The Big Bang is a theory on the beginning of the universe. It is the rapid expansion from a single point. It is supported by the fact that galaxies are moving away from us. The first subatomic particles formed include protons, neutrons and electrons.The theory was started by Georges Lemaître.
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| By NASA/WMAP Science Team - Original version: NASA; modified by Cherkash, Public Domain, Wikimedia Commons |
The very early universe
It is made of the following epochs: the plank, Grand Unification, inflationary, electroweak, quark and hadron epochs.
Plank Epoch
The Plank Epoch is the closest current physics can get to the absolute beginning of time. Little is known about it. General relativity proposes a gravitational singularity before this time, and the four fundamental forces may be unified at this time. The universe was only up to 35 m wide at this time 10-43 seconds after the Big Bang.
Grand Unification Epoch
The force of gravity separates from the other 3 fundamental forces, and the earliest particles are created during the Grand Unification Epoch. It lasted from 10-43 to 10-36 seconds after the Big Bang.Inflationary Epoch
The inflationary epoch was triggered by the separation of the strong nuclear force. The Universe underwent an extremely rapid expansion. It expanded 1026 fold to the size of around 10 cm. It lasted from 10-36 to 10-32 seconds.Electroweak Epoch
The electroweak epoch was when particle interactions created large number of exotic particles. W, Z and Higgs bosons were created. The Higgs field slows particles down and confers mass to them. It lasted from 10-36 to 10-12 seconds, at the same time as the inflationary epoch.Quark Epoch
The Quark Epoch was defined by the creation of quarks, electrons and neutrinos. The temperature of the universe cooled down to below 10 quadrillion degrees, and the four fundamental forces assume their current forms. Quarks and antiquarks annihilate each other upon contact, but due to baryogenesis, 1 in one billion quarks survived, creating matter. It lasted from 10-12 to 10-6 seconds.Hadron Epoch
During the hadron epoch, the temperature of the universe decreased to 1000000000000 degrees, cool enough to allow quarks to form hadrons. Electrons colliding with protons fused to form neutrons and gave off massless neutrinos. It lasted from 10-6 to 1 second.Early Universe
Neutrino Decoupling
Neutrinos ceased to interact with baryonic matter, so it stopped interaction with baryonic matter. It occurred during the time when the rate of weak interactions was slower than the rate of expansion of the universe. It occurred around one second after the Big Bang.Lepton Epoch
After the majority of hadrons and antihadrons annihilate each other, leptons and anti leptons dominate the mass of the universe. As electrons and positrons collide and annihilate each other, energy in the form of photos is freed up. Colliding photons create more electron-positron pairs. This happened 1 second to 3 minutes after the Big Bang.Nucleosynthesis
The temperature of the universe falls to 1 billion degrees Kelvin. After 20 minutes, the temperature and density of the universe prevented nuclear fusion from continuing. This happened between 3 to 20 minutes since the Big Bang.Photon Epoch
During this long period of gradual cooling, the universe is filled with plasma. Most leptons and anti leptons have annihilated by then, and most of the universe's energy is in the form of photons. This happened from 3 minutes to 240000 years after the Big Bang.
Domination of matter
Energy densities of matter and energy equalised and the universe got dominated by matter. The temperature allowed hydrogen and helium atoms to remain ionised. This happened after 47000 years.The first molecules
100000 years after the Big Bang, the first molecules formed. Although HeH+, a helium hydride ion, was proposed to be the first molecule, no evidence of it has been found in space.
Recombination
After the temperature of the universe fell to 3000 degrees, ionised hydrogen and helium capture electrons, making them neutral. The universe became transparent, making it the earliest epoch visible. This happened 377000 years after the Big Bang.
Photon decoupling
Different types of particles fell out of thermal equilibrium, This occurred due to the expansion of the universe. The dark ages was from 300000 to 150 million years. This Is the point of time when no stars gave off light, due to the absence of them. The universe was dominated by dark matter. Little happened during this period.
Over a large scale
Reionization
First quasars from from gravitational collapse, and the intense radiation they emit bonuses the surrounding areas.Formation of stars
Gravity amplifies slight irregularities in the density of primordial gas and pockets of gas become more dense. They will collapse under their own gravity, becoming hot enough, creating stars.
Reflections
I learnt how to speed type and the small parts of the Big Bang theory. I also learnt that physics breaks down in really small timescales and in really small spaces. I still wonder what would have triggered the Big Bang. I can apply the skill of typing quickly and not rushing the lecturees in real life. I think the format of the slides was good, but the random memes and forcing everyone to rush typing was a very bad part of the presentation. I would not rush everyone if I were the one conducting the lesson.
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