> A ship visits us at some point in the 1970s, and as it departs its Mind mischievously creates an EM signature crafted to baffle us.
The short story is "State of the Art", and is contained in a collection of short stories (some Culture, some not) of the same name. One of the final paragraphs in the story is a lovely testament to the prowess of Culture ships:
> The Arbitrary held its darkfield for a few minutes, then dropped it just past Mars (so there was just a chance it left an image on an Earth telescope). Meanwhile it was snapping all its various remote drones and sats away from the other planets in the system. It stayed in real space right up till the last moment (making it possible that its rapidly increasing mass produced a blip on a terrestrial gravity-wave experiment, deep in some mountain-mine), then totalled as it dispatched Linter's body into the stellar core, sucked a last few drones of Pluto and a couple of outlying comets, and slung Li's diamond at Neptune (where it's probably still in orbit).
The short story is "State of the Art", and is contained in a collection of short stories (some Culture, some not) of the same name. One of the final paragraphs in the story is a lovely testament to the prowess of Culture ships:
> The Arbitrary held its darkfield for a few minutes, then dropped it just past Mars (so there was just a chance it left an image on an Earth telescope). Meanwhile it was snapping all its various remote drones and sats away from the other planets in the system. It stayed in real space right up till the last moment (making it possible that its rapidly increasing mass produced a blip on a terrestrial gravity-wave experiment, deep in some mountain-mine), then totalled as it dispatched Linter's body into the stellar core, sucked a last few drones of Pluto and a couple of outlying comets, and slung Li's diamond at Neptune (where it's probably still in orbit).