The High Probability of Coincidence

Coincidences are quite likely.

The odds of any particular coincidence will be quite small. But there are so many possible coincidences that the odds of any coincidence are very high.

Take any deck of cards. Shuffle it, ideally 7 times*. What are the odds that you find a pair of queens on the top of the deck? About half a percent, it turns out. Very small.

CardShuffleBut what are the odds of finding a pair of any kind, anywhere in the deck? I don’t know actually. That’s hard to calculate. But it’s much, much larger.  Go ahead, check for yourself. I just tried it five different times myself, and never failed to find at least one pair. Often more than one.

This is probably fairly obvious. But you’d be surprised how easy it is to lose sight of it.

Before a presidential election, for example, news magazines tend to fill up with stories about weird things that can predict the results. They’re played for laughs, of course. But when you see these articles discussed in comments, you’ll find lots of readers determined to explain “why” these coincidences work.

Some of them may have explanations, it’s true.** But the point is, these coincidences don’t need explaining because their existence is not unlikely.

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Walking on Water (Now in Slow Motion)

Alright, I lied, this post isn’t strictly speaking about walking on water. It’s about walking on water and cornstarch–a combination you’re probably familiar with if you’ve ever been a kid or raised a kid. When I was in elementary school we called it “Oobleck,” a reference to this book. I’m sure it goes by a lot of different names, but that’s the one I’ll use here.

Oobleck, famously, flows like a liquid unless it is exposed to sudden force, at which point it “seizes up” and acts much more like a solid. As a result, you can walk on it, if you do it quickly enough, because the sudden forces of your footfalls make it go momentarily stiff. But you can’t stand on it, because while you’re still exerting a force on the Oobleck with your weight, that force is no longer sudden.

It’s all summarized nicely by the antics of these nice gentlemen on some sort of Barcelona-Based, Bill-Nye style science show. You don’t have to speak Spanish to appreciate it, but if you do, please tell me, is Google correctly translating the name of the show (“Hormiguero Cientifico”) as “Scientific Ant Hill”?

This is in fact a rather “old” clip by internet standards. What caught my attention this week is this newer video showing the same trick, but in super slow motion:

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