Inflationary cosmology is a different matter.
Inflation theory solves a few problems in non-inflationary cosmology.
Three "problems" in particular are: (1) The scarcity of magnetic
monopoles in the observable universe. (2) The "flatness" of the
observable universe. Inflation predicts that the mass density of the
universe ("omega") plus the cosmological constant ("lambda") should be
very close to 1. (Non-inflationary big-bang cosmology does not set such
tight limits.) Current observations set omega + lambda between roughly
0.3 and 2. (Recent supernova observations may have measured omega
and lambda even more precisely.) (3) The cosmic microwave background is
very nearly in thermal equilibrium everywhere we observe --- including
parts of the sky which should be "causally disconnected" from each
other. In non-inflationary big-bang cosmology, we know of no particular
reason why different parts of the universe which never had a chance to
interact with each other should be a the same temperature; the observed
thermal equilibrium is expected in inflation theory.
Because of how inflation solves these problems, I think most physicists
give inflation theory -- although it is still speculative -- a fair bit
of credence.
A prediction of inflation theory is the "many different universes." As
I understand it, it happens like this: Right after the big bang, the
"four basic forces" (gravity, electromagnetism, strong and weak nuclear
forces) operate as a single, unified force described by what is often
called the "theory of everything" (TOE). As the universe cools, gravity
uncouples from the other three forces, which are now described by the
"Grand Unified Theory." (Particle theorists are, of course, working
very hard on figuring out the GUT.) As the universe cools further, the
mathematical symmetries which GUTs have at higher energies break down.
The strong nuclear force uncouples from the weak nuclear force and
electromagnetism. The exact details of this "symmetry breaking" are not
understood because we don't yet know the details of the GUT, but it is
known that those symmetry-breaking details set the values of many
"fundamental constants" in physics: particle masses, coupling strengths
of the forces, etc.
The "inflationary epoch" is thought to happen after the TOE separates
into gravity + GUT, but before the spontaneous symmetry breaking of GUT
into strong force + electro-weak force. If inflation theory is true,
space expands (and matter cools) exponentially fast during the
inflationary epoch. The "spontaneously symmetry breaking" happens at
slightly different times in different regions of space. Each region
becomes its own "island universe," each much larger than our observable
universe. Since the symmetry-breaking happened differently in each
"universe," each could have somewhat different strong-force, weak-force,
and electromagnetic coupling constants, particle masses, etc.
What does this have to do with apologetics? If inflation theory is
true, it may have some impact on the "fine tuning" argument. It is
known that many of the "fundamental constants" of physics fall into very
narrow ranges which make life possible. If inflation theory is true,
then there could be a very great many different universes, each with its
own set of fundamental constants.
But how different could they be? That is unknown. All "universes"
which came out of inflation would have the same TOE (theory of
everything) and the same GUTs. Since we don't yet know what the correct
GUT is, we don't know how much variability there could be in the
"fundamental constants" set by symmetry breaking. Even supposing that
inflation *would* produce a huge number of universes with a great
variety of fundamental constants -- some of them "naturally" falling
into ranges suitable for life -- it still begs two important questions:
(1) How "finely-tuned" is the GUT and the TOE? and (2) Why should they
exist at all? I wouldn't dare predict an answer to the first question.
Whether inflation theory is true or not, we can praise the Creator for
an amazing creation. As for using "fine tuning" for apologetics, it
would seem that wise use is cautious use.
(Many thanks to my wife, Deborah Haarsma, for explaining inflationary
cosmology to me. Again.)
Loren Haarsma
----------
Deborah adds:
> Book on inflation:
>
> Alan H. Guth
> "The Inflationary Universe: The Quest for a New Theory of Cosmic
> Origins"
>
> I read a good review of it. Should be up to date, and straight from
> the source.
>
> This is Addison-Wesley's page for it:
> http://www2.awl.com/gb/authors/guth/inflationary.html