Check out this fantastic piece by Kit Sun Cheah, readers:
Between the Mythical and the Mechanical
Today when people think of science fiction and fantasy, chances are, they think of two separate genres. Science fiction, the genre of starships and computers and technology. Fantasy, the genre of knights and dragons and castles. Two distinct genres, and never the twain shall meet. The meeting of the two, science fantasy, was the exception, the red-headed stepchild, never part of the mainstream.
This wasn’t always the case.
The pulp era made no such distinction between science fiction and fantasy. Indeed, they cared little for what we would call genres today. The pulp grandmasters simply chose the aesthetics, setting, and tropes that best served the story.
Leigh Douglass Brackett is the queen of space opera. Through her Eric John Stark stories, she popularized the sword and planet story, a genre that combines advanced technology and fantastic futuristic locations with heroic adventures and melee combat.
Edgar Rice Burroughs’ John Carter of Mars combined sword and planet and portal fantasy fiction. Captain John Carter, once a soldier for the Confederate States of America, is mysteriously whisked away to a Mars teeming with life. Despite the high technology of the setting, swordfighting remains a critical element of conflict.
The Lensman series was a seminal space opera series. It features interstellar travel, warring alien races, and mental powers weaponized for mass warfare. The first two are sci-fi staples, but the last should—by today’s standards—fall under fantasy fiction.
The pulp era is filled with stories that, seen in a modern light, straddle the line between science fiction and fantasy. Even today, the split between ‘hard’ and ‘soft’ SF and fantasy is an illusionary one.