Sirens

As I was napping on a ride home from a UC San Diego tournament late at night on Sunday, I woke up to some heavy traffic due to a car accident. After a few minutes, a police car passed us with its sirens on, and it made me wonder why the colors red and blue were chosen for the lights. My guess was that the red gave a sense of urgency and also tends to mean stop, while the blue is harsh on your eyes and grabs your attention even more, since it stands out from the sea of red tail lights, especially in traffic at night. I looked this up later, and there doesn't appear to be one right answer, though my guesses are possible ones. At any rate, it took me a little while to fall back asleep after that.