I asked my wife, the astrophysicist, that very question last night.
Here's what she told me:
The redshift of the cosmic microwave background is about z=1100, which
corresponds to about 100,000 years after the big bang.
(That's when all those photons stopped being strongly coupled to (and
in equilibrium with) matter.)
After that, according to the "current lore," clouds of gas could collapse
into galaxies, and stars could form within them. Now, a recent paper
was published showing CO absorbtion lines with a redshift of z=4.78.
(My wife still hasn't told me what age that redshift corresponds to; if
it turns out to be an interesting number, I'll let you know.)
You need stars to get carbon and oxygen.
But here's the point: if astronomers eventually find evidence of galaxies
and stars at too high a redshift, then there just won't have been enough
time for them to have formed via gravitational collapse. (It's not a
problem yet, but a redshift of 5 is getting uncomfortably close.
And improved telescopes allow one to look at ever longer distances (ever
higher redshifts).)
If the "red shift gap" between cosmic microwave background and the oldest
stars/galaxies gets too short, cosmologists will be in the situation of,
"We don't know how they formed. We THOUGHT we knew, but we were wrong, our
models can't fit the data." In that case, we'd be in that scientific
nether region of No Known Natural Mechanisms; which, as we've discussed
previously, leaves you with philosophical and religious reasons for
chosing between Unknown Natural Mechanism vs. Improbable Coincidence vs.
Supernatural Intervention.
---------
So, based purely on these redshift measurements, is anyone ready to
argue for supernatural galactic formation? Probably not --- at least,
not yet.
Now let's make things more interesting.
Most recent measurements of Hubble's constant are converging to numbers
between 65 and 80.
If you take a cosmological model with Omega (the mass density of the
universe (Omega = 1 is just enough to "close" the universe gravitationally))
plus Lamda (the "vacuum energy density," corresponding to Einstein's
infamous "cosmological constant")
Omega + Lamda = 1 ; 65 < Hubble's Constant < 80
gives the age of the universe at 9.3 +/- 1 billion years.
Omega + Lamda = 0 (or a small number) ; same Hubble's constant
gives the age of the universe at 14 +/- 1.5 billion years.
(The matter we can observe, directly or indirectly, gives a measured
Omega about equal to 0.1)
Here comes the fun part: if you use the standard (and fairly
well-established) methods (not based on redshifts) for dating
the oldest stars in globular clusters, their age is
14.6 +/- 1.7 billion years.
So, if you you were so inclined, you _could_ make a case, with this data,
that there just isn't enough time for natural processes to form
the earliest galaxies and stars. You _could_ make the case, with this data,
for supernatural formation.
Considering all the other challenges facing galatic formation
(no detailed empirical model, lack of observed intermediates,
uncertainty about mechanisms), we return to the two questions I asked
earlier:
Why isn't anyone making such an argument?
How would you reply if someone did?
Loren Haarsma