Question

1] What existed before the universe?
2] How was the universe formed?
3] Was there ever a time when nothing existed or has something always been in existence?

Answer 1

1. Initial singularity. The initial singularity is a gravitational singularity predicted by general relativity to have existed before the Big Bang and thought to have contained all the energy and spacetime of the Universe.
2. Our universe began with an explosion of space itself - the Big Bang. Starting from extremely high density and temperature, space expanded, the universe cooled, and the simplest elements formed. Gravity gradually drew matter together to form the first stars and the first galaxies
3. Vilenkin's calculations show that a universe created from nothing is likely to be tiny, indeed — far, far smaller than, say, a proton. ... Although a universe, in Vilenkin's scheme, can come from nothing in the sense of there being no space, time or matter, something is in place beforehand — namely the laws of physics.