Twenty letters down, six to go, and it occurs to me that I haven’t really spent that much time talking about my core business – mechanical properties of materials. I included a good description of the key properties a couple of days ago and I’ve alluded to them here and there. And at this late stage, I don’t propose to mess with a winning formula. So, recalling that strength is what we use to measure the load applied to a given cross-section (stress = Load/cross-sectional area), let us take a look at unobtainium.
At first glance, unobtainium might be mistaken for an element actually found in the periodic table, as it sort of looks like one of the elements yet to be named. We can also hazard a guess that it is a metal, because of the –ium ending (although in “James Cameron’s Avatar” it’s supposed to be a mineral, although we can stretch things a little and suppose that the metal unobtanium is extracted from the mineral that has a complex scientific name that no-one can be bothered to use).
Unobtainium, in fiction, is usually a form of McGuffin, i.e. it is there simply to send hapless heroes off on an all-expenses paid jaunt that they might live through if they are lucky. The term was actually coined sometime in the 1950s, in the aerospace sector, and usually comes down to the old saw of “cheap, light, strong – you can have any two”. Sometimes one or other of these properties is replaced with another, say high temperature, or is added to the list. Most frequently, it comes down to cost and so, for example, titanium was a form of unobtainium because it was not available in the kind of quantities for the kind of price that would make certain products commercially viable. In some contexts (e.g. sending a man to the Moon), price becomes no object – but unobtainium rears its ugly head, in the shape of competing properties, or simply the unavailability of materials that have the required combination of properties.
A fundamental of unobtainium is usually that it be strong and light in order that less of it can be used – it can carry the high stresses that will be imposed on a smaller cross-section. One way of thinking about this is, traditionally, to think of the force acting on a stiletto-heel, which is significantly more than that which an elephant exerts on the ground. Here we see that a stiletto needs to be stronger than an elephant’s leg, although as ever things are rarely as simple as they look in terms of whether the elephant is doing a trick, whether either is running, over what kind of ground and so on.
The term wishalloy is sometimes used as well. In some contexts the words are used synonymously. Whilst I have been known to play fast and loose with the English language on occasion, one of the things that I think is important is to look at the ‘value’ of a given word. In some situations then, you might choose one word over another, because it has more ‘weight’ (or perhaps less), so for example you might use the word horrible and in others hideous – for me at least these carry slightly different connotations despite being nominally synonyms. Hence the difference between unobtainium and wishalloy, under most circumstances, is that unobtainium is plausible, perhaps even already exists, it’s just that it is in short supply, difficult to manufacture or work with, and one way or another costs the GDP of a small country for less than you actually need for your purposes. Wishalloy, by contrast, is pure wishful thinking, and probably not physically possible.
###Shameless self-promotion alert###
I recently coined the term wishalkene to denote a polymer with properties currently beyond those available to us for my chapter in the Secret Science of Superheroes, which is due out September this year – set your calendars.