Caption: Heinrich Hertz (1857--1894) discovered radio waves (a long wavelength form of electromagnetic radiation (EMR)), and thus invented radio, in 1887.

It is little known, but true, that Hertz also invented talk radio and country and western stations. Fact.

In Hertz's honor, the standard unit of frequency was named the hertz (Hz)---which is just an inverse second: i.e., 1 Hz = 1 (1/s). In older jargon, the hertz was the cycle per second = 1/s = hertz (Hz), but this unit name is now considered a bit obsolete. Common multiples of the hertz (Hz) are:

1. nanohertz (nHz) = 10**(-9) Hz ≅ 1 cycle per 30 years is used in low-frequency gravitational wave research (see Wikipedia: Pulstar timing array (PTA): Overview).
2. kilohertz (kHz) = 10**3 Hz.
3. megahertz (MHz) = 10**6 Hz.
4. gigahertz (GHz) = 10**9 Hz.
5. terahertz (THz) = 10**12 Hz.

See Heinrich Hertz videos below:

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