Welcome to the Science Asylum. I am Nick Lucid.
Look what I found in the tool box.
What, a flashlight?
I wonder what this button does.
Ahh! Turn it off! Turn it off!
Behave.
This device seems simple enough.
Two AA batteries, a 3 volt light bulb, and some metal to complete the circuit.
But how does that bulb make light?
What even is light?!
Yeah, we ask the deep questions around here.
Let’s take a closer look at that light bulb.
Inside the bulb there’s a coiled filament usually made of tungsten.
As it heats up, it starts to glow red, and then orange, yellow, and finally white.
The reason the filament heats up in the first place is because it’s a resistor.
That means the filament takes energy away from passing electrons
and its atoms vibrate faster.
Every time one bumps into another, they lose a little of that energy as light,
and we get a functioning flashlight.
Light is created whenever charges accelerate.
That means whenever they speed up, slow down, or change direction.
That’s true whether you’re talking about flash lights, or radio towers,
or the x-ray machine at the doctors, or your microwave oven.
Which is partly why the idea of electrons orbiting in atoms is totally ridiculous!
The electrons would continuously lose energy until the atom collapsed.
So light is just energy?
Ehhhh, not exactly.
Remember, energy doesn’t just float around on its own.
It has to be possessed by something.
Light is that something, but what is it, exactly?
Normal every day stuff fits into two categories: waves or particles.
This is a debate that has raged for centuries, so let’s take it slow.
Possibility #1: Light is a wave.
This was something proven by Thomas Young in 1801 using diffraction.
When you hear the word “wave” you probably think of water waves.
Not surprisingly, that’s actually where the word wave comes from.
But lots of things can wave.
You just have to get matter to move back and forth repeatedly.
If it happens in the Earth, you call it an earthquake.
If it happens in the air, you call it sound.
For light, amplitude measures brightness and frequency measures color.
But light travels through empty space where there isn’t any matter!!
That’s because light isn’t a wave in matter.
It’s an electromagnetic wave.
Electric and magnetic fields are created by charges.
Since charges have been around since the beginning of time,
so have those fields, and by default, so has light.
Light might need matter to be created, but it doesn’t need it to move around.
If that makes you uncomfortable,
let’s consider possibility #2: Light is made of particles.
This was an idea proposed by Isaac Newton in the late 1600s
and then supported by the work of Max Planck & Neils Bohr in the early 1900s.
It’s a pretty straight forward idea.
All the tangible things we interact with are made of particles:
Glass, water, air, even your own body!
So why would light be any different?
We call the particles of light “photons.”
How many photons there are in a beam of light determines its brightness.
More photons means brighter light, fewer photons means dimmer light.
So which is it?! Waves or particles?!
Both!
Photons are one of the many quantum beasts that lurk at the microscopic scale.
When we work with stuff down there
we have to let go of those kinds of distinctions.
Those things that you always hear being called “particles”
actually display properties of both.
They’re particle-waves.
Even with photons, frequency still measures color.
Photons have frequency!
But I don’t see any of that weirdness happening around here.
That’s because this stuff is made of tons of particle-waves.
Interaction compels these particle-waves to pick a side.
That’s why we never see it.
The only difference between what we call matter and what we call light
is what side they consistently choose.
Most of the time though, you’re not dealing with individual photons.
You’re dealing with a whole beam full of them
and calling light a wave works just fine.
Aaaaah Owww!
Yeah, it's not fun, is it?
So, what inanimate object should we think this deeply about next?
Let us know in the comments.
Thanks for liking, sharing, and subscribing.
And until next time, remember, it’s ok to be a little crazy.