RE: Bending Light

From: Brian K. Curley (Master of Time & Space) (bkc@axle.adp.wisc.edu)
Date: Thu 22 Feb 1996 - 02:50:13 EET


Having a close friend who's a PhD candidate in Engineering Physics, I
decided to pose the question on the impact of light curving upwards in
Glorantha to him. Attached is his response, essentially what has already
been speculated here previously but with some interesting embellishments.

Enjoy,

Brian

+-------------------------+------------------------------------------+
| Brian Curley | I'm your only friend... I'm not your |
| Holder of Previous | only friend, but I'm a little glowing |
| Knowledge | friend but really I'm not actually |
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Assumming the curvature isn't extreme (i.e. a flashlight beam would vanish
upward before i hit anything) the biggest effect would be at a distance.
The world would seem more round than it reaaly is (actually for all I know
this fictional world is flat). Think about it this way. On Earth the horizon
is the point that is a straight line from eye height to the tangent of
the Earth's curvature (ignoring effects of elevation such as mountains etc.)
Light travels from that point in a sraight line to our eyes. If it curved
up it would pass over our heads and we couldn't see that far. The horizon
would be the plas where the curved path of light from a closer point curved
up and intersected our eyes. This would make the Earth seem "rounder" or of
a smaller radius. It would also make a flat world have a horizon and seem
curved when it was not. I suspect this is the guys way of having a flat
world and still having a horizon so people can't see forever (with good
enough eyes).

Curving light would also have to be adjusted for in ranged combat (probably
only in very extreme ranges (i.e. super-artillary, miles and miles)
depending on the rate of curvature. If your bullet travels in a straight line
pointed at a target (along the beam of light) it would pass under the
target. Gravity would make it miss even more. This of course could be easily
adjusted for much as gravity is adjusted for in our world.

Another point. Signals with mirrors/flashlights/fires. They must point down
slightly. Two men on the top of two separated mountains cannot signal each
other with mirrors by reflecting light directly to each other. the light
must be reflected slightly down. This would also be easy to learn and
adjust for (especially as the curvature is probably small)

That's all off the top of my head. By the way what is the source of light
in this world. A sun, stars, moon etc. All of these things would be affected by
an affinity of light for the sky. And what exactly does he mean by sky.
In a flat world, if the stars are far away then you could see none near the
horizon (actually near it, other might appear near it). How this affects
astronomy depends on the physical make-up of the universe so I can't really
talk about it without more details.

Dana

PS: I missed ST-DS9 this week. Could I borrow your copy if you have one? or
at least could you tell me te episode title so I can look for it in re-runs.

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