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xkcd #3238: Soniferous Aether
(imgs.xkcd.com)
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/
Exactly, at least that's my understanding!