iPhone apps can tell many things about you through the accelerometer
> Now, if this social app is reading accelerometer data on your phone as well as the passenger’s phone, the app can easily figure out that both phones experience the same vibration pattern. ... Don’t be surprised if you receive a recommendation from the app to add this passenger as a friend.<p>Overall I find the article interesting but this quote is borderline tinfoily. Given the amount of noise in the accelerometer data and signal s much closer to the sensor than the bus itself - such as body movements, it would be hardly precise. Moreover the cost of doing all that research and computation as well as data transfer would hardly pay off.