explainer wrote:

I am out of my universe in this thread (or string, whatever), but was
wondering if the proposal offered by Geoffrey and Margaret Burbidge in
the November Discover magazine is worth a comment as I remember what my
physics professor liked to remind us: "in science, the jury is always
out, no matter the evidence".

http://www.discover.com/issues/nov-05/features/two-against-the-big-bang/

I read the article, but my science background is inadequate to compare
their suggestion with the big bang theory.

Thanks and all the best, Gordon Hill

I don't have access to discover online so can't comment on
this article except to say that the tone of the initial
three paragraphs seems a bit sensationalist, even
polemical. I'm vaguely familiar with the quasi-steady state
theories that Burbidge and Burbidge propose. They are
essentially refinements of ideas developed together with
Hoyle and Narlikar in the early 1990's, which in turn are a
continuing effort to save Hoyle's old steady state
cosmology.

The authors make some modifications to general relativity in
the case of strong gravitational fields, which is perfectly
fine. We can't be sure that classical general relativity is
right in such limits. But I think that all of that is more
or less a side issue as I'll explain.

Both the Burbidges and Hoyle are very solid scientists with
high reputations, and all made very significant
contributions in the early days of cosmology.

Now: Hoyle's steady state cosmology was an expanding
cosmology, there had to be new galaxies continuously formed
in the spaces that were opened up by the expansion. The new
galaxies required new matter in order to be able to
form.

Hoyle proposed, extremely ingeniously in my own view, that
hydrogen atoms were continuously being created out of
nothing in intergalactic space, but at a very slow rate, so
slow that it couldn't possibly be directly observed here on
earth. Over time, the hydrogen supposedly built up, formed
clouds, collapsed and then ultimately formed new galaxies
and stars, and this process simply continued forever. Hence
the universe was made to be apparently eternal and in some
sense, basically unchanging, or rather always changing in
basically the same way, forever.

You should understand that at the same time, a major issue
for cosmology, already before world war II, since processes
such as nuclear fission had just been observed, was the
detailed explanation of the origin and relative abundances
of the chemical elements in the universe. New
understandings of nuclear physics were being developed in
the years leading up to the war, and during and immediately
after the war there was very rapid progress.

Hoyle and Fowler in particular developed the idea that all
of the elements had been produced inside stars. Their work
remains critically important and the mechanisms they
proposed still remain as the widely accepted explanations
for the origin of all of the heavier elements.

At around the same time Gamow and collaborators, eventually
including Alpher and Bethe, in approaching the same problem
of nucleosynthesis, chose to work instead within the
cosmologies of Friedmann and Lemaitre, in which the universe
was said to have expanded from an initially dense state,
beginning at a fixed time in the past. They were able to
explain the abundances of the lightest elements, predicted
that almost no elements heavier than mass 8 would have been
produced in the early universe, and certainly by 1948 had
made the prediction that there would be a detectable relic
microwave background radiation.

Of course, this still left open the question where the
heavier elements had come from. The leading proposal is that
they have all been produced in stars by the mechanisms of
Hoyle and collaborators, and then gradually dispersed into
the interstellar medium by supernova explosions,

An astronomer named Andrew McKellan had in fact already
indirectly detected, in about 1940, the microwave radiation,
by the observation of the rotational spectra of certain
diatomic molecules in space, and he had inferred its rough
temperature, but he did not relate this discovery to
cosmological models and his work appears to have been
unknown to the workers on the big bang approach to
nucleosynthesis.

Then in about 1965 the microwave background was _directly_
detected, and it turned out to have close to the temperature
predicted in 1948 by the workers on the big bang
cosmologies. Lately it has been shown also by observation
that the microwave background has an extremely good
blackbody or thermal spectrum, too, and it is also observed
to be extremely uniform in all directions in the sky.

Now, with all of that background having been given, one
central criticism of the steady state models remains that
there exists no natural explanation at all in such models
for why the universal abundances of the lightest elements,
namely hydrogen, helium-(3,4), deuterium and lithium-7 come
in particular numerical ratios, all of which ratios are in
fact directly predictable in the big bang models given only
that a single parameter, the ratio of the number of photons
to the number of baryons in the early universe, is adjusted
externally to be about 10^10.

In addition, and much more importantly, the steady state
models have to resort to mechanisms that are very hard to
believe in order to produce the extremely uniform and very
close to thermal spectrum of the cosmic microwave
background. The steady state models say that all of the
helium-4 in the universe (which constitutes about 1/4 of the
matter in the universe by mass), has been produced in stars
by burning from hydrogen to helium. The heat liberated by
that combustion is said somehow to have become thermalized
due to interactions with dust, or by interactions with tiny
fingers of iron produced in supernovae explosions, or take
your pick. The point is, that it's very hard to explain both
the very good thermal spectrum of the background radiation,
and the extremely uniform distribution across the sky,
whereas these features are much more naturally explained in
the hot big bang picture.

But there are, nevertheless, many open issues left unsolved in
cosmology, and the conversation continues.

At around the same time Gamow and collaborators, eventually
including Alpher and Bethe,