World Lines As A Tool To Describe Events
A one-dimensional line or curve can be represented by the coordinates as a function of one parameter. Each value of the parameter corresponds to a point in spacetime and varying the parameter traces out a line. So in mathematical terms a curve is defined by four coordinate functions (where usually denotes the time coordinate) depending on one parameter . A coordinate grid in spacetime is the set of curves one obtains if three out of four coordinate functions are set to a constant.
Sometimes, the term world line is loosely used for any curve in spacetime. This terminology causes confusions. More properly, a world line is a curve in spacetime which traces out the (time) history of a particle, observer or small object. One usually takes the proper time of an object or an observer as the curve parameter along the world line.
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Famous quotes containing the words world, lines, tool, describe and/or events:
“This world is half the devil’s and my own,
Daft with the drug that’s smoking in a girl....”
—Dylan Thomas (1914–1953)
“I need not tell you of the inadequacy of the American shipping marine on the Pacific Coast.... For this reason it seems to me that there is no subject to which Congress can better devote its attention in the coming session than the passage of a bill which shall encourage our merchant marine in such a way as to establish American lines directly between New York and the eastern ports and South American ports, and both our Pacific Coast ports and the Orient and the Philippines.”
—William Howard Taft (1857–1930)
“And if thou wilt make me an altar of stone, thou shalt not build it of hewn stone: for if thou lift up thy tool upon it, thou hast polluted it.”
—Bible: Hebrew Exodus 20:25.
“The greatest honor that can be paid to the work of art, on its pedestal of ritual display, is to describe it with sensory completeness. We need a science of description.... Criticism is ceremonial revivification.”
—Camille Paglia (b. 1947)
“The return of the asymmetrical Saturday was one of those small events that were interior, local, almost civic and which, in tranquil lives and closed societies, create a sort of national bond and become the favorite theme of conversation, of jokes and of stories exaggerated with pleasure: it would have been a ready- made seed for a legendary cycle, had any of us leanings toward the epic.”
—Marcel Proust (1871–1922)