Is our universe one of many? Are we science experiments? Or perhaps nothing more than plants on the side of the 4th dimensional street?

Tell me about the 4th dimension.

A blind monk traveled into a forest carrying a bag. In it, there were a thousand dry paintbrushes. One and only one of those brushes was magic -- it would leave a mark, even when dry, and the mark would never fade, never diminish over time. Its mark would last forever. The monk wandered in the forest for fifty years. Every day at noon, he would reach into his bag and select a brush at random, and with this brush, he would draw on the nearest tree. Blind, he had no concept of what mark he left, if any. He had no notion of where a mark, if one were ever made, would reside; no concept of how many marks were made, if any. No concept of their significance, their beauty, their ugliness. He knew only to wander, to sit, to paint.

After fifty years, he returned to his monastery. The monks there asked him, where have you gone? He replied that he did not know. They asked him, what have you done? He replied that he did not know. They asked him what have you learned? He told them nothing. His story was lost forever.

Centuries later, a princess was walking through the forest and she came upon a tree with a strange design written upon it. She leaned to her closest advisor and asked, "Who has put this mark here? For what purpose? And what does it mean?" The advisor replied, "Who indead?"

We are that mark.

Tell me about the 4th dimension.

Ain't actually that interesting, been there myself. Its all full of hypercubes and jewish physics.