That being said, our real time began when our universe did, in an
inconceivably hot, dense, tiny spot just after the "Big Bang".
The bang wasn't an explosion in the usual sense but
rather the sudden
appearance of expanding space. Since then, a duration
comparable to about 13.82 billion earth
orbits has elapsed.
"Big Bang" is a term
coined by Fred Hoyle, a twentieth-century English astronomer,
science-fiction writer, and Big-Bang denier.
In 1948 Hoyle argued against a beginning of time, proposing instead a Steady State universe with infinite time. He
rejected both the Big Bang theory and the Book of Genesis as
pseudoscience, suggesting a creator.
But the challenge for Hoyle's theory was the expansion of our
universe over time, hardly a steady state, yet confirmed in 1927 by
Edwin Hubble. To explain the expansion, Hoyle postulated mini-bangs
of creation in between the galaxies, keeping the outward flow of matter
constant like a steadily flowing river.
But Hoyle's job got more difficult in the early 1960s
when radio sources were found to be more prevalent in the earlier
(farther away) universe than
in the more recent universe. In 1963, quasars were discovered but only in the distant past, creating more problems for
the Steady State folks.
In 1965, the observation of the cosmic microwave background (CMB), a radiation
with no discernable source, pretty
much killed the steady state theory. By contrast, the big bang theory had
predicted just such a background radiation.