This is discussion archived from a time before the current discussion method was installed.
From current revision: "There's also a very funky event-horizon analogue applying to fleets of accelerating starships; get far enough behind and you cannot catch up. It would be too much to hope for to see this in fiction, though.". I'm not sure what this is talking about, but would Alastair Reynolds's Pushing Ice count? It doesn't say anything about an event horizon, but the book does follow a crew of miners who land on an alien artifact that accelerates out of the solar system too fast for anyone to rescue them. On the other hand, it's implied that the reason nobody can catch up to them is because the artifact passed through a series of intermediate waypoints that changed its direction, rather than just because they're going too fast. —Document N
This trope could be justified by saying that the spaceship isn't actually orbiting and that it's really usually its engines to accelerate up fast/slow enough to cancel out gravity, so then when the engines go down gravity starts bringing it down like a helicopter. Why would anyone do this? Well there's a few reasons. 1st. It gives you the benefits of a geostationary orbit at any altitude. 2nd. If you have multiple ships you'd have to work out orbits for all of them that don't result in you crashing into each other. 3rd. Orbits would cause your formation to break up. 4th. If your fighting a battle it causes shrapnel to fall to the ground instead of staying in orbit and posing a threat to you. 5th. I'm not sure but it would probably simplify calculations for things like aiming, and also make it safer to drop Space Marines since they wouldn't already be flying around at 7km/s.
Photonics: By detecting "star-scale gravity" it should mean detecting the gradient of the metric, since the metric is always locally flat.
