Column: The electromagnetic magic inside a prox
It’s 3:15 a.m. Friday morning, and you’ve just gotten back from the Street. Approaching your dorm, you pull out your prox and slap it across the sensor. A light turns green, and, with a click, the door unlocks. For a hazy moment, as the door shuts behind you, you wonder what kind of magic enabled your piece of orange plastic to open doors with a wave.




