I watched a special years ago about what would happen to our infrastructure, buildings, etc if humans just blinked out of existence. The show start off advancing time, touching on events as they might occur. The very last thing to withstand the test of time was Mount Rushmore, due to be carved from granite. Mount Rushmore would stick around for a very very very long time and would be the last trace of us. But that’s just that one TV show special’s opinion, but it sounds pretty…solid to me.
but it sounds pretty…solid to me.
I see what you did there. I, for one, think it’s a rock solid pun that most will take for granite.
I wonder if Mt. Rushmore would be obvious if you’ve never seen a primate. If a super alien species is investigating, I can imagine them not realizing that it was designed by sapient life.
Almost certainly, depending on the time scale. Physical constructs will eventually break down, but the impact on the environment in total will likely be able to be deduced for millions of years.
For example, we already have a good record of the five previous mass extinction events, and can tie them directly to geological causes. On our current trajectory, a sixth wouldn’t necessarily tie well to any other factors other than the activity of a dominant species. This is one of many factors in the proposed geological epoch of the anthropocene.
What about plastics?
You think plastic lasts millions of years?
Yes, even in millions of years, traces of human civilization should still be easily detectable by a future civilization. The geological record will contain many elements that don’t occur naturally and would point to an industrial civilization. Some relics of human civilization will fossilize or otherwise be preserved. Finally, there will be well preserved human-made objects in space, either in high earth orbit or on the moon.
I would guess that things like massive landfill dumps would be almost impossible to wipe all trace of. There’s no natural process that can collect that huge number of different chemical elements in such high amounts into a single location. So even if literally everything manmade has broken down to its consistent elements, the presence of a mile-wide radius plot of earth containing every solid element in the chat would be a clear indicator that an advanced civilization must have been there.
Nokia 3310
It’d still be charged
That, and my old gameboy
I think GB really only had about 4 hours of battery life, idk how long it can go turned off but it’s probably greatly dwarfed by some modern phones.
Depends on the sort of batteries you use. Modern AA batteries are a lot more efficient than they were in 1989.
Depends on when the next intelligent species arises. Maybe they were the one that drove us to extinction!
But even if it takes a few million years, we’ve build massive amounts of infrastructure that won’t be going away anytime soon.
If we are talking millions of years it will become more and more unlikely that there will be anything left to find. In those timespans new geological formations happen.
Look at fossils as example. Yes, we have quite a lot of them but they stretch over a couple hundred million years, so imagen the things we don’t know about these periods. Now consider that modern humanity has been around for about 12 k years and the chances of researchers finding remains of our infrastructure in many million years by chance become tiny, just like the layers of sediment containing our remains.
What’s imho a lot more plausible is, that future researchers might find traces of our lasting impact on the atmosphere aka climate change in Arctic ice and wonder what caused it, prompting them to dig around in geological formations from our period which then might lead to some discovery.
Look at fossils as example. Yes, we have quite a lot of them but they stretch over a couple hundred million years, so imagen the things we don’t know about these periods
I get your point. But then again look at how many fossiles there still are. And those are all biologically, easily degraded. We’ve build quite sturdy things and even if only a tiny fraction survives there should be plenty for future archeologist to figure out that there was some civilisation at work.
With the extend that humans have changed the planet, we should leave a very obvious geological marker. Like suddenly there is plastic in the sediment layers …
The crust has a few tectonically stable regions that have never slid into the mantle. This is where we’ve found rocks that date all the way back to 2-3 billion-ish years. We call them geologic shields.
Our current activities would leave chemical markers in these regions that would be detectable for a very, very long time, and could come from no known natural process.
Otherwise you’re right, everything else eventually slides into the mantle and gets turned back into magma over a long enough timeframe.
To be fair, the effect of stuff being cycled back into the mantle doesn’t destroy every human artifact regardless, given that some of our constructs aren’t even on earth. Though I’m not sure that the odds of anyone actually finding one of our space probes is that high, the solar system is a big place after all.
Just a wee microscopic layer of plastic in the geological sediment.
Earth: Now with a bright & delicious hard candy shell!
A layer of space trash floating around the planet
A lot of that will eventually make its way back down to earth.
Some will still be there, especially in higher orbits, but the majority will eventually see orbital decay.
I’d guess that even in the higher orbits the manmade materials will eventually fall down or spin away over the span of a few hundred thousand years. Even if it is currently in a perfect locked orbit, there will be some amount of mass loss over time that will alter the orbit. But I’m no physicist, so i easily could be wrong
Any remaining Ice Sheets will have an accurate record of air emissions such as Carbon where the depth roughly equals the time since, and since just before the Industrial Revolution the amount of carbon emission shot up like the face of a cliff compared to the hundreds of millions of years before it.
A very thin smear of exhaust fumes, plastic, and rare radioisotopes.
The stuff humans have left on the Moon and Mars would probably be good indicators.
And a Tesla roadster flying about in orbit somewhere
Depends entirely on how long until the “next intelligent species to arise” (no reason to expect it ever will)
squirrels will be next
Fertilizer is what I’ve heard.
Long after the weight of ages has ground our works and bones to scattered dust, the changes we’ve made to the nitrogen cycle will stick out in the geologic record.
The jump from base levels of nitrogen to the obviously unnaturally higher amounts that would remain in layers from our time just wouldn’t have any explanation other than something did it on purpose. There’s basically no way for that level of increase to occur in what is geologically the blink of an eye without industrial capacity. Or that’s what I’ve heard.
I’ve heard that our nuclear impact will be seen for a very very long time from all the nuclear testing we did
And plastics
And our fertilizers
You’re thinking on the scale of thousands of years, you need to think on the scale of millions
A sharp increase in Carbon-14 would be visible for a few thousand years.
The rest of the elements released by nuclear testing? Not so much. Cs-137, and Sr-90 both have half lives of about 30 years. That means that after about 300 years, they’re both completely decayed into their daughter products.
Now, Cs-137 decays into Ba-137, which is stable. It’s also naturally occurring as about 11% of all Barium.
Sr-90 decays to Yt-90, spends a few days as such and then decays to Zr-90, another naturally occurring isotope. Zr-90 is a bit over 50% of all naturally occurring Zirconium.
Fertilizer is what I’ve heard.
Long after the weight of ages has ground our works and bones to scattered dust, the changes we’ve made to the nitrogen cycle will stick out in the geologic record.
The jump from base levels of nitrogen to the obviously unnaturally higher amounts that would remain in layers from our time just wouldn’t have any explanation other than something did it on purpose. There’s basically no way for that level of increase to occur in what is geologically the blink of an eye without industrial capacity. Or that’s what I’ve heard.
