The current cosmological understanding is that space "expands" based on the matter placed into it. There is no way to determine a finite maximum size (volume).
This is an area of active research... meaning, nobody really knows. The visible Universe has a radius of about 46 billion light-years. According to the "inflation" theory (basically, the modern...
There was no universe before the Big Bang, and we need to explain that a bit. The Big Bang brought with it space time, which is the fabric or the "space" that is the volume of the universe. It isn't...
How big is the Universe is a difficult thing to define. It's a bit like asking how far has a car travelled. From its start point, where it is now, or where it will be in the future? We know the...