Dopplr? Is that name supposed to mean something?
Yes. It’s named after Christian Doppler, the 19th Century Austrian scientist who came up with the hypothesis for what became known as the Doppler effect. That’s something we’ve all experienced when an emergency vehicle goes by with its siren on. The siren’s pitch is higher before it gets to you, and the pitch drops as it passes. You may also have heard of Doppler Radar–a method that weather forecasters use to measure the direction and velocity of storms.
