Before we worry about communicating with civilization far away in space but coexisting with us in time, we should work at communicating with civilizations coexi

Before we worry about communicating with civilization far away in space but coexisting with us in time, we should work at communicating with civilizations coexisting with us in space but far away in time. One of my favorite "out there" theories is that it's possible (and I mean conspiracy theory possible) that the Paleocene–Eocene Thermal Maximum[0] was caused by an industrial civilization facing the same global warming problem we are today right here on Earth, wiping itself and several other species at the time out, but otherwise leaving the planet fine and recovering in short geological time. The interesting part of this "theory" is that because PETM happened 50 million years ago, even if there was a civilization as complex and large as ours today, very little (essential none) evidence of it would survive. My last bit of techno optimism is that if we do find ourselves unquestionably headed towards climate catastrophe, we should start investing research into figuring out how we might send some kind of message to a future civilization that emerges 50-100 million years after us. Something along the lines of "human were here! watch out for those hydro carbons!" 0. https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Therm...