I have a very odd coincidence to report.
I like getting fun questions from folks, the kind that take a little bit of math and physics to explain, but wind up taking you to fun places. A common question like that is, "What would happen if everyone in China jumped all at once?" Would it throw the Earth out of orbit? Would it cause an earthquake? Would it do anything?
The answer is, essentially, no. I tackled this a few years back; there was this announcement by a group that wanted to get 600 million people to all jump at once so that the Earth would be pushed farther from the Sun and global warming would be solved.
Um, yeah. They called it World Jump Day, and I made quick work of it. Nothing at all would happen, for lots of reasons. Still, it's fun to think about, right? And it turns out World Jump Day was something of a prank anyway.
My opinion: science is always better when Felicia Day makes a cameo! And, of course, vsauce is right.
So anyway, I liked the video, and made a note to myself to write it up on the blog here. And then, literally the next day, what happens? My pal Randall Munroe (of xkcd fame) goes and writes about this very topic for his "what if?" series!
Although, to be fair, Randall takes it in a slightly different direction. Still. Weird.
Of course, coincidences happen all the time. It's a big world out there, with lots of things going on. There's bound to be the seemingly-spooky overlap or two between 'em.
And as a final note, if you want to read more about the gnarly math of millions of people jumping, Dot Physics has you covered.