What if everybody was sharing one universal dream? The “dream world” would be built by people’s memories, of real things or of fake things, and everything you see would be something that someone else (or yourself) has seen/imagined while awake. If this were true, then when you were in “dream world”, your mind wouldn’t be creating the crazy things, it would be seeing what has already been made. That could explain why sometimes you go to the same place in different dreams. And perhaps when you learn and/or create new stuff, “dream world” is expanded when you sleep and think about it. Perhaps this is why independent breakthroughs of the same thing are often made within a short time of each other; once someone has imagined it, the other person might stumble across it in their exploring.
Also, what if everybody you saw in the dream was simply exploring the world while they were asleep to? They probably wouldn’t remember seeing and interacting with you in their dreams though; after all, you remember very little of your dreams after you wake up. While this might not make sense if only one of you was asleep, it still would be interesting to think about.
Needless to say, this post was inspired by a weird dream I had a few nights ago