[ExI] QT and SR

[Damien Broderick]

At 11:59 AM 8/20/2008 -0700, Joff Davids wrote:

>The ships are assembled in space ready for departure.  They are  in
>the same reference frame.  Their clocks are synchronized.  The
>programs for acceleration are set to go, and are identical in both
>ships.  Off they go.  Messages are sent in both directions confirming
>initiation followed by progress reports at regular intervals.  Each
>message is time-stamped when sent and time-stamped upon receipt.
>John's time lag (communication latency) is anticipated, and then
>confirmed.  There is not the slightest confusion or divergence from
>plan.

Indeed. Since they know all about time dilatation and what to expect 
and how to interpret time-lagged information, there can't be any 
problem of that sort.

>Both ships accelerate in perfect formation, motionless with
>respect to each other, firmly ensconced in the same reference frame.
>Laser measuring devices, redundantly deployed on both ships monitor
>the distance between the two, and report... what?  Well, you tell me.

Jiv, I think the explanation is best displayed on a Minkowski 
diagram, with x and y rotated to x' and y', as shown in at least one 
of the sites referenced  early in this discussion.

But intuitively, I try to consider what happens to the two craft if 
they accelerate using the Nearly Magical Drive to the merest smidgen 
below light velocity. To an earth-based observer, they each shrink to 
a terrifying flatness in the direction of motion, and their clocks 
all but stop. What happens to the gap between these fast flat plates? 
(Btw, do they shrink from either end toward the middle of the craft, 
or backward from the bow to the propulsive units at the stern? Are we 
having fun yet?) If the string shrinks as well, as surely it must, 
won't it snap?

Powered by nothing better than intuition here, Goff, but still barely 
in the game.

Damien Broderick