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:
“Men should be saying “I want to become a woman.” The world would be a far better place if more men wanted to become women, than women wanted to become men.”
—Albert Halsey (b. 1923)
“[Children] do not yet lie to themselves and therefore have not entered upon that important tacit agreement which marks admission into the adult world, to wit, that I will respect your lies if you will agree to let mine alone. That unwritten contract is one of the clear dividing lines between the world of childhood and the world of adulthood.”
—Leontine Young (20th century)
“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)
“Write about winter in the summer. Describe Norway as Ibsen did, from a desk in Italy; describe Dublin as James Joyce did, from a desk in Paris. Willa Cather wrote her prairie novels in New York City; Mark Twain wrote Huckleberry Finn in Hartford, Connecticut. Recently, scholars learned that Walt Whitman rarely left his room.”
—Annie Dillard (b. 1945)
“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)