The basic concept behind Excalibur was conceived in the 1970s by George Chapline, Jr. and further developed by Peter L. Hagelstein, both part of Edward Teller’s “O-Group” in LLNL. After a successful early test in 1980, in 1981 Teller and Lowell Wood began talks with Ronald Reagan about the concept. These talks, combined with strong support from a like-minded group that met at the Heritage Foundation, were a major part of the series of events that ultimately led Reagan to announce the Strategic Defense Initiative (SDI) in 1983.
Sound weapon LRAD
Public application: Long Range Acoustic Device (LRAD)
Cavitation, which affects gas nuclei in human tissue, and heating can result from exposure to ultrasound and can damage tissue and organs. Studies have found that exposure to high intensity ultrasound at frequencies from 700 kHz to 3.6 MHz can cause lung and intestinal damage in mice. Heart rate patterns following vibroacoustic stimulation have resulted in serious arterial flutter and bradycardia. Researchers have concluded that generating pain through the auditory system using high intensity sound risked permanent hearing damage.
Extra-aural (unrelated to hearing) bioeffects on various internal organs and the central nervous system included auditory shifts, vibrotactile sensitivity change, muscle contraction, cardiovascular function change, central nervous system effects, vestibular (inner ear) effects, and chest wall/lung tissue effects. Researchers found that low frequency sonar exposure could result in significant cavitations, hypothermia, and tissue shearing. Follow-on experiments were not recommended.
Noise-induced neurological disturbances in humans exposed to continuous low frequency tones for durations longer than 15 minutes involved development of immediate and long-term problems affecting brain tissue. The symptoms resembled those of individuals who had suffered minor head injuries.