An answer: the relevance of invisibility to you!

Why put something scientific into a story? If it is merely to impress, in my opinion the effort is wasted. Putting in something necessary to make the story work is much better, however in my writing I would also like to show something about the scientific approach. I feel rather strongly about this latter purpose because we now have so much dependence on technology that we are beginning to create new problems arising from it (such as the dependency on oil, which must run out sooner or later) so we need to know how to address them. An important point about science is that collecting facts and doing mathematics are not the goals; rather the goals are to understand, and to make use of that understanding. Now, let’s reconsider The Invisible Man. In my previous blog, I asked the question, can you think of anything very important relating to invisibility that is relevant to your life? My guess is that most people would shake their heads in despair at that question. How can invisibility have practical use? You simply cannot make people invisible. 

The scientific approach looks at problems in a different way. The most common way is to ask and attempt to answer questions. So, why do we see things? Light comes from somewhere, strikes the surface of the object, and is reflected. We then ask, why is it reflected? Because the surface represents a change of refractive index. In The Invisible Man, Griffin became invisible by changing the refractive index of his body to that of air. Assuming that could be done, Griffin would truly be invisible, although there is a subtle price.

Changing a refractive index of an object is generally speaking impossible, but it is possible to immerse it in a medium with the same refractive index, in which case it will disappear, provided it is transparent. So now we ask, what is the difference between transparent and opaque objects? The answer is that opaque things have lots of internal surfaces (such as fractures between crystals) where light is reflected or scattered. We now see the price for Griffin: separate cells have surfaces, which perforce define changes of refractive index, so for Griffin to be invisible, he had to have no cells! That would make life somewhat difficult to maintain. Anyway, now we see we can make transparent objects become invisible by immersing them in a suitable fluid. That still leaves the question, why is this important for the average citizen? The answer is simple. Suppose you put a liquid on the surface of the skin that closely matches the refractive index of skin (about 1.5)? That makes all the roughness of the surface of the skin, which is quite effective at scattering light, invisible, which means that light passes deeper into the body. Now do you see the relevance? Think sunburn and skin cancer!

A number of oils have refractive indices around 1.47. Simply apply oils like coconut oil and you will baste in the sun! Get the skin wet with water (refractive index about 1.33) and your natural protection drops by about 50%. With close matching, very little reflection occurs. This becomes relevant when you apply sunscreens, because the carrying medium provides such matching, and removes almost all the natural reflectivity of the skin. The sunscreen, of course, stops the UV radiation while it is working, but if your sunscreen does not offer UVA protection, putting such screen on your skin may stop you burning, but it may pump the UVA into the lower dermis. Also, while a very high SPF may offer prolonged protection against UVB (which burns) the UVA screen usually decays more quickly. The SPF says nothing about UVA protection, and UVA is presumed to be capable of inducing a cancer. The remedy, of course, is to re-apply frequently, and I also recommend not rubbing it in, but merely smoothly spreading it and letting it dry.

The point I am trying to make is that a little bit of scientific reasoning, together with some necessary information, can lead to a much improved lifestyle. In my opinion, inserting some of these facts into stories, and showing how the reasoning works, is of some value. What do you think? In the meantime, next week I shall provide the answer to the other question that seems to be somewhat troublesome.

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