I’m having a short break from climate-related stories, and thought I’d write about invisibility instead. Last month I found an article in the Metro about a Chinese artist, Liu Bolin, who paints his body so that he merges with the background, a bit like a chameleon. (Here’s a similar article in the Mail on Sunday.) The idea is simple, actually, but the procedure is very fiddly and time-consuming, taking over ten hours to complete. Obviously you can still see that he’s there, if you look closely, but the average passer-by might not notice him at all.
When I was a lot younger, I was very self-conscious and the idea of moving around unseen seemed cool. That was before I learned about the possible drawbacks, though, by reading about the many problems faced by the character Griffin in The Invisible Man, by HG Wells – even moving around without being constantly bumped into would be a challenge in itself. Clearly, unless you just happened to be trying to infiltrate a military base in some sort of ninja operation, actually being invisible would be a pain for much of the time.
But there might still be occasions when being unnoticed would be helpful, for instance when trying to avoid a talkative but very boring acquaintance in the street. So it’s probably worth asking the question: is invisibility possible?
Surprisingly, science says yes, it is. In theory, a cloaking device could be devised consisting of “metamaterials” that can guide electromagnetic radiation around a central region (this has already been done on a small scale with microwaves.) However, it is foreseen that the device would have to be rather rigid and substantial, so unless you happen to be a Romulan spaceship, it probably won’t be something you can just slip on. In the near future, anyway. And even if they developed a prototype suit made of light-bending material (or something resembling Harry Potter’s invisibility cloak), making it work convincingly is likely to be something of a technological nightmare.
How do animals do this? Of course, chameleons, squid, flounder and other creatures that change colour, either for display purposes or to conceal themselves by matching their backgrounds, do so not by bending light rays but by using specialised skin cells called chromatophores, which change colour and form patterns. We humans have skin cells that darken when UV light stimulates the production of melanin, but alas their repertoire is limited (we range in colour from deep brown to pale pink – no sky blue, avocado or mauve, of course) and we cannot alter them quickly or at will.
(Incidentally, I had always thought that the skin cells of animals such as squid must somehow sense nearby colours and change themselves accordingly. Not so – the squid must be able to see its surroundings – the information reaches the chromatophores via the squid’s eyes.)
However, even if humans were genetically modified so that our skin could reproduce any colour of the rainbow in any conceivable pattern, this would still leave a problem, as we’d have to go about naked for this to work. So it’s back to the invisibility cloak idea, but instead of light-benders, the outer layer of the cloak might consist of arrays of cells that would sense their surroundings and change colour accordingly.
Something like this – “chameleon cloth” – has already appeared in science fiction, featuring in George RR Martin’s story Dying of the Light and more recently in the Polity novels by Neal Asher. So is it feasible? At least one company – Philips – is already developing “photonic textiles” which can be programmed to display text and images. Further down the line, a combination of minuscule programmable pigment cells and tiny sensors – nano-scale CCDs – could do the trick, perhaps.
Wearing a cloak or a sort of burkha made of chameleon cloth, a person might eventually be able to emulate Liu Bolin and fade into the background. It would be a lot faster and more sophisticated than using a paintbrush and palette, but the prototype would be somewhat expensive – for the likes of you and me, anyway. Maybe by AD 2075 invisibility cloaks will be manufactured on an industrial scale and everyone will be able to afford one, but until then, I imagine this technology is likely to be the prerogative of secret agents and super villains, the Bonds and Blofelds of this world.
Perhaps it already exists, and there’s someone standing unseen, just a few feet away from you, watching…
(It has also occurred to me that there are other ways to become invisible than distorting light or changing colour. Blending in with the surroundings is often simply a matter of not drawing attention to oneself, which can sometimes be a simple matter of carrying a clipboard and looking “official”. But that, I think, is the subject of a whole new blog post.)