[7]Primitive as early radios were by today’s standards, they brought a new era to communication at the time. Unmodulated CW (continuous wave) transmissions and crystal receivers were used to summon rescuers in the Titanic disaster of 1912, for example.
[8]Energy = h (Planck’s constant) × frequency. Planck’s constant is the energy of 1 quantum of radiation, and equals 6.62556 × 10⁻²⁷ erg-sec.
[9]Each photon carries 1 quantum of radiation energy, which is a unit equal to the product of the radiation frequency and Planck’s constant (see footnote [page 15]).
[10]Einstein was awarded the Nobel Prize in 1921 for his 1905 explanation of the photoelectric effect (in terms of quanta of energy) and not for his relativity theory.
[11]Einstein’s theoretical explanation applies in the case of stimulation of a single atom. In practical stimulation, directionality is enhanced by stimulating many atoms in phase.
[12]An atomic clock is a device that uses the extremely fast vibrations of molecules or atomic nuclei to measure time. These vibrations remain constant with time, consequently short intervals can be measured with much higher precision than by mechanical or electrical clocks.
[13]The 1966 Nobel Prize in Physics was awarded to Prof. Alfred Kastler of the University of Paris for his research on optical pumping and studies on the energy levels of atoms.
[14]See Accelerators, a companion booklet in this series, for a full account of the Stanford “Atom Smasher”.
[15]For descriptions of fission and fusion processes, see Controlled Nuclear Fusion, Nuclear Reactors, and Nuclear Power Plants, other booklets in this series.
[16]A bit is a digit, or unit of information, in the binary (base-of-two) system used in electronic data transmission systems.