Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Human civilisation in 1.5 billion years

  1. Jan 14, 2006 #1
    I once read a story on the internet, written by a supposed alien abductee, who said that intelligent insectoids will walk on earth in 1.5 billion years and find no evidence that humans ever existed. :biggrin:

    My question is:
    If all humans were to go extinct right now, what would be left of our civilisation in 1.5 billion years?
    Would a humanlike intelligence find and be able to recognise any ruins of things we built?
  2. jcsd
  3. Jan 14, 2006 #2


    User Avatar
    Gold Member

    In 1.5 billion years, I'd say not much. Long into the future I'd imagine there would be remains of cities in the sedimentary record. If humans went extinct right now, low-lying cities would not only gradually crumble, but flood and become buried under floodplains. So long as these are not subsequently eroded away, they will lithify and become a part of the sedimentary sequence until they are destroyed by erosion, or metamorphosed beyond all recognition. After 1.5 billion years it is likely that most of the rock has been lost though.
    I guess an additional advantage would be given to anything we have already buried, like nuclear waste.

    I wonder how well the stuff we leave in space would survive... Anyone know how likely it is a satellite will maintain its orbit, and how likely it is that the moon landers get hit by a meteor?
  4. Jan 14, 2006 #3
    There was a show on NGC in which they said a satellite can stay in proper orbit for 10 years to 15 years depending on how much fuel it has. I guess they come down after that and burn during reentry.

    Maybe its a good idea to build something that can withstand the forces of nature for a few billion years... if thats possible.
  5. Jan 14, 2006 #4
    Like Matthyaouw said already, we should scrutinize the moon surface for Dinosaur landers or something and those insects of 1,5 Byear in the future should look for our Apollo remains on the moon as well as some vehicles on Mars.
  6. Jan 14, 2006 #5
    Intellgent insectoids?He's wrong it's not going Intellgent insectoids It's going to be intellgnet squids I saw it on animal planet where there talking what life whould be like millons of years from now
  7. Jan 15, 2006 #6


    User Avatar
    Gold Member

    But this is 1.5 billion years ahead. The squid will have been and gone already. :tongue2:
  8. Jan 15, 2006 #7
    Not even animal planet is able to make accurate guesses on how life will be in two million years. The giant squid tale isn't true, it's merely a suggestion.
  9. Jan 15, 2006 #8
    Look at the obvious: mamalian life forms seem to have the ability to adapt exponentialy, is it fish, mamals, cephalopods, Insects, or plants, who will dominate?
    In our environment it's mammals. The inverse square law prohibits insects becoming large enough to become sentient, so only on low gravity worlds would they. And if low gravity there are much more viable alternatives. kinda funny the crap people will come out with. I'd imagine in certain conditions insects will rule a planet but mammalian type life forms will often dominate, for squid to become dominant would take a really wierd set of circumstances. Which is why I believe first contact will be between something different but fundamentally similar to us. And to be honest I don't believe Greg from wisconsin was the first person to make contact with an alien race:wink:
    Last edited: Jan 15, 2006
  10. Jan 15, 2006 #9


    User Avatar
    Gold Member

    In 1.5 billion years, anything on the surface of the Earth, even the most durable, will be subducted via tectonic activity back into the molten interior.

    Ironically, one of the only places evidence of our existence may remain is on the geologically dead Moon or Mars.
  11. Jan 15, 2006 #10
    I think alot of things will survive in 1.5 billions years. Unlike in any other time in history, people have manufactured billions or even trillions of products, ranging from tv, cars, trucks, tanks, airplanes, etc.

    Its just a number game, some of it has to survive because there is more human traces then there is time to destroy them.

    There is a rock in Australia that is believed to be as old as earth itself, forgot its name.
  12. Jan 15, 2006 #11
    Same with giant insectoid:rofl: There's probally no way to tell what Earth will look in 1.5 billon years if there's Earth still exist.
  13. Jan 15, 2006 #12
    Is there a geologist in the room? How old is Earth? And are we now capable of identifying anything that is 1.5 billion years old? Maybe an old chevy...
  14. Jan 15, 2006 #13


    User Avatar
    Gold Member

    Well, the Earth is ~5 billion years old.

    And as for things being around that long, well, most of Canada is 4 billion years old (Canadian Shield).

    So, I guess I just refuted my own claim about nothing lasting that long...
  15. Jan 16, 2006 #14


    User Avatar
    Gold Member

    There is definately rock older than 1.5 billion years. Due to its low density and greater thickness, continental crust will only subduct in very small quantities, so is largely preserved. The problem is, these ancient shield areas were probably formed as roots of mountain ranges- largely igneous, so no remains. They are so highly altered by metamorphosism that if there were any remains of life in them, they would be unidentifiable. There are sedimentary rocks surrounding these shields that age in the billions of years, so this suggests that there would probably be something left of the rocks from our age in 1.5bn years, but they may not be very extensive at the surface
  16. Jan 16, 2006 #15
    i heard that twinkies would survive that long.
  17. Jan 16, 2006 #16

  18. Jan 16, 2006 #17


    User Avatar

    Let's all go to the Twinkie factory after the end of the world. So we don't have to farm.
  19. Jan 17, 2006 #18


    User Avatar
    Science Advisor
    Homework Helper

    They must have been talking about a fairly low orbiting satellite (or maybe just giving an average since quite a bit of launch debris winds up in low earth orbit). The lowest stay up for less than a year. At around 700 km (a popular altitude), they'll stay up for maybe a hundred years. But, at an altitude of just 1500 km, they'll stay up for over 10,000 years.

    The only reason for geosynchronous satellites (over 35,000 km high) to come down is because sunlight has made their orbits elliptical enough that atmospheric drag can at least affect the satellite at perigee. After that, it's still a very slow process since most of the orbit is well above any atmospheric drag. I would have to imagine that 1.5 billion years would be more than enough time to do the trick, though.

    The Voyager satellites will be the first man made objects to leave the solar system (both are already past Pluto, but are still within the Sun's magnetic field). They'll run out of power around 2020, but that just means we won't be able to communicate them anymore. Both should last until they hit something. Of course, neither are coming back, so there won't be any trace of them on Earth.
  20. Jan 17, 2006 #19


    User Avatar
    Science Advisor
    Gold Member

    Hey I've heard that the shelf life of fruitcake is longer than the life of the shelf. Maybe the fruitcake we get for Christmas will still be around?
  21. Jan 17, 2006 #20


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    "Preservation" depends in large extent on "rapid burial." Keeping this in mind, it's possible that subterranean structures could be sufficiently filled with sediment following abandonment, extinction of the human race, that shapes would be preserved. The "Chunnel," Holland, Lincoln, Logan Island, Harbor (Baltimore), and other already buried tunnels, exist in a wide enough variety of geological domains that it's not unreasonable to expect that some would survive 1.5 Ga of uplift and erosion cycles.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook