Mohs Scale of Science Fiction Hardness.

Science fiction is broken up into tons of smaller subgenres. I could go on all day about different subgenres, examples, the things I like best about each, and so on and so forth. I’ll spare everyone that. Instead I want to talk about the distinction between two kinds of science fiction: hard sci-fi and soft sci-fi. This distinction goes hand in hand with the ideas some people have about the hard (natural) sciences and the soft (social) sciences.

Hard sci-fi is concerned with science. Here the science and technological aspects of the world are the main focus. These are the stories that are likely to be more predictive as they’re built on actual physical laws. Some authors are so dedicated to the rigidity of logic that the science they write into their stories, while fictional, is based entirely on actual science of our world. It is also the case that there are plenty of hard sci-fi stories that deal with totally fictional science, but within the confines of the universe they’re writing treat it as actual fact.

An example of hard sci-fi would be Tom Godwin’s “The Cold Equations”. The science of space travel within the story is 100% pertinent to the plot. It deals with the idea that space travel is so exact that a ship can only carry exactly what it needs to get to a destination. There are no extra supplies and not even extra fuel. In the story the pilot finds a stowaway and has to figure out what to do to save them from running out of fuel. If the shuttle was made to carry extra fuel then the additional weight from Marilyn then there would be no conflict.

Soft sci-fi is more occupied with emotion and character. In these stories we get worlds that we can assume are based around fictional scientific theory but that no one goes into detail about. We are more interested in the people living in this advanced (or less advanced) world and the mental effect and emotional strain it puts upon them. If you can answer the question "how does it work?" then you might not be reading a soft sci-fi story. There tends to not be very hard and fast guidelines for what makes or breaks a story of its softness. Essentially any that isn’t considered hard sci-fi is usually categorized as soft sci-fi.

Most of what Ray Bradbury writes would fall under this category. There’s very little actual science in any of his stories. Pick up The Martian Chronicles and you’ll find very little explanation for the space travel that’s going on. However, that isn’t the point of the stories. The wonderful parts of Bradbury’s fiction is the exploration of the human condition. What makes human nature human? Specifically when introduced to new worlds filled with new species.

I like both types of science fiction, though I’ll admit that I’m less likely to choose hard sci-fi if I’m looking for a fun beach read. I appreciate the work that goes into hard sci-fi but I’m not science minded myself and so the science, fictional or otherwise, all makes about the same amount of sense to me. TV Tropes has a funny article that deals with this distinction, riffing off the Mohs scale of hardness used in geology. Check it out if you feel like it.