SiS Quickie: In space, no one can hear you scream…

…and in an empty house, no one can hear you sing.

Since I work from home, I have the house to myself a lot. Between living with my folks, in a dorm, with roommates/upstairs and downstairs neighbors, and then with my folks again for a little while, this is really the first time in my life that this has been the case. What do I do with my newfound solitude?

I sing. Loudly and frequently.

I love singing and I HATE silence, which means I would hate being in outer space, where it’s impossible for sound waves to travel. (There’s also the part where I wouldn’t be able to breathe and my head would explode.)

Sound waves are mechanical waves. When a mechanical wave travels, particles have to move: the molecules in a rope move when you wave it back and forth, the water molecules in a pond move when you drop a stone and send ripples through it, and the molecules in air move when you make sounds. No medium to travel through = no molecules to move = no mechanical wave.

There are no such restrictions on light and heat, which are electromagnetic waves. Electromagnetic waves consist of moving electric and magnetic fields- no molecules required, no medium required. (Remember the ether that doesn’t actually exist?)

Light and heat from the sun can reach us through the vacuum of space because they are electromagnetic waves. Any scifi movie that depicts loud battles in space is scientifically inaccurate; there’s no medium for the sound waves to travel through. (Though if you expect scientific accuracy from your scifi movies, I pity you.)

Physics teacher protip: There is some variant of “Could we hear the moon explode? Explain.” on EVERY SINGLE introductory waves test. Be prepared.

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