[ExI] QT and SR

[Jeff Davis]

On Thu, Aug 7, 2008 at 9:53 AM, John K Clark <jonkc at bellsouth.net> wrote:
> "Jeff Davis" <jrd1415 at gmail.com>
>
>> The "solution" is wrong.  The strings do not break.
>
> I don't think it's wrong, I think the string would break.
>
>> If you were on board the space ships, in which frame of
>> reference the laws  of physics would operate in pedestrian
>> fashion,

The ships took off at the same time, accelerated at the same rate, and
maintained identical velocities throughout.  I am not an expert, and I
acknowledge that the ships are accelerating rather than gliding along
"on their inertia", but I kinda think this case fits the definition of
the same frame of reference, the same inertial frame of reference.

>> where is there any reason for the strings to break?
>
> If I tacked a string inside the cockpit of my accelerating spaceship
> from the front to back the string would NOT break because the atoms and
> electromagnetic fields inside the string would shrink at
> the same rate as the atoms in the cockpit walls. However if I tied
> a string from the front of my spaceship to the back of another 10
> feet ahead of mine and accelerating at the same rate the string would break
> because the atoms in the sting would shrink just as they did before but
> there is nothing else between the two spaceships to counterbalance that
> effect, there is only empty space.

It is my understanding that the Lorentz contraction is only observed
by an observer outside of the moving/accelerating reference frame.
Such an observer  would see the entire assembly shrink proportionately
along its length.  No breakage.  And a person on board the ships would
observe no shrinkage at all.  Again, no breakage.

>
> Also, when you hear the term "same frame of reference" it usually
> refers to an inertial frame of reference, but this one is accelerating
> so you have to be careful;

Again I need something authoritative sources to help clarify for me
what exactly constitutes a frame of reference, inertial frame of
reference, etc.

>  then you can have all sorts of pseudo forces
> operating WITHIN the frame, like tides. For example, General Relativity
> tells us that rockets firing their engines is equivalent to them falling in
> a gravitational field.

Umm, I think the equivalence/indistinguishablity is between the
gravitational **force** and the accelerative **force**.

> If they were falling toward a Neutron Star the lower
> one would be a little closer to the star and so puller a little faster than
> the one above

I believe this is a case of a gravitational force more complex due to
its spacial variation than was implied by Einstein when he  asserted
the indistinguishability of gravitational force and accelerative
force.

> and so the string would break even though some might say they
> are in the same frame of reference.
>>
>> Mr. Bell may have been a very bright fellow
>
> Indeed!
>
>> but outside his area of expertise just as likely to get it wrong
>
> That was his area of expertise.

Ok, you got me there, John.

Best, Jeff Davis