Hello all.

Just wondering if anyone could clear up my confusion about gravity and
other jazz.

I understand that gravity is the result of relative "distortion" of
space-time, but I'm not quite sure how that ends up making things
(matter, light, w/e) change their paths in space as they travel
through space-time.

Is the distortion in space-time comparable to a change in "density" of
space-time (from the same POV of all those bowling-ball-on-a-blanket
analogies)?


Also, I, like so many others, have some questions about black-holes. I
agree that from the POV of someone watching from just beyond the event-
horizon, someone else entering the black hole would never actually
pass the event-horizon, and that the daring astronaut that went black-
hole diving would appear to be squeezed as he approaches the
singularity after an infinite amount of time. I also accept that from
the POV of the daring astronaut, it would only take him a few minutes
to reach the singularity while time in the outside world appears to be
going infinitely fast. Am I right so far?

But what I don't understand is that from the POV of the daring
astronaut, he would feel any side-effects of actually reaching the
singularity. (Please correct me in my misunderstanding) to an outside
observer, the daring astronaut is getting squeezed into nothing
because the outside observer's units of measuring distance would have
increased infinitely compared to the daring astronaut's ruler. So the
astronaut's space has decreased (compared to the observer), but so did
everything inside of it including the astronaut and his unit of
distance and all his composing molecules, thus looking at himself, the
daring astronaut would not see or feel any change. Does this make
sense?

Now assuming that at least the astronaut's camcorder survives, what
would be recorded after it reached the singularity? Would it do
something cool like pass through some wormhole and come out a white-
hole somewhere? Or would it simply pass the singularity and launch out
the other side of the black-hole with the same velocity that it
entered with (of course after several infinite amounts of the outside
observer's time)? Or is it all guesswork after that, and I don't need
to worry about it because I'll never see anybody black-hole diving
anyway?

I'm also wondering how can there even be a singularity when to an
outside observer, no matter ever actually reaches that point, so a
point of infinite density is never actually created?


Sorry, I'm a newbie
but I appreciate any responses.

thomat65

On Fri, 07 Sep 2007 04:30:00 -0000, thomat65 wrote:

Hello all.

Just wondering if anyone could clear up my confusion about gravity and
other jazz.

I understand that gravity is the result of relative "distortion" of
space-time,

If by "distortion," you mean that there are normal distances and times
between events which have been stretched and/or compressed by gravitation,
then no, that is not how general relativity, Einstein's theory of
gravitation, describes space-time. It is often described that way in the
popular press because it's easier than teaching the readers general
relativity.

but I'm not quite sure how that ends up making things
(matter, light, w/e) change their paths in space as they travel
through space-time.

Relativity models time as a fourth dimension of an modified version of the
concept of space that we call spacetime. In this spacetime, nothing is
changing. Your birth, every event in your life, and your death all exist
at different points along a line in spacetime, which we call your
worldline.

Newton's first law states that when no external forces on an object, then
if it is at rest, it will remain at rest, and if it is in motion, it will
continue to move along a straight line with constant velocity. We need to
reformulate this law as a statement about the worldlines of objects that
have no external forces acting on them. So let's start with a simple case,
a train car that can move forward and backward along a straight railroad.
To simplify things, we'll put the railroad in space, where there is no
gravity. We can draw on a piece of paper the two-dimensional cross-section
of spacetime that contains the railroad. This type of diagram is called a
spacetime diagram. We can draw the train's worldline by plotting the
distance the train has gone down the track as the x coordinate, and the
time as the y coordinate. If the net external force on the train is zero,
the x and y coordinates will satisfy the equation

x = v*y + x0

where x0 is the train's position at time zero, and v is the constant
velocity of the train. If you plot this equation, you get a straight line.
So the spacetime version of Newton's first law is that where there are no
external forces on an object, the worldline of the object is straight.

In highschool we learn a system of axioms about points, lines, and planes
called Euclidean geometry. But Euclidean geometry is not the only possible
geometry. For example, one of the theorems you can prove from the axioms
of Euclidean geometry is that the sum of the angles in a triangle is 180
degrees. But we can construct geometries in which this theorem isn't true.
For example, we can construct an alternate version of plane geometry by
using the points on a sphere as our points, and the great circles on the
same sphere as our lines. Then in the triangle formed by drawing a line
from the north pole down to the equator, going east 90 degrees, and coming
back up to the north pole, the angles add up to 270 degrees. We can
formulate this geometry without ever referring to a third dimension; we
just have to accept that the lines follow different rules than the ones
we're used to.

In general relativity, gravity is not modelled as a force. A freely
falling object has no external forces acting on it, and by the spacetime
version of Newton's first law, its worldline is straight. It is the
objects lying on the ground that have curved worldlines; their worldlines
are curved, concave upwards, because of the upward force on them from the
ground.

What general relativity has to explain is: If a falling object's worldline
is straight, and if the worldline of the center of the earth is straight,
then why does the distance between them decrease at an increasing rate as
one moves forward in time along the worldlines? General relativity
explains this by postulating a non-Euclidean geometry. To see how this can
work, consider two longitude lines on the surface of the earth. As one
moves from the equator to the north pole, the distance between them
decreases at an increasing rate. But both longitude lines are parts of
great circles, and one can construct a geometry in which straight lines
behave like the great circles on a sphere.

Is the distortion in space-time comparable to a change in "density" of
space-time

No. There is no distortion of spacetime, and there is no concept analogous
to density for spacetime in general relativity.

(from the same POV of all those bowling-ball-on-a-blanket
analogies)?

Those are only analogies, and one should be careful not to draw more out of
them than the point they're trying to get across, which is that the
presence of the bowling ball is affecting the behavior of the "straight"
lines along the blanket (which are not actually straight, but they
represent straight lines in spacetime).

Also, I, like so many others, have some questions about black-holes. I
agree that from the POV of someone watching from just beyond the event-
horizon, someone else entering the black hole would never actually
pass the event-horizon,

If by "from the POV" you mean that this is what the outside observer will
see by means of light rays coming to his eyes, then this is correct so far,
because light at or below the event horizon will never reach the outside
world.

and that the daring astronaut that went black-
hole diving would appear to be squeezed as he approaches the
singularity after an infinite amount of time.

I think this would be true for someone looking at it from the side, but
what an observer sees by means of light isn't really important; it's just
an illusion. But I doubt that was what the person who described it to you
had in mind. It sounds an awful lot like they were pretending that the
Schwarzschild coordinates were actual distances and times, which is a lot
like pretending latitude and longitude differences are actual distances
along the earth's surface.

What will actually happen to the infalling astronaut, assuming a limited
strength for his body, is that he will be ripped apart along the up-down
direction (where down here means toward the black hole) and squeezed in the
horizontal directions. This is of course from his perspective; other
people might see something different, but their perspectives can only come
from light and other signals that come out to them from the astronaut, and
sensors getting those signals can be fooled, particularly if they evolved
in a nearly Euclidean geometry.

I also accept that from
the POV of the daring astronaut, it would only take him a few minutes
to reach the singularity

This is correct.

while time in the outside world appears to be
going infinitely fast.

But this last statement is wrong. The infalling observer only sees a few
minutes of the remaining history of the outside world before reaching the
singularity.

Am I right so far?

But what I don't understand is that from the POV of the daring
astronaut, he would feel any side-effects of actually reaching the
singularity. (Please correct me in my misunderstanding) to an outside
observer, the daring astronaut is getting squeezed into nothing
because the outside observer's units of measuring distance would have
increased infinitely compared to the daring astronaut's ruler.

The explanation you have apparently read is analogous to someone saying
that the reason planes from Los Angeles to Beijing fly over Alaska is that
metersticks get longer in the east-west direction when you take them to the
polar regions, so a path through Alaska has a shorter subjective length as
measured by the metersticks along the plane's path. This is something you
might say if you were pretending that latitude and longitude differences
were actual distances, and weren't willing to explain that the earth isn't
actually flat. Analogously, spacetime is not Euclidean, and units of
distance no more change when you bring them close to a black hole than they
change when you take them to Alaska.

There will be effects on the astronaut, but they have nothing to do with
this imaginary squeezing. Assuming the feet of the astronaut are pointed
toward the black hole, the worldlines of the astronauts head and feet, in
the absense of a very strong force to make them do otherwise, will each
follow a straight worldline. But since the geometry near the black hole is
highly non-Euclidean, these straight worldlines rapidly diverge from each
other, ripping the astronaut in two.

So the
astronaut's space has decreased (compared to the observer), but so did
everything inside of it including the astronaut and his unit of
distance and all his composing molecules, thus looking at himself, the
daring astronaut would not see or feel any change. Does this make
sense?

You are right in concluding that the Schwarzschild coordinate system will
cause the same effects on the astronaut that the latitude-longitude
coordinate system has on an Alaskan, i.e., none whatsoever. In addition,
the astronaut will be ripped apart as his head and feet both follow
straight worldlines.

Now assuming that at least the astronaut's camcorder survives, what
would be recorded after it reached the singularity? Would it do
something cool like pass through some wormhole and come out a white-
hole somewhere? Or would it simply pass the singularity and launch out
the other side of the black-hole with the same velocity that it
entered with (of course after several infinite amounts of the outside
observer's time)? Or is it all guesswork after that, and I don't need
to worry about it because I'll never see anybody black-hole diving
anyway?

Nobody knows.

I'm also wondering how can there even be a singularity when to an
outside observer, no matter ever actually reaches that point, so a
point of infinite density is never actually created?

The description that you have heard called the "outside observer's POV" not
only is a highly distorted depiction of reality, but it also fails to cover
all the points of spacetime. So some events that take place in reality are
missing from the distorted story.

--
Jim E. Black

thomat65 wrote:

Hello all.

Just wondering if anyone could clear up my confusion about gravity and
other jazz.

Gravitation. Gravity is the reason gravitational attraction is
everywhere normal to the geoid even though the Earth is not spherical.

I understand that gravity is the result of relative "distortion" of
space-time,

Spacetime curvature and spacetime torsion have no empirical
divergences to date. Metric gravitation is easier to calculate than
affine or teleparallel gravitation theories. They all give rigorously
identical answers except in cases of angular momentum. Even then, the
divergence is probably less than 10^(-12) relative for the most
extreme cases known to date.

That could change around Christmas.

but I'm not quite sure how that ends up making things
(matter, light, w/e) change their paths in space as they travel
through space-time.

Otherwise unperturbed centers of mass apparently travel along minimum
action geodesics - straight lines in spacetime but not in space.
Massless particles (e.g., photons) and relativsitic massed particles
behave differently,

http://arXiv.org/abs/gr-qc/9909014
Amer. J. Phys. 71 770 (2003)
Phys. Rev. Lett. 92 121101 (2004)
falling light

Is the distortion in space-time comparable to a change in "density" of
space-time (from the same POV of all those bowling-ball-on-a-blanket
analogies)?

Rubber membrane models are exactly wrong. Draw a triangle on a
Euclidean planar stretched elastic membrane. Its interior angles sum
to exactly 180 degrees. Add a mass to distort the membrane. The
triangle's interior angles now sum to *less* than 180 degrees as it
puckers. Draw a triangle (photon paths) in Minkowski space. Its
interior angles sum to exactly 180 degrees. Add a gravitating
mass. The triangle's interior angles now sum to *more* than 180
degrees.

The interior diameter of any black hole, within its event horizon, is
infinite. All interior directions point toward the singularity.

Also, I, like so many others, have some questions about black-holes. I
agree that from the POV of someone watching from just beyond the event-
horizon, someone else entering the black hole would never actually
pass the event-horizon, and that the daring astronaut that went black-
hole diving would appear to be squeezed as he approaches the
singularity after an infinite amount of time.

Quadrupole distortion re tides. An initial solid sphere will elongate
along a line radial to the attractive center of mass and pinch along
the normal waist. That is what causes ocean tides - and why the tide
on the opposite side of the Earth bulges *away* from the moon. Now
tell us why there is a phase lag between the highest tide and the
fullest moon.

I also accept that from
the POV of the daring astronaut, it would only take him a few minutes
to reach the singularity while time in the outside world appears to be
going infinitely fast. Am I right so far?

The astronaut's POV becomes incalculable when gravitation and quantum
field theory have comparable contributions.

But what I don't understand is that from the POV of the daring
astronaut, he would feel any side-effects of actually reaching the
singularity.

Don't bet on that.

(Please correct me in my misunderstanding) to an outside
observer, the daring astronaut is getting squeezed into nothing
because the outside observer's units of measuring distance would have
increased infinitely compared to the daring astronaut's ruler. So the
astronaut's space has decreased (compared to the observer), but so did
everything inside of it including the astronaut and his unit of
distance and all his composing molecules, thus looking at himself, the
daring astronaut would not see or feel any change. Does this make
sense?

Nope. It certainly isn't Newtonian. The interesting parts aren't
decribed by any other aspect of physics, either. Consider a
Schwarzschild (no rotation) hypermassive black hole whose event
horizon radius is galactic. The event horizon external surface
curvature is essentially (but not quite) zero. There would be
infintesimal tidal forces as one lowered an astronaught on a tether
through the event horizon. Nevertheless, once "inside" there is no
path that constitutes an exit. WHOA! What about the tether? Hence
the problem.

Now assuming that at least the astronaut's camcorder survives, what
would be recorded after it reached the singularity?

How long does it take to traverse an infinite distance? What is the
geometry of spacetime within the event horizon? Is the contained
volume constrained to have the same physical laws as the outside?
String theory demands the landscape, 10^1000 acceptable vacuum
solutions. It's a big number.

Would it do
something cool like pass through some wormhole and come out a white-
hole somewhere?

Do you like breathing and eating? Both are contingent on certain
boundary conditions, ditto temperature and pressure for survival. You
can trivially put a bacterial culture in water into a diamond press
and give it 75,000 atmospheres of presure. Isotropic compression is
bad for living things - and that is nowhere near gravitational strong
field or quantum mechanical aberrations.

The bottom of the Mariana Trench is no more than 1100 atmospheres
(108.6 MPa), 11°19'N, 142°15'E. At 10,916 meters depth there were
observed flounders and shrimp (23 January 1960). That is nowhere near
75,000 atmospheres. It makes a difference.

[snip]

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2

"Uncle Al" wrote in message
...

[snip wet fart]

--


'we establish by definition that the "time" required by
light to travel from A to B equals the "time" it requires
to travel from B to A' because I SAY SO and you have to
agree because I'm the great genius, STOOOPID, don't you
dare question it. -- Rabbi Albert Einstein

http://www.androcles01.pwp.blueyonde...rt/tAB=tBA.gif

'we establish by definition that the "time" required by
light to travel from A to B doesn't equal the "time" it requires
to travel from B to A in the stationary system, obviously.' --
Heretic Jan Bielawski, assistant light-bulb changer.

Ref: ups.com


"SR is GR with G=0." -- Uncle Stooopid.

The Uncle Stooopid doctrine:
http://sound.westhost.com/counterfeit.jpg

"What can be asserted without evidence can also be dismissed without
evidence." -- Uncle Stooopid.


"Counterfactual assumptions yield nonsense.
If such a thing were actually observed, reliably and reproducibly, then
relativity would immediately need a major overhaul if not a complete
replacement." -- Humpty Roberts.

Rabbi Albert Einstein in 1895 failed an examination that would
have allowed him to study for a diploma as an electrical engineer
at the Eidgenössische Technische Hochschule in Zurich
(couldn't even pass the SATs).

According to Phuckwit Duck it was geography and history that Einstein
failed on, as if Eidgenössische Technische Hochschule would give a
damn. That tells you the lengths these lying *******s will go to to
protect their tin god, but its always a laugh when they slip up.
Trolls, the lot of them.

"This is PHYSICS, not math or logic, and "proof" is completely
irrelevant." -- Humpty Roberts.

Androcles wrote:

"Uncle Al" wrote in message
...

[snip wet fart]

--

'we establish by definition that the "time" required by
light to travel from A to B equals the "time" it requires
to travel from B to A' because I SAY SO and you have to
agree because I'm the great genius, STOOOPID, don't you
dare question it. -- Rabbi Albert Einstein

http://www.androcles01.pwp.blueyonde...rt/tAB=tBA.gif

'we establish by definition that the "time" required by
light to travel from A to B doesn't equal the "time" it requires
to travel from B to A in the stationary system, obviously.' --
Heretic Jan Bielawski, assistant light-bulb changer.

Ref: ups.com

"SR is GR with G=0." -- Uncle Stooopid.

The Uncle Stooopid doctrine:
http://sound.westhost.com/counterfeit.jpg

"What can be asserted without evidence can also be dismissed without
evidence." -- Uncle Stooopid.

"Counterfactual assumptions yield nonsense.
If such a thing were actually observed, reliably and reproducibly, then
relativity would immediately need a major overhaul if not a complete
replacement." -- Humpty Roberts.

Rabbi Albert Einstein in 1895 failed an examination that would
have allowed him to study for a diploma as an electrical engineer
at the Eidgenössische Technische Hochschule in Zurich
(couldn't even pass the SATs).

According to Phuckwit Duck it was geography and history that Einstein
failed on, as if Eidgenössische Technische Hochschule would give a
damn. That tells you the lengths these lying *******s will go to to
protect their tin god, but its always a laugh when they slip up.
Trolls, the lot of them.

"This is PHYSICS, not math or logic, and "proof" is completely
irrelevant." -- Humpty Roberts.

[unsnip]
Consider a
Schwarzschild (no rotation) hypermassive black hole whose event
horizon radius is galactic. The event horizon external surface
curvature is essentially (but not quite) zero. There would be
infintesimal tidal forces as one lowered an astronaught on a tether
through the event horizon. Nevertheless, once "inside" there is no
path that constitutes an exit. WHOA! What about the tether? Hence
the problem.

Go ahead, Androclitty, resolve the contradiction. Assuredly vermin
that would invest 56 lines as above can add a paragraph to resolve the
issue preceding.

If you know you are an idiot, and we know you are an idiot, and each
knows the other knows you are an idiot, and even other idiots know you
are an idiot - and you are a boring idiot - why do you further pursue
the point?

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2

"Uncle Al" wrote in message
...
: Androcles wrote:
:
: "Uncle Al" wrote in message
: ...
:
: [snip wet fart]
:
: --
:
: 'we establish by definition that the "time" required by
: light to travel from A to B equals the "time" it requires
: to travel from B to A' because I SAY SO and you have to
: agree because I'm the great genius, STOOOPID, don't you
: dare question it. -- Rabbi Albert Einstein
:
: http://www.androcles01.pwp.blueyonde...rt/tAB=tBA.gif
:
: 'we establish by definition that the "time" required by
: light to travel from A to B doesn't equal the "time" it requires
: to travel from B to A in the stationary system, obviously.' --
: Heretic Jan Bielawski, assistant light-bulb changer.
:
: Ref: ups.com
:
: "SR is GR with G=0." -- Uncle Stooopid.
:
: The Uncle Stooopid doctrine:
: http://sound.westhost.com/counterfeit.jpg
:
: "What can be asserted without evidence can also be dismissed without
: evidence." -- Uncle Stooopid.
:
: "Counterfactual assumptions yield nonsense.
: If such a thing were actually observed, reliably and reproducibly, then
: relativity would immediately need a major overhaul if not a complete
: replacement." -- Humpty Roberts.
:
: Rabbi Albert Einstein in 1895 failed an examination that would
: have allowed him to study for a diploma as an electrical engineer
: at the Eidgenössische Technische Hochschule in Zurich
: (couldn't even pass the SATs).
:
: According to Phuckwit Duck it was geography and history that Einstein
: failed on, as if Eidgenössische Technische Hochschule would give a
: damn. That tells you the lengths these lying *******s will go to to
: protect their tin god, but its always a laugh when they slip up.
: Trolls, the lot of them.
:
: "This is PHYSICS, not math or logic, and "proof" is completely
: irrelevant." -- Humpty Roberts.
:
: [unsnip]
: Consider a
: Schwarzschild (no rotation) hypermassive black hole

I will consider it if you show me one first.

"Those who know nothing would best limit their discourse to their
knowledge base." -- Uncle ****wit.

On Sep 7, 6:15 am, Jim Black wrote:
On Fri, 07 Sep 2007 04:30:00 -0000, thomat65 wrote:
Hello all.

Just wondering if anyone could clear up my confusion about gravity and
other jazz.

I understand that gravity is the result of relative "distortion" of
space-time,

If by "distortion," you mean that there are normal distances and times
between events which have been stretched and/or compressed by gravitation,
then no, that is not how general relativity, Einstein's theory of
gravitation, describes space-time. It is often described that way in the
popular press because it's easier than teaching the readers general
relativity.

but I'm not quite sure how that ends up making things
(matter, light, w/e) change their paths in space as they travel
through space-time.

Relativity models time as a fourth dimension of an modified version of the
concept of space that we call spacetime. In this spacetime, nothing is
changing. Your birth, every event in your life, and your death all exist
at different points along a line in spacetime, which we call your
worldline.

Newton's first law states that when no external forces on an object, then
if it is at rest, it will remain at rest, and if it is in motion, it will
continue to move along a straight line with constant velocity. We need to
reformulate this law as a statement about the worldlines of objects that
have no external forces acting on them. So let's start with a simple case,
a train car that can move forward and backward along a straight railroad.
To simplify things, we'll put the railroad in space, where there is no
gravity. We can draw on a piece of paper the two-dimensional cross-section
of spacetime that contains the railroad. This type of diagram is called a
spacetime diagram. We can draw the train's worldline by plotting the
distance the train has gone down the track as the x coordinate, and the
time as the y coordinate. If the net external force on the train is zero,
the x and y coordinates will satisfy the equation

x = v*y + x0

where x0 is the train's position at time zero, and v is the constant
velocity of the train. If you plot this equation, you get a straight line.
So the spacetime version of Newton's first law is that where there are no
external forces on an object, the worldline of the object is straight.

In highschool we learn a system of axioms about points, lines, and planes
called Euclidean geometry. But Euclidean geometry is not the only possible
geometry. For example, one of the theorems you can prove from the axioms
of Euclidean geometry is that the sum of the angles in a triangle is 180
degrees. But we can construct geometries in which this theorem isn't true.
For example, we can construct an alternate version of plane geometry by
using the points on a sphere as our points, and the great circles on the
same sphere as our lines. Then in the triangle formed by drawing a line
from the north pole down to the equator, going east 90 degrees, and coming
back up to the north pole, the angles add up to 270 degrees. We can
formulate this geometry without ever referring to a third dimension; we
just have to accept that the lines follow different rules than the ones
we're used to.

In general relativity, gravity is not modelled as a force. A freely
falling object has no external forces acting on it, and by the spacetime
version of Newton's first law, its worldline is straight. It is the
objects lying on the ground that have curved worldlines; their worldlines
are curved, concave upwards, because of the upward force on them from the
ground.

What general relativity has to explain is: If a falling object's worldline
is straight, and if the worldline of the center of the earth is straight,
then why does the distance between them decrease at an increasing rate as
one moves forward in time along the worldlines? General relativity
explains this by postulating a non-Euclidean geometry. To see how this can
work, consider two longitude lines on the surface of the earth. As one
moves from the equator to the north pole, the distance between them
decreases at an increasing rate. But both longitude lines are parts of
great circles, and one can construct a geometry in which straight lines
behave like the great circles on a sphere.

Is the distortion in space-time comparable to a change in "density" of
space-time

No. There is no distortion of spacetime, and there is no concept analogous
to density for spacetime in general relativity.

(from the same POV of all those bowling-ball-on-a-blanket
analogies)?

Those are only analogies, and one should be careful not to draw more out of
them than the point they're trying to get across, which is that the
presence of the bowling ball is affecting the behavior of the "straight"
lines along the blanket (which are not actually straight, but they
represent straight lines in spacetime).

Also, I, like so many others, have some questions about black-holes. I
agree that from the POV of someone watching from just beyond the event-
horizon, someone else entering the black hole would never actually
pass the event-horizon,

If by "from the POV" you mean that this is what the outside observer will
see by means of light rays coming to his eyes, then this is correct so far,
because light at or below the event horizon will never reach the outside
world.

and that the daring astronaut that went black-
hole diving would appear to be squeezed as he approaches the
singularity after an infinite amount of time.

I think this would be true for someone looking at it from the side, but
what an observer sees by means of light isn't really important; it's just
an illusion. But I doubt that was what the person who described it to you
had in mind. It sounds an awful lot like they were pretending that the
Schwarzschild coordinates were actual distances and times, which is a lot
like pretending latitude and longitude differences are actual distances
along the earth's surface.

What will actually happen to the infalling astronaut, assuming a limited
strength for his body, is that he will be ripped apart along the up-down
direction (where down here means toward the black hole) and squeezed in the
horizontal directions. This is of course from his perspective; other
people might see something different, but their perspectives can only come
from light and other signals that come out to them from the astronaut, and
sensors getting those signals can be fooled, particularly if they evolved
in a nearly Euclidean geometry.

I also accept that from
the POV of the daring astronaut, it would only take him a few minutes
to reach the singularity

This is correct.

while time in the outside world appears to be
going infinitely fast.

But this last statement is wrong. The infalling observer only sees a few
minutes of the remaining history of the outside world before reaching the
singularity.

Am I right so far?

But what I don't understand is that from the POV of the daring
astronaut, he would feel any side-effects of actually reaching the
singularity. (Please correct me in my misunderstanding) to an outside
observer, the daring astronaut is getting squeezed into nothing
because the outside observer's units of measuring distance would have
increased infinitely compared to the daring astronaut's ruler.

The explanation you have apparently read is analogous to someone saying
that the reason planes from Los Angeles to Beijing fly over Alaska is that
metersticks get longer in the east-west direction when you take them to the
polar regions, so a path through Alaska has a shorter subjective length as
measured by the metersticks along the plane's path. This is something you
might say if you were pretending that latitude and longitude differences
were actual distances, and weren't willing to explain that the earth isn't
actually flat. Analogously, spacetime is not Euclidean, and units of
distance no more change when you bring them close to a black hole than they
change when you take them to Alaska.

There will be effects on the astronaut, but they have nothing to do with
this imaginary squeezing. Assuming the feet of the astronaut are pointed
toward the black hole, the worldlines of the astronauts head and feet, in
the absense of a very strong force to make them do otherwise, will each
follow a straight worldline. But since the geometry near the black hole is
highly non-Euclidean, these straight worldlines rapidly diverge from each
other, ripping the astronaut in two.

So the
astronaut's space has decreased (compared to the observer), but so did
everything inside of it including the astronaut and his unit of
distance and all his composing molecules, thus looking at himself, the
daring astronaut would not see or feel any change. Does this make
sense?

You are right in concluding that the Schwarzschild coordinate system will
cause the same effects on the astronaut that the latitude-longitude
coordinate system has on an Alaskan, i.e., none whatsoever. In addition,
the astronaut will be ripped apart as his head and feet both follow
straight worldlines.

Now assuming that at least the astronaut's camcorder survives, what
would be recorded after it reached the singularity? Would it do
something cool like pass through some wormhole and come out a white-
hole somewhere? Or would it simply pass the singularity and launch out
the other side of the black-hole with the same velocity that it
entered with (of course after several infinite amounts of the outside
observer's time)? Or is it all guesswork after that, and I don't need
to worry about it because I'll never see anybody black-hole diving
anyway?

Nobody knows.

I'm also wondering how can there even be a singularity when to an
outside observer, no matter ever actually reaches that point, so a
point of infinite density is never actually created?

The description that you have heard called the "outside observer's POV" not
only is a highly ...

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Dear Jim Black: The standard definition of a triangle is a three-sided
polygon whose angles add up to 180 degrees. Curves aren't segments of
a polygon. Explaining "space-time" is a waste of your time, and the
readers' time, because: I have invalidated the Michelson-Morley
experiment. Haven't heard? Such experiment doesn't have an
unchanging CONTROL light course, just two identically changing (with
respect to TIME, not speed and distance) TEST light courses. Data
comparisons can only be made if one set of data remains unchanging, or
is at least different. Interference is just a comparison of two light
beams traveling different courses. If each quantum (or photon, if you
wish) always requires the same amount of TIME to circuit its course
regardless of the orientation of the apparatus relative to Earth's
velocity vector, then there will be no interference fringe shifts.

My "NoEinstein" Interferometer Type 1 has an unchanging CONTROL light
course, and a changing TEST light course that detects Earth's movement
in the cosmos quite well. Einstein said no Earth based experiment
could do that. But he was wrong, again^100 Power.

Lorentz's laughable idea that all matter (and rulers) contracts in the
direction of motion was just his botched attempt to explain the nil
results of M-M. Since I have invalidated M-M, as explained above,
then there is no contraction factor Beta that is so basic to both of
Einstein's theories. No valid M-M-no valid contraction factor Beta!
No valid contraction factor beta-no valid space-time, and all of its
mishmash! - NoEinstein -