We are also fortunate that the viscoelasticity of spacetime precludes superpositional bombs. If a ship in FTL space flies over a mass in STL space that produces less than 1/100,000 g, and the ship returns to subluminal space at that precise moment, the ship and the mass will push each other apart with equal force, preventing either object from intersecting. If they did intersect, the resulting explosion would be on par with an antimatter detonation.

Once a spaceship has entered superluminal space, straight-line flight is usually the most practical choice. However, a limited amount of maneuverability is possible by carefully increasing the energy density on one side or another of the bubble. This will cause that side of the spaceship to slow, and thus the vessel as a whole to turn. But it is a gradual process and only suitable for small course corrections over long distances. Otherwise you risk destabilizing the bubble. For more substantial changes, it is better to drop back into subluminal space, reorient, and try again.

Any changes in heading that occur in FTL will be reflected upon returning to STL. Likewise any changes to total momentum/speed, with the degree of change being inversely proportional.

Technically it is possible for two ships in FTL to dock, but the practical difficulties of matching exact velocities, as well as the mathematics of merging Markov Bubbles, means that while it has been done with drones, no one—to our knowledge—has been crazy enough to try it with crewed ships.

Although a ship within a Markov Bubble can never directly observe its FTL surroundings, some level of sensory information is possible. By pulsing the bubble at the appropriate frequencies, FTL particles can be created on the outer surface of the membrane, and these can be used both as a form of radar as well as a signaling mechanism. With careful measurement, we can detect the return of the particles when they impinge upon the bubble, and this allows us to interact with superluminal space, albeit in a crude manner.

This is the same method by which FTL comms and sensors work. Both may be used far closer to a star or planet than one can maintain a Markov Bubble, but as with the bubble, there is a point at which the associated gravity hills become too steep for all but the slowest, most energetic FTL signals to climb.

Due to the protection of the bubble, a ship retains the inertial frame of reference it had prior to FTL, which means it does not experience the extreme time dilation that an exposed superluminal particle would. Nor does it experience any relativistic effects at all (the twins of the famous twin paradox will age at the same rate if one of them takes an FTL flight from Sol to Alpha Centauri and back).

This, of course, leads us to the question of causality.

Why, one might ask, doesn’t FTL travel allow for time travel, as all the equations for special relativity seem to indicate? The answer is that it doesn’t, and we know this because … it doesn’t.