Photograph courtesy NASA/Brad Hansen (UCLA)/Harvey Richer
(UBC)/Steinn Sigurdsson (Penn State)/Ingrid Stairs (UBC)/Stephen
Thorsett (UCSC) The most popular theory of our universe's origin
centers on a cosmic cataclysm unmatched in all of history—the
big bang. This theory was born of the observation that other
galaxies are moving away from our own at great speed, in all
directions, as if they had all been propelled by an ancient
explosive force. Before the big bang, scientists believe, the
entire vastness of the observable universe, including all of its
matter and radiation, was compressed into a hot, dense mass just
a few millimeters across. This nearly incomprehensible state is
theorized to have existed for just a fraction of the first
second of time. Big bang proponents suggest that some 10 billion
to 20 billion years ago, a massive blast allowed all the
universe's known matter and energy—even space and time
themselves—to spring from some ancient and unknown type of
energy. The theory maintains that, in the