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.