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xkcd #3238: Soniferous Aether (imgs.xkcd.com)

submitted 2 days ago by xkcdbot@lemmy.world to c/xkcd@lemmy.world

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xkcd #3238: Soniferous Aether

Title text:

Imagine you could ride alongside a sound wave. It would probably be pretty cool, right? We're putting in a departmental budget request to buy a really fast plane so we can check it out.

Transcript:

Transcript will show once it’s been added to explainxkcd.com

Source: https://xkcd.com/3238/

explainxkcd for #3238

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[–] GreyEyedGhost@piefed.ca 1 points 2 days ago (1 children)

I haven't looked into it recently, and the only answer I recall is "because". Ultimately, the higher the refractive index, the slower the speed of light in that substance. As for fiber optics, the 0.66 c, which isn't a claim I made, could be in part due to reflection increasing the path length, or it could be net speed including repeaters/amplifiers, or something else.

[–] probable_possum@leminal.space 1 points 2 days ago* (last edited 2 days ago) (1 children)

Repeaters and refraction explain a lot. The remaining slow down of light - if you factor those effects out, feels a bit magical. The effect isn't as big as on Pratchett's Disc World, but the air actually slows down the light. And fiber does too.

Disc World wiki:

Light is so oddly affected by magic, as it passes into the Disc's atmosphere, it actually slows down from millions to hundreds of miles an hour. One odd effect of this is that the Disc has time zones, when, as a flat world, it shouldn't. Another effect is that, as reported in Thud!, the red- and blue-shifting of light becomes noticeable when travelling at speeds of merely a hundred and twenty miles per hour.

[–] GreyEyedGhost@piefed.ca 2 points 2 days ago

Well, it's an explanation!