It’s one thing to talk about The Birthday Problem—or Paradox, or Conundrum: that in a group of 23 people it’s more likely than not that two people will have the same birthday—same month, same day.
It’s quite another to put it to the test and check it out, but that’s what I did at the wedding Lynn and I recently attended in Norfolk, Virginia. Rachel Singer and Andrew “Dusty” Rhodes were getting hitched and we wouldn’t have missed it, since we’ve known Rachel since she was—what, two years old?—and we lived next door, back in the New York days.
Between courses and before the dancing starts, there’s usually some down time at weddings. The Birthday Problem is a great way to cruise around to other tables and chat with people you’ve never met. At our table Mark Tieman, a doctor from New York, plunged into the AI on his phone to find out why the thing works. Which prompted Joan Rockwell, the mother of the bride, to said, “Boy, we’ve got a bunch of nerds at this table.” But then she’d had a few cocktails. (I was on her left, and kept telling her if she was going to blow chow to do so to the right. She was fine.)
I didn’t wait around for Mark to give me the details; I was only planning to ladle out the basics to folks and see if it worked. Because when it does, it has the charm of a parlor trick since it seems so counterintuitive.
The theory does involve some esoteric math, beyond my descriptive powers to begin with, first explained to me by the late David Clarkson of Newfane, Vermont. We went on a hike in the Newfane forest once with David and enough other hikers that we able to check the theory out. Sure enough, we found a match.
So I plunged into action at the wedding and started toting up results. Damned if I didn’t find the first match—September 2—after asking exactly 23 people their birth dates.
So why stop there? After only eight more queries there were four matches. Twelve more asks after that ran the total to seven, including a young woman named Becky, born on January 21—my birthday.
Dusty and Rachel, wearing his jacket
The dancing soon revved up, the wedding cake was carved and Rachel and Dusty were hauled up on chairs for the hora. My last foray canvassed 13 people, yielding no further pairs. So the final stats, which the world will little note nor long remember, were seven birthday matches among 56 people. A good haul. David Clarkson would be grinning. And come January 21, I’ll try to remember to raise a glass to Becky.
I first put this up on my Substack page, Tom’s Bedellicatessan
