For many years modern cosmology was only concerned with the nature of time. They wanted to explain the Big Bang and the nature of energy and gravity. But that was about to change.
Mathematicians were in a search for the very first thing in existence, and had reasoned that the Big Bang needed room for expression. The question of three-dimensional space was then ushered in as the third most important question in modern cosmology.
Scientists began to be more inquisitive about the nature of the universe. Many now believe not even space existed before the Big Bang. They like to define nothing as the absence of space, the absence of time, or the absence of anything associated with information.
Quantum physics has already reasoned that information does not require any real space to exist in. This makes it theoretically possible for information to exist in the absence of space and time. However, the definition of nothing has to preclude this possibility. Not even a zero can be used mathematically to describe nothing, as zero is considered to be information.
But not everyone is in agreement with the idea of no space as a description of what it was like before the Big Bang. Those who disagreed came up with a simplified version of nothing as empty space, or a space without energy or gravity in it. So another interpretation of nothing is nothing in a pre-existing space.
The definition of nothing is being endlessly debated by mathematicians and cosmologists. There seem to be too many paradoxes to consider in order to satisfy everyone, and with good reason. Physicists claim they need a mathematical language to describe the singularity of the Big Bang, and that without this language, they will never be able to explain how the Big Bang happened. They want to believe there is information in nature yet to be discovered.
Meanwhile, mathematicians cannot agree on a definition for infinity, and insist there is no information in nature for the physicists to decode anyway, because there is nothing there to begin with.
This has not deterred one renowned physicist from explaining how empty space can produce a universe. Our universe is now believed to be flat, which means it will eventually halt in the expansion and begin to fade out.
A flat universe is only possible if there happen to be equal amounts of energy and gravity. It then becomes theoretically possible for a universe to spring forth from nothing, because energy is positive and gravity is negative, and they each cancel out.
There is one brave physicist who has something more to say about nothing and in doing so, may be bringing us ever so closer to the truth about nature. We have professor Lawrence Krause to thank for his lectures.
In my opinion the professor has described a flat universe very truthfully and adequately until he gets to a vacuum fluctuation as the root cause for a Big Bang. How can you assume all of empty space (a pre-existing space with nothing in it) has weight and can eventually fluctuate?
If a pre-existing space is truly empty, it is incapable of action and reaction. The cause for a Big Bang must be explained in another way, and perhaps without the convenience of pre-existing space. But of course professor, you already knew that.