If you haven't yet, try googling "Silurian hypothesis". That is a thought experiment (not really a hypothesis as such) that says, suppose a high-tech civilization existed on this planet during the Silurian Period, i.e. ~400 million years ago. Would we know? What signs would there be and how obvious would they be? (This is generally thought to be about when air-breathing terrestrial animals were first appearing, so presumably any such actual civilization on Earth would've had to've been alien colonists, I suppose.) There have been a lot of essays and even some peer-reviewed papers on the subject. Often such writings are a jumping-off point for considering what will be left of our own high-tech civilization 400 million years from now.
My recollection is that our longest-remaining traces will be geological evidence of a mass extinction event as well as an unusually rapid increase in atmospheric carbon over a very short timeframe (and no evidence of concurrent volcanic activity or any other natural explanation). The evidence of such things will be part of the geological record long after all our concrete and plastics and dead bodies have dissolved to nothing. Also, square/rectangular traces of building foundations will be obvious for a very long time-- and clearly artificial, since right angles are not super common in nature (though one can still imagine far-future skeptics arguing for some natural cause nonetheless)-- long after there's little or nothing else left of the buildings themselves.
The Silurian hypothesis was inspired by a Doctor Who episode which portrayed a civilization of lizard people living on Earth during the Silurian Period, who (coincidentally? I guess?) called themselves the Silurians.
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branchandroot
Silurian Hypothesis
Date: 2023-06-04 05:07 pm (UTC)My recollection is that our longest-remaining traces will be geological evidence of a mass extinction event as well as an unusually rapid increase in atmospheric carbon over a very short timeframe (and no evidence of concurrent volcanic activity or any other natural explanation). The evidence of such things will be part of the geological record long after all our concrete and plastics and dead bodies have dissolved to nothing. Also, square/rectangular traces of building foundations will be obvious for a very long time-- and clearly artificial, since right angles are not super common in nature (though one can still imagine far-future skeptics arguing for some natural cause nonetheless)-- long after there's little or nothing else left of the buildings themselves.
The Silurian hypothesis was inspired by a Doctor Who episode which portrayed a civilization of lizard people living on Earth during the Silurian Period, who (coincidentally? I guess?) called themselves the Silurians.
-troy jones iii