History of the Universe
Destenie
The Big Bang Theory
The Big Bang Theory is the leading explanation to the start of the Universe. It suggests that the universe was 10 million degrees and gradually cooled. Cosmic Microwave Background or light was made when free electrons and nuclei created neutral atoms. The evidence that the Universe has been expanding comes with something called RedShift of light. And Chemical Composition takes a big part with helium and hydrogen used in the Big Bang.
Evidence supporting the Big Bang
RedShift
RedShift is a term to describe how far away a distant object is. It's the process of sound waves changing into higher and lower frequencies. This shifting of frequencies is called the Doppler effect. Other galaxies are moving away from us, The further away from the galaxy the more its light is RedShifted. The most likely explanation is that the whole universe is expanding.
Cosmic Microwave Background (CMB)
CMB is electromagnetic radiation as a remnant from the early stage of the universe in Big Bang cosmology. It was made when free electrons and nuclei created neutral atoms and is also known as light. CMB is a huge thing that supports the Big Bang. This suggests that the Universe is filled with radiation.
Composition of the Universe
Chemical Composition is dominated by hydrogen and helium produced in the Big Bang. This is where the earliest stars and galaxies condensed consisted primarily of hydrogen and helium. It's basically the chemicals that were related to making the Big Bang Theory.