First described in an eponymous episode of the Rocky and Bullwinkle show, the (mythical) mineral '''upsidasium''' is negatively affected by Gravity. That is, gravity makes it fall upward rather than down. This has the unfortunate effect of making any samples you dig up (mine) out of the ground easy to lose (i.e. "dropping" it may allow it to "fall" off into space). On the show, the government needed upsidasium, so Bullwinkle and Rocky had to outwit Pottsylvanian spies Boris_Badenov and Natasha_Fatale to retrieve the hard-to-handle substance. Various nano-scale engineering thought-experiments yield substances that would be lighter than air but nevertheless solid and reasonably robust. Manufacturing an Aerogel filled with Helium rather than Air would create a lighter-than-air solid, but the helium would almost immediately leak out, and the fun would be short-lived. It is possible that Nanotechnology will eventually come up with a diamond matrix filled with helium and sheathed in some substance that is impermeable to helium, but no such thing is currently known to exist. Possible uses for such upsidasium-like materials include Aircraft and Airships that are safer, lighter, and more durable than current materials allow. Category:The_Rocky_and_Bullwinkle_Show Category:Thought_experiments Category:_Nanotechnology