License plate scanners and public privacy

Here’s a story from last month about the Boston police and the use of license plate scanners. The scanners in question are just video cameras with some clever software designed to read plate numbers as they drive by. That may seem high tech now, but you’ll be doing it with your phone by Labor Day. Google recently demonstrated similar software that can read street address signs from Street View imagery.

So this Boston story is being presented as violation of privacy. Is it? What it really points to the slippery boundary between public and private these days. The technology required to build a plate scanner these days is not expensive. And it can’t be illegal to write down the license plate of a vehicle parked in a public place. What’s new is that you and your friends, just in the process of driving around with plate scanners, can assemble detailed information about the comings and goings of all your neighbors. The information is all public. I don’t see a way to stop it. This public-as-private pattern is showing up all over the place. The human form of the plate scanner problem is unsolicited face recognition. It’s not illegal for me to capture you in photo, and if the giant cloud brain is big enough to spot you in an incriminating position, that’s going to cause some discomfort.

This is already happening. The NameTag facial recognition app uses publicly available data to match your face with your name. This is what might be called a privacy invasion, only it’s powered by people’s natural desire to post labeled images of themselves on the web. The NameTag people are just aggregating that information. Did they sin?

One redeeming part of the story is that humans evolved in a world without privacy. We have no “biological expectation” of privacy. Google’s Vint Cerf went so far as to call privacy “an anomaly”. For almost the entire history of the human race, people have lived in small communities in which every action was accountable, every deed was scrutinized and judged by neighbors. We come from a small town, and to that small town we return. Welcome home.

The Feast of Crepusculus Winter-Rise

Okay, one more post about this solstice business, and then we’ll put it to bed for another six months or so.

January 3rd was the day, at my latitude, with the latest sunrise. Having safely passed that date, we are now well and truly growing the day at both ends. Despite cold days ahead, we can nevertheless look forward to rapidly expanding sunlight hours. That counts for a lot in my book. Anyway, as you can quickly deduce, there are four crepuscular extremes during the year: earliest and latest sunrise, and earliest and latest sunset. If we are to recognize the special nature of any of these days, we should be prepared to recognize all of them. With that in mind, I dub them Crepusculus Winter-Set, Crepusculus Winter-Rise, Crepusculus Summer-Rise, Crepusculus Summer-Set. Bit of a mouthful, I know, but it’s all in the name of thoroughness.

As part of pondering sunrises late and early, I asked myself this question: who shares the instant of that latest sunrise with me? It’s not hard to work it out on a map, but doing the calculations was fun. Here it is on a globe view.


And here we are zoomed in to the east coast of the U.S. As you can see, dawn’s rose-red fingers tickle almost the entire eastern seaboard at the same instant. I share that moment of daybreak with people from the western tip of Cuba to the north shore of Iceland.


If you’re curious about how I created the plot, I talk about it more in a MATLAB-related post over here: Crepuscular Isochrons: Sunrise Here and There.