Metals are here, will recycle in the earth. Where will it go?
Comment on What would remain for a future species if humans were to vanish tomorrow?
sxan@midwest.social 2 days ago
The biggest challenge for future intelligent species, and the reason why I know we’re the first technological ones, is that we’ve mined all of the easily accessible metals and all of the easily accessible fossil fuels. Any intelligence arriving after us is going to have to make a civilization without iron, precious metals, oil, or coal. Unless you get into some sci-fi bio-engineering scenario where they’re growing high tech, they’re doomed to being stuck in the stone age. It’s going to be hard for them to escape the planet, defend it from asteroids, deal with super-volcanoes, build advanced calculating devices… all of the stuff we would already find challenging even with all the resources we have.
Millions of years are not enough to replenish the fossil fuels, and the sun is going to start expanding before enough life lives and dies to produce any useful amount of biomass. Before then, more metals will become accessible, in places, but good luck working it at industrial levels without fossil fuels.
I’m not saying it’s impossible, but we’ve given a severe handicap to advancing beyond a rudimentary agrarian society for any successor species; even if it’s our own descendants re-arrising from a post-apocalyptic environmental catastrophe.
mitrosus@discuss.tchncs.de 2 days ago
BurgerBaron@piefed.social 2 days ago
Lower end of Earth being in the habitatal zone being just 1 billion years left. Our consumption of the easy to reach resources before them arriving to the scene, I think you're likely right.
Upper estimates are ~3 billion for habital zone, and Red Giant phase being ~5 billion years from now for factoid funsies.
realitista@lemmy.world 2 days ago
AFAIK metals don’t really go away over time so I would think they would be easy to harvest from the metals that are here today, no?
Simulation6@sopuli.xyz 2 days ago
I read a SIFI story were a future civilization was mining rebar out of collapsed cement structures and wondering how the ancients managed to get iron into rocks.
sxan@midwest.social 2 days ago
Any worked iron product rusts. If we’re talking about evolutionary time scales, any exposed metal - which is most of it - is going to be unusable within thousands of years, and even rebar embedded in concrete will be gone in millions. Heck, our concrete isn’t even as good as the Romans’, and even that’s going to break down in thousands of years.
We’ve stripped the raw, surface, easily accessible stuff and worked it into things that will degrade. There may be some scavenge, but nothing that can be gathered in any quantity to build an industrial society on. At best, future societies will be like medieval Japan, where iron is rare and steel precious and hoarded, only unlike Japan, there won’t be a future where they can import huge quantities of the stuff from China or Australia, because getting to the deposits now requires an industry and advanced mining equipment… which is all made out of iron they won’t have.
Gold will be interesting. Again, it’s not just laying around everywhere just under the surface. Instead, there will be isolated pockets of huge piles of the stuff. Gold doesn’t degrade, but it’s all hoarded. There’s a bunch in electronics, but in tiny, tiny amounts in each device; trying to salvage that is really hard, and yields trace amounts. No more nuggets the size of your thumb, or your fist. If a future civilization could build a global economy, then gold wouldn’t be an issue. Uranium will be hard, as will platinum, and platinum is a useful, but consumable, catalyst, and rare even today it’ll be almost unheard of in a perpetually pre-industrial post-apocalypse.
Fossil fuels are going to be the big issue, though. What’s left will simply be inaccessible, and without fossil fuels you don’t have plastics, industry, fertilizers at scale, global transportation, or the ability to work whatever metal you can find, at any scale.
realitista@lemmy.world 2 days ago
But even rusted iron can be re-smelted, no?
sxan@midwest.social 2 days ago
Rust needs to be reduced back to ore, using a reactive, usually coke. Coke is purified coal. Coal is a fossil fuel. You can do it with charcoal, which can be made by burning wood, so it’s possible without coal, just not as efficient. This assumes you can gather the rust - it tends to break down and disperse into the environment, but if you broke up concrete to get at rusted rebar and could collect the rust, you could reduce it with charcoal.
Again, it’s a matter of scale. We mine iron and deposits because we can get large amounts in seams. If you’re trying to harvest rust and reduced it with charcoal, you’re producing iron on the scale of making knives and swords, not cars, or combine harvesters, or more rebar.
It’s a chicken-egg problem. We have been able to come as far as a have because oil, coal, and iron were just laying around on the surface, in huge quantities. Those are gone, and now you need the big tools first to get at the reserves that are left.
shalafi@lemmy.world 2 days ago
Earth would never get fossil fuels back as their formation was dependent on lacking fungi to break plants down. This is indeed our one shot.
Geobloke@aussie.zone 2 days ago
Well, no. Arabian oil is only a few million years old and peat, a precursor to coal, is still being formed. I could imagine new oil being formed in the Gulf of Mexico and in the Indonesian archipelago