How to Design Beacons for Humanity's Afterlife

Let's say we had a way to distribute beacons around our solar system (or beyond) that could survive for billions of years, recording what our civilization has achieved. What should they be like? It's easy to come up with what I consider to be sophomoric answers. But in reality I think this is a deep--and in some ways unsolvable--philosophical problem, that's connected to fundamental issues about knowledge, communication and meaning. Still, a friend of mine recently started a serious effort to build little quartz disks and have them hitch rides on spacecraft, to be deposited around the solar system. At first I argued that it was all a bit futile, but eventually I agreed to be an advisor to the project, and at least try to figure out what to do to the extent we can. We just have to think about archaeology to know this is hard. What exactly was some arrangement of stones from a few thousand years ago for? Sometimes we can pretty much tell, because it's close to something in our current ...