Alternate Realities

According to people who know more about these things than me, there are many alternate realities that we cannot see. I really don't know how this works, but I have heard many people say that basically there are so many infinite possibilities throughout time and space that anything you imagine is true someplace, somewhere.
I think about this a lot, because I think it's fun imagining myself in alternate realities doing spectacular things. Somewhere I am a great vet student, a Food Network chef, an author of good repute, a flying ace, the definition of cool, a famous singer, etc. Some things are more normal like, I don't have Diabetes, I already have kids, I have a really cool job that I like, or I have fabulous pets.Then there are the really fun things, like living in the world of Harry Potter, having super powers, being an ancient Chinese warrior, or being a World War II nurse (That one isn't necessarily fun I guess).
But I wonder...if anything is possible am I discovering something that is already there, or am I creating something new every time I imagine something? Am I something someone has imagined? Is this world a story from across the universe? If so what happens if we are forgotten? Will we just go on and on, or will we fade away??? And what power we have if we can create things for other realities! We can imagine peace and happiness for entire planets, stop hunger, cure disease save people. If anything is possible, then can we do the impossible?

This is what I think about during class.

* Not my artwork, way too good!