My theory is that all matter, space, and time is completely meaningless and irrelevant due to it being simultaneously infinitely large and infinitely tiny at the same time. There are infinite universes, each one smaller and larger than the rest, an infinite amount of universes packed in every infinitely tiny area of space. We are one universe in a long line of infinite universes.
My other theory, the semi-religious-possibly-sacrilegious one, is that God (or whatever you want to call them) is a being who has evolved to be able to understand and create all matter, space, and time, a fate that the human race will eventually share as we evolve and learn. Matter, space, and time are illusions, easily manipulable, easy understood, influenced, and changed if you know how.
However, going back to my other theory, God is not the Ultimate Being. They ARE a god, but since size and the amount of universes are infinite, there are always other levels of existence to move to, levels outside human comprehension. For all we know, the entire universe could just be an insignificant blip in the "grand scheme of things". Nothing ends. Everything is infinite.
The question is, could we eventually measure infinity?