 | Timeline of the Big Bang: Encyclopedia II - Timeline of the Big Bang - The very early universe
Timeline of the Big Bang - The very early universe
All our understanding of the very early universe is very speculative. No accelerator experiments probe sufficiently high energies to provide insight into this period. Scenarios differ radically. Some ideas include the Hartle-Hawking initial state, string landscape, brane inflation, string gas cosmology, and the ekpyrotic universe. Some of these ideas are mutually compatible, others are not.
Timeline of the Big Bang - The Planck epoch – 10-43 seconds
See also: Quantum gravity, String theory, and Loop quantum gravity
If supersymmetry is correct, then at this time the four fundamental forces – electromagnetism, weak nuclear force, strong nuclear force and gravity – all have the same strength, and are unified into one fundamental force. Little else is known about this epoch, although different theories make different predictions. Einstein's theory of general relativity predicts a gravitational singularity before this time. Physicists hope that speculative theories of quantum gravity, such as string theory and loop quantum gravity, will eventually lead to a better understanding of the singularity, or even allow us to calculate what came before.
Timeline of the Big Bang - The Grand Unification Epoch – 10-33 seconds
Main article: Grand unified theory
As the universe expands and cools from the Planck epoch, gravity begins to separate from the fundamental gauge interactions: electromagnetism and the strong and weak nuclear forces. Physics at this scale may be described by a grand unified theory in which the gauge group of the Standard Model is embedded in a much larger group, which is broken to produce the observed forces of nature. Eventually, the grand unification is broken as the strong nuclear force seperates from the electroweak force. This should produce magnetic monopoles.
Timeline of the Big Bang - Cosmic inflation
Main article: Cosmic inflation
The temperature, and therefore the time, at which cosmic inflation occurs is not known. During inflation, the universe is flattened and the universe enters a homogeneous, isotropic rapidly expanding phase in which the seeds of structure formation are laid down in the form of a primordial spectrum of nearly-scale invariant fluctuations.
During reheating, the exponential expansion that occured during inflation ceases and the potential energy of the inflaton field decays into a hot, relativistic plasma of particles. If grand unification is a feature of our universe, then cosmic inflation must occur during or after the grand unificatied symmetry is broken, otherwise magnetic monopoles would be seen in the visible universe. At this point, the universe is dominated by radiation.
Main article: Baryogenesis
No known physics can explain the fact that there are so many more baryons in the universe than antibaryons. In order for this to be explained, the Sakharov conditions must be met at some time after inflation. There are hints that this is possible in known physics and from studying grand unified theories, but the full picture is not known.
Other related archives21 centimeter radiation, Baryogenesis, Big Bang, Big bang nucleosynthesis, Big crunch, Big rip, Cosmic inflation, Cosmic microwave background, Earth, Electroweak force, Galaxy formation, Grand unified theory, Hartle-Hawking initial state, Hawking radiation, Heat death, Higgs boson, Higgs mechanism, Large-scale structure of the cosmos, Loop quantum gravity, Quantum gravity, Quark-gluon plasma, Reionization, Sakharov conditions, Solar system, Standard Model, Star formation, String theory, Structure formation, Supersymmetry breaking, TeV, Ultimate fate of the universe, Vacuum metastability disaster, active galaxies, antibaryons, baryons, closed, clusters of galaxies, cosmic microwave background, cosmic neutrino background, cyclic model, dark energy, ekpyrotic universe, electromagnetism, electroweak force, false vacuum, flattened, gauge group, gauge interactions, general relativity, gravitational singularity, gravity, hadrons, line of neutral hydrogen, loop quantum gravity, magnetic monopoles, neutrinos, neutrons, oscillatory universe, particle accelerators, perturbation theory, phantom energy, plasma, population III stars, protons, quark-gluon plasma, quasars, scientific theory, stars, string landscape, string theory, strong nuclear force, superclusters, supersymmetry, symmetry is broken, tunnel, vacuum expectation value, weak nuclear force
 Adapted from the Wikipedia article "The very early universe", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki |
