big Bang  Quick Reference  The hypothetical but widely accepted
‘explosive’ event that marked the origin of the universe as we
know it. At the time of the Big Bang, the entire universe was
squeezed into an infinitely small, hot, superdense state. The
Big Bang explosion threw this compact material outwards,
producing the expanding universe seen today (see redshift). The
cause of the Big Bang is unknown; observations of the current
rate of expansion of the universe suggest that it took place
about 13–14 billion years ago. The Big Bang theory began modern
cosmology.  According to a modified version of the Big Bang
theory, called the inflationary theory, the universe underwent a
rapid period of expansion shortly after the Big Bang, which
accounts for its current large size and uniform nature. The
inflationary theory is supported by the most recent observations
of cosmic background radiation.  Subjects: physics — astronomy
and cosmology.  Reference entries  See all related reference
entries in Oxford Index »