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It's incredibly improbable. While much of the planet's surface is recycled constantly, there are also huge swaths of land that are billions of years old and hav

It's incredibly improbable. While much of the planet's surface is recycled constantly, there are also huge swaths of land that are billions of years old and haven't changed enough to hide evidence of complex society. Dinosaur fossils are rare, but not that rare. Tiny ones are abundant. If all life on earth ceased today, you could come back here in a billion years and find plenty of evidence everywhere. Maybe it's not 100% impossible, but it's so improbable that it belongs alongside other fringe theories.

TheOtherHobbes 7y ago
I like to entertain a mad fringe theory that the K-Pg asteroid was a war weapon. You might think no species would be insane enough to consider bombing its own planet to the point of extinction-level oblivion, but - that doesn't appear to be true.
yellowapple 7y ago
> there are also huge swaths of land that are billions of years old and haven't changed enough to hide evidence of complex society Do you have any examples? The article in the sibling comment to yours directly states that the oldest large-scale swath of land (in the Negev Desert) only dates to 1.8 million years.
- caymanjim 7y ago
  That's the oldest surface land, but the oldest crust is 4.4 billion years in Australia, and there are other places with less-old-but-still-billions crust. Natural erosion in those areas exposes extensive history, and we can dig too. [1]: https://news.nationalgeographic.com/news/2014/02/140224-oldest-crust-australia-zircon-science/ https://news.nationalgeographic.com/news/2014/02/140224-olde...
  - yellowapple 7y ago
    Surface land (current or former) is the only really relevant source of potential evidence here, though (unless we're specifically looking for subterranean civilizations, or perhaps for remains of old mines or wells).
    - caymanjim 7y ago
      Surface land is a bit of a misnomer here. While the crust is 4.4B years old in Australia, that doesn't mean all 4.4B years are sub-surface. The top surface there is new, but there are exposed areas going back billions of years. This is how all fossils are found; the oldest surface is the 1.8M Negev desert, but we constantly find 300M year old dinosaurs sticking out of the sides of river valleys and other eroded areas. My point is that we'd also find evidence of a billion-year-old advanced civilization the same way, and that in Australia in particular, you can go all the way back to the formation of the planet.

TheOtherHobbes 7y ago

I like to entertain a mad fringe theory that the K-Pg asteroid was a war weapon. You might think no species would be insane enough to consider bombing its own planet to the point of extinction-level oblivion, but - that doesn't appear to be true.

yellowapple 7y ago

> there are also huge swaths of land that are billions of years old and haven't changed enough to hide evidence of complex society Do you have any examples? The article in the sibling comment to yours directly states that the oldest large-scale swath of land (in the Negev Desert) only dates to 1.8 million years.

caymanjim 7y ago
That's the oldest surface land, but the oldest crust is 4.4 billion years in Australia, and there are other places with less-old-but-still-billions crust. Natural erosion in those areas exposes extensive history, and we can dig too. [1]: https://news.nationalgeographic.com/news/2014/02/140224-oldest-crust-australia-zircon-science/ https://news.nationalgeographic.com/news/2014/02/140224-olde...
- yellowapple 7y ago
  Surface land (current or former) is the only really relevant source of potential evidence here, though (unless we're specifically looking for subterranean civilizations, or perhaps for remains of old mines or wells).
  - caymanjim 7y ago
    Surface land is a bit of a misnomer here. While the crust is 4.4B years old in Australia, that doesn't mean all 4.4B years are sub-surface. The top surface there is new, but there are exposed areas going back billions of years. This is how all fossils are found; the oldest surface is the 1.8M Negev desert, but we constantly find 300M year old dinosaurs sticking out of the sides of river valleys and other eroded areas. My point is that we'd also find evidence of a billion-year-old advanced civilization the same way, and that in Australia in particular, you can go all the way back to the formation of the planet.