It's a staple of science-fiction and fantasy - that beneath the world we know, there lies another world, one that is strange, alien, perhaps magical. How do writers create those worlds, and how do they intertwine them with our own? Here, I want to look at some classic examples...
1. Narnia - entrances to other worlds
In some fantasy series, the real world acts as a springboard - it's the place the hero comes from, so we can relate to them, but there are worlds beyond their own. For C.S. Lewis, his heroes in The Magician's Nephew reach them by means of the wood between the worlds:
“As he rose to his feet he noticed that he was neither dripping nor panting for breath as anyone would expect after being under water. His clothes were perfectly dry. He was standing by the edge of a small pool—not more than ten feet from side to side in a wood. The trees grew close together and were so leafy that he could get no glimpse of the sky. All the light was green light that came through the leaves: but there must have been a very strong sun overhead, for this green daylight was bright and warm. It was the quietest wood you could possibly imagine. There were no birds, no insects, no animals, and no wind. You could almost feel the trees growing. The pool he had just got out of was not the only pool. There were dozens of others—a pool every few yards as far as his eyes could reach. You could almost feel the trees drinking the water up with their roots. This wood was very much alive.”
Every one of these pools was really a gateway to another world. When young adventurers brought enchanted wood back from Narnia, wood that was eventually used to create a famous wardrobe, we were left with magical portals that linked the two worlds.
Although Lewis' novels are probably the most famous example, the same approach is used in countless other fantasy books. A subtly different version of the idea is used in The Matrix, where the reality we know is but a façade.
For Neo, the choice he made would tear the scales away from his eyes, and reveal the truth about the world he knew - about the world we know. Approaches like these are rarer, and more philosophical; they're also both creepy and fun!
2. Harry Potter - a hidden world
In contrast, a far more popular approach is to imagine that another world lies within the one we know, a world usually known in ancient times but forgotten as man has grown more 'enlightened'. Nowhere has this idea been used more effectively than in J.K. Rowling's Harry Potter novels, where the wizard world runs separately to that of the 'Muggles'. Wizards and witches walk among us, and we do not know; strict laws govern their interaction with those who lack magic. Platform Nine and Three Quarters, inaccessible to Muggles, stands as a poignant symbol of this division.
The magical worlds that lie beneath our own are hidden, sometimes by our own ignorance, other times because of vast conspiracies - ancient orders who conspire to keep us from the truth, or ruthless villains who seek to preserve their power. In Buffy the Vampire Slayer, the authorities are complicit in keeping the demonic problems of Sunnydale secret; the Mayor himself is a villain, and we later learn that even the world's governments are truly aware of the evils that exist.
The hero is often an ordinary man or woman (usually a teenager) who learns they have links to this hidden world - from Harry learning he is a wizard, to Clary drawn into her mother's Shadowhunter legacy. Other times, everyday people are drawn into the world - people like Bella, who unwittingly plunges into the realm of vampires and werewolves in Twilight.
Frequently, the villain of the pieces has a plan that will bring the two worlds into collision, exposing the hidden world to the one we know - and usually conquering it.
3. The Marvel Cinematic Universe - another world revealed
At the end of Iron Man, the Marvel Cinematic Universe took a different approach; they had Tony Stark go public as Iron Man, and from there we - the viewers - were gradually introduced to a secret world history embracing everything from Captain America to Hank Pym's Ant-Man. Marvel's Phase One trod a careful line, with metahuman activity carefully suppressed - as always - by S.H.I.E.L.D. In The Avengers, though, things changed. New York was invaded, and no cover story could explain it away.
Marvel's Phase Two deliberately caused more destruction - Captain America: The Winter Soldier brought Helicarriers falling out of the sky in Washington DC, while Avengers: Age of Ultron featured a destructive Hulk rampage - and the devastation of Sokovia. From the outset, the events of Captain America: Civil War were inevitable, as the public reacted in horror as they saw beings beyond their ken unleashed upon the world.
The classic Heroes series followed this pattern, with the metahumans always on the verge of discovery - and culminating in Claire's decision to go public about her powers.
4. The DC Universe - when worlds collide
In contrast, the DC Cinematic Universe opens with devastation on a scale Marvel only reached by Avengers: Age of Ultron. DC actually opens with our world faced with the hidden, with the alien beings of cosmic power going to war. It leads the DC movies to a similar place - one where society has to work out how to deal with this strange new world - but it has a very different tone.
This is rarer. In this approach, there are no secret explorations of a hidden world of superhumans; instead, there's a bold declaration, "See, they are with us!"