Exactly how large is the universe? Where do its boundaries lie?
Measured in light years, about 45 billion in all directions from our galaxy.
The real answer is, no one knows. One of the things talked about in scientific circles is the shape of the universe. Some believe it flat while others believe it shaped much like a soccer ball.
But there is what appears to be a nonsensical quality of the universe: every galaxy appears to be moving away from every other galaxy at an accelerating speed. And, every galaxy sits in the middle of the universe. The space-time continuum is not linear but even knowing that only muddies the waters over how large it is, what shape it is, and even how old it is.
As to boundaries, there are none, another enigma.