# deceleration parameter

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## deceleration parameter

(dee-sel-ĕ-ray -shŏn) Symbol: q 0. The rate at which the expansion of the Universe changes with time as a result of self-gravitation. It is dimensionless and can be given in terms of the cosmic scale factor, R:
q 0 = –R (d2R /dt 2)/(dR /dt )2

Values of q 0 less than 0.5 are associated with an ever-expanding open Universe; values exceeding 0.5 imply that the Universe is closed and will collapse at a finite time in the future. If q 0 is equal to 0.5 then the Universe is infinite and space is Euclidean. See also mean density of matter; Universe.

References in periodicals archive ?
obtained the deceleration parameter of the present universe to be [q.
To quantitatively see how the mass M(t) varies with time and depends on the deceleration parameter q, we plot in Fig.
Another very important quantity in cosmology is the deceleration parameter q, which is given by:
Solving (24) for the deceleration parameter of the universe we obtain
Next, in a flat universe filled with nonrelativistic matter, that is, p = 0, corrected for the graviton contribution, we have that the deceleration parameter given by [37]
For best performance, the assumed deceleration parameter of the algorithm must be less than or equal to that of the driver and the assumed reaction time must be greater than or equal to that of the driver.
0] (the cosmic expansion rate), and the deceleration parameter, [q.
One of these numbers is the deceleration parameter, [q.
t), and the deceleration parameter (t) are plotted in Figures (1-5).
0]), and the change in that rate with time (described by the deceleration parameter, or [q.
One approach involves studying the slowing down of galaxies' outrushing motions, a measure of which is the so-called deceleration parameter, |q.
Farmington Hills, MI) looks at the rate of brake application, compares it to a set of deceleration parameters, and increases brake pressure to meet requirements.

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