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Intro to the Universe

[Key Words] [General] [The Planck Era] [The Universe Today]

Key Words

 

General
The universe began with a bang. This is known as the big bang. The big bang happened about 15 billion years ago. We do not know exactly what caused the big bang, but we do know what happened fractions of a second after it.

In the very (very, very, very...) early universe, all the the forces of nature (gravity, electromagnetism, the strong nuclear force, and the weak nuclear force) were all combined into one force known as the Superforce. Matter and energy were not separate forces as they are today. Space-time was folded, compressed, squashed, and bent to fit into.

The Planck Era
The Planck era (named after the German physicist Max Planck) lasted from the big bang to 10-43 seconds (that's a decimal point with 42 zeros after it and a one at the end.) All the forces of nature were combined into the superforce. Nothing can be explained or defined in this time because it was then when the laws of physics were still forming. Temperatures were as hot as 1032 K (degrease Kelvin.)

By 10-35 seconds, the Superforce had already split up into to forces: gravity and the Grand Unified Theory (GUT). The GUT combined electromagnetism, the strong nuclear force, and the weak nuclear force. Temperatures had fallen to 1027 K. Here, the GUT split into the strong nuclear force, and the electroweak force, along with the rapid formation of quarks, leptons, and their anti-matter equivalent components. When this happened, the universe went through a short but very large expansion. Space-time began to unfold its self and spread out faster than the speed of light. This lasted for 10-32 seconds before the universe resumed it's previous rate of expansion.

At 10-12 seconds, the electroweak force separated into the electromagnetic force and the weak nuclear force. Now, all of the four forces of nature were separated. Particles were continuing to form and constantly were getting annihilated. By 10-6 seconds, quarks were starting to combine into pairs or triplets. Anti-particles annihilated them, but a tiny residue (1 part every billion) was left which was able to form all the matter that is present in the universe. A large number of photons were created at this point.

By 1 second, the temperature had fallen below 1010 K. five seconds afterward, neutrinos and anti-neutrinos stooped interacting with other forms of matter. After the universe was 10 seconds old, protons and neutrons become coming together to form deuterium nuclei . The strong nuclear force took hold between one and five minutes. This brought protons and neutrons together in helium nuclei. This prevented neutrons from decaying into protons and electrons. Even so, energy levels were still so high that atoms were totally ionized and existed as atomic nuclei in a sea of electrons.

About 300,000 years after the big bang, temperature had dropped to about 3000 K. At this temperature, the electromagnetic force allowed electrons to be captured by atomic nuclei. All the electrons that were floating around were captured by the atomic nuclei, and photons were, for the first time, able to travel large distances without being blocked by matter. The universe now became transparent. Matter began to collect to gather into huge clouds and the large-scale structure of the universe began.

The Universe Today
Today, the average temperature of the universe is at a mere 3 K. As the universe continues to expand, the temperature will continue to decrease.

Next Topic: The Expanding Universe

[Key Words] [General] [The Planck Era] [The Universe Today]



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