Handwavium is Mania, obviously!
Well, not quite: the appearance of Handwavium was caused by what was essentially a Maniac Storm triggered and fuelled by a threshold level of nostalgia (or something that might be called "Bardo Longing") rather than a sudden shift in scientific Consensus. It is a substance that provides the initial Mania for the act of creation, and remains in trace amounts generating enough Mania to allow the Wonder's continued function.
Alternately and more simply, Handwavium is Mania generated by fanac (including amateur astronomy and "space speculation") as opposed to other miscellaneous thought.
Seriously, I think everyone is entitled to pet hypotheses, but the true origin of Handwavium shouldn't be pinned down even outside of the stories. It just appeared from nothing and without ascertainable cause, like a cat getting under foot when it was in the opposite corner of the house a moment ago.
Well, not quite: the appearance of Handwavium was caused by what was essentially a Maniac Storm triggered and fuelled by a threshold level of nostalgia (or something that might be called "Bardo Longing") rather than a sudden shift in scientific Consensus. It is a substance that provides the initial Mania for the act of creation, and remains in trace amounts generating enough Mania to allow the Wonder's continued function.
Alternately and more simply, Handwavium is Mania generated by fanac (including amateur astronomy and "space speculation") as opposed to other miscellaneous thought.
Seriously, I think everyone is entitled to pet hypotheses, but the true origin of Handwavium shouldn't be pinned down even outside of the stories. It just appeared from nothing and without ascertainable cause, like a cat getting under foot when it was in the opposite corner of the house a moment ago.