In 1952, German physicist Winfried Otto Schumann theoretically predicted the electromagnetic resonance occurring in the cavity between Earth's surface and the ionosphere. In the 1960s, these predictions were experimentally confirmed. The fundamental frequency of 7.83 Hz is considered the natural heartbeat of our planet.
The ~100 km cavity between Earth's surface and the ionosphere acts like a massive waveguide. Lightning activity pumps energy into this cavity, creating EM waves that circle the Earth. Resonance occurs when the wavelength equals Earth's circumference.
Schumann resonance contains multiple harmonics: SR1=7.83 Hz (fundamental), SR2=14.3 Hz, SR3=20.8 Hz, SR4=27.3 Hz, SR5=33.8 Hz. Each harmonic reflects different ionospheric conditions. Modern measurements can detect 9-10 harmonics.
Today, Tomsk SOS, Greenland Array, Hawaii VLF, Antarctic Base, and 100+ other stations worldwide collect Schumann data. SRL Observatory combines this data in real time.
The connection between Schumann resonance and human physiology remains a research topic. The overlap of 7.83 Hz with human alpha brain waves raises the question: coincidence or evolutionary adaptation? New research may support the Magnetic Field Theory.