Using the known laws of physics the big bang occurred when the universe was nothing but a gravitational singularity, but this theory relies on general relativity and is expected to break down due to quantum effects. The question though is what created this singularity?

Regardless how deep we get involved with astrophysics and cosmology, we will never understand how this infinite gravitational location in spacetime occurred. Usually everything we know comes from something but in regards to this original singularity we just have to accept that it was there so human logic has a starting point in regards to existence...

Creation Of The Universe

So this singularity that came from nothing expanded due to very high-density and high-temperature that the four fundamental forces (electromagnetism, gravitation, weak nuclear interaction, and strong nuclear interaction) became one fundamental force and eventually exploded assumingly 13.7 billion years ago. In order to expand an even older variable without origin, TIME, had to be in place that allowed this expansion and explosion which formed galaxies full of matter.

The Creation Of Earth

It is assumed that 4.54 billion years ago, an accumulation of particles and gaseous matter from the solar nebula were gravitationally attracted in a massive object which eventually created planet earth. Volcanic outgassing created the primordial atmosphere but it contained almost no oxygen which made it uninhabitable. Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. Earth cooled over time and caused the formation of a solid crust, while allowing liquid water on the surface.