What is the Big Bang theory?
The Big Bang theory says that the universe was very hot and concentrated in the distant past and, ever since then, space has been stretching and cooling. This is the only theory that successfully explains the observations made by astronomers. Astronomers see galaxies moving apart from one another: space in the universe is stretching. Astronomers see a remarkably uniform microwave glow everywhere in the sky; this is the heat left over from an earlier time, when the universe was very hot. This was predicted by the Big Bang theory BEFORE it was discovered! Astronomers measure how much of each of the lightest chemical elements (like hydrogen, deuterium, and lithium) are in space; their abundances agree with what was calculated to have been in an earlier time when the universe was so hot that it was like a nuclear fusion reactor, building up the lightest elements. The heaviest elements (like carbon, nitrogen, and carbon) were made later in stars. Stars are mostly made of hydrogen. The Big B
The Big Bang theory is science’s best explanation of how the universe was created. The theory asserts that our entire universe was created when a tiny (billions of times smaller than a proton), super-dense, super-hot mass exploded and began expanding very rapidly, eventually cooling and forming into the stars and galaxies with which we are familiar. This event is said to have happened approximately 15 billion years ago. Rather than expanding outward into some preexisting vacuum, the event of the Big Bang was space itself expanding – perhaps at speeds greater than light. (While Einstein’s theory of relativity forbids anything within space from travelling faster than light, it sets no limitations on how fast the fabric of space itself may expand.) The Big Bang theory was originally developed in the late 1920s by Georges-Henri Lemaître, a Belgian Catholic priest and astronomer, an early advocate of solutions to the general relativity field equations which predicted our universe was expand
The big bang theory is the theory that the universe started from a single point, and has been expanding ever since. This has been well-established by observations, such as the apparent movement of galaxies away from us, and the cosmic microwave background radiation believed to be the leftover light from the big bang. The evidence for a big bang having taken place about 15 to 20 billion years ago is overwhelming, so I naturally believe that it is the case. However, if your real question is “why did the big bang happen in the first place?” then that ceases to be an astronomical question, but a religious one. Some astronomers, who are religious, argue that the big bang theory confirms the existence of God and the basic elements of the creation story as told in the Bible. First came light, then the heavens, then the Earth … However, many other scientists do not. Scientists, like people in most any profession, have a vast diversity of religious beliefs. Some of us attend houses of worship
