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In a Nutshell – Kurzgesagt/YouTube

Watch: What Is Light Anyway? Explained!

Let’s break this down.

16 OCT 2015

What exactly is light? We’re forever surrounded by it and it’s pretty much the entire means by which we understand the Universe and our place in it, and yet for such a fundamental part of our existence, it’s so easy to take it for granted, or sometimes forget about it altogether.


But if you can’t remember the fundamental science of light you learned in high school (or maybe you weren’t paying attention that day…), this excellent 4-minute video by Kurzgesagt (aka ‘In a Nutshell’) provides an excellent primer on that whole wavy physics thing that’s kind of essential for everything else in the Universe to function.

As Kurzgesagt explains, light technically refers to photons, which are indivisible energy particles. In addition to being a particle, light also behaves like a wave, and when people talk about light, what they’re mostly referring to is visible light, which is only a fraction of the whole electromagnetic spectrum – most of which we can’t see with our eyes.

Visible light, which is also known as red light, is in the middle of the spectrum, but apart from that, what’s so special about it? That is, compared to the other kinds of frequencies (gamma rays, x-rays, ultraviolet etc) that also constitute electromagnetic radiation?

“Well, absolutely nothing,” says Kurzgesagt. “We just happen to have evolved eyes that are good at registering exactly this part of the electromagnetic spectrum.” But this wasn’t just a coincidence.

Without giving too much away, the key to our ability to perceive visual light has got something to do with its properties in water, and also where our eyes come from, in an evolutionary manner of speaking.

But what about light, where does it come from? Why is it the fastest thing in the Universe? And what the heck is c – the universal physical constant – anyway? Fret not, check out the video above, and all will be explained!

And note: you might want to watch this one twice – there’s an awful lot of amazing stuff here getting squeezed into just 4 minutes. You don’t want to miss it.

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