What is your model as to the evolution of the universe, Sci?
Ah, good, an easy question, one much easier than a final exam that asks one to write the complete history of the Popes, on the spot.
Big Bang researchers suggest ‘symmetry’ as a basis for the universe, and we might note that a lack of anything has perfect symmetry. If the universe encompasses everything (time, space, and matter), nothing exists outside of it and therefore nothing existed before it, leading to a total baryonic number of zero. So, anyway, this symmetry has all of the forces being equal, with everything so hot and dense that matter cannot even form yet, nor spacetime, or at least it was the same everywhere, although twisted and convoluted—nor any separation yet; it was pure symmetry.
Obviously the symmetry was broken, making for less ‘order’ and more chaos, the tendency being for ‘entropy’ to march on. Spacetime arrives when what is called ‘supergravity’ separates into the combined nuclear forces (strong, weak, electromagnetic) and gravitation. Matter makes its first appearance during this era as just a composite form, called Grand Unified Theory or GUT matter. GUT matter is a combination of what will become leptons, quarks, and photons. In other words, it contains all the superpositions of future normal matter. But, during the GUT era, it is too hot and violent for matter to survive in the form of leptons and quarks.
Even though the baryon number is extremely small (10^-10), why isn’t it zero? In Nature, there are only three natural numbers, 0, 1 and infinity. All other numbers require explanation. What caused the asymmetry of even one extra matter particle for every 10 billion matter/anti-matter pairs?
One answer is that the asymmetry occurs because the universe is out of equilibrium. This is clearly true because the universe is expanding, and a dynamic thing is out of equilibrium, for only static things are stable. There are particular points in the history of the universe when the system is way out of equilibrium, and those the symmetry breaking moments. And Noether’s conservation derivations, such as from time-translation, may lose their kilter if time alters from its point-of view invariance.
Notice also that during the inflation era, any asymmetries in the microscopic world would be magnified into the macroscopic world. One such quantum asymmetry is CP violation As the Universe expands and cools the process of creation and annihilation of matter/anti-matter pairs slows down. Soon matter and anti-matter has time to undergo other nuclear processes, such as nuclear decay. Many exotic particles, massive bosons or mesons, can undergo decay into smaller particles. If the universe is out of equilibrium, then the decay process, fixed by the emergent laws of nature, can become out of balance if there exists some asymmetry in the rules of particle interactions. This would result in the production of extra matter particles, rather than equal numbers of matter and anti-matter, and we have one in 10 billion, for we know the photon count.
In the quantum world, there are large numbers of symmetric relationships. For example, there is the symmetry between matter and anti-matter. For every matter particle, there is a corresponding anti-matter particle of opposite charge. In the 1960's, it was found that some types of particles did not conserve left or right-handedness during their decay into other particles. This property, called parity was found to be broken in a small number of interactions at the same time the charge symmetry was also broken and became known as CP violation.
The symmetry is restored when particle interactions are considered under the global CPT rule (charge - parity - time reversal), which states that that a particle and its anti-particle may be different, but will behave the same in a mirror-reflected, time-reversed study. During the inflation era, the rapid expansion of spacetime would have thrown the T in CPT symmetry out of balance, and the CP violation would have produced a small asymmetry in the baryon number. This is another example of how quantum effects can be magnified to produce large consequences in the macroscopic world. CP violation, by itself, is not sufficient to resolve the matter/anti-matter asymmetry. However, it is an example of what may be a class of reactions that produce more matter than anti-matter. The sum of these reactions explains the baryon number.
The discovery of the cosmic microwave background (CMB) confirmed the explosive nature to the origin of our Universe. For every matter particle in the universe there are 10 billion more photons. This is the baryon number that reflects the asymmetry between matter and anti-matter in the early universe.
Looking around the Universe its obvious that there is a great deal of matter. By the same token, there are even many, many more photons from the initial annihilation of matter and anti-matter.
Most of the photons that you see with your naked eye at night come from the centers of stars. Photons created by nuclear fusion at the cores of stars then scatter their way out from a star’s center to its surface, to shine in the night sky. But these photons only make up a very small fraction of the total number of photons in the Universe. Most photons in the Universe are cosmic background radiation, invisible to the eye.
Cosmic background photons have their origin at the matter/anti-matter annihilation era and, thus, were formed as gamma-rays. But, since then, they have found themselves scattering off particles during the radiation era. At recombination, these cosmic background photons escaped from the interaction with matter to travel freely through the Universe.
As the Universe continued to expanded over the last 14 billion years, these cosmic background photons also ‘expanded’, meaning their wavelengths increased. The original gamma-ray energies of cosmic background photons has since cooled to microwave wavelengths. Thus, this microwave radiation that we see today is an ‘echo’ of the Big Bang.
During inflation, the virtual particles of the pairs appearing got separated so quickly that they couldn’t annihilate, and so they went to be rather enduring.
In sum, and in importance, spacetime separated from matter and the rest is history.