Why Light curves

From: Joerg Baumgartner (joe@toppoint.de)
Date: Fri 23 Feb 1996 - 19:24:00 EET


This rehash of the curving light discussion brings me to a couple of questions.

What is the medium light has to travel in? I think that there are four or
five separate media light is known to travel through in Glorantha.

The first is Aether. This is the natural medium for light. The sky dome is
made up from it, and I think that ideal travel of light (whether circular or
straight) is possible only in this medium. It may also have a strong
attraction for stray light, causing light beams in mundane Glorantha to
curve up.

The most commonly used medium light has to move through on Glorantha,
however, is Air (at least where humans are concerned). The Air of the middle
world is the bent air, the bent element, according to the Entekosiad. The
Dara Happan concept of Right Air might include an air which offers no
distortions or intensity loss to light...

The next important medium is Water. We know from the Oceans descriptions
(e.g. in Tales 10) that Water absorbs light, similar to our world. The
absorbent quality of Water may be related to its closeness to Darkness? Its
distortive qualities are somewhat known in Glorantha: the rainbow is the
result of water (and air) interacting with light. Rainbow Girl is an air
spirit in Nomad Gods, though, so the main blame could still be on the air in
between the droplets. Mist is known to diffuse light, but again this is air
paired with water. But then, non-air related phenomena are obscure subjects
of study to mankind, so neither the Yuthuppan nor the Jrusteli opticians are
likely to have researched this. Are there any sun-worshipping mermen?

Earth in whatever form rarely figures as a medium for light, more often as
it's source of reflection. The explanation might be that Earth formed the
regular border to the Light Realm in the ideal creation of the world. Still,
there are certain forms of Earth which can transmit light: glass, crystals,
thin parchment, etc. I have no offhand explanation for most of these, though
for glass I can say that this is fire-treated earth, and therefore
transparent. Light in glass may even move in straight lines...

Darkness is not really a medium for light, but simply an absorbent. Light
may pierce the Darkness (as the stars prove, which shine at night). However,
the seeing rays get swallowed by the ever-hungry darkness, which is why
nobody can see well in the dark. Spells like Catseye (or whatever the
renamed Yelmalio version is called) reduce the absorbtion.
Because Darkness absorbs so strongly, we have no reliable reports about the
curvature or otherwise behaviour of light.

Looking at these media, I find that air (which has been bent by
Umath/Rebellus Terminus) bends light. Air does affect archery as well, as I
can tell from personal experience. Still, air is the most common medium for
light, and archery.

Hmm. A Farsee spell might do little else than reduce the bending and
diffusing influence of air on light, or alternatively eye-rays.

Oh, I forgot one medium: the spirit world. Here the properly attuned
eye-rays perceive life-force (magic) instead of mundane light, but the
overall effects are very similar (note all the rules on how hard substance
is penetrated).

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