So I understand that light is energy and can be modelled as a wave, where different frequencies are perceived as different colours. All good. But I don’t really understand that. I can understand sound because you can view it as changes in air pressure – and that can explain how sound travels and how it is perceived. But I can’t find anything similar intuitive explanation of how light works – how it is physically manifested, how it travels, and how it can be understood in terms of a wave. Any explanation I can find assumes that you already understand the light as waves concept.
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The answer is…light isn’t a wave. It’s just wave-like.
At least, it’s not like what you might picture when you think of a wave, like a wave on the ocean or a sound wave.
For centuries, scientists struggled with this. Experiments showed that light had frequencies that could even interfere with each other, just like sound.
But if light is a wave, it’s a wave *in what?* Ocean waves are carried by water. Sound waves are carried by air. But light happily travels through outer space, where there’s nothing. So what kind of wave is carried by nothing?
For a while they thought there must be something called the “luminiferous aether” (light-bearing heavenly air) that pervaded space. It was supposed to have contradictory properties – it was extremely rigid, to transmit light waves so fast, and yet completely intangible, because physical objects aren’t affected.
They tried a lot experiments to find the aether and nothing worked (until Thor 2).
So scientists just gave up.
Nowadays, we think of light as an electromagnetic wave in “space”, but this isn’t very helpful to visualize what’s happening.
Especially because, half the time, light acts like a particle! It comes in little units (photons) and with a solar panel you can turn it into little units of electricity (electrons)? Now what? Wave AND particle?
It’s better to think of waves as a *metaphor* for how light works. Light works the way light works. It doesn’t have to behave like anything we are familiar with in the everyday world. Some of the math looks like the same math we use for sound waves. Some of the behavior looks like waves to our intuition.
But light just acts like itself.
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