Curved Light

From: Nick Brooke (D&T CAS) (100656.1216@compuserve.com)
Date: Thu 22 Feb 1996 - 15:56:29 EET


______
Ian G. writes:

> Yes, Nick, I did read your discussion of the moon being in different
> phases depending on where the observer stands... I just don't like it.

Sure. Your post didn't mention this, which is why I mentioned the Codex take
(Joerg's, Martin's and my own) and where to find it. As I hope I've always said
re: how the Moon looks, I really don't care what it gets up to in other folks'
campaigns. There is so much confusing source material out there (RQ2 had it
invisible outside the Glowline and always appearing full within it: phases? What
phases?) that I wanted to produce my own reconciliation.

> My proposal that the red face of the moon attracts light and the black face
> was only intended as a thought provoker.

Sorry: I read you saying that the curved-light theory meant it "must" attract
light. As one of the originators of the theory, I felt moved to comment, since
this came as news to me.

> It seemed to me that while we were playing with the effect of curving light
> we might consider localized effects near the terminator of the moon.

Absolutely! It's entirely possible the "moon-ring" effect visible inside the
Glowline is caused by just such an interplay of local celestial phenomena.

> I think the curving light theory should be explored more...

I agree! You did this brilliantly with the Path of Yelm, which I accept 100% as
the Gloranthan explanation for the Sun's movement. But I think the best way to
explore the theory is by looking at celestial phenomena and working out the
curved-light explanation for why they look the way they do: not (as you seemed
to be doing) to say that the Red Moon must appear weirdly distorted because of
the theory. I think we can safely say she looks round from the ground.

> Come on Nick, let go of your own theories for a moment and play with this
> one...

Hey: I never said that you were *wrong*. I mentioned that I had a solution to
the "problem" which you might not have read, and answered a question about how
the dark side of the moon might look. Sorry if this contribution rubbed you up
the wrong way.

___
Pam writes that curving light

> would cause a discrepancy between an object's true location and its
> image over distance, and may make things like archery more difficult.
> Interesting, then, that only the sky cults have truely mastered long-
> distance archery! Must be due to being "in tune" with the behavior of
> light and vision in Glorantha.

Certainly true. If you fire an arrow at a target that's a long way away, it's
more likely you'll miss him. This is empirically true, and (to my mind) proves
the curved-light theory beyond reasonable doubt ;-)

NB: curved light also means that Farsee spells can be used to see "beyond the
horizon", as these impel greater vim and vigour to the hypothetical rays
emanating from your eyes.

          _______ ____
Thanks to Brian's friend Dana for the physical excursion: nice to read an
outsider's opinion. So arrows fired at distant targets might hit the ground in
front of them, eh? Gee, these wacky Gloranthan physics make the strangest things
happen ;-)

______
Dane's perceived problem -- "We're all standing at the bottom of a bowl" --
seems to be obviated if you trace the upward-curving rays *from* the eyes of the
observer instead of *to* them. Here's the famous Ascii diagram of a ship below
the horizon, with just the crow's nest visible:

___________
Real-world:

     O - - - - - - - - - - - - - -V
     A |
    =========== |
               ======= ____|___
                      ===== \___|__/
                           ===========

__________
Glorantha:
                              - - V
                        - - - |
                - - - - |
    O - - - - - ____|___
    A \___|__/
    ==================================

Where ====== is the sea's surface (curved in the real world, flat in Glorantha),
- - - - is the line of sight (vice versa), and the man and boat should be obvious.
(The man is, of course, a Tsankth buccaneer walking on the water). From this
diagram, it looks to me like only the tops of distant objects would be visible.

The theory that sight works through rays emanating from the eyes was cooked up
by some Greek (I'm at work and don't have my books handy), and held its own in
the classical world for centuries, so I don't think we need worry that it's
completely untenable.

====
Nick
====

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