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From: euren@ttds.UUCP (Leif Euren)
Newsgroups: net.games.frp
Subject: Re: Infravision from a physical point of view
Message-ID: <860@ttds.UUCP>
Date: Thu, 14-Mar-85 08:32:42 EST
Article-I.D.: ttds.860
Posted: Thu Mar 14 08:32:42 1985
Date-Received: Sun, 17-Mar-85 21:04:46 EST
References: <4962@ukc.UUCP>
Reply-To: euren@ttds.UUCP (Leif Euren)
Organization: The Royal Inst. of Techn., Stockholm
Lines: 38

Joe Jaquinta writes:
>Effecively infravision is just another colour. The normal human eye can
>see in the electromagnetic spectrum from red to violet so extend this
>to from infra-red to (possibly ultra-) violet. Things like ``switching''
>Infravision and off and ``concentrating on infravision'' and `letting
>your eyes adjust'' just don't make sense.  Your eyes adjust to the dark
>because of the difference in brightness, not colour.

As far as I know, the human retina contains of two kinds of
light-sensitive cells (I can't get their correct english names, but
let's call them `rods' and `taps'), of which the taps `come in three
colours' but are less sensitive. Should one give a physiological
explanation to infra-vision, I'm tempted to assign it to the more
sensitive rods. As everybody knows, it takes 10-20 minutes to aquire
night vision (changing from taps to rods), but a mere instant to
destroy it (changing back). With this explanation, Gygax is right.


>The old trick of casting continual light on a stone and hanging it in a
>lantern should work without spoiling infravision.

According to what's said above, it shouldn't.


Of course, it's completely ridiculous to give scientific explanations
to fantasy concepts. And what do we know about elven physiology?  In
the AD&D universe I'm Mastering, seeing comes from the sight-beams
emanating from each persons eyes (thats why you sometimes can feel if
someone is looking at you), and even then I discourage my players to
use their infra-vision. It hasn't been useful to them, anyway.

>Just a note: both invisibility and darkness cancel infravision.

In any case, you are right about this!
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