Cosmological Distance
A distance far beyond the boundaries of our Galaxy. When viewing objects at
cosmological distances, the curved nature of spacetime could become apparent.
Possible cosmological effects include time
dilation and redshift.
Distance measures are used in physical cosmology to give a
natural notion of the distance between
two objects or events in the universe. They
are often used to tie some observable quantity
(such as the luminosity of a distant quasar, the redshift of a distant galaxy, or the
angular size of the acoustic peaks in the CMB power spectrum) to another quantity that is
not directly observable, but is more convenient for
calculations (such as the comoving coordinates of the quasar, galaxy, etc.). The distance
measures discussed here all reduce to the naïve notion of Euclidean distance at low redshift.
In accord with our present
understanding of cosmology, these measures are calculated within the context of general relativity, where the Friedmann-Lemaitre-Robertson-Walker solution
is used to describe the universe.
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