Watch the video above and listen carefully for what sounds like a human voice during the second spin. That’s not an audio recording or a broadcast transmitted over radio…it’s not human at all. It’s an auditory effect that’s created by military scientists who manipulated the air with lasers — and it’s the Pentagon’s most interesting idea for stopping people charging checkpoints, or just scaring the crap out of them.
The U.S. military’s Joint Non-Lethal Weapons Program, or JNLWD, is inching closer to a weapon that alters atoms to literally create words from thin air. It’s called the Laser-Induced Plasma Effect and, fingers crossed, they hope to be able to say intelligible words within the next three years.
The weapon is composed of two parts: first, a femtosecond laser, which shoots a burst of focused light for 10−15 seconds, just long enough to rip the electrons from air molecules and create a ball of plasma. (Sometimes called the fourth state of matter, plasma is a field of electrified gas, highly responsive to electromagnetic effects.) The scientists then hit that plasma field with a second nanolaser, tuned to an extremely narrow range of wavelengths. They use that to manipulate the plasma field in a way that can produce light and noise. Get the interaction precise enough and you get something that sounds like a haunted walkie-talkie.