The U.S. military completed a round of testing of the Active Denial System, a weapon that inflicts searing pain at a distance -- but (according to the military) produces no injury. It motivates targets to run away -- and fast. It's been certified for use in Iraq.

The ADS shoots a beam of millimeters waves, which are longer in wavelength than x-rays but shorter than microwaves -- 94 GHz (= 3 mm wavelength) compared to 2.45 GHz (= 12 cm wavelength) in a standard microwave oven.

The longer waves are thought to limit the effects of the radiation. If used properly, ADS will produce no lasting adverse affects, the military argues.

Documents acquired for Wired News using the Freedom of Information Act claim that most of the radiation (83 percent) is instantly absorbed by the top layer of the skin, heating it rapidly.

The beam produces what experimenters call the "Goodbye effect," or "prompt and highly motivated escape behavior." In human tests, most subjects reached their pain threshold within 3 seconds, and none of the subjects could endure more than 5 seconds.

Boing Boing worries the weapon will be used for torture.