Dear George Dishman:
"George Dishman" wrote in message
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"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox
wrote in message news:tfUHe.236624$Qo.33184@fed1read01...
Dear Tom Roberts:
"Tom Roberts" wrote in message
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N:dlzc D:aol T:com (dlzc) wrote:
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Tom, I am given to understand that the CMBR was
produced by an opaque "medium" (CMBRM).
Yes. In the early universe no atom could remain an atom
very long because the high temperature gave other particles
enough kinetic energy so a simple collision often/usually
would ionize the atom. So between a few seconds and
~300k years after the big bang the universe was filled with a
charged plasma consisting primarily of electrons
and protons. When the temperature had been reduced
enough so most collisions did not have enough K.E. to
ionize the atoms the electromagnetic attraction between
protons and electrons quickly caused them to form
hydrogen atoms. The charged plasma was essentially
opaque to all types of EM radiation (hence it was black),
but the hydrogen is transparent to most EM radiation.
So in a short time the radiation emitted by the plasma
could suddenly propagate over large distances. It is
remnants of this radiation we see as the CMBR.
But the CMBR is free of the absorption bands of
"cooler" hydrogen. Let's pretend a timeline, with
"CMBRM stops glowing" at 300,000 pBB (post-Big Bang). What
about this Universe filling, formerly
opticaly dense, hydrogen at 301,000 pBB? Does this
mean that it all coalesced to "structures" in
next-to-no-time?
No, it was still hot, though slightly cooler, and
still ubiquitous and pretty much homogenous but
instead of being a hot dense opaque plasma, it
was a hot dense transparent non-ionised gas. To
get a picture in your mind, watch this video of
the Landolt reaction and imagine it happening in
reverse:
http://video.uni-regensburg.de:8080/...lt_Reaction.rm
I don't have the applet required to play it. I found another
site that had it in Quicktime. Hydrogen absorbs light. We find
its signature everywhere we look, when we look at point sources.
But we don't find it with the CMBR. And it has been exposed
longer, assuming the Universe filling gas didn't coalesce.
At some point the CMBR had redshifted enough so it could
not be absorbed at all by hydrogen, and since then the
universe has been transparent to it (except for isolated
objects we call stars).
Let me ask a related question. The CMBRM has been
described as opaque and isothermal. Presumably "opaque"
could be defined as no emissions detectable from beyond a
certain place (watch my terms).
"a certain place" may give the wrong impression
although obviously we are "here".
We can't see beyond the CMBRM, so it is opaque. If we were on
the inside of an event horizon, we could not see beyond that
Universe's Big Bang, and see specular images of the container
Universe. The Big Bang (aka. the inside of an event horizon) is
opaque *without* invoking space-filling hydrogen plasma.
It is perhaps
better to consider opaque in this case in terms
of the mean free path of a photon being greater
than the time from emission to the time of
complete transparency multiplied by the speed of
light regardless of where the photon is emitted
since the CMBRM was almost homogenous throughout
the universe.
So let me ask this question about the Universe that contains
ours...
There is no "Universe that contains ours" in the
Big Bang model so it is not meaningful to ask the
question.
The Schwarzchild solution to GR for a black hole, describes
another Universe inside the black hole, with internal time
starting where external space leaves off. Since the Big Bang
model is commonly dressed in the clothes of GR, are you sure
'There is no "Universe that contains ours" in the Big Bang model
so it is not meaningful to ask the question'?
You say imagine the Landolt reaction in reverse... imagine that
our Big Bang is the inside of the event horizon of the (probably
really big) black hole that contains our Universe.
So sure are you?
David A. Smith