Proper Distance Vs. Comoving Distance From Small Galaxies To Galaxy Clusters
Within small distances and short trips, the expansion of the universe during the trip can be ignored. This is because the travel time between any two points for a non-relativistic moving particle will just be the proper distance (i.e. the comoving distance measured using the scale factor of the universe at the time of the trip rather than the scale factor "now") between those points divided by the velocity of the particle. If the particle is moving at a relativistic velocity, the usual relativistic corrections for time dilation must be made.
Read more about this topic: Comoving Distance
Famous quotes containing the words proper, distance, small, galaxies, galaxy and/or clusters:
“The reputation of generosity is to be purchased pretty cheap; it does not depend so much upon a mans general expense, as it does upon his giving handsomely where it is proper to give at all. A man, for instance, who should give a servant four shillings, would pass for covetous, while he who gave him a crown, would be reckoned generous; so that the difference of those two opposite characters, turns upon one shilling.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (16941773)
“The distance between your place in the kitchen and Miss Vollards place in the dining room is considerable.”
—Blake Edwards (b. 1922)
“In the pink light
the small red sun goes rolling, rolling,
round and round and round at the same height
in perpetual sunset,”
—Elizabeth Bishop (19111979)
“Dont you see whats at stake here? The ultimate aim of all scienceto penetrate the unknown. Do you realize we know less about the earth we live on than about the stars and the galaxies of outer space? The greatest mystery is right here, right under our feet.”
—Walter Reisch (19031963)
“for it is not so much to know the self
as to know it as it is known
by galaxy and cedar cone,
as if birth had never found it
and death could never end it:”
—Archie Randolph Ammons (b. 1926)
“Where we such clusters had,
As made us nobly wild, not mad;
And yet each verse of thine
Outdid the meat, outdid the frolic wine.”
—Robert Herrick (15911674)