It didn't answer my basic question about black holes.

Since gravity causes time dilation, and the time dilation of an object at 
the event horizon is infinite when viewed from without, why do we have to 
worry about singularities? As an object approaches its Schwarzchild radius 
its time slows down when viewed from our frame of reference, and so it can 
never actually shrink to the radius. As it approached the radius the 
radiation from the surface would get red-shifted to buggery, causing the 
power emitted by the surface to approach zero, so we would see it get redder 
and fainter but never black out completely. From our frame of reference, 
singularites would take an infinite amount of time to form, so it doesn't 
make sense to talk about them existing.

"Basil Jet"  wrote in message
news:_K2Im.72993$KU2.62220@newsfe26.ams2...
>
> It didn't answer my basic question about black holes.
>
> Since gravity causes time dilation, and the time dilation of an object at
> the event horizon is infinite when viewed from without, why do we have to
> worry about singularities? As an object approaches its Schwarzchild radius
> its time slows down when viewed from our frame of reference, and so it can
> never actually shrink to the radius. As it approached the radius the
> radiation from the surface would get red-shifted to buggery, causing the
> power emitted by the surface to approach zero, so we would see it get redder
> and fainter but never black out completely. From our frame of reference,
> singularites would take an infinite amount of time to form, so it doesn't
> make sense to talk about them existing.


Zeno was the chap for that kind of thing - he seemed to cover just about
every paradox involving infinity even if black holes and Schwarzchild radii
were a bit before his time

http://plato.stanford.edu/entries/paradox-zeno/

the best known of course being Achilles and the Tortoise

http://www.mathacademy.com/pr/prime/articles/zeno_tort/index.asp



michael adams

...





>
>

michael adams wrote:
> "Basil Jet"  wrote in message
> news:_K2Im.72993$KU2.62220@newsfe26.ams2...
>>
>> It didn't answer my basic question about black holes.
>>
>> Since gravity causes time dilation, and the time dilation of an
>> object at the event horizon is infinite when viewed from without,
>> why do we have to worry about singularities? As an object approaches
>> its Schwarzchild radius its time slows down when viewed from our
>> frame of reference, and so it can never actually shrink to the
>> radius. As it approached the radius the radiation from the surface
>> would get red-shifted to buggery, causing the power emitted by the
>> surface to approach zero, so we would see it get redder and fainter
>> but never black out completely. From our frame of reference,
>> singularites would take an infinite amount of time to form, so it
>> doesn't make sense to talk about them existing.
>
> Zeno was the chap for that kind of thing - he seemed to cover just
> about every paradox involving infinity even if black holes and
> Schwarzchild radii were a bit before his time
>
> http://plato.stanford.edu/entries/paradox-zeno/
>
> the best known of course being Achilles and the Tortoise
>
> http://www.mathacademy.com/pr/prime/articles/zeno_tort/index.asp

Zeno's paradox is a load of crap, because it ignores the fact that an 
infinite number of infintesimal quantities can give a finite sum. It's not 
relevant to my comment anyway.

On Tue, 3 Nov 2009 23:09:46 -0000, "Basil Jet"
 wrote:

>
>It didn't answer my basic question about black holes.
>
>Since gravity causes time dilation, and the time dilation of an object at 
>the event horizon is infinite when viewed from without, why do we have to 
>worry about singularities? As an object approaches its Schwarzchild radius 
>its time slows down when viewed from our frame of reference, and so it can 
>never actually shrink to the radius. As it approached the radius the 
>radiation from the surface would get red-shifted to buggery, causing the 
>power emitted by the surface to approach zero, so we would see it get redder 
>and fainter but never black out completely. From our frame of reference, 
>singularites would take an infinite amount of time to form, so it doesn't 
>make sense to talk about them existing.
>

An hour of bollocks. We don't know if they exist but they might be a
bit like a waterfall.

"Mike Plowman"  wrote in message news:avc2f5hfs3bf4o8asv75t6vidd7oeotccb@4ax.com...
>
> An hour of bollocks. We don't know if they exist but they might be a
> bit like a waterfall.

Surely an hour of expert talking heads is better than a comic actor?

But you are certainly right that the waterfall analogy did not work.

By about halfway through, my main question was why physics
professors still use blackboards rather than whiteboards.

-- 
NST.

In article <4af13c68$0$9512$bed64819@gradwell.net>,
NoSpamThanks  wrote:
>By about halfway through, my main question was why physics
>professors still use blackboards rather than whiteboards.

Especially considering it must be easier to draw an accurate
picture of a black hole on a whiteboard.

Francis

"NoSpamThanks"  wrote in message 
news:4af13c68$0$9512$bed64819@gradwell.net...
>
> "Mike Plowman"  wrote in message 
> news:avc2f5hfs3bf4o8asv75t6vidd7oeotccb@4ax.com...
>>
>> An hour of bollocks. We don't know if they exist but they might be a
>> bit like a waterfall.
>
> Surely an hour of expert talking heads is better than a comic actor?
>
> But you are certainly right that the waterfall analogy did not work.
>
> By about halfway through, my main question was why physics
> professors still use blackboards rather than whiteboards.
>
> -- 
> NST.

Because they are used to them (being mostly older men)?

I got interested too and found
"White Boards versus Black Boards"   where you can read why to your heart's 
content. ;))
http://www.physics.brown.edu/physics/userpages/staff/Gerald_Zani/bw.htm

Google is a marvellous thing!

Skeats

On Wed, 04 Nov 2009 12:35:40 GMT, "Skeats"  wrote:

>
>"NoSpamThanks"  wrote in message 
>news:4af13c68$0$9512$bed64819@gradwell.net...
>>
>> "Mike Plowman"  wrote in message 
>> news:avc2f5hfs3bf4o8asv75t6vidd7oeotccb@4ax.com...
>>>
>>> An hour of bollocks. We don't know if they exist but they might be a
>>> bit like a waterfall.
>>
>> Surely an hour of expert talking heads is better than a comic actor?
>>
>> But you are certainly right that the waterfall analogy did not work.
>>
>> By about halfway through, my main question was why physics
>> professors still use blackboards rather than whiteboards.
>>
>> -- 
>> NST.
>
>Because they are used to them (being mostly older men)?

Some of them weren't born when white boards became wide spread.

>
>I got interested too and found
>"White Boards versus Black Boards"   where you can read why to your heart's 
>content. ;))
>http://www.physics.brown.edu/physics/userpages/staff/Gerald_Zani/bw.htm
>
>Google is a marvellous thing!

Scary!!
-- 

Martin

NoSpamThanks  wrote:
> 
> "Mike Plowman"  wrote in message news:avc2f5hfs3bf4o8asv75t6vidd7oeotccb@4ax.com...
>>
>> An hour of bollocks. We don't know if they exist but they might be a
>> bit like a waterfall.
> 
> Surely an hour of expert talking heads is better than a comic actor?

Sadly it was radio + some pretty pictures.

> 
> But you are certainly right that the waterfall analogy did not work.

At least the old B&W clips attempted to explain space-time distortion; I'd
never seen the Jelly one before :-)

> By about halfway through, my main question was why physics
> professors still use blackboards rather than whiteboards.

Or why they stand in empty offices staring into the distance.

-- 
We all remember how many religious wars were fought for a
religion of love and gentleness; how many bodies were burned alive
with the genuinely kind intention of saving souls from the eternal
fire of hell. -- Karl Popper

"Francis Burton"  wrote in message 
news:1257324506.424955@irys.nyx.net...
> In article <4af13c68$0$9512$bed64819@gradwell.net>,
> NoSpamThanks  wrote:
>>By about halfway through, my main question was why physics
>>professors still use blackboards rather than whiteboards.
>
> Especially considering it must be easier to draw an accurate
> picture of a black hole on a whiteboard.

Surely it's easier on a blackboard?
You don't have to draw anything at all.....

Col

Mike Plowman  wrote:
> An hour of bollocks

So Horizon is an hour of bollocks. Dare I say it but that is like saying 
that bears shit in the woods, and that the Pope is Catholic. 


-- 
_______________________________________________________

			ACHTUNG!!!
Das machine is nicht fur gefingerpoken und mittengrabben. 
Ist easy schnappen der springenwerk, blowenfusen und 
corkenpoppen mit spitzensparken. Ist nicht fur gewerken by 
das dummkopfen. Das rubbernecken sightseeren keepen hands 
in das pockets. Relaxen und vatch das blinkenlights!!!
_______________________________________________________

Nomen Publicus  wrote:

> NoSpamThanks  wrote:
>> By about halfway through, my main question was why physics professors
>> still use blackboards rather than whiteboards. 
> 
> Or why they stand in empty offices staring into the distance.

That one is easy. It's because they are on Horizon, and the touchy feely 
director has asked them to stop for a moment and empathise with his 
plight as a wannabe drama director who has to earn a living making crappy 
documentaries because no-one thinks he is up to directing the next Jane 
Austin series.


-- 
_______________________________________________________

			ACHTUNG!!!

Das machine is nicht fur gefingerpoken und mittengrabben.  Ist easy
schnappen der springenwerk, blowenfusen und corkenpoppen mit
spitzensparken.  Ist nicht fur gewerken by das dummkopfen.  Das
rubbernecken sightseeren keepen hands in das pockets.  Relaxen und
vatch das blinkenlights!!!
_______________________________________________________

On Wed, 4 Nov 2009 21:21:27 +0000 (UTC), Gordon Freeman wrote:
> Nomen Publicus  wrote:
>
>> NoSpamThanks  wrote:
>>> By about halfway through, my main question was why physics professors
>>> still use blackboards rather than whiteboards. 
>> 
>> Or why they stand in empty offices staring into the distance.
>
> That one is easy. It's because they are on Horizon, and the touchy feely 
> director has asked them to stop for a moment and empathise with his 
> plight as a wannabe drama director who has to earn a living making crappy 
> documentaries because no-one thinks he is up to directing the next Jane 
> Austin series.

Alternatively, the scientist said something that had a technical word in it. After
they cut that piece (for obvious reasons: it is the beeb after all) they had
to fill the gap with whatever they had left.

On Thu, 05 Nov 2009 11:51:18 GMT, pete  wrote:

>Alternatively, the scientist said something that had a technical word in it. After
>they cut that piece (for obvious reasons: it is the beeb after all) they had
>to fill the gap with whatever they had left.

Gruyere cheese?
-- 

Martin

On Nov 4, 7:58 am, Mike Plowman  wrote:

> An hour of bollocks. We don't know if they exist but they might be a
> bit like a waterfall.

An hour of blurry, jerky, repetitive shots and scientists made to pose
awkwardly on street corners or in darkened rooms for no good reason.
But Horizon has done worse.

Basil Jet wrote:
> It didn't answer my basic question about black holes.
> 
> Since gravity causes time dilation, and the time dilation of an object at 
> the event horizon is infinite when viewed from without, why do we have to 
> worry about singularities? As an object approaches its Schwarzchild radius 
> its time slows down when viewed from our frame of reference, and so it can 
> never actually shrink to the radius. As it approached the radius the 
> radiation from the surface would get red-shifted to buggery, causing the 
> power emitted by the surface to approach zero, so we would see it get redder 
> and fainter but never black out completely. From our frame of reference, 
> singularites would take an infinite amount of time to form, so it doesn't 
> make sense to talk about them existing.
> 
> 
Yeah but they do still exist, and they do still consume stuff. You're 
right, from our frame of reference light from an object falling in would 
be red-shifted down into the microwave, but for an object entering the 
event horizon the black holes effect would be very real.

Abo wrote:
> Basil Jet wrote:
>> It didn't answer my basic question about black holes.
>>
>> Since gravity causes time dilation, and the time dilation of an
>> object at the event horizon is infinite when viewed from without,
>> why do we have to worry about singularities? As an object approaches
>> its Schwarzchild radius its time slows down when viewed from our
>> frame of reference, and so it can never actually shrink to the
>> radius. As it approached the radius the radiation from the surface
>> would get red-shifted to buggery, causing the power emitted by the
>> surface to approach zero, so we would see it get redder and fainter
>> but never black out completely. From our frame of reference,
>> singularites would take an infinite amount of time to form, so it
>> doesn't make sense to talk about them existing.
> Yeah but they do still exist, and they do still consume stuff. You're
> right, from our frame of reference light from an object falling in
> would be red-shifted down into the microwave, but for an object
> entering the event horizon the black holes effect would be very real.

If you tried to enter a black hole, wouldn't the universe end before you 
reached the event horizon, rendering the fact that you were close to a black 
hole fairly irrelevant?