This should start with the origin of the universe. The universe originated from the Big Bang. 65.438+0.38 billion years ago, there was a point that existed and did not exist, a point with infinite mass, infinite density and wireless high temperature, which is also known as singularity. Singularity cannot be calculated by modern physical formulas, and all physical laws are invalid at singularity. This magical singularity broke out 138 billion years ago and expanded rapidly in a very short time. How fast? Every billionth of a second, space expands 1000 billion times. For example, the universe expanded from the size of a hydrogen atom to the size of a baseball in less than a billionth of a second, and from the size of a golf ball to the size of the earth in the same time! The universe in this period was in an "expanding" state.

At the moment of the Big Bang, a large amount of energy and matter burst out and expanded outward at an alarming rate.

During the explosion, a lot of energy and matter are ejected from the singularity. After the "expanding" universe cooled rapidly, particles in space began to synthesize. First quarks condense into protons and neutrons, and then protons and neutrons gather together to form nuclei. The earliest nuclei in the universe are hydrogen nuclei and helium nuclei. The universe in this period is a high-temperature chaotic state full of energy and particles.

Quarks synthesize protons and neutrons.

Hydrogen nucleus and helium nucleus

After 380,000 years, electrons joined them to form atoms, which are still mainly hydrogen and helium. During this period, the universe gradually cooled down and began to become orderly.

= hydrogen atom and helium atom with electrons

After 400 million years, under the action of gravity, hydrogen began to gather together, forming primitive stars and galaxies. The universe in this period can be said to be the embryonic form of the modern universe.

A nectar-like protogalaxy

Later, after a long evolution of1300 million years, the universe became what it is now. If you use a picture to represent this process, as shown below:

To sum up, the evolution of the universe is roughly as follows: singularity explosion-high temperature inflation-high temperature chaos-orderly cooling-primitive galaxies-modern universe.

-The above content is taken from Millay's children's book A Brief History of Life.