Waves: same object, a thousand disguises
Waves, in physics, are one of the most transversal concepts there is. The same mathematical apparatus — propagation speed, wavelength, frequency, the superposition principle, reflection, refraction, diffraction, the Doppler effect — describes phenomena of such different nature that at first sight they would not seem related: the plucking of a guitar string, the propagation of sound through air, the seismic waves that cross the Earth, the light arriving from the Sun, the radio waves that carry a mobile phone signal, the gravitational waves detected by LIGO. What they have in common is not the nature of the medium (in some cases there is not even a medium!) but the mathematical form of the phenomenon: a disturbance that propagates while preserving its identity. This is one of the most elegant examples of how physics, once it has understood a language, applies it to entirely new contexts: the study of sound carried out by Helmholtz in the nineteenth century paved the way for that of radio in the twentieth century and for that of quantum signals in our own century. Learning waves well is, in a sense, learning a universal dialect of physics (Battimelli and Stilli 1999; Feynman, Leighton and Sands 1963).
Collegamenti
Argomenti: Waves
Esercizi collegati: Worked exercise — The cyclist and the acoustic mirror · Problem — Ultrasound wavelength in an ultrasound scan · Problem — Doppler radar and the car’s speed