Is Upsidaisium the secret metal from the movie Avatar that made the mountains float?

I believe it was called Unobtainium.

no that was unobtainium

The other posters are correct.

Here is an article describing the material and its history.

“The term originally comes from aerospace engineering, where it was used to refer to materials that would be perfect for a particular design if not for the inconvenient fact that they were unavailable – either because they were too expensive, or did not actually exist.”

Unobtainium is that same material that will get my 14 year old son to stop arguing with everything I say.

@fordest To be fair, there are other materials that will also do that. Unobtanium is so difficult to obtain and thus so incredibly expensive that you would never consider using it for a task where some less expensive and exotic material would suffice. Unfortunately, employing most of the alternatives (arsenic, laughing gas, sodium pentathol, heroin, etc) may be considered illegal in your particular jurisdiction. Consult local ordinances before turning to any such options, and if that reveals that available materials are all illegal, relocate to an adjacent sector of space outside that currently subject to government regulations. Or just wait 20 or 30 years and when the rebelliousness comes home to roost, enjoy the moment when you can say, “I tried to tell you back when you were 14, remember?”:-)

^My kids are a little younger, but I have been using Benadryl. Just sayin’.