[Q
That just isn't the case. It began 14 billion years ago.
We don't know that as a fact.
We have some evidence that may be the case but that is far from knowing for sure. We don't even know for sure that there was a Big Bang. We suspect there was based upon some constant background space noise and the evidence that the universe seems to be expanding but that is far from being conclusive.
If there was a Big Bang we have no idea what existed before the event or where the energy come from or what initialed the event. We sure as hell can't explain the physics of what happen. The Big Bang is against all the laws of physics as we know them. For instance, we have no idea what gravity is or where it came from but that is the basic glue of Creation.. If the gravity constant was a little less or a little more we would have no universe as it exist now.
There are many things for us to learn about the universe. Just about 80 years ago we didn't even know other galaxies existed. Fifteen years ago we didn't know if any other solar system had any planets.
Thinking that the universe magically created itself out of nothing is the modern day equivalent of believing that the universe is being carried on the back of some giant turtle.