A speculation about the Geisterdamen
I've been thinking about the Geisterdamen. They're rather unusual, aren't they? Some people have speculated that the Geisterdamen might be cave dwellers, or perhaps the inhabitants of another dimension.
I just realized that there might be a simple explanation for who they are and where they come from. It all has to do with the fact that the Professors are very familiar with the tropes of classic science fiction and fantasy, and have used (and sometimes subverted) most of them in Girl Genius. But there's one we haven't encountered ... yet.
We know these things about the Geisterdamen:
* They are very, very pale, and they associate with distinctly unusual fauna -- notably the giant spiders -- that also are very, very pale
* They speak an unknown language (which we readers often refer to as "Geisterspeech")
* They call Europa "the Shadow World"
* According to Agatha H. and the Airship City, Lucrezia and her family hail from Novaya Zemlya, in the Arctic Ocean north of the Ural Mountains, and apparently encountered Geisterdamen there
There's a classic SF/fantasy/adventure trope that can explain all this:
The Geisterdamen live inside the Hollow Earth.
The idea is an old one, and was used most notably in Verne's Journey to the Center of the Earth and in Burroughs' Pellucidar series. Two common elements of the scheme are a "Central Sun" at the Earth's geometric center, and a large opening to the Earth's outer surface at the North Pole.
Explanations: The Geisterdamen and their critters are pale because the Central Sun is much cooler than the sun in our sky; it doesn't emit much ultraviolet light, so they don't tan (they need all the vitamin D they can get). They call the outer surface of the Earth the "Shadow World" because our sun rises and sets, and they see shadows here; inside the Hollow Earth their Central Sun is always directly overhead, so objects don't cast shadows. The Geisterdamen speak an unknown language because they have been isolated for thousands of years ... even though they aren't all that far away, as the crow flies mole digs; the main passage between the inner and outer worlds is somewhere near Novaya Zemlya.
This theory might even elucidate Zola's remark: Ooooh, and that's why no one's been able to find the Citadel of Silver Light. Amazing! And it explains so much!"
UPDATE: It also explains the odd shift in gravity while Zeetha was ill aboard the expedition's airship -- she thought everything in the room was upside down, because the airship was crossing the boundary between the interior gravitational field and the exterior field. (In our universe, the entire interior of a hollow planet would be in a zero-G condition, but we already know that the physics and chemistry of Agatha's world are different from ours.)
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