Familiar territory
When we’re standing on the ground, we feel gravity. That’s our everyday experience.
When we see pictures of people in space, they are always weightless. That’s our observed experience of space.
Weightlessness might be fun for a while, but it’s pretty inconvenient for everyday living. A lot of sci-fi universes introduce gravity in space by spinning whatever structure people are in. This, again, is familiar territory to a lot of people. Who hasn’t ridden on a playground roundabout as a child, and experienced the outward pull as the ride spins faster? Scale that up, and it’s easy to picture a spinning drum floating in space with people standing upright on the inner surface.
Less intuitive approaches
Spinning space stations bring back the convenience of gravity, but they also impose engineering challenges of their own, and the physical fact of being inside a spinning structure tends to intrude or constrain the story. Docking and undocking, for example, or experiencing different weights depending how close you are to the axis of spin. Many sci-fi universes hand-wave the problem away with some other artificial gravity that allows you to have a normal-looking setting in space without having to constantly acknowledge the source of your weight.
The Videshi world does introduce weight in space in a couple of ways, both relying exclusively on known physics.
Constant acceleration
When Jonathan joins the heavy hauler Herald of Freedom, he is weightless at first. The ship is in orbit, and it’s no different from astronauts on the ISS.
But once the ship is under way, everyone feels a normal sensation of weight. This is because the moving ship is kept under constant acceleration along its up/down axis. This acceleration mimics the effect of gravity. As Einstein explained in his theory of general relativity, acceleration and gravity are equivalent – you literally can’t tell the difference.
Of course, accelerating like that for days at a time builds up quite a speed. At some point we need to kill that speed by turning around and accelerating in the opposite direction. We could cut the engines for a few minutes while turning around, but that would mean putting everyone into free fall and fastening all loose objects. A lot of inconvenience. I ducked this by having the ship maneuver very gently while keeping the acceleration going. It’s a bit like going round a very gentle curve in the road, there might be a tiny sideways pull, but not enough to notice. Yes, the vector of thrust will give the ship a sideways push as it turns, but space is vast and the effect of that push is small in comparison and easily compensated-for. The net result is that passengers get a smooth ride.
Actual gravity in unexpected places
When the team is hopping around the Videshi world on one of the alien ships, they sometimes get a rough ride, but their feet (mostly) stay on the floor, even out in space.
How is that possible? This seems to violate our intuitive notion that people in space are weightless. It’s easy to assume that there’s no gravity up there outside the atmosphere.
Easy, but wrong!
Astronauts on the ISS are floating around, not because there’s no gravity, but because they’re in free fall. At the height off the ground the ISS orbits, Earth’s gravity is almost as strong as at the surface. But orbiting craft move sideways so fast that even though they’re falling they keep missing the planet!
When you see a rocket launch a craft into orbit, it goes up but then veers off at an angle to the ground. Most of the effort expended during launch is not spent gaining height, but actually goes into kicking the craft sideways fast enough to stay in orbit.
The difference is that Videshi pilots are not trying to go into orbit. They’re simply gaining enough height to clear most of the atmosphere. Going straight up is like riding an elevator up a very … very … tall building. You’ll still feel weight all the way to the top.
And when they appear at a different point above the planet, they don’t have all that orbital velocity to deal with. They just need to lower themselves down in a controlled landing.
Ian S. Bott, Writer and artist 