FTL

Date: Thu, 17 Aug 1995 14:06:04 -0700 (PDT)
From: John ---- ---------- <-------@uclink.berkeley.edu>
Subject: FTL

>Shalom Zaidfeld, if get the name of the publication where that mentioned
>paper will be published, could you please inform me.
>
>Thanks,
>
>Joni Virolainen

	Could you inform me as well?  Or perhaps just post it to the list? 
I saw the article describing the Alcubierre drive and I've been thinking how
it might be adapted to Trav.  Unfortunately, my knowledge of physics is 
limited. I'll give a brief description of the drive in the hopes of 
provoking discussion :)
	The drive creates a local distortion of spacetime that creates and
expansion behind the ship and a corresponding contraction in front of the
ship.  This leaves the ship in free-fall and gives it no "real" 
acceleration in that it does not suffer time dilation.  However the ship
does gain "coordinate" acceleration in that it moves.  Because the ship
stays within its local light cone (the light, and everything within the
radius of the disturbance is also accelerated) the ship can travel much
faster than light (relative to a stationary observer at the ships starting
point).  In fact, Alcubierre postulates that the ship could travel almost
instantaneously.
	There are some curious things about the drive though.  For 
instance, the article states that halfway to its destination, the ship 
must perform a familiar turn-over maneuver to accelerate in the opposite 
direction.  What if the drive failed before turn-over, would the ship 
continue traveling at FTL speeds essentially forever?  Would it be 
destroyed?  And what about the ships local light cone?  If it is being 
accelerated also then it will quickly leave the region of the disturbance 
and begin to move more slowly than the space craft, allowing the ship to 
catch up and the light to be caught in the disturbance again.  This would 
seem to my layman's eyes to create something analogous to a sonic boom 
coming from the ship.
	There are of course many other interesting things about a ship 
which travels in this fashion, and since, according to Shalom Zaidfeld 
this idea is gaining scientific recognition, this may be the way humanity 
someday reaches the stars.

	-- M.