Als Superkrachten Echt Waren: Onzichtbaarheid

Wat als onzichtbaarheid niet alleen het verhaal van epische stripverhalen was? Is het wetenschappelijk mogelijk om onzichtbaar te zijn? In deze serie pakt Joy Lin zes superkrachten aan en onthult hoe wetenschappelijk realistisch ze voor ons stervelingen kunnen zijn.

Wouldn't it be great if we could be invisible? Ha, right? I mean, we could spy on people without being noticed and do whatever we want without being held responsible.

Now, magicians have figured out how to utilize full-sized mirrors to bend light in order to create disappearing illusions. Scientists have created metamaterials to guide rays of light around tiny, two-dimensional objects. Cameras can also film what is behind you and project the image so you appear invisible from the front. However, none of these options can make an object as large as a person appear invisible for all angles and distances while its moving.

But if you are truly invisible, as in from within, here are a few problems you may not have thought about before.

To move around undetected by other people, you would have to be totally naked. Even if it's freezing outside!

You can't carry anything, including your wallet and keys, otherwise people would just see your wallet and keys floating around.

Drivers and people on the street can't see you either, therefore they can and will run into you at some point.

Oh, and you better not wear any perfume or make any noise breathing, otherwise they'll know you're there.

And, just because you start off invisible, doesn't mean you'll stay that way. What if someone accidentally spills scolding hot coffee on you? And what if it rains?

But if you think only liquid can make you visible, you're wrong. Dust consists of dead skin cells from humans, soil particles, and fibers from clothes made from cotton and other materials. Dust sticks to the moisture on our skin when we sweat and the tiny hairs on our skin when we are dry. So, even if you are invisible, dust would still land on every part of you.

We usually don't notice the dust on our skin because we can't see a thin layer of dust on top of our skin color. But, if you're invisible, people would see a human-shaped blob of dust walking around with extremely dirty soles. Gross!

What do you think the world looks like if you are invisible? Well, the answer is nothing. The reason you can't see in the dark is because there is no light. To see an apple, light has to hit the apple and return it to your eyes. Then, the retinas in your eyes catch the light reflection for your brain to interpret into the image of an apple.

If you're invisible, then, by definition, light would travel through you or around you instead of bouncing off you for people to see. But that means that retinas in your eyes are not catching the light, either. Therefore, your brain has nothing to interpret into an image. Can you see your reflection without a mirror to stop the light? No. So, when you can't be seen by others, you also cannot see. Ouch!

Now, have you given any thought as of whether the invisibility is permanent? If it is, how can you receive medical treatment from a doctor if you're injured? The doctor wouldn't know where to apply ointments or bandages because they cannot access your injury.

For that matter, you can't see it either. I mean, what if you have an illness or an infection? How can the doctor diagnose you without being able to see the color change or inflammation?

And what if everyone is permanently invisible? Well, think about how boring the world would be without seeing people on the streets, on TV, or at home on your computer like right now. It's lonely being invisible.

Now, which superpower physics lesson will you explore next? Shifting body size and content, super speed, flight, super strength, immortality, and invisibility.

 

Bron: TED.com