Until science fiction becomes fact (which does happen) it is as much fantasy as Hogwarts and Middle Earth. Many science fiction movies contain elements associated with fantasy - the flying creatures in Pandora, for example. But James Cameron’s movie also contains elements that belong to science fiction. So if the two genres keep blurring into each other, can they be said to be separate any more? Is there such a thing now as ‘pure’ science fiction, and ‘pure’ fantasy?

Traditionally, writers like H.G. Wells and Mary Woolstencraft Shelley set the parameters for science fiction. The story had to involve scientific principle and gadgetry, no matter how far fetched. Wells’ time machine and Shelley’s mad scientist with his storm driven re-animation machine were scientific in nature, even if fantastic in concept. Later, the rise of ‘hard’ science fiction meant that writers had to know as much about science as they knew about fiction, and the science had to be feasible or very soundly based on known scientific principles.

Using this definition, Star Wars IV, V, and VII are pure fantasy, since everything is posited on the existence of a magical ‘Force’ that gives the Jedi and the Sith their power. But in his later films, Star Wars I, II and III, George Lucas introduced a ‘scientific’ explanation for the Force, bringing his creation closer to the parameters of science fiction. Not that close, mind.

‘Hard’ science fiction can be found in movies like Starship Troopers, I Robot, Bladerunner and Alien. These movies bristle with technology, and hard questions about our future in space travel, robotics and other scientific advances. There is an element of fantasy in that it all has to be imagined, but that is the dilemma with all fiction set in the future.

Pure fantasy does not need to take what could, can or may be possible into account. Middle Earth, Hohwarts and Narnia simply don’t exist, they are the product of their creators’ imaginations. Elves, dragons, orcs, gnomes, vampires, werewolves et al, do not exist. They have never been scientifically proved to exist. They, and the worlds they inhabit, are fantasy, and even when fans and writers try to trump up scientific explanations for their existence, they remain fantasy.

But increasingly, science fiction is becoming softer, and blending itself in with fantasy, and this can be confusing long time fans. Is James Cameron’s Avatar science fiction or fantasy? The answer is that it is both. It uses science to create a future in which humans can be represented by ‘avatars’ on another planet (and of course it takes science to get there in the first place) with fantastical CGI representations of that other world and the creatures in it.

Science fiction has been called ‘speculative fiction’ and other names in an attempt to get it further away from its original science based premise, but fiction that uses science will always be science fiction, and fiction that uses mythical creatures and wizards will always be fantasy. But when the two genres overlap, it’s a win-win for movie fans, opening up endless possibilities and extraordinary journeys through time, space and imagination.