers
for the center of a black hole."

Of course, when checking candicate alternatives, they need to stand a lot of
tests, and a lot will fail at them.

Post a reply to this message

Warp <war### [at] tagpovrayorg> wrote:
>   The observer who is falling into the black hole does experience the
> crossing.

.... unless there's an effect at the EH that prevents him from doing so.

If the victim is disintegrated into sub-atomic particles that can no longer
interact with each other nor the outside world at the very instant he crosses
the EH, I guess the answer to the question whether he ever experiences the
crossing must, once again, be the Zen "mu".

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> Do you go to the doctor to check if you have the flu, even if you have no
> symptoms? No, because lack of evidence is evidence to the contrary. :-)

LOL! I tried to find a good scientific example, but didn't come up with anything
good - yours hits the mark ;)


> > 2) Object to the notion of a singularity to be possible. This implies that
> >    GR equations do *not* work in all possible situations, and that they
> >    start to deviate in extreme conditions. However, no concrete evidence
> >    of this exists,
>
> Except fermions.

Well, even with fermions, it is questionable whether this is a problem with GR,
or rather with QM.


> I don't think anyone on p.o-t knows whether GR or QM is wrong for sure.

I think you can apply this theory to outside p.o-t as well... there's currently
little evidence to the contrary ;)

Post a reply to this message

>  Yet, this is not as simple as it sounds in any case. The slingshot effect
> is always relative to something. For example interplanetary gravitational
> assist is relative to the Sun. The Sun itself cannot be used for a 
> slingshot
> effect inside the solar system (it could be used for a slingshot relative
> to the galaxy, but not relative to the solar system).
>
>  With this taken into account, can you just go from Earth to the nearest
> black hole, get an enormous speedup and come back at 100x the speed and
> slam onto Earth at that speed? From a gravity assist only, I don't think 
> so.

I was thinking, it doesn't really matter about a gravity slingshot for time 
travel, just speeding up as you go close to the black hole will suffice to 
allow you to travel forward in time.  It doesn't matter if you slow down on 
the way back because you've already done the time-travelling bit as you went 
around the black hole close to the speed of light.

Post a reply to this message

Warp <war### [at] tagpovrayorg> wrote:
>   If we assume the mass of the black hole would decrease, then the EH would
> recess. The photons which were emitted extremely close to the EH will get
> a speedup when the EH recesses. Basically the "point of entry" will stop
> being *at* the EH and becomes being *above* it. Thus all the photons will
> reach the external observer in finite time. The external observer will
> end up actually "seeing" the falling object cross the EH.

I guess it will rather be that as the black hole evaporates, the EH will shrink
as you said, but the "victim" will still seem to "stick" to it.

So from an outside observer's point of view, the moment the "victim" reaches the
singularity will be when the EH has "boiled down" to the singularity, and will
be identical with it.


It's still an interesting question though how the EH can ever boil down to
singularity if it still has the mass of a spacecraft. And all the other stuff
still sticking to its EH.

Which leads me to believe that in fact, the very moment you reach the EH of a
black hole you just simply evaporate.

Which, again, leads me to believe that there is actually no mass at all *inside*
a black hole: All that makes up the gravity well is the stuff busy falling into
it. From an outside observer unable to ever reach the EH - except due to
quantum fluctuations. Which will cause them to reach it at last and instantly
evaporate.


Duh. That's sounds simple enough to actually be true!


Now *why* would you evaporate if you reached the EH? Maybe because you would zip
off straight towards the singularity because all those evil vectors head straigt
there - but you can't stay there because, after all, it's a singularity, a "mu"
location where nothing can be - not even you, although it looks like you just
fell into there. But then again, *are* you really where you seem to be?

Enter QM: If you *can't* be there where you most likely *are*, then you must be
someplace where it's quite *unlikely* (though not perfectly impossible) that
you're there... like, say, not in the grasp of That Nasty Big Black Hole after
all... like, say, Hawaii... Alas! If only you hadn't opted for that job as a
space cadet... But... hey, did you, after all? It's a bit unlikely that you
did, given the fact that it made you end up somewhere you cannot possibly be...
so maybe you stayed home after all - or at least one of your electrons did...
Whoops! Off here goes one of your elementary particles... Or you could have
died in that explosion at Tau Alpha Ceti 6, and be part of that fascinating
dust cloud out there... Whoops! Here goes another one...

Hey, I like this idea...


Boys, I don't want to brag, but could it be that I'm just hatching an important
idea here...?? It looks to me like things are falling into place this way:

- It would explain what the singularity in the GR equations actually means: A
"forbidden point" in spacetime. A place that is not. GR being unable to give
proper results for this point because the only proper result is "mu". In fact,
it would mean that giving nonsense results for such a point would actually be a
*prerequisite* for a good theory, unless you're using it for Zen archery target
practice. Fascinating!

- It would explain where Hawking radiation actually comes from. And why it
doesn't lose information: It's still there. It has stayed home at Hawaii, got
blown up at Alpha Ceti 6, whatever - it never fell into the hole in the first
place.

Note that there's no contradiction there: All of your particles that ever
interacted with anything still "outside" on your way to the black hole
(including particles that interacted with particles that interacted with
particles that interacted with anything "outside") did pass on their
information at the very moment they interacted, so no loss happend there; for
all the particles that did not interact, QM says Schroedinger's Cat never fell
into the black hole in the first place - because now that the Black Hole Box
has evaporated, you find that you never even managed to trap it there in the
first place. It must have slipped out quietly while you were still fiddling
with the lock. Darn!

So what are black holes? Looks like a reroll in a random generator trying to
obtain a certain random distribution... or some "game over - reload saved
game?" popups for individual particles :P.

- It would explain the fermion paradoxon: If there's no fermion at the
singularity in the first place, there's no need to worry about a second fermion
trying to occupy the same spot.

<wild_guess>
Then again, maybe the fermion mechanism is actually the key to understanding the
singularity from a QM point of view: If energy densities are high enough, like
in a collapsing superstar, maybe this is sufficient to slam two fermions
together into the same quantum state, creating a particle that doesn't allow
*any* other particle to share the same spot...
</wild_guess>

However, I'd rather guess that the singularity is a forbidden point because it
is a "border" of spacetime, in a sense, and that this border is not included in
spacetime.


>   After all, how would the external observer actually see the black hole
> getting smaller?

Smaller EH of course.

>
> > looks like even after he's past the event horizon, which would imply the
> > universe hasn't ended for *him*?
>
>   I don't think that's possible. When he is exactly at the EH, the entire
> EH engulfs the entire view on all sides. He doesn't see anything else
> than the EH. What he "sees" inside... I don't know.

"Mu" again.

As I pointed out previously, I see the EH as being identical to the singularity
- a single point in spacetime blown up to macroscopic dimensions.

Actually, stating that the singularity is something which is not, this also
means that the EH is something which is not. Spacetime ends an infinitesimal
distance away from it. You can't reach it - being there is impossible, and
impossible is less likely than the infinitesimally small probability of not
having steered too close to the black hole in the first place.

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Darren New <dne### [at] sanrrcom> wrote:
> I don't know either. By now, I'm entirely in BS mode. :-)

BS is actually a good fertilizer...

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nemesis <nam### [at] gmailcom> wrote:
> It's also interesting that a blackhole is as obscure as the future and
> the objects farther away we can get a glimpse of are from a bright
> distant past that gets away from us under heavy acceleration...

Maybe we're all getting that one wrong, and the universe is actually far smaller
than we think. Maybe what we see "out there" is just one single "hypermassive"
black hole at the very other "side" of the universe - and it keeps sucking
spacetime away from us...?

Maybe what we see isn't the "big bang" after all, but the "big crunch"?

After all, there's still some quadrupole anomaly to explained in cosmic
background radiation; maybe a rotating hypermassive black hole would do the
job?


Now, why on earth - erm, I mean, why in the universe - would we happen to live
exactly on the opposite side of that hypermassive black hole? Good point -
maybe the anthropic principle comes into play here. Or maybe we're not, but
spacetime may have some weird symmetry that the distance to the HMBH measured
in one direction would automatically require the distance to it in the opposite
direction to be equal - which would explain the quadrupole anomaly.


(Okay, I'm back entirely in BS mode again now, too :))

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"clipka" <nomail@nomail> wrote:
> >   After all, how would the external observer actually see the black hole
> > getting smaller?
>
> Smaller EH of course.

.... and - which I forgot to note - as it is absolutely impossible for anything
inside the EH to ever get back out, nothing inside it would get "re-exposed" to
the outside (if there ever *was* anything truly inside it :P); instead, the
whole spacetime near the EH would shrink with it - the nearer, the stronger the
shrinking effect (though at the same time the region would probably become less
distorted)...

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