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:
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—Samuel Beckett (1906–1989)
“When the rose reigns, and locks with ointments shine,
Let rigid Cato read these lines of mine.”
—Robert Herrick (1591–1674)
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—Charles Horton Cooley (1864–1929)
“If you describe things as better than they are, you are considered to be a romantic; if you describe things as worse than they are, you will be called a realist; and if you describe things exactly as they are, you will be thought of as a satirist.”
—Quentin Crisp (b. 1908)
“Turn where we may, within, around, the voice of great events is proclaiming to us, Reform, that you may preserve!”
—Thomas Babington Macaulay (1800–1859)