* The singularity: The Big Bang theory suggests the universe started from a state called a singularity. This singularity is a point of infinite density and temperature, beyond the realm of our current understanding of physics. We can't apply our usual concepts of space and time to this state.
* No "before" in the traditional sense: The Big Bang represents the beginning of time and space as we know it. There wasn't a "before" in the sense we're used to thinking about.
However, we can think about the early universe:
* Inflation: After the Big Bang, a period of rapid expansion called inflation is theorized to have occurred, expanding the universe exponentially. This expansion smoothed out the universe and is thought to be responsible for the large-scale structure we see today.
* Early universe size: While the universe is expanding, it's impossible to say how "large" it was in the very first moments after the Big Bang. It was incredibly dense and hot, and our current understanding of physics breaks down at these extreme conditions.
In essence, we can't say how big the universe was "before" the Big Bang because the concept of "before" doesn't really apply. The Big Bang is the beginning of space and time as we know them.
