Comoving Distance - Proper Distance Vs. Comoving Distance From Small Galaxies To Galaxy Clusters

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:

    But as these angels, the only halted ones
    among the many who passed and repassed,
    trod air as swimmers tread water, each gazing
    on the angelic wings of the other,
    the intelligence proper to great angels flew into their wings,
    the intelligence called intellectual love....
    Denise Levertov (b. 1923)

    Under all conditions well-organized violence seems to him the shortest distance between two points.
    Leon Trotsky (1879–1940)

    A certain degree of ceremony is a necessary outwork of manners, as well as of religion; it keeps the forward and petulant at a proper distance, and is a very small restraint to the sensible and to the well-bred part of the world.
    Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)

    Don’t you see what’s at stake here? The ultimate aim of all science—to 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 (1903–1963)

    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 (1591–1674)