In a recent article in Science Daily, scientists have mentioned the possibility of a mirror universe to account for some particle behaviors. A little something to consider for your tabletop roleplaying setting. In a campaign I ran last Fall, there was a strange ghostly scene playing out over and over in an abandoned outpost. When the players disrupted the sequence by removing a powerful object from the location, they were shifted over to a parallel timeline that served, virtually, as a mirror universe in which history had played out quite differently than in their own. The adventurers didn't discover this immediately, though they suspected something had changed, but only realized the full impact after some time.Although much of what had changed was theoretically in the favor of the group, enough of it was also very unsettling and sometimes outright terrible. They spent several game sessions figuring out just how to set things right and did so as soon as they were able. Read more from Science Daily here!