Theory

A theory is a man-made statement that attempts to explain fundamental concepts. They are not proven to be true but usually are inferred based on known facts. One common example is the theory of evolution. This theory states that all creatures we see today came from a same cause some time ago. This same cause is proposed to be a common ancestor which many believe to be a single celled organism. This cannot be proved, nor will it ever be proved, but mainstream science has accepted this as fact. This theory of evolution also led to a theory of evolution for celestial bodies. Taking this train of thought, if evolution is true, then all planets and other celestial bodies came from a singular cause. This cause is proposed to be a singular "Big Bang" that exploded all matter that ever has existed in this universe all over also causing an expansion of the universe. This theory is backed up only by the proposed expansion of the universe. After developing the necessary technology to use the light coming from other stars and planets and split it up according to atomic spectra, scientists have observed that these spectra have shifted towards the red end of the light spectrum. This is called redshift and is one big proponent of reasoning to conclude that the universe is expanding (See: Doppler Effect). This coupled with another famous theory of how gravity works, scientists have claimed for a truth that the universe is expanding and therefore came from a singular cause: the Big Bang.