Big Bang is a widely accepted theory about the beginning of our universe. It states that the universe began from a incredibly dense point called singularity where all the universe's matter and energy was concentrated in that dense point. How did the universe all compress together to that dense point which contained the universe's matter and energy? The answer is gravitational force. Gravitation depends on mass of an object and the distance from it. It means that the gravitational force would increase with increase in mass and decrease with increase in distance. Therefore, the gravitational force at that dense point would be so high that it would compress it smaller and smaller to form a singularity. What happened after it? Ka-Boom... that dense point exploded with tremendous release of energy, throwing off all the matter it contained. After a few stages after the explosion, matter cooled down and formed basic elementary particles like electrons and neutrinos which then further formed atoms of hydrogen and helium. the atoms came together to form nebulas, nebulas cooled down and due to gravitational, formed the first stars of the newly born universe. Stars and other celestial objects came together and formed galaxies. Quite fascinating isn't it? But does this theory actually work out? Is Big Bang really possible?