In 1871, several years after the publication of Alice's Adventures in Wonderland, its author, Charles Dodgson -- by then better known as Lewis Carroll -- posed a question of another young girl named Alice. He gave her an orange and asked her which hand she was holding it in. She said it was in her right hand. He then instructed her to look in the mirror and to tell him which hand the girl in the mirror was using to hold the orange. "The left hand," said Alice. "Exactly," Dodgson replied, "and how do you explain that?" Unhindered by adult logic, his young friend ventured a response that became the inspiration for Through the Looking-Glass: "If I was on the other side of the glass, wouldn't the orange still be in my right hand?"*
Dodgson, who was left-handed and sometimes wrote letters using mirror-writing, took obvious delight in depicting a world in which normal expectations are confounded, and logic is stood on its head. An Oxford mathematician who loved games and puzzles, he also published academic papers on cryptology. Through the Looking-Glass unfolds like a chess game in a parallel universe. To approach the Red Queen, you must walk away from her. Cake is passed around first and then sliced. The White Queen moves backward in time, putting on a bandage, screaming in pain and finally pricking her finger.
Dodgson is not alone in his fascination with parallel universes. They have long since become a staple of science fiction, spurred on by physicist Paul Dirac's speculations in the 1920s about the existence of anti-matter. Kurt Vonnegut's whimsical alter ego, the science fiction writer Kilgore Trout, maintained that mirrors were really holes between two universes. He called them "leaks" and would sometimes warn children not to get too close: "You wouldn't want to wind up in the other universe, would you?" Like most science fiction writers, Kilgore Trout had little grasp of real science. However, quantum theory does allow for parallel universes, many of which have been explored imaginatively on episodes of Star Trek. So-called mirror worlds solve one of the more perplexing aspects of the universe we live in, which is that neutrinos -- one of the building blocks of matter -- only spin in one direction, creating a fundamental asymmetry. The existence of mirror worlds would restore balance to creation by allowing mirror-neutrinos to spin in the opposite direction.
The world that we see in the mirror in very much like this one, except right and left appear to have been reversed. To be consistent, you would think that up and down would also be reversed, but they are not. As for right and left, the mirror actually reverses front and back, so that your mirror image faces toward you rather than in the direction you are facing. That's not all. We like to think the face that stares back at us in the mirror is the spitting image of our own, but we have no proof of that. The only way we can verify that the face in the mirror is ours is to look in the mirror, which merely begs the question.
As a young man, the philosopher Douglas Harding was hiking in the Himalayas when suddenly he saw the world as it actually was, rather than as he thought it was supposed to be. There was one small difference between the two that changed everything. In the place normally occupied by his head -- or what he thought of as his head -- there was a hole. He realized the hole had always been there; he just hadn't noticed it before. From his vantage point, he could see his arms and legs and torso, but they didn't appear to be attached to anything. There was only a vast empty space filled with grass, trees, sky and snow-capped mountains in the distance -- an entire universe in the space between his shoulders.
There is indeed a hole in the universe, but you won't find it by looking in a mirror or in a telescope. You'll never find the hole that way, because you're already looking through it. It's as if you've put your face up to the opening in one of those fences that allow you to watch a a new building going up, and you can't see the hole you're looking through because you're too close to it. Forget about mirror worlds or parallel universes. The universe that appears through the hole is this one, which raises another question. If the universe is this one, what's on this side of the hole, the side I'm looking through? That's the scary part. There doesn't appear to be anything on my side of the hole.
*See Peter Gardner's notes to The Annotated Alice by Lewis Carroll
Kurt Vonnegut, Breakfast of Champions
Douglas Harding, On Having No Head