In article ,
Nicolaas Vroom writes:

On Wednesday, 25 October 2017 23:34:51 UTC+2, Richard D. Saam wrote:
On 10/25/17 1:06 AM, Phillip Helbig (undress to reply) wrote:

"Dark matter" that we just doesn't seem able to see easily. But not
anything exotic. Just that: normal matter.

There are many arguments against this hypothesis, the main ones being
big-bang nucleosynthesis and CMB observations, which both agree that
most of the "missing matter" (i.e. "dark matter" as the term is normally
used) cannot be baryonic.

With what certainty should the 'cannot be' assertion be made. In
science, such absolute assertions are very rare. Current big-bang
nucleosynthesis calculations and CMB observation dark matter
correlations should not exclude a complementary dark matter contribution
by some other mechanism.

The whole issue is not dark matter because what is the definition?
The issue is the relation between baryonic versus nonbaryonic matter
in the universe and in our galaxy.

Right.

The Book the Big Bang by Joseph Silk defines the following events:
1) Big Bang
2) Particle Creation
3) Annihilation of proton-antiproton pairs
4) Annihilation of electron-positron pairs
5) Nucleosynthesis of helium and deuterium
6) (1 week) Radiation thermalizes prior to this epoch
7) (10 Years) Universe becomes matter dominated.
8) (300000 Y) Universe becomes transparant
9) (1-2 bil Y) Galaxy formation begins

My question is what is the percentage of baryonic matter in each
and which particular processes caused these changes. (roughly)

After 3) and 4) the ratio is fixed. (Strictly speaking electrons are
not baryonic matter, but they are known matter and in any case, with
equal numbers of protons and electrons, the mass of electrons is
negligible.)

Suppose that all nonbaryonic matter in the universe (in outer space and
in our Galaxy Halo) are neutrino's

Doesn't seem to be possible, because neutrinos can't be heavy enough to
be cold dark matter, and warm dark matter is ruled out by structure
formation.

when and how did they form?

Like all the other particles. (Some neutrinos formed later, in
nucleosynthesis and so on, but, like photons, by far the most are from
the cosmic background.)

See also: https://arxiv.org/abs/1505.01076
"Big Bang Nucleosynthesis: 2015"
In this article the word nonbaryonic is not mentioned.

Non-baryonic matter is not really relevant for nucleosynthesis.

The word dark matter is mentioned at the pages 3 and 16.

These days, in a cosmological context, "dark matter" means
"non-luminous, transparent, non-baryonic matter apart from neutrinos".

https://en.wikipedia.org/wiki/Big_Ba...esis#Deuterium
"This explanation is also consistent with calculations that show
that a universe made mostly of protons and neutrons would be far
more clumpy than is observed.[8]"

Right.

This raises the question how important is nonbaryonic matter
for the evolution of the Universe?

Very. Without dark matter, the fluctuations observed in the CMB would
not have had time to form the structure we see today. Although the book
is mainly about MOND, Bob Sanders's book DECONSTRUCTING COSMOLOGY gives
a good, unbiased overview of standard structure formation. (Bob is a
MOND enthusiast, but the evidence for MOND comes from galaxy-scale
physics. Even he admits that structure formation without the standard
dark-matter scenario doesn't seem to work.) Also, since most of the
matter is non-baryonic, without it the universe would not be nearly
flat (assuming that everything else stays the same).