Unwired energy questions asked, answered

I was somewhat bewildered by the “Unwired Energy” Physics Update.

Energy transfer using electromagnetic resonance is used today in thousands of locations around the world—door locks, toll roads, and many more upcoming applications such as airport luggage tracing and supermarket checkouts. All RFID (radio-frequency identification) tags are powered with LC resonant circuits.

Actually, nearly 50 years ago, when I was in primary school, I built a diode radio receiver that drew operating energy from a circuit tuned to a radio-station frequency. A diode was used to detect the signal that drove an earphone. No battery was involved.

I don’t think the MIT work is really new physics but rather an attempt at improved engineering for, say, transferring sufficient energy to drive laptops. Radiating hundreds of watts of RF in a room or several thousand watts in a coffee shop seems to me to be too risky for people and will not be accepted.