Glossary
The Steady-State Theory

The Steady-state theory is based on an extension of the Cosmological Principle such that
  • On a large scale, the universe is both homogeneous and isotropic (in 3-D space AND TIME), and has/will always be so.
To keep the mean density of the universe constant in the light of the (local) expansion requires the continuous creation of matter
  • at a rate of about one hydrogen atom per 6 cubic-km per year
Note that (to at least some), the continuous creation of matter is not really any more strange than (say) the creation of the whole universe in an instant (eg. in a Big Bang).

Since the CMB (detected in 1965), does seem to support an early, hot phase of the universe, the Hot Big Bang model gained support among most cosmologists at the expense of the Steady-state Theory.

Origins

1948 -- Hermann Bondi, Thomas Gold and Fred Hoyle. Several modifications were made in the 1950s.

Attractions

  • Avoids (metaphysical) questions like what happened before the Big Bang ?

Problems