Early stage of the Big Bang: About 654.38+03.7 billion years ago, it was very small, with extremely high density and extremely high temperature, which was called singularity.

0.0 1 s after the big bang: about 1000 billion degrees, mainly photons, electrons and neutrinos. Proton neutrons only account for a part of 1 000 million, which is in thermal equilibrium, the system expands rapidly, and the temperature and density decrease continuously.

0. 1 s after the big bang: about 30 billion degrees, and the neutron-proton ratio decreased from 1.0 to 0.6 1.

After BIGBANG 1 sec: about 1000 billion degrees, neutrinos escape outward, and the positive and negative electrons undergo annihilation reaction, and the nuclear force is not enough to bind neutrons and protons.

5- 10 seconds after the big bang: about 10 15 degrees, protons and neutrons formed.

After the Big Bang 10-35 seconds: about 10 27 degrees, gravitational separation, quarks, bosons and leptons formed.

After BIGBANG 13.8 seconds: about 3 billion degrees, stable nuclei (chemical elements) such as hydrogen and helium are formed.

After the Big Bang 10-43 seconds: about 10 32 degrees, the universe emerged from the background of quantum fluctuations.

35 minutes after the big bang: about 30 billion degrees, the primary nuclear reaction process stopped and neutral atoms could not be formed.

300,000 years after BIGBANG: About 300 billion degrees, neutral atoms were formed by chemical combination. The main component of the universe was gaseous substances, which gradually condensed into high-density gas clouds under the action of self-gravity until stars and star systems.

From: /view/ 14565.htm