starship-design: re: Twin Paradox

[Steve VanDevender <stevev@efn.org>]

Steve Revilak writes:
 > /However, the Twin non-Paradox would still happen even if one twin stayed
 > /on a fast-moving spaceship while the other took a relativistic jaunt in
 > /the ship's shuttlecraft; the one who left and came back on the
 > /shuttlecraft would be younger.
 > 
 > 	Could you point me toward a little more info on this phenomenon? 
 > Are we referring to biological twins, or 'twins' as in equivalent beings
 > coexisting in parallel universes?

The so-called "Twin Paradox" refers to a thought-experiment in
relativistic physics where one of a pair of biological twins takes a
trip in a starship at relativistic speeds while the other remains on
Earth.  Biological twins were chosen simply because they are the same
age at the start of the trip.  The traveling twin, on his return, has
aged less than the twin who stayed at home because of relativistic
effects.  Usually the paradox is posed with the misleading implication
that the situations of the two twins are symmetrical, but the paradox is
resolved by showing that the traveling twin, who had to accelerate and
decelerate during his trip, therefore took a different path through
spacetime and experienced a different amount of elapsed time.

Since this mailing list is for discussion of space travel methods that
are compatible with existing laws of physics, we tend not to talk about
parallel universes, warp drives, and other fanciful but unlikely
things.

My posting that you replied to contained a reference to an introductory
text on relativistic physics that covers the Twin Paradox in detail.