ETYM Greek kosmos the world + -logy: cf. French cosmologie.
1. The branch of astrophysics that studies the origins and structure of the universe; SYN. cosmogony.
2. The metaphysical study of the origin and nature of the universe.
The study of the history of the universe.
Branch of science or philosophy dealing with the origin and structure of the universe.
Branch of astronomy that deals with the structure and evolution of the universe as an ordered whole. Its method is to construct “model universes” mathematically and compare their large-scale properties with those of the observed universe.
Modern cosmology began in the 1920s with the discovery that the universe is expanding, which suggested that it began in an explosion, the Big Bang. An alternative—now discarded—view, the steady-state theory, claimed that the universe has no origin, but is expanding because new matter is being continually created.
There are a number of differences in the conclusions that can be drawn from the steady-state and Big Bang theories. For example, the number of galaxies per unit volume should not change with distance if the steady-state theory is correct, but should increase with distance if an evolutionary theory is correct for in looking over a distance we are also looking back in time with the universe gradually getting more compact. The latest counts of faint radio sources do seem to indicate an increase in the number per unit volume with distance; they support an evolutionary model. Again the mixture of old and new galaxies should be the same at both small and large distances according to the steady-state theory but the proportion of young objects should increase with distance for the evolutionary theories. Although the nature of quasars are not yet understood they do appear to be young objects, and they are found only with large red shifts (meaning far back in time), so their very existence seems to disprove the steady-.
State theory. Another piece of evidence for the Big Bang theory is the 2.7 K isotropic radiation, which was first observed in 1965 and can be interpreted as that predicted as a necessary consequence of the Big Bang. If this identification is accepted, the present temperature can be used to calculate what that of the primeval atom must have been in the early stages of its expansion, and thus predict what the initial ratio of hydrogen to helium should have been, a prediction that turns out to be quite consistent with observation.
Finally, as far as present observational data is concerned, there is no indication that the rate of expansion is in any way slowing down, and thus no evidence to support the oscillating models of the universe that had sometimes been suggested when it was conceived as possible that the rate of expansion of the universe could not only be slowed down but actually reversed. + prikaži više