Supervillain Science: The Invisible Women
Posted by Science Oxford on October 2, 2009 | comments
Welcome, aspiring supervillains to part 1 of an introductory course in Eeevil!
Over the course of the Supervillain Science series you will learn how to apply science and scientific thinking to the thorny problem of how to take over the world.
As we all know, the actual taking over of the world is simple, it’s always just one thing that gets in our way – Superheroes. So we’ll be concentrating on how to defeat a couple of the more well known examples of this pathetic class of individuals, and hopefully you’ll go away with a few ideas of how to beat your own super-nemeses.
THE INVISIBLE WOMEN
One of the most important things when you’re planning on crushing the world in your iron grip is *secrecy*. It’s no good developing a really good freeze ray if everyone can read about it on your blog. This is why The Invisible Woman, from that group of super-dopes The Fantastic Four, is so irritating. She has the ability to turn invisible at will, as well as project unbreakable force fields. So not only can she sneak up on you, she can then break your stuff. The question becomes: how to we detect her presence?
Well, let’s assume she doesn’t break any of the major laws of physics. A couple of the smaller ones, sure, but none of your biggies. What is the mechanism by which she can turn invisible?
Don’t worry we have a theory! – she is manipulating the refractive index of her entire body…I’ll show you.
Watch the video below, you can see we have here a simple Pyrex beaker, submerged within this larger beaker of oil…
Can you see how the smaller beaker appears not to be there?
I assure you this guy has never been bathed in cosmic radiation, so how was he able to turn this beaker invisible?
Simple – through the use of SCIENCE!
When light is moving through the same medium, it moves in straight lines – everyone knows that, that’s why we can’t see around corners. But if you have two different media beside each other, say air and water, light can bend.
Light moves at different speeds through different materials – think walking through the air vs walking through the water. When a light ray hits one of these boundary points at an angle, the first side to hit the new medium, say the water, is moving slower than the other half, so it develops a kink, which sends the light in a different direction.
You can see this effect if you look down into a glass of water with a coin in it, or into a swimming pool.
The amount that a material ‘kinks’ light is related to what’s called it’s ‘refractive index’.
So, for example, air, glass and water all have different refractive indices, so when the light goes from air to glass, it kinks, then from glass to water, it kinks again. We can see this kink, so that tells us where the boundary between all these things are. But two materials with the same refractive index don’t kink light at all – which is what’s happening with our pyrex – pyrex and vegetable oil have near-identical refractive indices, so the light goes straight through the pyrex in the oil without kinking, so we can’t see it.
So, back to the invisible woman. Her powers must allow her to control her own refractive index, so that it matches whatever is surrounding her – air, water etc. So she’s invisible. But being invisible has one, major flaw to it- any guesses as to what this might be?
It’s that being invisible makes you blind. In order for us to see, light has to hit the back of our eye. If you’ve changed the refractive index of your body, then light is going straight through there, so you can’t see.
Now, the fact that she doesn’t stumble her way around walking into chairs, walls and people, tells us that she must be able to see. And the key to this is to remember that there’s more to light than what we can see – so while visual wavelengths pass through her eye, some other wavelength must be hitting her eye in order for her to see.
My guess is that it’s in the Infra-Red – other wavelengths wouldn’t give as much information.
The problem with seeing in the Infra-Red is that her world would look a lot different to ours. For a start, she can’t see computer screens. Lights also look different – normal bulbs seem incredibly bright, as they give off light in almost every wavelength, but energy saving bulbs don’t help her at all (that’s one of the reasons they save so much energy – they don’t waste energy putting out wavelengths we can’t see in anyway). Candles, and £5 notes also look funny to her.
So how do we use all of this knowledge to bring about her inevitable defeat?
Well, we kit our evil lab out with only energy-saving light bulbs, so we can see and she can’t. When we lure her into our lair we communicate with our henchmen only through LCD monitors, so she won’t get tipped off. Then we use our IR camera here to look for the floating pair of eyeballs.
She’ll never see it coming…
What do you think?