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Was There A
Beginning To
Time?
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Time
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Yes, there was a beginning to time. However, a cautionary note is
in order.
Although our psychological sense of past, present, and future is strong, time may not
be a fundamental physical entity at all. Rather, it may simply express the numerical order of
material changes.
For example, when your being moves from point 1 to
point 2, you don't exist at a later point in "time", only
in numerical order.
In this sense, the universe is timeless even though we use the word "spacetime"
to describe it. It isn't 3D in space and 1D in time, but
rather 4D in space.
"Time" certainly plays an important role in comparing durations and in
describing physical systems but it may relate only to how space
is quantum-networked and entangled, rather than describing something
apart from space.
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The Bang
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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 of the word but rather
the sudden appearance of expanding space. A duration
equal to about 13.82 billion Earth years has elapsed since.
"Big Bang" is a term
coined somewhat mockingly by Fred Hoyle, a 20th century English astronomer,
science fiction writer, and big-bang denier. In 1948, he 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
pseudo-sciences that suggest a creator.
But the challenge for Hoyle's theory was the observed expansion of our
universe over time, hardly a steady state. To explain the
expansion, which was confirmed in 1927 by Edwin Hubble, Hoyle postulated Mini-Bangs
in between the galaxies of our universe that keep the outward flow of matter
constant, like a steadily flowing river.
But Hoyle's job got more difficult in the early 1960s when sources of radio-frequency
electromagnetic radiation were found to be more prevalent in the early
(distant) universe than they are now, once again contradicting a steady-state universe. In 1963, quasars, which almost only occur in the distant past, were discovered.
Then, in 1965, the observation of the cosmic microwave background (CMB), a
radiation with no discernable source, pretty much killed the Steady State theory.
What's more, the Big Bang
theory had predicted just such a background radiation.
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Imaginary Time
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When physicists try to extrapolate back in time from the earliest
well-understood state of the universe (a miniscule fraction of a
second after the big bang), they quickly hit a gravitational (curvature) "singularity" where
classical laws break down: gravity, material density, and temperature
become infinite. And spatial dimensions shrink to zero.
To the rescue comes imaginary time, which treats time like a dimension of
space and successfully predicts quantum behavior.
The state of
the universe in real time can be calculated from its state in imaginary time.
Moreover, singularities like the big bang don't interrupt imaginary
time.
So, a beginning of real time doesn't
violate any physical laws, nor does it suggest a creator.
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The Point
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Steven Hawking has shown that the Big Bang could've started as an ordinary point on
the
3D
surface of our 4D spacetime, just like the North Pole is an ordinary point on
the
2D surface of our 3D planet.
The sudden expansion of the point and the rapid inflation
of the
universe would borrow energy from the intense gravitational field to create
matter. No physical laws would be violated and the gravitational debt
could be repaid at the end of
the universe.
In 1994, when a "Big Bang" renaming contest in Sky and Telescope
magazine failed to pick a winner, Fred Hoyle said of the Big Bang, "Words are like
harpoons
Once they go in, they're very hard to pull out."
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