🚀 go-pugleaf

davev@bnr.ca (David Villeneuve) writes:

[Solar sail stuff deleted, since many have answered]

>b)  Why is or why is not faster than light travel possible?  I
>    know that as an object approaches the speed of light it's
>    mass approaches infinity, and that besides needing infinite
>    propellent, you need to eject it just as fast, using conventional
>    means.  I'd be interested in the non-conventional.

Your mass argument is only one. There's a deeper General Relativistic 
argument that a world line that is once time- or space- or light-like
keeps this property unless some discontinuity appears, i.e. infinite
acceleration. On the other hand, just this property defines 
slower-than-light, faster-than-light, and light velocity.

There are some theoretical ways to circumnavigate this restriction, e.g. by 
nontrivial topology (worm holes), in GR. If however these worm holes can be
contained, or even constructed or utilized, in the real world, is an open 
question (K.S. Thorne has done some research on that in the last few years).

Another aspect is that in principle there may be matter that always moves
FTL. Particles with this prop are called tachyons (due to G. Feinberg).
See e.g. the sci.physics FAQ list for discussion. However it is improbable
that "normal" (v<c) matter has any possibility to exchange information with
tachyons, provided they exist, so that FTL *travel* is probably not possible
by using them.

BTW: what has FTL-Travel to do with this group (alt.sci.PLANETARY, which
  IMHO means Solar System planets, which are just those that can be reached 
  with v<c in reasonable time) ?
--
 Hartmut Frommert                 <phfrom@nyx.uni-konstanz.de>
 Dept of Physics, Univ of Constance, P.O.Box 55 60, D-W-7750 Konstanz, Germany
                                           -- Eat whale killers, not whales --