Okay, I came up with a kind of weird / funny one for U, but it is very much entrenched in sci-fi (and other fiction).
The reason humans went to a planet full of dragon-riding smurfs.
Unobtainium is exactly what is sounds like – an unobtainable, or very hard-to-get substance.
Something so exotic, so rare, for all we know, it could do anything! Examples abound in all kinds of fiction:
Wolverine’s claws are made of Adamantium
, a non-existent metal alloy that can cut through anything. Captain America’s shield is made of Vibranium
, and indestructible metal. The warp core of the Starship Enterprise uses dilithium
, a substance somehow able to keep matter and antimatter from immediately annihilating. Heck, in a way, antimatter itself is a sort of unobtainium – gathering enough of it to be useful would be very difficult, and keeping it from violently blowing up any matter around it would be very difficult.
In fantasy worlds, there are wonderful metals like mithril and Valyrian steel – strong, and often imbued with magical qualities. You also have variants of mythological items, like orichalcum, a metal mentioned by Plato as he described Atlantis, or the Philosopher’s Stone, the ingredient sought and never found by ancient alchemists that would turn lead into gold (sigh, I hope American kids haven’t grown up thinking that’s a “Sorcerer’s Stone” – stupid publishers thinking they need to dumb things down grumble, grumble …)
When a writer needs a material that defies known laws of physics, what does he do? Same thing he always does – make some stuff up.
Real World Unobtainium?
Actually there are quite a few examples of “unobtainium” in the real world. A great example is Greek Fire
– no one is quite sure how the stuff was made, but it was apparently a devastating weapon. Before modern refinement techniques, aluminium was nearly an unobtanium simply because it was so difficult to extract.
Research into carbon nanotubes
is a modern day quest for unobtanium – short lengths have been made, but it’s extremely expensive to make. This is the stuff that could make space elevators
possible, so let’s hope there’s a breakthrough soon.
http://tvtropes.org/pmwiki/pmwiki.php/Main/Unobtainium – Don’t blame me if you get stuck at TV Tropes for a few hours!