Darksense, NOT X-ray vision from Ian Gorlick on 1997-06-20 (Glorantha Digest Vol 04)

From: Ian Gorlick <igorlick_at_nortel.ca>
Date: 20 Jun 1997 17:31 EDT

Darksense will not allow a troll to scan for pregnancy, a full belly, or old broken bones from a distance of several meters. Take a look at how ultasound works. In order to get the shitty images that we do with the best equipment available, you have to put the transceiver in direct contact with the body AND put in an acoustic jelly to improve the sound transmission.

The strength of signal return from any interface is a function of the difference in the indices of refraction of the two materials, which for sound is pretty much related to the density of the material. The reflection from the air/skin boundary is going to swamp out any traces of signal from the interior interfaces between flesh/bone, or flesh/uterine-fluid. Think of trying to look at something through a half-silvered mirror using a miner's lamp attached to your forehead. All you see is the reflection from the mirror even though there is light going through the mirror and illuminating stuff behind it.

A trollish healer or midwife might learn how to grease her muzzle and stick it into intimate contact with a patient and thus get some limited view of the interior, but this is a highly specialized skill. Remember, she will have to get the return signal through skin and bone conduction, not through her ears which she normally uses for darksense.