The "Big Bang Theory" holds that the universe was formed by the expansion of a dense and hot singularity after a big bang 654.38+03.7 billion years ago.
1927, Belgian astronomer and cosmologist Lemaistre (George Ma Le? Tre) put forward the big bang hypothesis for the first time. 1929, American astronomer Hubble put forward Hubble's law that the redshift of galaxies is proportional to the distance between galaxies, and deduced the theory of inflated universe with long distance between galaxies.
At the beginning of the explosion, matter can only exist in the form of basic particles such as electrons, photons and neutrinos. The continuous expansion after the explosion of the universe caused the temperature and density to drop rapidly. With the decrease and cooling of temperature, atoms, nuclei and molecules are gradually formed and combined into common gases. Gas gradually condensed into nebulae, which further formed various stars and galaxies, and finally formed the universe we see today.
Neutron:
The concept of neutron was put forward by British physicist ernest rutherford, and its existence was confirmed by james chadwick's experiment of bombarding with alpha particles in 1932.
Neutron is one of the nucleons that make up the nucleus. Neutron is an indispensable component of the chemical elements that make up the nucleus (note: atoms do not contain neutrons). Although the chemical properties of atoms are determined by the number of protons in the nucleus, without neutrons, it is impossible to form elements other than hydrogen with only one proton because of the repulsive force between positively charged protons (protons are positively charged and neutrons are uncharged). Neutrons consist of two lower quarks and an upper quark.
2021115 It was learned from China University of Science and Technology that Chinese scientists have accurately measured the neutron electromagnetic structure.