[Physics] Physics Digest, Vol 1, Issue 13

[Ilja Schmelzer]

> Taking into consideration the Big Bang event, which presumably produced at first only
> "energy",? then under what conditions did energy condense into the known particles?

One should know what is the real mainstream position about this:  We
have GR, a classical theory, and using this theory leads to a
singularity at the Big Bang. The density would become infinite. This
does not mean that there really is some singularity.  It only means
that GR reaches its domain of applicability near the Big Bang
singularity and should be replaced, in some future, by a yet unknown
better theory.

The first candidate for this better theory would be quantum gravity.

Inflation theory, in its standard form, does not change this.  For
some common misrepresentations of inflation, see
http://ilja-schmelzer.de/relativity/inflation.php  The standard
inflation theory is based, essentially, on some change of state of
matter, thus, before this change we have yet a similar universe full
with some (even if other) matter, thus, giving a singularity.  Thus,
essentially invalid.

So, the singularity itself is not a prediction of the actual
mainstream.  The mainstream waits for some theory of quantum gravity
to tell something about the region near the singularity.

What is named Big Bang in Standard Model of Cosmology is a dense state
after the singularity. Very dense in comparison with the universe
around us now,  roughly the density where we can make some reasonable
physics now - say, neutron start density.   May be higher - it depends
on how much one trusts the Standard Model of particle physics being
able to make reasonable predictions.