# Using math to get out of a ticket

By now perhaps you’ve seen this floating around the internet. It was reported here and here and here and here, at least.

Physicist Dmitri Krioukov got a \$400 ticket for not making a full stop at at stop sign. He wrote a paper explaining why the police officer could have been wrong, went to court, and got the fine lifted.

If you haven’t read the paper, I encourage you to do it. It’s fairly short and only requires knowledge of a Calculus. Here is a direct link to the pdf. Here’s the abstract:

We show that if a car stops at a stop sign, an observer, e.g., a police officer, located at a certain distance perpendicular to the car trajectory, must have an illusion that the car does not stop, if the following three conditions are satisfi ed: (1) the observer measures not the linear but angular speed of the car; (2) the car decelerates and subsequently accelerates relatively fast; and (3) there is a short-time obstruction of the observer’s view of the car by an external object, e.g., another car, at the moment when both cars are near the stop sign.

What do you think? Is Professor Krioukov just trying to buffalo the court, or does he have a legitimate case? I guess if there’s any doubt at all about his guilt, then he should be forgiven the fine. And that’s what the court did rule.

However, there is one particular assumption that he makes which is absolutely way-off (look at the paper and notice the key on Figure 3, labeling the blue curve). But the court certainly didn’t catch that. Like I said, he may have been trying to pull the wool over the eyes of the court with lots of math and physics.

Despite the fact that he published his paper on April 1st, I do think this story is true. Like I said, though, the paper does contain an error. So despite all of his good effort, I think he should have been given the ticket. The court didn’t notice it, but he pulled a fast one on them! (pun intended!)