Personal power and how we confer it is the layer of worldbuilding where writers of science and writers of magic come together.

• Magic and the ability to wield it confers power. Magical creatures, elves, mythical races, mythological gods and demigods – these are some of the many natural and supernatural components of fantasy.
• Science and superior technology also confer power. Science fiction embraces current physics and theoretically possible technology, taking them into the near or distant future.

Speculative fiction is comprised of two overarching genres: science fiction and fantasy. The choice to make the technology of science or the technology of magic the primary source of power in your story determines which side of the coin lands up. The way you choose to go determines the sub-genre.

A novel set firmly in the technology of the past with no magic is not mainstream sci-fi. If it falls in late Victorian…