9 ms·

Such as?

• TheHumanist 3y ago
  That's a frustrating response, because you must surely understand as a whole what they are saying. Artifacts that would have been used by these civilizations, whatever those may have been.
  • hh3k0 3y ago
    > That's a frustrating response, because you must surely understand as a whole what they are saying. It's late and I couldn't come up with something that'd survive the timespan in question, so I just wanted an example.
    • almostnormal 3y ago
      Mirror on the moon.
      • saalweachter 3y ago
        Hmmm, assuming there were an extra retro reflector on the moon, have we pointed a laser at enough of the moon to find it? At what rate would it acquire dust without wind?
    • holoduke 3y ago
      Carbon ceramic brake discs from supercars will likely to survive a few billion years.
      • andrewinardeer 3y ago
        Surely plate tectonics after a few billion years would move these disc brakes down into the Earth's mantle and melt them?
        • thfuran 3y ago
          That depends where you leave them.
        • nemo 3y ago
          We have fossils that are > 3 billion years old. While subduction does steadily erase the past, not everything subducts. See: https://en.wikipedia.org/wiki/Craton https://en.wikipedia.org/wiki/Craton
  • Johnny555 3y ago
    Its a reasonable question - what human made artifacts would survive for hundreds of millions of years? Would concrete and steel buildings still be intact after hundreds of millions of years of erosion and weathering? Would objects in a 5 story deep basement be intact? Would even something we placed on the moon be visible after a 500 million years of micrometeorite impacts?
    • halfcat 3y ago
      Erosion would happen, but also icebergs would wipe out anything like buildings during the next ice age. And eventually subduction would consume the existing earth’s surface into the inner molten layer, leaving behind zero trace, but that might take hundreds of millions of years.
      • Gare 3y ago
        Cratons don't get subducted, that's a common misconception. https://en.wikipedia.org/wiki/Craton https://en.wikipedia.org/wiki/Craton
        • halfcat 3y ago
          Interesting! Thank you. So craton areas, say, near the equator where icebergs may not reach, could possibly contain remnants from indefinitely old civilizations?
  • aaron695 3y ago
    [dead]
  • alexey-salmin 3y ago
    Which exact artifacts do you have in mind that won't desintegrate in a few hundred million years? Pyramids won't last even one million and they're not among the most fragile products of human civilization. You may have confused geology with archeology, they operate on completely different time scales.
    • nemo 3y ago
      Coins in the right conditions last two thousand years easily (I collect ancient coins, have some that are 2500 years old that are in excellent condition). I expect in the right conditions some would last a few hundred million years. There's plenty of other non-biodegradable, chemically inert, discoverable things like stainless steel tools, gold jewelry, and other artifacts that humans make that could easily persist for millions of years.
      • elbasti 3y ago
        I have no idea if a coin can last 100 million years under excellent conditions, but just to contextualize: The difference between a coin lasting a thousand (10^3) years and 100 million years (10^8) is five orders of magnitude. That's the difference between 1,000 years and...3 days. "I collect sandwiches. I have some that are 3 days old and in excellent condition. I expect that in the right conditions one could last 1000 years"
        • nemo 3y ago
          As soon as coins appear in a geologic stata they become the most common archaeological artifacts found from humans, and at this point we've got hundreds of billions of them spread all over the globe with many becoming lost in spots where even if they were submerged in water, they could easily still remain intact for hundreds of millions of years. Not all coins are inert, but many are, and many really are going to stick around millions of years. While volcanic heat and pressure can mangle inert metals, not many other natural processes will. There's no magical entropy that would cause inert artifacts in geologically stable areas that some coins would wind up in to just lose their form magically. In our world today there's a lot of stainless steel, gold, and other inert artifacts that are going to persist for hundreds of millions of years. It's not like there's volcanoes everywhere, nor do tectonic plates subsume everything - we've got Cambrian fossils after all...