Thoughts about the universe

I've recently thought about space, galaxies and most specifically the universe. What is it? I am more asking and theorizing that is it the end of all things? What would happen when  you reach the end? Does it even end? It could be like our world perhaps and once we do get to the end we could travel all the way back around to our own planet as if you were sailing a sea around our world. Or after it possibly there is just emptiness. Or a very out there thought is that what if like galaxies there isn't justone singular universe. What if there are many? I think just the ideas and just thinking about this topic is so fascinating. You could theorize so many possibilities for it. Just the thoughts of a nerdy and silly man.