Re: Sensor Range Question [Evasion]

On Thu, 29 Apr 1999, Andrew Evans wrote:

> >On Wed, 28 Apr 1999, djwj wrote:
> >
> >> Real Theoretical physics here, you have been warned:
> >
> >You mean "real" from the point of science fiction, not fact, right?
> 
> Ah ha!   A Physicist.   This is also my Doctoral subject, although
some
> while ago now.   I have been watching this thread and thinking -
although
> not saying - that in fact fast-than-light travel - at least by Special
> Relativity is not impossible.  The equations come up with some weird
answers
> (involving the square root of -1 if I remember rightly) and what those
> answers might mean is unknown but the problem is, I believe, that
travelling
> AT the speed of light is impossible and thus (or even hence) getting
to FTL
> speeds from this sub-light state is impossible.   If however you
already
> were travelling at those speeds then the equations do produce answers,
> just - from memory - imaginary numbers, right?

this reminds me of two things.

firstly, i remember reading somewhere that relativity only forbids
travelling at lightspeed or integer multiples thereof; thus, it is
perfectly allowable to travel at 1.5c. the trouble is, of course, that
it's rather hard to get from 0c to 1.5c without going through 1c. there
are a three ways round this i can think of:

(i) exploit the granularity of time (quantum theory and that) to make
the
transition from travelling at (1 - iota) c to (1 + iota) c, where iota
is
some very small quantity, in a quantum of time, so at no point in time
are
you doing exactly c.

(ii) find some way of going round 1c. i suspect this is what the
infamous
hyperspace bypass of the Vogon-bulit ilk is for ..

(iii) hope nobody important is looking (i have visions of Einstein's
ghost
shouting "Oi! Kirk! NO!"), although this basically amounts to (i)
(explanation for quantisation of time: god only checks the universe
every
so often :-).

i might have read this non-integer-c thing somewhere scientific
(although
certainly not recent or reputable), but it's more likely it was some
dire
1950s SF.

secondly, i would reproduce this from "STAR DRIVES IN SCIENCE FICTION: A
Catalog" by Geoffrey A. Landis <geoffrey.landis@lerc.nasa.gov>:

----- BEGIN -----
url: http://www.clark.net/pub/nyrath/stardrv.txt

[2.2.1.3] TACHYONIC TRAVEL

Tachyonic travel notes that faster than light speeds are in fact
permitted
by relativity for bodies of imaginary rest mass, and assumes that there
is
some way to reach the faster than light state (often invoking
"tunneling")
from slower than light states without leaving "real" spacetime.  (nb:
tachyonic FTL travel still has causality paradoxes in special
relativity).

----- END -----

which is similar. i add that in the star trek (TOS) technical manual,
there was a chart of space vs time or something which clearly indicated
that there were goings-on with imaginary time and space at warp speeds.

anyway, my money's on the back rays every time*.

Tom

* ha! get *that* reference!