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.
Read more about this topic: World Line
Famous quotes containing the words world, lines, tool, describe and/or events:
“My uncle Toby had scarce a heart to retalliate upon a fly.
Go,—says he, one day at dinner, to an over-grown one which had buzz’d about his nose ... go poor Devil, get thee gone, why should I hurt thee?—This world surely is wide enough to hold both thee and me.”
—Laurence Sterne (1713–1768)
“The opera isn’t over till the fat lady sings.”
—Anonymous.
A modern proverb along the lines of “don’t count your chickens before they’re hatched.” This form of words has no precise origin, though both Bartlett’s Familiar Quotations (16th ed., 1992)
“Is it not possible that an individual may be right and a government wrong? Are laws to be enforced simply because they were made? or declared by any number of men to be good, if they are not good? Is there any necessity for a man’s being a tool to perform a deed of which his better nature disapproves?”
—Henry David Thoreau (1817–1862)
“Cruelty is a mystery, and the waste of pain. But if we describe a word to compass these things, a world that is a long, brute game, then we bump against another mystery: the inrush of power and delight, the canary that sings on the skull.”
—Annie Dillard (b. 1945)
“It is clear to everyone that astronomy at all events compels the soul to look upwards, and draws it from the things of this world to the other.”
—Plato (c. 427–347 B.C.)