"The Universe"
First off let's determine what it is, according to definition - The Universe is all of space and time and their contents
In other simpler terms the Universe is everything.
One question that people have been trying to find the answer to is How did it begin, the Universe.
Big Bang theory: According to the standard Big Bang model, the universe was born during a period of inflation that began about 13.7 billion years ago. Like a rapidly expanding balloon, it swelled from a size smaller than an electron to nearly its current size within a tiny fraction of a second
q. Does this really tell us how the Universe began? What was there before the period of inflation? What caused the period of Inflation? What gave birth to the Universe? If it was from a "multiverse", what made that universe. (Multiverse-a collection of universes as in a collection of soap bubbles all touching, used to be called bubbleverse, until Star Trek took bubble verse and made it a one person universe.)Creation theory: Creationism is the religious belief that the universe and life originated "from specific acts of divine creation", as opposed to through natural processes, such as evolution. Wikipedia
q. This theory also has questions that can not be answered. Such as if in the beginning there was nothing, then where did God come from to create the Universe? From another Universe? How was that one created?Those are the two primary methods that people have heard about how the Universe came into being. There are other theories, such as the Multiverse hypothesis, and others. I have yet to see anything that can really answer how the Universe Came into being.
Random Picture I took.
Sometimes thinking about the Universe can get us little bit squirrely in the head.
We may not even be asking the right question to learn of the origins of the Universe, it may be a steady state system, if so it is one very strange steady state system. The answers may be untangled by quantum physics entanglement theory, or it could be as simple as it just happened, and thus was born the Universe.
As for myself, I do not think we are ready to accept how the Universe came into being, my own theory is that it was done by magic. Where that magic came from well we will never know. It does not matter what theory is put forth there will always be holes in it and it will never be provable.
It could be the universe is like that little tiny space in a circle that mathematics can not account for. There may be no such thing as a closed loop. The further out we look, the more holes we see, the closer we look the more empty space we see.
We are and always will be destined to live between the spaces of space both macro and micro. We are betweeners, we live and we die, and we do all of that while thinking about the sky and space. From our first unsatisfactory answer of "They just look like they twinkle Joey, it is really because of the sky they twinkle". Or "Daddy why is the sky blue", answers. We are just children. We are learning, and we are growing. Yeah we are growing older.
Are we on a Larry Niven Ringworld, only instead of a regular ring, are we instead on a Mobius Ring always looking out, and no matter what way we turn we can never look inward, because we live on the outside edge?

Well that's a few of my thoughts on "The Universe", so now it's "Second Star to the left and straight on 'til tomorrow". ("Second star to the right and straight on 'til morning") The original quote.