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At one level yes, most everything built will disintegrate with time, but we have fossilized footprints from dinosaurs. An industrial society disappearing without a trace seems unlikely. Although the vast majority of the evidence would be lost there will always be traces left if you know what to look for.

The thing is, it’s probably unbelievable when you do find evidence. https://archaeology-world.com/200-million-year-old-shoe-prin...

Interesting article, but unfortunately none of it is verifiable. It cites creationism.org (!!!) as a source and concludes that the fossil shoeprint is regrettably lost.

> It cites creationism.org (!!!)

Ouch... that's an enormous red flag. That irrecoverably tarnishes the entire article.

Yeah, that was part of the point I implied. Much fossils were found before “modern archaeological practices” were invented and used. Now, we only have myths (for lack of a better word) about them. So it only enhances the unbelievability of the item.

Another point that I don’t see made, is that if there was advanced tech, the “artifacts” were likely used until they ceased to exist and/or their purpose was lost.

Just think about our own society. If our entire power grid was lost, we would probably lose the ability to repair/rebuild them within a few generations. There may be pockets where electricity still runs, and some people will remember, but there will be no way to build new computers or phones, so they will invariably be brought to wherever electricity still exists, but even then, the ability to recreate them will cease to exist.

The dinosaurs lived for a couple hundred million years. An industrialized society might last a few thousand.

You'd want to compare the total number of dinosaurs that ever lived against the number of fossil-izable and recognizable artifacts an industrialized society ever created.

True... Assuming that any individual has an equally likely chance of getting fossilized. It also brings up the idea of whether or not we would know if some fossilized specimen or footprint belonged to an animal or a civilized individual.

Those people need to watch a few episodes of the TV series Life After People. Watching it, and realizing that everything around us would literally start to fail in a matter of days without us as its caretakers, really brought home the impermanence of everything. Skyscrapers are certainly not going to outlast ancient cave dwellings. In a matter of a couple hundred years, I would be surprised if a single skyscraper was still standing without us to keep it up. I’ve seen unmaintained buildings falling a part after a mere decade of disuse; a skyscraper lasting for a century or two would be extremely durable on the scale of modern buildings.

Nobody is building for the super long term, we expect on some level that new will replace the old at some point.

This man is trying to build a clock to last 10k years. https://longnow.org/clock/

For what it's worth, the Spivey Building is almost 100 years old and it's been abandoned since the '50s.

https://en.wikipedia.org/wiki/Spivey_Building

St. Louis has a lot of cool abandoned architecture, although you might want to be careful wandering around East of the river.

I wonder how many cities have abandoned towers that became historical places thanks to longstanding traditions of not being able to afford a demolition.

I wonder how long the Egyptian pyramids would last.

As the pyramids are constructed of limestone, they would desolve during the next wet phase of the sahara ( previous wet period ~20kya and 12.5 kya ).

https://en.wikipedia.org/wiki/Sahara_pump_theory

Forget skyscrapers, instead consider this: footprints. You likely made millions of them in your life. How many of them still exist? Approximately zero. It's hard to think of something more ephemeral.

Yet dinosaur footprints have been fossilized. They're found all around the earth.

I'm sure our civilization has already created a gazillion things more permanent than them.

Yeah, but consider the base rate. Even if the things we create are more permanent that footprints, there are just so many footprints that some of them, by unbelievable triple-corner case coincidences, end up here for us. Even if the chance per footprint is really low, there are so many of them made over the course of hundreds of millions of years that it doesn't matter. Our 100 year industrial history is nothing compared to that.

Is total human/intelligent species population not a prerequisite for industrialization. If so, we would expect to see a lot of fossilized remains, which we have not seen.

We have found exactly one (1) skeleton of a Clovis person, the dominant human culture of North America for several centuries, right up until exactly the start of the Younger Dryas cold spell, only 12900 years ago.

Some structures should survive millions of years in dry buried conditions. Like bank vaults made of thick stainless steel buried in Arizona.

I strongly agree with this take.

I've been working on a paper comparing the effects of the Anthropocene to mega catastrophes in the geologically recent past. In addition to the Younger Dryas Impact (12kya), there's the Oruani (26kya) and Mt Toba (77kya) eruptions. From my calculations, it seems the climate change from each of these dwarfs any actions humans are currently capable of, namely petrocarbon burning and also total nuclear war.

I'm also critical of the account given to these events in the IPCC reports.

It seems unbelievable to me that the climate change debate isn't considering these more, so I'm still debugging the numbers and research. But happy to take comments from anyone who's interested!

https://docs.google.com/document/d/1yo9yHMfEnEepefDCRdar-B-4...

The earth is warming at a rate of four Hiroshima bombs per second [1] primarily because of human actions. I haven't read your document but it sounds like you're grossly underestimating our energy output.

[1] https://archive.thinkprogress.org/earths-rate-of-global-warm...

Regarding Toba, Le Wik has this to say:

The erupted mass was, at the very least, 12 times greater than that of the largest volcanic eruption in recent history, the 1815 eruption of Mount Tambora in Indonesia, which caused the 1816 "Year Without a Summer" in the Northern Hemisphere.[8] Toba's erupted mass deposited an ash layer of about 15 centimetres (5.9 in) thick over the whole of South Asia. A blanket of volcanic ash was also deposited over the Indian Ocean, the Arabian Sea, and the South China Sea.[9] Deep-sea cores retrieved from the South China Sea have extended the known reach of the eruption, suggesting that the 2,800 km³ calculation of the erupted mass is a minimum value or even an underestimate.[10] Based on new methods (crystal concentration and exponential), the Lake Toba Caldera possibly erupted as much as 3,200 km³ of ignimbrite and co-ignimbrite.

I think its more likely your cursory dismissal which is failing to appreciate the magnitude of this event, than that the person who is actually crunching the numbers is getting it wrong. But what do I know?

I spent some more time on this and now have a comparison table, with citations in my doc. V8 volcanoes still look more energetic and happen once every million years. @ancientworldnow, I'd note that the figure of 4 Hiroshimas/second is the measure of Global Warming, not of human energy production. Hansen acknowledges this in the linked TED talk from your citation, at about 7 minutes in ("it's about 20 times greater than all the energy used by humanity"). To get a sense of comparison, I also found that is the total energy released by a hurricane (note, ~99% hurricane energy is released in evaporation, the kinetic is ~1%):

Mt. Toba 74kya, VEI 8/M8.8 eruption energy: 1e21-1e22 Joules

Global Warming: 7.88e21 Joules/year

A hurricane: 1e21 J

Hiawatha Crater impact energy: 3e21 J

Human energy production 2013: 5.7e20 J/year

Mt. Tambora 1815, VEI 7 eruption energy: 1.3e20 J

Largest earthquakes 2: 1e19 J

Mt. Pinatubo 1991, Krakatoa 1883; VEI 6 eruption energy: 8.3e17 J

Mt. St. Helens 1980, VEI 4 eruption energy: 1e17 J

World nuclear weapon stockpile yield (estimate 2, extrapolated from USA): ~1e16 J

United States nuclear weapon stockpile yield 2020: 1.37e15 J

M8 Volcanoes once every million years, but M7 yield > 10x more energy over time:

“Analysis of this dataset indicates that eruptions of size M8 and larger have occurred with minimum frequency of 1.4 events/Ma… While the effect of any individual M8 or larger eruption is considerable, the time-averaged impact (i.e., erupted mass*frequency) of the very largest eruptions is small, due to their rarity. The long-term, time-averaged erupted mass flux from magnitude 8 and 9 eruptions is ~10–100 times less than for M7 eruptions; the time-averaged mass eruption rate from M7 eruptions is 9,500 kg s1, whereas for M8 and M9 eruptions it is ~70– 1,000 kg s1. Comparison of the energy release by volcanic eruptions with that due to asteroid impacts suggests that on timescales of <100,000 years, explosive volcanic eruptions are considerably more frequent than impacts of similar energy yield. This has important implications for understanding the risk of extreme events.” - Mason et al2

I think you're right, if you take the extreme events that have happened on this planet - and arguably the ice ages themselves also belong there, human activities haven't yet produced anything of that magnitude.

The question is how many more years do you want to give it until we do. These are huge slow systems we are looking at, at the point there is clear evidence around us that disaster is on the horizon, it is already several decades too late to do anything about it.

Previous catastrophes did not vent the millions of tons of hydrofluorocarbons into the atmosphere that we will, that break down into a greenhouse gas thousands of times as potent as CO2. (We thought switching from CFCs to HFCs would save us. Joke's on us!) The total of HFCs currently in circulation, eventually leaked or vented, will produce as much greenhouse effect as all the CO2 currently in the atmosphere. (A sharp minority of the responsible people collect it for disposal.) So, it's not just CO2.

The US is supposed to switch from HFCs to something else around 2024. A lot of companies are switching to propane refrigerant ahead of time because it's cheaper, and worry about it igniting has dissipated, vs. looming ecological catastrophe.

BTW, to my knowledge the Greenland structure has not been reliably dated, nor even confirmed to be a bolide crater (although it seems like one). YD bolide impact seems pretty secure, though.

Temperature change might be a relatively minor effect of the CO2 concentration peak. Ocean acidification causing a collapse at the base of the food web, as marine animals become unable to fix calcium to make shells, might be more important.

It's not clear to me that volcanoes don't release both CFCs and HFCs. Do you have a citation?

I'm looking at the wiki articles, and then at the related chem articles about HFC types and synthesis. I'm not a chemist, but a quick look around makes me think the known CFC, fluorocarbon and halomethanes in volcanic gases would suggest the same or similar compounds as in our engineering uses.

https://en.wikipedia.org/wiki/Volcanic_gas#Composition https://en.wikipedia.org/wiki/Halomethane https://en.wikipedia.org/wiki/Hydrofluorocarbon

On Hiawatha, agreed it's not yet dated, though it is recent: "The age of the crater is presently unknown, but an impact sometime during the Pleistocene is consistent with presently available geological and geophysical data." - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6235527/

They also raise the possibility that some of the radar returns indicate it's still hot in the center of the impact area(!). If so, it's probably one of the YDB impactors.

Btw, there's been another one discovered near it: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL07.... They say they don't think it's related, though it does still have large features that should have been eroded away if it were really old. We'll see!

Has anyone methodically looked for artificial materials like microplastics in the geological strata?

Yes, in that people try and identify what’s there. No, in that it’s not expected to find evidence of a prior advanced civilization. The prior existence of oil as an easily recoverable resource is a strong indicator that nothing like our civilization existed in the last several million years.

Indeed most of our fossil fuels were created during a window in the evolution of life on Earth where plants had developed tough cell membranes that the microbiota could not deal with and transformed the planet into a massive mountain of underbrush in a heavily oxygenated environment. The forest fires must have been spectacular. Trees grew tall and eventually died. Then they fell over, but did not rot. Instead stacking deeper and deeper. This is why we have seams of fossil fuels in the ground to draw from today.

If we wipe ourselves out the following civilization will have a much tougher time getting through their equivalent of the industrial age, especially if they're dealing with the aftereffects of climate change.

But not finding fossil fuels wouldn't tell you anything, because nobody knows how much there ought to be.

If they discovered better sources of energy a little faster, they would stop pumping almost immediately. But for politics, the US might easily have started the switch to wind power forty years ago, and billions of barrels' worth would still be in the ground.

Oil is useful for a lot more than just burning it. Fertilizers, plastics, and asphalt are the most well known but a host of industrial processes use it as a feedstock. It’s only recently that oil has been hard to find, initially it was seeping up from the ground which still occurs on the sea floor in some areas making it hard to miss.

So some other civilization could exist without using it, but they would look nothing like ours.

It is one thing to use it, entirely another to exhaust it. A civilization consuming only 1% as much could look very similar, if it were not dependent on oil for fuel.

We don't need to exhaust it. We only need to exhaust the easy to find sources.

Oil is overwhelmingly used by burning it and its products. Only 4% of it goes to plastic production.

It’s not just plastic but also Asphalt, Lubricants, Fertilizer, etc. However, let’s assume they only used 10% as much oil as us and only used oil for ~100 years before dying off.

They would still have started with easily extracted sources not offshore oil or ultra deep oil. The world had very easily extracted oil when we started. Further, there is no missing oil based on geology.

Oh, you have checked? There have been no dry wells?

I wonder where the term "dry well" came from.

Most dry wells are around oil fields. We have fairly good understanding about the overall geology of oil fields, but you can have a dry well 50m from an active well. What we don’t have is most expected oil fields without oil.

That's true about the oil; coal too. If we're not completely wrong about how those resources are created (there are some alternate theories) then we're the first civilization to use them.

However, most of what I've read about prehistoric advanced civilizations discussed them using crystals (quartz) and deriving energy from the earth. Some form of piezoelectricity. There are theories today connecting earth quakes, quartz deposits, and ball lightning, which could be hinting at an energy source we haven't explored yet.

We sent humans to space and robots to Mars and other planets, we are extracting energy from nuclear fission, we will likely build an artificial star soon enough. It's extremely unlikely that we could have missed some mysterious quartz power source.

That's all nice and dandy until aggressive aliens wielding muskets show up in wood & brass starship: https://en.wikipedia.org/wiki/The_Road_Not_Taken_(short_stor...

The premise of this story is hilarious and wonderful to contemplate as a possible scenario. Food for thought and thanks for the link. I'd never heard of it before.

After a couple thousand years of computational evolution, if you don't think there'd be a possible reason for leaving behind massive silicon crystals... Well, you haven't been reading enough science fiction.

If you could grow pure crystals more easily (thinking Diamon Age), why not have giant plates serving as a piezo generator or ambient electromagnetic waveguide harvesters?

So a civilization thousands years more advanced than us failed to go to space (evidenced by the fact that they did not leave behind any space junk) but somehow produced energy from crystals?

FWIW, space junk wouldn't necessarily survive that long. Things on lower orbits would deorbit themselves quickly without station keeping. Things on higher orbit would get pushed away by solar radiation over long time, and degrade under high-energy radiation (such as UV rays). What remains would be hard to find, because space is big, so it would have to be fairly large and/or fairly reflective for us to notice now.

Wouldn’t any constant force tend to ellipticize the orbit and lead to a return to earth?

Would have to do the math to be sure, but doing some quick simulations in my mind - I believe you're correct, modulo the impact of the orientation of that force changing (Earth goes around the Sun). Let me illustrate with a diagram:

                      PROGRADE
                     (raise apo)
                          | 
           +--------------+--------------+
           |                             | 
           |   ->      --->---      ->   |
           +-  ->    -/       \-    ->  -+
               ->   /           \   ->  
             / ->  /    /II\     \  |   -+
       +----+  ->  |   |IIII|    |  |    +- IN SHADOW
       |     \ ->  \    \II/    /   |   -+
       |       ->   \           /   ->
       |   +-  ->    -\       /-    ->  -+
       |   |   ->      ---<---      ->   |
    RADIAL |                             |
     IN    +--------------+--------------+
  (also raise apo)        |
   ((I think...))     RETROGRADE
                     (lower peri)

This shows a body in orbit (the empty sphere) around the body (the filled sphere). The orbit goes clockwise, sun radiation comes from the left, arrows illustrate the acceleration it creates on the body. Simulating it in my head, I believe such setup would lead to the orbit getting elliptical, with the apogee getting larger and the perigee getting smaller, all the way until either the perigee hits the atmosphere or the body reaches escape velocity (thanks to small, but unbalanced contribution labeled RADIAL IN).

I'm not sure how long such a process would take for a satellite not designed to exploit solar radiation for propulsion, nor whether it wouldn't be dwarfed by other orbit-disturbing influences such as the Moon and other planets.

Also: aerobraking a highly elliptical orbit isn't going to leave you much of a satellite to find.

(Note: I studied orbital mechanics in university on Kerbin, under Jebediah Kerman, so I might be wrong here.)

It would only be eclipsed, daily, during a small part of each half-year, no? And, on alternating sides of its orbit.

Usually people blame the moon, and three-body dynamics, for disrupting other Earth orbits.

> evidenced by the fact that they did not leave behind any space junk

Whatever space junk we leave behind will be gone 100 years from now. https://www.nasa.gov/news/debris_faq.html

That’s really not what that means. The 4th satellite Vanguard 1 was put into orbit in 1964 and it’s expected to have a 240-year orbital lifetime despite getting to within 657.3 kilometers of earth. https://en.wikipedia.org/wiki/Vanguard_1

Geosynchronous satellites 35,786 km (22,236 mi) are going to be up there for a very long time.

PS: If you’re interested https://aiaa.kavi.com/apps/group_public/download.php/3172/IS...'

And anything that went to solar orbit will be the more or less for ever, subject only to the slow erosion of thermal cycles over the eons. And all Pioneers, Voyagers and New Horizons will not have to sustain even that, just comic rays.

BTW, it's a bit mind boggling how big and empty even just interplanetary space is - there could be wrecks of an unlucky discovery fleet paying a visit couple milion years ago and we might never find them unless they come really close to Earth or other sensor rich human inhabitted place or possibly still produce some active emissions (outgassing, sporadic radio signals, abnormal heat absorption/radiation, weird albedo variations, etc.).

I think that’s just for lower orbits, I was under the impression our geosynchronous satellites will be up there for millions of years (unless future humanity cleans up the geosynchronous graveyard orbit)

There is the hypthecial concept of a https://en.wikipedia.org/wiki/Nuclear_lightbulb which pending some so far unavailable metamaterial would reach temperatures of up to 20,000°C and generate mostly hard UV-light in a closed cycle.

Which reminds me of some decsriptions of Indian Vimanas, or rather the parts about their engines, which allegedly were made of some crystals.

We know about the KT extinction layer (which contains a lot of iridium, a potentially extremely useful but rare metal) but attribute it to meteorite ejecta. It also coincided with large scale climate and environmental changes. That's the only candidate I know of as a non-geologist.

This argument disproves fossils.

E: To be pedantic, it only disproves most fossils.

And, as predicted by the argument, the fossils don't abound, and to find them you have to start digging.

I wonder if that's always been the case. Maybe humans quickly cleaned up all the easily accessible fossils before realizing what they were. Ancient Greeks thought they'd found a giant's bone and other cultures seem to have used dinosaur fossils as inspiration for myths of dragons. Even western researchers a few hundred years ago thought dinosaur bones were just recent animal bones. Imagine how careless every previous civilization was with them.

Maybe the biggest obstacle to archeology is having people around who are interested in explaining what they're seeing. Science is a very rare thing for human cultures to spontaneously do. Even the 1000s of years old Chinese civilization never invented science and had to wait for it to be imported. I tend to think that human societies naturally actively discourage science because they'd quickly think up and memetically spread myths for any unexplained phenomena then anyone challenging the popular myths would have to be a misfit and that would come with punishment because misfits were generally harmful to society in the short term.

> Even the 1000s of years old Chinese civilization never invented science and had to wait for it to be imported.

This line didn't pass the sniff test for me, so I did a quick Wikipedia check on the history of science in China. [1] Given the fact that Chinese Society has a large population and long written history, it seemed a bit strange to think that science and technology might have been imported from elsewhere 1000 years ago.

It was actually quite cool! Turns out gunpowder and crossbows were invented there for gaining an advantage in war. [3][4] In AD 132, Zhang Heng created the first seismometer to study or detect earthquakes. [2] Looks like China's had science longer than the United Kingdom's been united.

EDIT: added newlines to break up the Wikipedia hyperlinks

[1] https://en.wikipedia.org/wiki/History_of_science_and_technol...

[2] https://en.wikipedia.org/wiki/Seismometer#Ancient_era

[3] https://en.wikipedia.org/wiki/Crossbow#East_Asia

[4] https://en.wikipedia.org/wiki/Gunpowder

Yup. From what I remember my history, it was the other way around: China was ahead to a lot of discoveries, some of which the West has imported only centuries later.

Interesting thought in your second paragraph. Through similar reasoning it would also follow that one of the bigger forces promoting science - or at least applied science - would be war. It's one of those things that keep you grounded in reality - the ship will either sail or it will sink; the shell will either land on target or it will miss. When your invention is going to be put into combat use, you can't get away with nice-sounding stories. You get instant and often visceral feedback.

I'd say so but only once the science is advanced enough to be of more use than technology developed by trail and error and intuition, which is a pretty high bar. Just think that when steam engines were already in use commercially, we didn't even have the law of conservation of energy, and the whole field of thermodynamics was developed afterwards. We made metal and gunpowder without chemistry, electric lights without electromagnetism, etc.

For clarity, I'm not counting engineering and technology as science. You can develop techniques for building ships that float without understanding anything about buoyancy or mechanics of materials but just though gradual evolution of ideas and passing knowledge down through generations of craftsmen.

More broadly: survival. The crop that will grow or wither, the patient who will recover or die. Etc.

That's quite a different concept. Agriculture techniques would have evolved that way but entirely devoid of science or understanding of how they worked, just evolution of ideas ossified into wisdom. Colonists in new countries experienced crop failures because they couldn't predict how things would behave in the different climates/ecosystems and just applied their "dumb" knowledge. I heard about a hunter-gatherer society that used a seemingly pointless ritual to decide where to get food each day. They had only a superstitious explanation of how it worked until we eventually figured out that the ritual was actually a random number generator that helped them to spread their gathering more uniformly or prevent prey from learning their habits or something along those lines. We can do a lot without understanding.

Medicine was a complete shit-show until modern science because people didn't even understand how to test if it caused patients to live or die! Even today in modern China, doctors still prescribe useless herbs based on superstition. They've stripped away the obvious nonsense about stars and planets that it used originally but still explain it using a mythical description of how the body works and how traditional medicines interact with it.

I guess you could say domains involving physical construction that had to be customized to varying circumstances required better understanding of the underlying physical processes at play.

So building war implements, like weapons and armor, and techniques, like how to target a canon, but also non-military disciplines, like the construction of buildings and bridges, the manufacture of commercial goods, etc.

I agree that they'd be underground.

If someone starts looking they will find this layer containing plutonium-244 (which is made by nuclear explosions, 80 million year half life) and microplastics, and yeah that will make it pretty obvious. But I think you're right that if it was even 5 million years in the future you would really have to be looking for it.

I strongly doubt microplastics would survive heat and pressure well enough to not revert back to oil/gas/coal.