Artificial Gravity

What it Is
The ability to create gravity in an otherwise zero-gravity environment like outer space, a space shuttle, or an orbiting space station.


Who Invented It
I've seen credit given to Olaf Stapleton as early as 1930, but I don't think we can give credit for this idea to any one author or group. The belief that any person having an adventure in outer space could walk around while they were in orbit has been a standard trope since the start of the genre. Just to double check, I grabbed my copy of the 1954 novel Treachery in Outer Space. Sure enough, Tom Corbett and the other space cadets were walking through the ships and space station.


The Science Behind Artificial Gravity
Start with your basic 7th grade understanding of gravity. Everything has a gravitational pull. You, me, the moon, your coffee mug... the strength of your gravitational pull is dependent on your mass.

The moon has enough gravity to pull a wandering astronaut toward it. Your coffee mug might attract an astronaut, but not because of gravity.


The Math Behind the Science

(G*m1*m2) / r^2

Where G is a constant called the gravitational constant. m1 and m2 are the masses of the two objects involved in the gravitational pull, and r is the distance between these two objects.

Still With Me?
Space ships and orbiting space stations tend to be much smaller, and much lighter, than a planet. M1 and M2 in the equation above are just too small to create a gravity worth noticing.

If you want your characters to walk around a space ship (let alone run, jog, or [insert amusing activity here] in the normal fashion) you need to counteract the low masses with some sort of device.

Option 1 - Centrifugal Force!
One of the most popular ideas for creating gravity has been centrifugal force. Just put a spin on your super-sized space station and the force that makes you feel heavy on the Tilt-a-Whirl at the county fair will keep your feet firmly planted on the wall.

Pros: This idea could probably work.
Cons: Something big enough and heavy enough to work like this is going to be a pain to build, and cost more money than anyone really wants to spend. Which explains why ISS doesn't spin.

Option 2- Magnets!
When in doubt, magnetic boots. Okay, not the best choice. Magnets would probably interfere with the computers, and just sticking to the wall wouldn't actually negate the negative affects of zero-G.


Option 3- Something Else...
Authors through the years have come up with other ideas. Using dense matter to make the ship's core thus increasing M1. Spinning plates under the deck to create friction of some kind. Gravity Web Vests, and other ideas.

Take Home Message
Your readers probably won't expect an explanation for why you have gravity in space unless you set the book in 2012. If people are willing to accept the idea of faster-than-light travel and laser shows in space than gravity won't be to hard for them to forgive.

I would still love to see a sci-fi novel set without the gravity.

There are a whole host of problems associated with zero-G living. Muscular atrophy, heart problems, reentry to gravity wells... Humans can live in zero-G, it's the trip back to Earth that kills them. Still, I'm surprised more of the SFR crowd hasn't explored all the amorous possibilities of a zero-G environment.

And, space mystery writers! This could be the new version of the Murder-on-the-Train books that were popular a half-century ago. Instead of everyone lost on a train, you could have a corpse slowly spinning in the middle of a room, drops of blood splatter hanging in bright red spheres.

If you want to read up on current research consider checking these links:
A new spin on an old idea
MIT Artificial Gravity generator
Astronauts Eating in Space (thank you for letting me repost the orange picture)