Re: Fantasy relativity

Heya folks,

        Though this isn't a discussion of fantasy relativity, I'm
not changing the subject so that people who have killed this thread
don't need to see this.

>Static said:
>In our last episode, Thatotherguy said:
>>I'll make it simple Static.  You said from a ship traveling at
>>lightspeed you can't see anything.  You're wrong.  Even your own
>>Einsteinian lack of explanation admits it.  You are wrong.  How many
>>other ways do you want it said.  Your statement was wrong.
>
>       I'm confused.  Are you saying that -- I'm talking real life
>here, not SJ -- you can actually see outside of a craft travelling at
>C?  Or are you saying that I'm  wrong, wrong, wrong about that in
>relation to SJ (i.e. travelling at the speed of light -- whether it's
>equivalent to SJ speed or some other finite constant -- does not make
>the world go black)?

        Since Thatotherguy never clarified his statement, I'll go
under the assumption that he meant I was wrong in the real worlds
sense.  What follows is why everything outside of a ship would be
black at light speed -- whether that speed is 300,000,000 m/s or
100,000,000 mi/day -- according to Special Relativity.  What things
can look like in a fantasy, non-reletavistic way is up to the DM.

        First, I'd like to get down some of the basics.  As one
approaches the speed of light (I'll use "C" to denote it, but it
could just as easily be SJ speed), time dialation occurs.  This
depends on the percentage of C you're travelling.  The Lorentz-
Fitzgerald contraction (gamma, given by the equation gamma =
(1-v^2/c^2)^(-1/2)) is the ratio of shiptime to oustide time.
(For example, at ~0.866C, gamma = 2, so two seconds pass on the
ship for every observed one second outside.

        The "why is it dark" question can be answered by applying
the above fact.  Since objects give off a certain amount of light
per unit of time (or reflect an amount per unit time), they will
appear to get dimmer in relation to the above ratio.  For example,
for the above ship travelling at 0.866C, two seconds pass for every
one second on the outside.  So, during those two seconds, the ship
"saw" only one seconds worth of light.  Objects directly in front
or behind the ship will therefore seem half as bright.  (Objects
off to the sides will get dimmer with cosine of the angle multiplied
by gamma, since their relative speeds arn't as high.)

        As the ship accelerates, gamma approaches infinity, until
the objects directly in front and behind disappear from sight.  The
objects to the sides will get dimmer -- though not as fast, until
at C (I'm assuming the ship could actually travel *at* C) the "ring"
of visible objects (where the angle from the direction of flight will
be 90 degrees) is infinitesimally thin -- effectively non-existant,
leaving the outside view completely dark.

        Red-/blue-shift, unlike what I said before (I was wrong
on that point) would *not* take the light out of the visible range.
What happens is that invisible light (infrared and ultraviolet)
are shifted into the visible range.  So, as long as stars emit light
along most of the spectrum, they would be visible with respect to
red-/blue-shift.

        I hope that explained it well enough.  If anybody's interested
in some URLs which explain this stuff with more math, let me know and
I'll send 'em out. :)

-Static

p.s.  Please note that I don't use relativity, or much "hard science"
at all in my campaigns.  The above is simply an explanation of one of
the side-effects of including it.

--
  "Why does it always end in tears?" -Crichton

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