A → cosmological model according to which
the → Universe has no beginning and no end and maintains the same
mean density, in spite of its observed expansion, by the continual
creation of matter throughout all space.
The theory was first put forward by Sir James Jeans in about 1920 and
again in revised form in 1948 by Hermann Bondi and Thomas Gold. It was
further developed by Sir Fred Hoyle to deal with problems that had
arisen in connection with the alternative → Big Bang model.
Observations since the 1950s have produced much evidence
contradictory to the steady state theory and supportive of the
Big Bang model. More specifically, the steady state theory attributed the
→ cosmic microwave background to
→ thermal radiation
from → dust clouds, but this cannot account for a single
→ blackbody spectrum. Moreover, the steady state theory
lacked a plausible mechanism for the creation of matter in space.
See also → perfect cosmological principle.
See also: → steady; → state;
→ theory.
