The Big Bang as Scientific Fact
Unlike some of the other contributors to this
volume, I have the luxury of dealing with a well defined topic for which a
great deal of hard data are available.
My charge is to argue why a reasonable person should accept the Big Bang
as proven scientific fact. In his recent book Before the Beginning,the British cosmologist Sir Martin Rees wrote that he was “fairly sure” of the
Big Bang - at the 90% level. Actually, I suspect that Martin was being a bit
coy, for in fact it is impossible to do any constructive research in cosmology
today without standing firmly on the Big Bang model. Most cosmologists, I
suspect - I among them - would side with the famous Russian cosmologist Jakob
Zeldovich, who said in 1982, “I am as sure of the Big Bang as I am that the
Earth goes around the Sun”.
My task is specifically to motivate and
defend the Big Bang model, but what exactly do I mean by the “Big Bang”? In what follows I take a narrow definition
of the Big Bang as a moment in the finite past at which our Universe had very
high density and (as explained later) a very high temperature. This claim is concrete, and the evidence for
it is overwhelming. In defining the Big
Bang so narrowly, I am deliberately sidestepping such broader questions as, did
the Universe begin with the Big Bang?
Did space and time begin with the Big Bang? What came before the Big
Bang? These and other harder questions will be the topic of later chapters in
this volume - I have the easy job of setting the stage.
Contributed by: Dr. Sandra Faber