The early plasma was hot because it was formed during the Big Bang, which released an enormous amount of energy. This energy caused the particles in the universe to move rapidly, resulting in high temperatures.
The early plasma was extremely hot, with temperatures reaching up to billions of degrees Celsius. This intense heat was necessary for the formation of the first atoms and the beginning of the universe as we know it.
As the universe expanded, the early plasma began to cool down due to the decrease in density. This allowed the particles to spread out and the temperature to decrease, eventually leading to the formation of atoms and the cooling of the universe.
The temperature of the universe is different now because it has continued to expand and cool over billions of years. As the universe expanded, the particles became more spread out, resulting in a decrease in temperature. Additionally, the formation of stars and galaxies also played a role in cooling the universe.
We know that the early plasma was hot through various observations and experiments, such as the cosmic microwave background radiation. This radiation is the leftover heat from the Big Bang and is a strong piece of evidence for the early plasma being hot. Additionally, the abundance of light elements in the universe also supports the idea of a hot early plasma.