Curdled milk, of a peculiar kind, made after a Bulgarian recipe and called "yaghurt," is now a Parisian fad and is believed to be a remedy against growing old. A correspondent who has tried it, says he would prefer to die young. (1905, The Elk Falls Journal)
Now I'm tempted to start telling people that I secretly don't actually know how to do any physics calculations, and so all the answers in What If are based on me actually trying to do the thing and then reporting what happened, but phrased as if it's hypothetical.