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:
“The mark of the man of the world is absence of pretension. He does not make a speech; he takes a low business-tone, avoids all brag, is nobody, dresses plainly, promises not at all, performs much, speaks in monosyllables, hugs his fact. He calls his employment by its lowest name, and so takes from evil tongues their sharpest weapon. His conversation clings to the weather and the news, yet he allows himself to be surprised into thought, and the unlocking of his learning and philosophy.”
—Ralph Waldo Emerson (1803–1882)
“I am so tired of taking to others
translating my life for the deaf, the blind,
the “I really want to know what your life is like without giving up any of my privileges
to live it” white women
the “I want to live my white life with Third World women’s style and keep my skin
class privileges” dykes”
—Lorraine Bethel, African American lesbian feminist poet. “What Chou Mean We, White Girl?” Lines 49-54 (1979)
“The first tool I step on
Turned into a weapon.”
—Robert Frost (1874–1963)
“In eloquence, the great triumphs of the art are when the orator is lifted above himself; when consciously he makes himself the mere tongue of the occasion and the hour, and says what cannot but be said. Hence the term abandonment, to describe the self-surrender of the orator.”
—Ralph Waldo Emerson (1803–1882)
“We have defined a story as a narrative of events arranged in their time-sequence. A plot is also a narrative of events, the emphasis falling on causality. “The king died and then the queen died” is a story. “The king died, and then the queen died of grief” is a plot. The time sequence is preserved, but the sense of causality overshadows it.”
—E.M. (Edward Morgan)