puzzle in relativity

Bill Snyder · science forum beginner Joined: 08 May 2005 Posts: 38

On 13 Jul 2006 13:27:08 GMT, Jeff…Relf <Jeff_Relf@Yahoo.COM> wrote:

T Wake · science forum Guru Joined: 08 May 2005 Posts: 1978

"Jeff.Relf" <Jeff_Relf@Yahoo.COM> wrote in message
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T Wake · science forum Guru Joined: 08 May 2005 Posts: 1978

"Jeff.Relf" <Jeff_Relf@Yahoo.COM> wrote in message
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Bill Snyder · science forum beginner Joined: 08 May 2005 Posts: 38

On Thu, 13 Jul 2006 20:07:12 +0100, "T Wake"
<Usenet.es7AT@gishpuppy.com> wrote:

tadchem · science forum Guru Joined: 03 May 2005 Posts: 1348

Bill Snyder wrote:

I used to work with a Bill Snyder in Denver 5-6 years ago. You?

Tom Davidson
Richmond, VA

Bill Snyder · science forum beginner Joined: 08 May 2005 Posts: 38

On 13 Jul 2006 13:38:30 -0700, "tadchem" <tadchem@comcast.net> wrote:

Phineas T Puddleduck · science forum Guru Joined: 01 Jun 2006 Posts: 759

In article <cIOdnQEvb5p-BCvZRVnytQ@pipex.net>, T Wake
<Usenet.es7AT@gishpuppy.com> wrote:

PD · science forum Guru Joined: 03 May 2005 Posts: 4363

Jeff...Relf wrote:

T Wake · science forum Guru Joined: 08 May 2005 Posts: 1978

"PD" <TheDraperFamily@gmail.com> wrote in message
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The Ghost In The Machine1 · science forum Guru Joined: 25 Mar 2005 Posts: 1551

On Tue, 11 Jul 2006 10:11:09 -0700, cafeinst wrote:

Sorcerer1 · science forum Guru Joined: 09 Jun 2006 Posts: 410

"The Ghost In The Machine" <ewill3@earthlink.net> wrote in message
news:pan.2006.07.15.20.33.27.747137@earthlink.net...
| On Tue, 11 Jul 2006 10:11:09 -0700, cafeinst wrote:
|
| > I found this here:
| > http://www.geocities.com/ResearchTriangle/System/8956/problems/probs.htm
| >
| > "Five stuntmen are riding upon a large sled across an icy pond. In the
| > center of the pond is a hole exactly the same size as the sled, and the
| > stuntmen are travelling towards it at near the speed of light. When they
| > reach the hole, a man standing beside the hole hits the sled with a
| > sledgehammer to drive it into the hole. According to the stuntmen, the
| > hole decreases in length due to the effects of special relativity, and
| > thus they slide over and do not fall in. But the man standing beside the
| > hole sees the length of the sled decrease due to relativity, and so the
| > sled slips easily into the hole. Clearly the stuntmen or the hammer man
| > cannot both be right, so what happens?"
|
| First, the delta-momentum for any speed where relativistic effects are
| going to be greater than the radius of a molecule is so ridiculously high

Vague. What is the threshold for an effect to change from Newtonian
to relativistic?
[rest snipped]

Androcles.

The Ghost In The Machine1 · science forum Guru Joined: 25 Mar 2005 Posts: 1551

On Sat, 15 Jul 2006 21:04:30 +0000, Sorcerer wrote:

Sorcerer1 · science forum Guru Joined: 09 Jun 2006 Posts: 410

"The Ghost In The Machine" <ewill3@earthlink.net> wrote in message
news:pan.2006.07.16.01.08.27.22076@earthlink.net...
| On Sat, 15 Jul 2006 21:04:30 +0000, Sorcerer wrote:
|
| >
| > "The Ghost In The Machine" <ewill3@earthlink.net> wrote in message
| > news:pan.2006.07.15.20.33.27.747137@earthlink.net...
| > | On Tue, 11 Jul 2006 10:11:09 -0700, cafeinst wrote:
| > |
| > | > I found this here:
| > | >
http://www.geocities.com/ResearchTriangle/System/8956/problems/probs.htm
| > | >
| > | > "Five stuntmen are riding upon a large sled across an icy pond. In
the
| > | > center of the pond is a hole exactly the same size as the sled, and
| > | > the stuntmen are travelling towards it at near the speed of light.
| > | > When they reach the hole, a man standing beside the hole hits the
sled
| > | > with a sledgehammer to drive it into the hole. According to the
| > | > stuntmen, the hole decreases in length due to the effects of special
| > | > relativity, and thus they slide over and do not fall in. But the man
| > | > standing beside the hole sees the length of the sled decrease due to
| > | > relativity, and so the sled slips easily into the hole. Clearly the
| > | > stuntmen or the hammer man cannot both be right, so what happens?"
| > |
| > | First, the delta-momentum for any speed where relativistic effects are
| > | going to be greater than the radius of a molecule is so ridiculously
| > | high
| >
| > Vague. What is the threshold for an effect to change from Newtonian to
| > relativistic?
|
| All effects are relativistic.

Thank you.

I did say "greater than the radius of a
| molecule". However, your example of moving towards a candle will
| definitely slow down one's wristwatch (as observed by someone next to the
| candle) -- although the amount of slowdown is ridiculously small for
| someone moving at 3 m/s = 10^-8 c.

He walks away from another candle simultanously with walking toward the
first.
His ridiculous wrist watch needs 6 ridiculous hands, one ridiculous molecule
apart,
although the separation of the candles is constant and not ridiculous.
[rest snipped]
Androcles

The Ghost In The Machine1 · science forum Guru Joined: 25 Mar 2005 Posts: 1551

On Sun, 16 Jul 2006 07:38:25 +0000, Sorcerer wrote:

Sorcerer1 · science forum Guru Joined: 09 Jun 2006 Posts: 410

"The Ghost In The Machine" <ewill3@earthlink.net> wrote in message
news:pan.2006.07.16.16.12.35.332064@earthlink.net...
| On Sun, 16 Jul 2006 07:38:25 +0000, Sorcerer wrote:
|
| >
| > "The Ghost In The Machine" <ewill3@earthlink.net> wrote in message
| > news:pan.2006.07.16.01.08.27.22076@earthlink.net...
| > | On Sat, 15 Jul 2006 21:04:30 +0000, Sorcerer wrote:
| > |
| > |
| > | > "The Ghost In The Machine" <ewill3@earthlink.net> wrote in message
| > | > news:pan.2006.07.15.20.33.27.747137@earthlink.net...
| > | > | On Tue, 11 Jul 2006 10:11:09 -0700, cafeinst wrote:
| > | > |
| > | > | > I found this here:
| > | > | >
| > http://www.geocities.com/ResearchTriangle/System/8956/problems/probs.htm
| > | > | >
| > | > | > "Five stuntmen are riding upon a large sled across an icy pond.
In
| > the
| > | > | > center of the pond is a hole exactly the same size as the sled,
| > | > | > and the stuntmen are travelling towards it at near the speed of
| > | > | > light. When they reach the hole, a man standing beside the hole
| > | > | > hits the
| > sled
| > | > | > with a sledgehammer to drive it into the hole. According to the
| > | > | > stuntmen, the hole decreases in length due to the effects of
| > | > | > special relativity, and thus they slide over and do not fall in.
| > | > | > But the man standing beside the hole sees the length of the sled
| > | > | > decrease due to relativity, and so the sled slips easily into
the
| > | > | > hole. Clearly the stuntmen or the hammer man cannot both be
right,
| > | > | > so what happens?"
| > | > |
| > | > | First, the delta-momentum for any speed where relativistic effects
| > | > | are going to be greater than the radius of a molecule is so
| > | > | ridiculously high
| > | >
| > | > Vague. What is the threshold for an effect to change from Newtonian
to
| > | > relativistic?
| > |
| > | All effects are relativistic.
| >
| > Thank you.
| >
| >
| > I did say "greater than the radius of a
| > | molecule". However, your example of moving towards a candle will
| > | definitely slow down one's wristwatch (as observed by someone next to
| > | the candle) -- although the amount of slowdown is ridiculously small
for
| > | someone moving at 3 m/s = 10^-8 c.
| >
| > He walks away from another candle simultanously with walking toward the
| > first.
| > His ridiculous wrist watch needs 6 ridiculous hands, one ridiculous
| > molecule apart,
| > although the separation of the candles is constant and not ridiculous.
|
| The separation of the candles is affected as well. The walker will
| measure, if he bothers to, a distance which will vary from the candles'
| own measurement between themselves.

No he won't, he'll use a tape measure.
[rest snipped]
Androcles

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