(ed.). Gravitational waves (IOP, 2001)(422s).

Chapter 1Gravitational waves, theory and experiment(an overview)Ignazio Ciufolini 1 and Vittorio Gorini 21 Dipartimento di Ingegneria dell’Innovazione, University ofLecce, ItalyE-mail: ciufoli@nero.ing.uniroma1.it2 Department of Chemical, Mathematical and Physical SciencesUniversity of Insubria at Como, ItalyE-mail: gorini@fis.unico.itGeneral relativity and electrodynamics display profound similarities and yetfundamental differences [1, 2]. In this connection, it may be interesting to pointout some historical analogies between the two fields.The enormous success of Maxwell’s equations did not rest only in thefact that they incorporated, together with the Lorentz force equation, all thelaws of electricity and magnetism, but also that on their basis James ClerkMaxwell (1831–1879) was able (in 1873) to predict the existence of a solutionconsisting of electric and magnetic fields changing in time, carrying energy andpropagating with speed c in vacuum: the electromagnetic waves. Nevertheless,some distinguished physicists, such as Lord Kelvin, had serious doubts about theexistence of such waves: ‘The so-called “electromagnetic theory of light” has nothelped us hitherto . . . it seems to me that it is rather a backward step . . . the onething about it that seems intelligible to me, I do not think is admissible . . . thatthere should be an electric displacement perpendicular to the line of propagation’.However, in 1887, eight years after Maxwell’s death, electromagnetic waveswere both generated and detected by Heinrich Hertz (1857–1894); then, in 1901,Guglielmo Marconi transmitted and received signals across the Atlantic Ocean.In the twentieth century the detection and study of electromagnetic waves,other than visible light, opened a new era of dramatic changes in the knowledge ofour universe: cosmic radio waves, discovered in the 1930s, revealed in subsequent1