I'm not convinced city lights would be what we're looking for. Visible light from space is "waste energy" and, over time, our civilization has gotten better ab

I'm not convinced city lights would be what we're looking for. Visible light from space is "waste energy" and, over time, our civilization has gotten better about wasting less. It's certainly imaginable that a civilization 10,000 years more advanced than us (a blink of eye in geologic time) would not have visible waste light. Given how rapidly VR, remote work/telepresence, and so on is advancing, it's plausible that a civilization slightly more advanced than us won't even physically travel their bodies anymore, or potentially not even use biological bodies at some point, resulting in difficulty detecting any sort of industrial emission or spectrum from the planet.