Non-lethal yet still horribly unpleasant weapons are all the rage these days, from puke rays to pink tasers. What's the next step? How about a beam that inserts voices into your head? Yes, you could be minding your own business looting a Best Buy during a riot and all of the sudden there's a voice coming from inside your own brain saying "We're really disappointed with you."
It's a pretty insane idea, but one that's actually been proven to work, at least in a basic form.
Because the frequency of the sound heard is dependent on the pulse characteristics of the RF energy, it seems possible that this technology could be developed to the point where words could be transmitted to be heard like the spoken word, except that it could only be heard within a person's head. In one experiment, communication of the words from one to ten using "speech modulated" microwave energy was successfully demonstrated. Microphones next to the person experiencing the voice could not pick up the sound. Additional development of this would open up a wide range of possibilities.
This technology requires no extrapolation to estimate its usefulness. Microwave energy can be applied at a distance, and the appropriate technology can be adapted from existing radar units. Aiming devices likewise are available but for special circumstances which require extreme specificity, there may be a need for additional development. Extreme directional specificity would be required to transmit a message to a single hostage surrounded by his captors. Signals can be transmitted long distances (hundreds of metres) using current technology. Longer distances and more sophisticated signal types will require more bulky equipment, but it seems possible to transmit some of the signals at closer ranges using man-portable equipment.
Luckily for you lawbreakers out there, this is taken from a recently declassified document that was initially written about 10 years ago. There are no hints that one of these things has been developed, but it's certainly possible that it's happening in the still-classified vaults of the Pentagon. So I guess we'll just have to wait and see whether the voices in your head are really being beamed there from black helicopters or if you're just crazy. [Danger Room]