The Soldier, the first in a new trilogy set in the Polity Universe, is out now from TOR.
If you want to write SF you must have some understanding of the ‘science’ bit. You have to know the rules.
Stuff doesn’t stop:
If you throw a rock in the vacuum of space it will, barring some other object getting in the way, continue travelling in the direction you threw it, at the speed it achieved when you threw it, forever. This applies to all objects moving in vacuum including people and spaceships. Don’t make the mistake I found in one SF book, by a well-known fantasy writer, of thinking that once the rocket engine of his spaceship went wrong, the ship would trundle to a halt like a Ford that just blew its head gasket.
Every action . . .
Newton’s third law tells us that ‘every action has an equal and opposite reaction’ so if you throw a rock in space, that action will propel you in the opposite direction though, not as fast, since you mass more. This applies to the travelling spaceship above: it accelerated to get moving, so it needs to apply an equal and opposite deceleration to stop it. But what is a stop?
It’s all on the move and all relative:
Your spaceship accelerated from one point and the equivalent deceleration brings it to a stop relative to that point. The problem here is that the mentioned point would also be on the move. If the spaceship was ‘above’ Earth, well, it was above a spinning, wobbling object swinging around a sun also on the move in shifting star systems also swinging round a galaxy that is also on the move in an immense universe.
Up is down:
A concomitant problem with everything being relative is that you’re writing in a language designed for a planetary environment and, once you get outside of that, you begin to find the language’s limitations. There is no up and down in space. It is even difficult if you try to attach it to the person. Does the spaceman look down at his feet, or up at them? This can get annoying when writing about vacuum combat but there are ways round that, cheating being the prime one. I cite this as the reason for the invention of artificial gravity in spaceships: it’s convenient for the writer.
That damned Einstein:
Of course, one of the physical rules of our universe is that nothing can travel faster than the speed of light. This is a bit of a bind if you want your characters zipping about in spaceships and having adventures on various alien worlds, since the nearest sun to us is 4.2 years away at that speed. So, again for convenience, we have hyperspace or, as it is in my books, underspace, where spaceships submerge to travel instantly to any destination. But here there are . . . difficulties. If, for example, you travel two light hours away, you must remember that, looking back, you’ll be seeing yourself for those two hours. . .
It is worth noting that you have to know the rules, in order to break them convincingly.