theory: [noun] a plausible or scientifically acceptable general principle or body of principles offered to explain phenomena. The Big Bang theory is universally accepted by those who do research on the development of the universe, galaxies, and stars as the cause of the origin of the universe. The Big Bang theory says that the universe has developed by expanding from a hot dense state with everything exploding away from everything else. What caused this explosion is Science, religion and the Big Bang Theory. Whenever a major new scientific theory comes along, there is a tendency to mix it together with religion, and the outcome is often both unexpected and unfavorable. When the distinction between science and religion is clearly understood, such problems can be avoided. The history of the Big Bang theory What is the Big Bang Theory? by Matt Williams, Universe Today The history of the universe starting the with the Big Bang. A billion years after the big bang, hydrogen atoms were eqr3.