The Quark-Lepton era begins at 10-32 seconds after the Big
Bang sintgularity (i.e. 1/100,000,000,000,000,000,000,000,000,000,000th
of a second, for thos ewho like a lot of zeros). The temperature has cooled
to 1015 degrees Kelvin (1,000,000,000,000,000 degrees).
At this time there are only three fundamental forces, gravity, the strong
nuclear force, and the electro-weak force.
However the universe was still expanding and hence cooling. By the time a one millionth of a second had passed since the original singularity, the universe was about the same diameter as the Solar System is now (only it was a 4 dimensional hypersphere rather than a sphere such as we can comprehend). The temperature had dropped to 1,000,000,000,000 degrees Kelvin. It was no longer hot enough to maintain the creation and annihilation of quark-anti-quark pairs and so quarks freeze out of the universe. From this moment on they could only occur as pairs or triplets, never alone.
At this time the universe has a baryon-antibaryon asymmetry which results from post-inflationary violating processes, explained in terms of of decay a hypothetical X-boson resulting from an asymmetry in the electro-weak force. This means that for every 109 (i.e. every billion) antiparticles craeted, one buillion and one particles are formed.
As the energy drops further the heavy particles known as baryons (protons
and neutrons) freeze out. The energy density is no longer sufficient
to create and maintain protons. There is a tremendous annihilation
as the matter and anti-matter protons and neutrons destroy each other.
The 109 particle/antiparticle pairs annililate, leaving one
billion photons for every proton in the universe. Due to the fortunate
(for us) asymmetry in the ratio of baryons to antibaryons one in one billion
baryons survive (not having an anti-matter partner to annihilate with).
If not for this there would be no matter in the universe now, and we wouldn't
At one second after the Big Bang, the universe has a radius of about 4 light-years (about the distance from here to the nearest star outside our solar system) and a temperature of around 1,200,000,000 degrees. There is no longer enough heat to maintain the creation pairs of the electrons and positrons (the electron's antiparticle). So they are frozen out, just as the baryons were, and like the baryons then proceed annihilate each other, only one out of every billion electrons surviving, and the electron era camme toi an end.
The neutrinos meanwhile had lost enough energy so that they pretty much stopped reacting with the other particles of matter. They became the ghostly particles tehy are now, wizzing aroudn the universe, passing through planets and stars as if they were not there.
The freezing out of the neutrinos ended the ability of neutrons and
protons to turn into each other through reactions with the electrons, positrons and neutrinos. The result is that there were 6 protons for every neutron. Further radioactive decay oiver teh next
three minutes (when the Radiation Era began)
meant that further neutrons would turn into protons, electron and antineutrinos.
Quark Soup - The Elementary Particle Era
Big Bang page
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