One of the more
controversial theories in current cosmology is the existence (or not)
of what's been dubbed the “multiverse.” It posits that our known
universe (the one we live in and that originated from the Big Bang
some 13.8 billion years ago) is not the only one—that there are an
infinite number of universes, even though we are unable to detect
them. The fact that we are unable to demonstrate their existence is
why some cosmologists dislike the theory. A bedrock of the scientific
method is the requirement that theories are testable. We currently
cannot put the multiverse theory to the test—and we may never be
able to. That makes some scientists feel it really isn't science.
So why did such a
contentious hypothesis ever arise? It came about in part, because
cosmologists were wrestling with another conundrum, called the “fine
tuning” problem. I have written a blog on this topic before (“Fine
Tuned Just for Me?”, in January 2011). Briefly, this idea arose
when cosmologists realized some years ago that our universe's
physical properties include a couple dozen or so parameters whose
values must be exactly what they are; otherwise our universe
could not exist as it does. A few examples of these parameters: the
weight of an electron, the strength of gravity, the electrical charge
of subatomic particles, the speed of light, etc. Change any one of
these parameters by the slightest amount and our universe would never
have survived the Big Bang beginning.
Cosmologists are stumped
by the fine-tuning enigma—mostly because they have no idea why
these parameters are precisely what they are. Nothing in our
cosmological comprehension dictates what their numerical values must
be, so how did they get to be what they are? Theologians have
a ready answer: God set those parameters, when he created the
universe. To scientists that answer is quite unacceptable, because
(1) it's just another untestable proposition and (2) many scientists
are already convinced that God is a figment of human imagination.
As the British
astrophysicist Bernard Carr once quipped, “If you don't want a God,
you better have a multiverse.” Why? Because, if the concept of the
multiverse is true, it avoids the God hypothesis by creating an
infinite number of universes with an infinite number of values for
those physical parameters, and in just one of those infinite
number of universes the parameters will have exactly the
values that our does. This is us!
Thus, according to the
multiverse hypothesis, creation is a random process. Theologians hate
that idea. Some cosmologists may be uncomfortable with it, but to
them it beats believing in God. It's sort of like the
famous-but-ridiculous concept that if you have an infinite number of
monkeys, each with a typewriter, sooner or later one of them will
duplicate a Shakespearean play. It is conceptually possible, but not
very satisfying.
But the possibility of a
multiverse did not arise in some scientific minds solely from the
problem of fine tuning by avoiding God. There are a few other
cosmological theories that also point to a multiverse. Three of them
are (1) the many-worlds theory of quantum mechanics, (2) inflationary
cosmology, and (3) string theory. I will not take the time to delve
into these topics right here (I'm not sure I could!), but just want
to make mention of the fact that more than one cosmological
discipline has found itself pointing toward the multiverse as a
solution to their particular conundrum. In other words, the
multiverse theory did not arise solely due to some scientists'
antipathy toward the existence of God. In fact, a crucial reason why
the multiverse concept keeps hanging around—despite its inability
to be tested—is that it satisfies several cosmological puzzles, as
listed in the three theories above.
More on the multiverse
next time...
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