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Tuesday, 24 November 2009 02:11 |
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As the Universe cools a weak asymmetry in the direction towards
matter becomes evident. Matter that is massive is unstable,
particularly at the high temperature in the early Universe. Low mass
matter is stable, but susceptible to destruction by high  energy
radiation ( photons).
- as the Universe expands and cools, matter begins to dominate over radiation
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As the volume of the Universe increases, the lifetime of stable
matter (its time between collisions with photons) increases. This
also means that the time available for matter to interact with matter
also increases. |
- even during these early times, entropy controls the progression of the structure of the Universe
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The Universe evolves from a pure, energy dominated domain to a more
disordered, matter dominated domain, i.e. entropy marches on. |
- baryon production ends the matter production phase, however, matter and anti-matter should be made in equal
amounts
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The last two stages of matter construction is the combining of three
quark groups into baryons (protons and neutrons), then the collection of
electrons by proton/neutron atomic nuclei to form atoms. The
construction of baryons is called baryongenesis.
Baryongenesis begins around 1 second after the Big Bang. The equilibrium
process at work is the balance between the strong force binding quarks
into protons and neutrons versus the splitting of quark pairs into new
quark pairs. When the temperature of the Universe drops to the point
that there is not enough energy to form new quarks, the current quarks
are able to link into stable triplets. |
- note that anti-matter is rare today, so where did it all go?
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As all the anti-particles annihilate by colliding with their matter
counterparts leaving the remaining particles in the Universe to be
photons, electrons, protons and neutrons. All quark pairs have reformed
into baryons (protons and neutrons). Today, only around exotic objects like
black holes, do we find any anti-matter, anti-mesons (quark pairs) or any of
the other strange matter that was once found throughout the early
Universe. |
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