Application
Perhaps surprisingly - electromagnetic fields and forces acting on charges depend on their history, not their mutual separation. The calculation of the electromagnetic fields at a present time includes integrals of charge density ρ(r', tr) and current density J(r', tr) using the retarded times and source positions. The quantity is prominent in electrodynamics, electromagnetic radiation theory, and in Wheeler-Feynman absorber theory, since the history of the charge distribution affects the fields at later times.
Read more about this topic: Retarded Time
Famous quotes containing the word application:
“It is known that Whistler when asked how long it took him to paint one of his “nocturnes” answered: “All of my life.” With the same rigor he could have said that all of the centuries that preceded the moment when he painted were necessary. From that correct application of the law of causality it follows that the slightest event presupposes the inconceivable universe and, conversely, that the universe needs even the slightest of events.”
—Jorge Luis Borges (1899–1986)
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—Thomas Henry Huxley (1825–95)