Nehaveigur

As a kid, before I knew better, I liked to read Erich von Däniken. In Chariots of the Gods, he explained that the pyramids were built by aliens and that evidence of extraterrestrial development aid is evident in the artifacts of other ancient civilizations too. More recently, additional outlets such as Ancient Aliens on History Channel have also discovered this as an appealing and profitable premise. Unfortunately, despite many of us wishing it were true, there isn’t any archeological site that’s not more plausibly explained by boring old history.

Ancient aliens are also alive and well in fiction. Jack McDevitt’s The Engines of God is one of my favorite sci fi novels. It’s about a future in which we have developed faster than light travel. We fly to other stars and on their planets discover the ruins of ancient, long-gone alien civilizations. At its core, it’s a plausible premise. Just as on Earth the artifacts of a civilization survive for longer than the civilization itself, it’s reasonable to expect the same thing for alien civilizations.

What would those alien artifacts look like? Would we be able to recognize them? One way to approach this is to consider the types of artifacts we could plausibly make that could be found by another civilization far in the future. The artifacts most likely to survive and be encountered would be those that we launch out of the solar system, like the Voyager probes in the 1970s. Future probes would likely not look too different. We may choose to give them a greater level of autonomy so that they can continue to operate once we stop sending them signals because they’re too far away or because we’ve forgotten about them. We may want to make them smaller, so that it’s easier to accelerate them to very high speeds. Or we may want to make them larger, which would increase the options for their capabilities, like autonomous propulsion. We would make those choices after considering the tradeoffs.