Re: There is no physical length contraction
- From: "Whoever" <noone@xxxxxxxxxxx>
- Date: Thu, 16 Jul 2009 08:54:33 +1000
"Uncle Ben" <ben@xxxxxxxxxxx> wrote in message news:7d1a8e55-1569-4bf0-acad-04b0f585fc29@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Jul 15, 8:33 am, "Whoever" <no...@xxxxxxxxxxx> wrote:"Uncle Ben" <b...@xxxxxxxxxxx> wrote in message
news:e3e70f24-ac59-4cf6-9886-2af0788a83f0@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> On Jul 15, 7:58 am, "Whoever" <no...@xxxxxxxxxxx> wrote:
>> "Uncle Ben" <b...@xxxxxxxxxxx> wrote in message
>>news:8ea7b297-4ba1-4302-9923-04f6c3368a90@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> > On Jul 15, 2:06 am, "Whoever" <no...@xxxxxxxxxxx> wrote:
>> >> "Uncle Ben" <b...@xxxxxxxxxxx> wrote in message
>> >>news:8190fb0e-a55e-4117-8093-01c3a066328c@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> >> > On Jul 14, 6:50 pm, shuba <tim.sh...@xxxxxxxxxxxxx> wrote:
>> >> >> Uncle Ben wrote:
>> >> >> > Maybe I am in the minority of the "SRians" here, but the >> >> >> > breaking
>> >> >> > of
>> >> >> > a
>> >> >> > string seems awfully "physical to me, projection or not.
>> >> >> > Cf:"Bell's
>> >> >> > Spaceship Paradox", in Wikipedia.
>> >> >> Can you point to *any* inertial frame where the string isn't
>> >> >> measured to break to support your bizarre idea that Lorentz
>> >> >> contraction has something to do with an analysis of the
>> >> >> experiment? Do you know what a coordinate transformation is? Or
>> >> >> do you simply deny that the Lorentz contraction is based on a
>> >> >> coordinate transformation?
>> >> >> Of course a breaking string is physical. This doesn't support
>> >> >> your tired strawman about Lorentz contractions.
>> >> >> ---Tim Shuba---
>> >> > Tim, we have been over this before. I respect your point of >> >> > view,
>> >> > and
>> >> > I wouldn't dream of trying to persuade you otherwise.
>> >> > But I have a point of view also. The Principle of Relativity
>> >> > entitles
>> >> > me to analyze physical phenomena from any inertial frame I >> >> > choose.
>> >> > I
>> >> > choose the launch frame.
>> >> Fine
>> >> > In that frame the length of the string remains constant.
>> >> No .. the string length in the launch frame does not stay constant.
>> >> The
>> >> string is moving in the launch frame, so is length contracted in >> >> that
>> >> frame.
>> >> In the launch frame it is the distance between corresponding points >> >> on
>> >> the
>> >> spaceships that is constant.
>> >> In the (non-inertial) frame of reference of either space ship (or >> >> the
>> >> string), the distance between corresponding point on the spaceships
>> >> increases.
>> >> In either case, the string has to stretch to stay connected to the
>> >> ships,
>> >> and so will eventually break.
>> >> > The only
>> >> > thing that later changes from the launch conditions is the speed >> >> > of
>> >> > the ships w.r.t. the launch frame. Since we agree that the >> >> > string
>> >> > breaks, I point to that change as the only reasonable cause.
>> >> > Arguments don't age if they are sound.
>> >> They need to BE sounds first It sounds like you are mistaken on >> >> your
>> >> explanation here.- Hide quoted text -
>> >> - Show quoted text -
>> > The argument is as sound as the principle of the homogeneity of >> > space.
>> > Here is the argument that in the launch frame the distance between >> > the
>> > ships -- and thus the length of the string -- is constant:
>> But the string will be length contracted. The ships will try to >> stretch
>> the
>> string to remain at that length
>> > In the launch frame, the motors of the two spaceships fire at the >> > same
>> > time. The ships are identical. The only difference between the >> > ships
>> > is their initial position.
>> Yeup
>> > Therefore the distance travelled by each ship in a given time (in >> > the
>> > launch frame) is the same. Therefore the initial distance between >> > the
>> > ships does not change (w.r.t. the launch frame).
>> Yeup
>> > Your criticism?
>> You didn't take into account the length contraction of the moving >> string-
>> Hide quoted text -
>> - Show quoted text -
> With respect to the launch frame:
Yes
> The string is tied to the ships. If the ships remain separated by a
> fixed distance, the string cannot contract. That's why it breaks.
So you didn't read what I said when I said the same thing ...
>> >> No .. the string length in the launch frame does not stay constant.
>> >> The
>> >> string is moving in the launch frame, so is length contracted in >> >> that
>> >> frame.
>> >> In the launch frame it is the distance between corresponding points >> >> on
>> >> the
>> >> spaceships that is constant.
>> >> In the (non-inertial) frame of reference of either space ship (or >> >> the
>> >> string), the distance between corresponding point on the spaceships
>> >> increases.
>> >> In either case, the string has to stretch to stay connected to the
>> >> ships,
>> >> and so will eventually break.
> (It is presumed in this problem that the string is too weak to affect
> the motion of the spaceships.)
Yes .. I am assuming that.- Hide quoted text -
- Show quoted text -- Hide quoted text -
- Show quoted text -
I'm sorry if I missed something. What I saw in your posts was a
denial of my claim that the string does not contract. You said, I
understood, that the string does contract in the launch frame, pre-
break.
Perhaps you meant that the string "tries to contract," to
anthropomorphize it. To me, "contract" means to change to a shorter
length. It does not mean "suffers an increase of stress."
Is that our difference?
Yeup .. in the launch frame the string stretches in order to retain the same measured length because it is undergoing contraction, How long it is able to keep that length depends on far it can stretch before breaking. If it has no 'stretch' in it at all, then it will snap just after launch.
.
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- Re: There is no physical length contraction
- From: shuba
- Re: There is no physical length contraction
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