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 world is a fine place. The only thing wrong with it is us. How little justice and humility there is in us, how poorly we understand patriotism!”
—Anton Pavlovich Chekhov (1860–1904)
“Child of Light! thy limbs are burning
Through the vest which seems to hide them;
As the radiant lines of morning
Through the clouds ere they divide them;
And this atmosphere divinest
Shrouds thee wheresoe’er thou shinest.”
—Percy Bysshe Shelley (1792–1822)
“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)
“Living in cities is an art, and we need the vocabulary of art, of style, to describe the peculiar relationship between man and material that exists in the continual creative play of urban living. The city as we imagine it, then, soft city of illusion, myth, aspiration, and nightmare, is as real, maybe more real, than the hard city one can locate on maps in statistics, in monographs on urban sociology and demography and architecture.”
—Jonathan Raban (b. 1942)
“This is certainly not the place for a discourse about what festivals are for. Discussions on this theme were plentiful during that phase of preparation and on the whole were fruitless. My experience is that discussion is fruitless. What sets forth and demonstrates is the sight of events in action, is living through these events and understanding them.”
—Doris Lessing (b. 1919)