Not THAT kind of black hole. Sheesh! So I have been reading off and on
about black holes for years. One of the theories about objects falling
into black holes says that an observer outside a black hole watching
an object fall into a black hole will see the object make it to the
event horizon and just hover there. I have not yet found an
explanation for this that I understand. Can anyone point me to a book
that explains this? I have also been thinking about what happens to
someone that crosses the event horizon in the case of extremely large
black holes. Since the gravity gradient would be small at the event
horizon the person crossing it would not be pulled apart at the time
of crossing. So now this person is hurtling toward the black hole and
if this person looks directly at the black hole there will be nothing
to see because the gravity is so high that escape velocity exceeds the
speed of light. But photons crossing the event horizon at an angle
should spiral into the black hole. So if the person inside the event
horizon looks in any other direction they will be able to see this
light. Finally, since the escape velocity just on the other side of
the event horizon is just a little higher than the speed of light
wouldn't that mean that someone crossing the event horizon would be
traveling at the speed of light? And if that is so then wouldn't this
person's life span be essentially infinite if observed from outside of
the black hole? And is this infinite lifespan the reason why the
person from our outside observer's point of view would seem to just
hover at the event horizon? If that's the reason it still doesn't make
sense to me. I think about this and talk to my friends and relatives,
some of whom are very smart, and I get no understanding. And drinking
more beer doesn't seem to help either.
Please feel free to correct me if any of the assumptions I have made
are wrong.
Eric

On 6/20/2014 10:35 AM, wrote:
Not THAT kind of black hole. Sheesh! So I have been reading off and on
about black holes for years. One of the theories about objects falling
into black holes says that an observer outside a black hole watching
an object fall into a black hole will see the object make it to the
event horizon and just hover there. I have not yet found an
explanation for this that I understand. Can anyone point me to a book
that explains this? I have also been thinking about what happens to
someone that crosses the event horizon in the case of extremely large
black holes. Since the gravity gradient would be small at the event
horizon the person crossing it would not be pulled apart at the time
of crossing. So now this person is hurtling toward the black hole and
if this person looks directly at the black hole there will be nothing
to see because the gravity is so high that escape velocity exceeds the
speed of light. But photons crossing the event horizon at an angle
should spiral into the black hole. So if the person inside the event
horizon looks in any other direction they will be able to see this
light. Finally, since the escape velocity just on the other side of
the event horizon is just a little higher than the speed of light
wouldn't that mean that someone crossing the event horizon would be
traveling at the speed of light? And if that is so then wouldn't this
person's life span be essentially infinite if observed from outside of
the black hole? And is this infinite lifespan the reason why the
person from our outside observer's point of view would seem to just
hover at the event horizon? If that's the reason it still doesn't make
sense to me. I think about this and talk to my friends and relatives,
some of whom are very smart, and I get no understanding. And drinking
more beer doesn't seem to help either.
Please feel free to correct me if any of the assumptions I have made
are wrong.
Eric


Can't help with a book, but the way I think of it -
think of a shock wave.

When a physical thing passes through a media faster than the media
can get out of the way, a shock wave is created (in that media).

Like supersonic flight, for instance.
Air molecules can't move out of the way quickly enough and pile up
into a high pressure wave. (air is a compressible media)

While I'm probably wrong, that's how I see the whole particle/wave
question in light and electromagnetic phenomenon.

The photon is the particle part; the wave is the shock wave created
by that photon passing through the media.

The next (unresolved) question is - what is the media?

Anyway, back to your question...

AT the event horizon, the acceleration level is 1.0 C (the speed of
light in a vacuum). Is that really a "weak" gradient?

I would think a person (or thing) would be pulled apart but a much
lower gradient that that...

For what it's worth.

Richard Lamb
(the Cavelamb)

SNIP
AT the event horizon, the acceleration level is 1.0 C (the speed of
light in a vacuum). Is that really a "weak" gradient?
Well, the gradient is the difference in the pull of gravity over the
length of your body. If you are close to the singularity the
difference in pull from your head to your toes is so high you will be
torn apart into a long, thin stream of your constituent parts. But far
enough away from the singularity the difference is so slight you won't
even notice the very slight stretching when you pass through the event
horizon.
Eric

I would think a person (or thing) would be pulled apart but a much
lower gradient that that...

For what it's worth.

Richard Lamb
(the Cavelamb)

I would think a person (or thing) would be pulled apart but a much
lower gradient that that...

For what it's worth.

Richard Lamb
(the Cavelamb)



On 6/20/2014 4:11 PM, wrote:
SNIP
AT the event horizon, the acceleration level is 1.0 C (the speed of
light in a vacuum). Is that really a "weak" gradient?
Well, the gradient is the difference in the pull of gravity over the
length of your body. If you are close to the singularity the
difference in pull from your head to your toes is so high you will be
torn apart into a long, thin stream of your constituent parts. But far
enough away from the singularity the difference is so slight you won't
even notice the very slight stretching when you pass through the event
horizon.
Eric

But AT the event horizon, where the gravitational pull exceeds the speed
of light, I somehow suspect that you are WAY too close to be that far away.

As far as the floating or hovering theory goes, what point-of-view do we
attribute that to? Surely not someone outside the event horizon...

On 06/20/2014 02:11 PM, wrote:
SNIP
AT the event horizon, the acceleration level is 1.0 C (the speed of
light in a vacuum). Is that really a "weak" gradient?
Well, the gradient is the difference in the pull of gravity over the
length of your body. If you are close to the singularity the
difference in pull from your head to your toes is so high you will be
torn apart into a long, thin stream of your constituent parts. But far
enough away from the singularity the difference is so slight you won't
even notice the very slight stretching when you pass through the event
horizon.

There's no gravity outside the event horizon. Gravity, like light,
doesn't escape.

"bbold/b" fired this volley in news:lo2jib$qe5$1
@speranza.aioe.org:

There's no gravity outside the event horizon. Gravity, like light,
doesn't escape.

Ooookayy... then "esplain me to it Lucy", how does a black hole attract
anything toward itself, if gravity can't escape?

Gravity isn't an 'emission', it's a bending of space around a mass. It
doesn't HAVE to 'escape'... it's just 'there'.

Lloyd

On Fri, 20 Jun 2014 08:35:30 -0700, etpm wrote:

Not THAT kind of black hole. Sheesh! So I have been reading off and on
about black holes for years. One of the theories about objects falling
into black holes says that an observer outside a black hole watching an
object fall into a black hole will see the object make it to the event
horizon and just hover there. I have not yet found an explanation for
this that I understand. Can anyone point me to a book that explains
this?

snip

Stephan Hawking, "A Brief History of Time". There's a sequel, which I
haven't read, but I do like the guy's writing.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

On Fri, 20 Jun 2014 15:33:43 -0500, Tim Wescott
wrote:

On Fri, 20 Jun 2014 08:35:30 -0700, etpm wrote:

Not THAT kind of black hole. Sheesh! So I have been reading off and on
about black holes for years. One of the theories about objects falling
into black holes says that an observer outside a black hole watching an
object fall into a black hole will see the object make it to the event
horizon and just hover there. I have not yet found an explanation for
this that I understand. Can anyone point me to a book that explains
this?

snip

Stephan Hawking, "A Brief History of Time". There's a sequel, which I
haven't read, but I do like the guy's writing.
I've read it. It does not explain the "hovering" phenomena very well.
Eric

On Fri, 20 Jun 2014 14:12:14 -0700, etpm wrote:

On Fri, 20 Jun 2014 15:33:43 -0500, Tim Wescott
wrote:

On Fri, 20 Jun 2014 08:35:30 -0700, etpm wrote:

Not THAT kind of black hole. Sheesh! So I have been reading off and on
about black holes for years. One of the theories about objects falling
into black holes says that an observer outside a black hole watching
an object fall into a black hole will see the object make it to the
event horizon and just hover there. I have not yet found an
explanation for this that I understand. Can anyone point me to a book
that explains this?

snip

Stephan Hawking, "A Brief History of Time". There's a sequel, which I
haven't read, but I do like the guy's writing.
I've read it. It does not explain the "hovering" phenomena very well.
Eric

Maybe we all need to learn special relativity and work through it
ourselves.

I do know that the biggest challenge presented by black holes is that,
basically, the math breaks down. Relativity is a theory that's tacked
onto classical mechanics, so it works just peachy as long as quantum
effects don't come into play. Quantum mechanics is formulated assuming a
flat space-time, so it works just peachy as long as relativistic effects
don't come into play.

So it's not surprising that the explanations should be a bit shaky and
hard to wrap your head around -- theoretical physicists can't agree on
the details, so why should we be able to understand?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

On Friday, June 20, 2014 8:54:05 PM UTC-4, Tim Wescott wrote:
On Fri, 20 Jun 2014 14:12:14 -0700, etpm wrote:

Stephan Hawking, "A Brief History of Time". There's a sequel, which I
haven't read, but I do like the guy's writing.
I've read it. It does not explain the "hovering" phenomena very well.
Eric

Maybe we all need to learn special relativity and work through it
ourselves.

"Space time physics" by Taylor and Wheeler is (IMHO) the best special relativity (SR) book. Easy to do as a self study.
http://www.amazon.com/Spacetime-Phys.../dp/0716723271


I do know that the biggest challenge presented by black holes is that,
basically, the math breaks down. Relativity is a theory that's tacked
onto classical mechanics, so it works just peachy as long as quantum
effects don't come into play. Quantum mechanics is formulated assuming a
flat space-time, so it works just peachy as long as relativistic effects
don't come into play.

So it's not surprising that the explanations should be a bit shaky and
hard to wrap your head around -- theoretical physicists can't agree on
the details, so why should we be able to understand?

Yeah I think there are lots of different ideas, but we just don't have much data
on black holes so it's hard to pick between them.

To Eric, I don't have any books. And I still have plenty of things I don't understand about SR*, let alone GR. But let me start simple.
(Oh and this is my understanding and may be totally full of holes,
black, blue or otherwise.)
1.) according to SR photons don't experience any time!
(OK that just blows me away! But apparently it's true.)
2.) Let's first start from inside the black hole.
The gravity is so strong that photons can't get out.
(That's what makes it black.)
But how do you stop a photon that doesn't experience time?
The solution (I'm told) is to say there is no such thing as time at the event horizon.
3.) Well at this point I'm totally stuck. (as I think most people are.) We don't have any idea how to deal the event horizon. It's kinda outside all our physics ideas, maybe another beer is a good idea!
4.) Then coming at the event horizon from the other side.. well there is still this "no time" point.

And now back to my soldering iron.

George H.
*I'm still very much puzzled by the twin paradox.
It seems to me there must be some such thing as the ether
(or Aether if you prefer) that defines some sort of fixed (low velocity) coordinate system to the universe.
There's an idea (I've lost the guys's name...) that the vacuum, (with all it's virtual particles) forms this ether.



--



Tim Wescott

Wescott Design Services

http://www.wescottdesign.com

fired this volley in news:ddb0b8c9-307d-4e02-8722-
:

1.) according to SR photons don't experience any time!
(OK that just blows me away! But apparently it's true.)

It gets weirder... Two spin-coupled sub-atomic particles may be separated
by _any_ distance, and any change in spin of one is _instantaneously_
reflected in the other.

URK!

Lloyd

On Wed, 25 Jun 2014 09:12:12 -0700 (PDT), wrote:

On Friday, June 20, 2014 8:54:05 PM UTC-4, Tim Wescott wrote:
On Fri, 20 Jun 2014 14:12:14 -0700, etpm wrote:

Stephan Hawking, "A Brief History of Time". There's a sequel, which I
haven't read, but I do like the guy's writing.
I've read it. It does not explain the "hovering" phenomena very well.
Eric

Maybe we all need to learn special relativity and work through it
ourselves.

"Space time physics" by Taylor and Wheeler is (IMHO) the best special relativity (SR) book. Easy to do as a self study.
http://www.amazon.com/Spacetime-Phys.../dp/0716723271


I do know that the biggest challenge presented by black holes is that,
basically, the math breaks down. Relativity is a theory that's tacked
onto classical mechanics, so it works just peachy as long as quantum
effects don't come into play. Quantum mechanics is formulated assuming a
flat space-time, so it works just peachy as long as relativistic effects
don't come into play.

So it's not surprising that the explanations should be a bit shaky and
hard to wrap your head around -- theoretical physicists can't agree on
the details, so why should we be able to understand?

Yeah I think there are lots of different ideas, but we just don't have much data
on black holes so it's hard to pick between them.

To Eric, I don't have any books. And I still have plenty of things I don't understand about SR*, let alone GR. But let me start simple.
(Oh and this is my understanding and may be totally full of holes,
black, blue or otherwise.)
1.) according to SR photons don't experience any time!
(OK that just blows me away! But apparently it's true.)
2.) Let's first start from inside the black hole.
The gravity is so strong that photons can't get out.
(That's what makes it black.)
But how do you stop a photon that doesn't experience time?
The solution (I'm told) is to say there is no such thing as time at the event horizon.
3.) Well at this point I'm totally stuck. (as I think most people are.) We don't have any idea how to deal the event horizon. It's kinda outside all our physics ideas, maybe another beer is a good idea!
4.) Then coming at the event horizon from the other side.. well there is still this "no time" point.

And now back to my soldering iron.

George H.
*I'm still very much puzzled by the twin paradox.
It seems to me there must be some such thing as the ether
(or Aether if you prefer) that defines some sort of fixed (low velocity) coordinate system to the universe.
There's an idea (I've lost the guys's name...) that the vacuum, (with all it's virtual particles) forms this ether.



--



Tim Wescott

Wescott Design Services

http://www.wescottdesign.com
Thanks for the book suggestion. I'll look it up. As for photons being
stopped by the whatever if they don't experience time I don't see how
that is a problem. As gravity gets stronger the path the photon takes
gets more and more curved. Eventually the path is curved to the point
that the path curves back into the black hole. Where, I assume, the
photon is absorbed and converted into some other form of energy or
matter. Maybe just energy. I'm not clear as to whether matter can
exsist inside a black hole. Maybe just degenerate matter.
Eric

On 06/20/2014 02:12 PM, wrote:
On Fri, 20 Jun 2014 15:33:43 -0500, Tim Wescott
wrote:

On Fri, 20 Jun 2014 08:35:30 -0700, etpm wrote:

Not THAT kind of black hole. Sheesh! So I have been reading off and on
about black holes for years. One of the theories about objects falling
into black holes says that an observer outside a black hole watching an
object fall into a black hole will see the object make it to the event
horizon and just hover there. I have not yet found an explanation for
this that I understand. Can anyone point me to a book that explains
this?

snip

Stephan Hawking, "A Brief History of Time". There's a sequel, which I
haven't read, but I do like the guy's writing.
I've read it. It does not explain the "hovering" phenomena very well.
Eric

There is no time at the event horizon, so no space-time. Inside a
singularity, there is no space or time. Between the two, a black hole
spins at thousands of RPM. There's where the time is.

We see a repeating pattern moving out from a point - no space-time,
space-time, no space-time, space-time...

On 6/20/2014 11:35 AM, wrote:
Not THAT kind of black hole. Sheesh! So I have been reading off and on
about black holes for years. One of the theories about objects falling
into black holes says that an observer outside a black hole watching
an object fall into a black hole will see the object make it to the
event horizon and just hover there. I have not yet found an
explanation for this that I understand. Can anyone point me to a book
that explains this?

And drinking
more beer doesn't seem to help either.

Eric


Switch to Scotch!

On Sat, 21 Jun 2014 00:27:57 -0400, Tom Gardner Mars@Tacks wrote:

On 6/20/2014 11:35 AM, wrote:
Not THAT kind of black hole. Sheesh! So I have been reading off and on
about black holes for years. One of the theories about objects falling
into black holes says that an observer outside a black hole watching
an object fall into a black hole will see the object make it to the
event horizon and just hover there. I have not yet found an
explanation for this that I understand. Can anyone point me to a book
that explains this?

And drinking
more beer doesn't seem to help either.

Eric


Switch to Scotch!

Best suggestion yet!

On 6/20/2014 10:35 AM, wrote:
Not THAT kind of black hole. Sheesh! So I have been reading off and on
about black holes for years. One of the theories about objects falling
into black holes says that an observer outside a black hole watching
an object fall into a black hole will see the object make it to the
event horizon and just hover there. I have not yet found an
explanation for this that I understand. Can anyone point me to a book
that explains this? ...

I don't know which layman's expose would be best; Hawking's don't really
talk thru it that much as I recollect altho it's been a while since last
read them.

It's a fignewton of the space-time curvature owing to the intense
graviational force and since in general relativity there is no
coordinate-independent way to say that two distant events are happening
"at the same time." The proper time of any observer is only defined
locally.

You can begin to see (so to speak ) the "why" of "forever to fall in"
by looking at the paths of emerging light rays. The event horizon is
called a "lightlike surface"; light rays can remain there. For an ideal
black hole the light can stay there without escaping. So, watching from
a safe distance, you see the object fall more and more slowly as the
light delay increases. You'll never see it actually get to the event
horizon. This is really an optical effect caused by the paths of the
light rays.

But, don't think the object will still be visible forever, either,
because as things get closer to the event horizon, they also get dimmer.
So things would disappear as they got close.

But, the above is without quantum effects; Hawking even in the Brief
History of Time follows the chapter on black holes with one entitled
"Black Holes Ain't So Black" or similar where he brings in some of the
other effects. I've not tried to keep at all current on what other
tidbits of strangeness is considered likely owing to those refinements
that have followed since the roughly '90s time frame.

--