The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. [1] The concept of an expanding universe was scientifically originated by physicist Alexander Friedmann in 1922 with the mathematical derivation of the Friedmann equations.

Most physicists believe the universe was born in a big bang 13.8 billion years ago. In it, the energy making up everything in the cosmos we see today was squeezed inside an inconceivably small space – far tinier than a grain of sand, or even an atom.

About 13.8 billion years ago, the Big Bang gave rise to everything, everywhere, and everywhen—the entire known Universe. What caused the Big Bang? What happened that first moment at the beginning of the Big Bang? When did the first stars form?

4 天之前 · The Big Bang Theory explains how the universe began with an infinitely hot and dense single point that inflated to form the ever-expanding cosmos we see today.

2023年12月18日 · According to the theories of physics, one second after the Big Bang, the heat of the universe caused atoms to collide with enough force to create a ten billion degree soup of neutrons,...

2024年2月28日 · New ideas and major discoveries made during the 20th century transformed cosmology – the term for the way we conceptualize and study the universe – although much remains unknown. The universe’s first stars were 30 to 300 times more massive than our Sun and millions of times brighter.

Big-bang model, widely held theory of the evolution of the universe. Its essential feature is the emergence of the universe from a state of extremely high temperature and density—the so-called big bang that occurred 13.8 billion years ago. Learn more about the big-bang model in this article.

Most scientists now believe that we live in a finite expanding universe which has not existed forever, and that all the matter, energy and space in the universe was once squeezed into an infinitesimally small volume, which erupted in a cataclysmic "explosion" which has become known as the Big Bang.

The Big Bang model is that the universe began in an extremely dense and hot condition and has expanded. The theory suggests that redshift proves the universe is expanding. [1]The Big Bang is a physical theory about how the universe started expanding, and then made the stars and galaxies we see today. The Big Bang is the name that scientists use for the most common theory of the universe, [2 ...

Scientists who study the origin, evolution, and ultimate fate of the universe (cosmology) believe that the universe began in an explosion, called the Big Bang, approximately 13.7 billion years ago. This explosion was not an explosion of particles through space, like fireworks, but a rapid expansion of space itself.