from PART II - PHYSICAL APPLICATIONS
Published online by Cambridge University Press: 05 July 2013
The miracle of the appropriateness of the language of mathematics to the formulation of the laws of physics is a wonderful gift which we neither understand nor deserve. We should be grateful for it and hope that it will remain valid in future research and that it will extend, for better or worse, to our pleasure, even though perhaps also to our bafflement, to wide branches of learning.
(Eugene Wigner)Electromagnetic wave radiation is remarkable for two reasons: 1) it spans a vast spectrum of wavelengths providing for a wide range of physics and applications, and 2) it does not require a medium within which to travel. While all electromagnetic waves travel at the speed of light if traveling through a vacuum, they span ten orders of magnitude in wavelength, essentially corresponding to the full range of sizes that exist in the universe. Amazingly, the governing equations of electromagnetic waves, which do not require a medium, and physical waves, which do, are essentially the same. Rather than a guitar string or gas molecules, however, electromagnetic waves travel via massless photons. While the photons do not have mass, they do carry energy; it is this energy that determines their wavelength. A photon's energy is directly proportional to its frequency (and inversely proportional to the wavelength).
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