[as the] Radar Sweeps

In 1973, still fours years before starting my persona-shaping stint as an air traffic controller, I had a formative experience. I was living in San Francisco at the time, it was a Saturday afternoon, and I was going to attend a party at a friend’s house that night. The crowd would mostly be people I had not yet met.

That afternoon I was at 5th and Market Streets, downtown, watching a street artist performing in front of an appreciative crowd at the cable car turnaround. San Francisco is a great place for people watching and I lingered for a bit taking note of the exquisite variety of the audience. With a little imagination I could see people I was certain were first generation Chinese tailors, retired Irish longshoremen, City College students, Scandinavian tourists in addition to all of the stoned-out hippies. I watched others linger and enjoy the day, and the scene, as I was; a few dropped some change into the busker’s bucket. I wasn’t trying to keep track, but I noticed who did while I was there. One of those who gave up some cash was about my height - 6′3″ - with long curly hair, dark framed glasses; hard to miss.

At the party that night I had been there about an hour, when this very same guy walks in. “How weird is that?!”, I thought. Just to make sure I wasn’t deluding myself I asked him: was he the guy? Yes, he was at 5th and Market earlier that afternoon and yes, he put some $$ in the bucket. Ok, so I have a coincidence. Big deal.

But, of course, like any good answer it just provoked more questions: how many other times had I crossed that guy’s path that day without noticing? That month? What about others: if there was one random guy whose path intersected mine twice in one day, were there others? How many? Was this simply going on all the time, silently and unnoticed? I started to imagine a large RADAR screen on which you could visualize movements of various people, unknown to each other, whose paths crossed multiple times.

I’ve thought about that RADAR screen many times since and speculated on the answers to those questions. Then last Saturday I had a similar occurrence. I had an 11AM appointment in Los Angeles and was driving North from Orange County on the 405 to get there. Passing Long Beach I noticed a silver car ahead with the vanity plate “DANA PT”. I generally tend to notice vanity plates and it so happens that I was in Dana Point a week ago for a friend’s surprise 50th birthday party, so perhaps I was a bit subconsciously predisposed to noticing “Dana Point-ish” things.

I went on to my appointment on Wilshire, stopped for coffee at Peet’s in Westwood, and headed back South on the 405. Just South of LAX as I stare out from my “surrounded-by-a-million-cars” stupor, what do I see immediately in front of me? A silver car with the license plate “DANA PT”. Is that weird? Is it a statistical anomaly, a 1-in-a-million shot? Or is it happening all the time, silent and [mostly] unnoticed?

Some quick math: the Southbound 405 is generally 5 lanes wide. Using an interval from front bumper to front bumper of 100′ [the real number is probably much smaller] and a speed of 70 miles/hour [the real speed is certainly higher] I calculate over 18,000 cars passing any given point on that freeway each hour that morning. And somehow I wind up behind the same random guy twice in the same day, in opposite directions? [And no, he was not my meeting in LA]

I’m baffled impressed. Should I be?

This entry was posted on Tuesday, December 4th, 2007 at 5:39 am and is filed under Probability. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.