[Spaceships] Reactionless Drives, Pseudovelocity, and NOT breaking a setting (much)

[Emerald Cat]

Originally Posted by David Johnston2

Pseudovelocity doesn't make you invisible or unstoppable. It is not Relativistic Kill Vehicles.

Right. To clarify, this is because you don't gain any velocity when using a pseudovelocity drive by definition. Obviously, if you don't gain any velocity it won't work as a kinetic kill missile.

Reactionless drives without the pseudovelocity modification do have this problem. How exactly does one stop a relativistic kill vehicle? Blowing it up will only work at close range if the shrapnel is too small to cause damage to the planet. With enough lead time, you could theoretically use your own reactionless drive to divert the object.

But unless you have FTL sensors you would have to detect it accelerating to light speed. According to relativity, the speed of light is the fastest information can propagate. Once the ship is traveling near light speed, sensors would be detecting the ship as it arrives. If that happens, the defenders have lost.