Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Would it be possible to detect an industrial civilization in geological record?

arxiv.org

Post reply on HN
Print view View original

141–150 of 181 posts

Re: Would it be possible to detect an industrial civilization in geological record?

#141

Post by lazyjones »

timoth3y wrote: post #87

It more convincing to look at it the other way. It's not what such civilizations would have left, but what they would have taken. Our early civilizations found easily accessible deposits or tin, copper, gold, etc that would have been depleted if another advanced civilization had existed in the past 10 million years or so.

> Our early civilizations found easily accessible deposits or tin, copper, gold, etc that would have been depleted if another advanced civilization had existed in the past 10 million years or so.

Perhaps they also found remains of other advanced civilizations and axploited those?

10 million years is nothing in geological terms.

Re: Would it be possible to detect an industrial civilization in geological record?

#142

Post by TeMPOraL »

nraynaud wrote: post #60
TeMPOraL wrote: post #44

Earlier quoted context omitted.

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.)

Re: Would it be possible to detect an industrial civilization in geological record?

#143

Post by TeMPOraL »

danbolt wrote: post #106
lopmotr wrote: post #52

Earlier quoted context omitted.

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…

> 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 100…

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.

Re: Would it be possible to detect an industrial civilization in geological record?

#144

Post by dvdkhlng »

rmtech wrote: post #140

Yes, it will definitely be possible via hundreds of different pathways, some of which they thought of in the paper and others that they didn't. > The Anthropocene layer in ocean sediment will be abrupt and multi-variate, consisting of seemingly concurrent specific peaks in multiple geochemical proxies, biomarkers, elemental composition, and mineralogy. It will likely demarcate a clear transition of faunal taxa prior…

> One that they didn't mention was our artifacts on the moon which will last 100 million years or so. Geostationary and HEO satellites will stay for a while but I'm not exactly sure how long.

Erosion due to micrometeorites erodes the surface of the moon at 1mm per 1e6 years [1]. I wonder whether erosion of human-made moon artifacts will commence at a comparable rate.

Note that the hull thickness of the apollo lander is just 0.3 mm [2]. Part of the propulsion system, tanks etc. would be the components to last longest, butt 100 million years may be quite a stretch.

[1] https://mauricejscollins.wixsite.com/moonscience

[2] https://space.stackexchange.com/questions/924/what-would-hav...

Re: Would it be possible to detect an industrial civilization in geological record?

#145

Post by zaphirplane »

filoeleven wrote: post #123

One of my favorite quotes from Iain M. banks’ Culture series, paraphrased here since I don’t recall which book it’s in, is that technological progress is more like scaling a rock face than climbing a ladder. There is so much room for surprise and incomprehension. I sometimes think about how vast the parameter space of our physical universe is, and if that vastness means we wouldn’t be able to recognize ancient advanc…

Why do you think that an old civilization with deeply held beliefs of gods, magic, seers, oracles ... etc find it hard to believe that a library worth of books has been shrunk down. There is only a small window where magic/gods was being supplanted by monotheistic dogma that is plausible. On the other hand you tell me this dot contains the total sum of knowledge and I’d be nice ... or a drop of this liquid would destroy a solar system I’d be where is the lid

Re: Would it be possible to detect an industrial civilization in geological record?

#146

Post by 74ls00 »

oh_sigh wrote: post #111
timoth3y wrote: post #87

It more convincing to look at it the other way. It's not what such civilizations would have left, but what they would have taken. Our early civilizations found easily accessible deposits or tin, copper, gold, etc that would have been depleted if another advanced civilization had existed in the past 10 million years or so.

Tin was actually very hard to find. Which is a huge problem for civilizations that wanted to be a part of the Bronze age. Most of the tin used in Europe and western Asia was mined from just a few places in England, France, and Spain. if you find an Assyrian weapon from the 12th century BC in northern Iraq, it shouldn't surprise you if you find it was forged with tin mined in Cornwall.

IIRC tin was one of main motivating factors for the Roman invasion of Britain

Re: Would it be possible to detect an industrial civilization in geological record?

#147

Post by Retric »

bufferoverflow wrote: post #101
Retric wrote: post #56

Earlier quoted context omitted.

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 nothin…

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.

Re: Would it be possible to detect an industrial civilization in geological record?

#148

Post by shadowprofile77 »

m4rtink wrote: post #115
vbezhenar wrote: post #24

Earlier quoted context omitted.

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.

Re: Would it be possible to detect an industrial civilization in geological record?

#149

Post by mongol »

zaphirplane wrote: post #145
filoeleven wrote: post #123

One of my favorite quotes from Iain M. banks’ Culture series, paraphrased here since I don’t recall which book it’s in, is that technological progress is more like scaling a rock face than climbing a ladder. There is so much room for surprise and incomprehension. I sometimes think about how vast the parameter space of our physical universe is, and if that vastness means we wouldn’t be able to recognize ancient advanc…

Why do you think that an old civilization with deeply held beliefs of gods, magic, seers, oracles ... etc find it hard to believe that a library worth of books has been shrunk down. There is only a small window where magic/gods was being supplanted by monotheistic dogma that is plausible. On the other hand you tell me this dot contains the total sum of knowledge and I’d be nice ... or a drop of this liquid would dest…

What would persuade them? It would be really hard to explain how it would be possible.

Re: Would it be possible to detect an industrial civilization in geological record?

#150

Post by mongol »

sjy wrote: post #130
JoeAltmaier wrote: post #124

Earlier quoted context omitted.

It wouldn't take a complex material to recognize a previous civilization. Their civil engineering activities would give them away completely. Archaeologists can read worked surfaces with amazing skill. E.g. a bed of pebbles could be a lake bed, a road surface, a floor inside a building, a foundation, and there's ways to distinguish them. Unless the soil was erased/reformed completely there would be a record of almost…

Geologic time is certainly enough to erase evidence of worked soils. It spans billions of years, the destruction and formation of continents, and multiple global mass extinctions. Archaeology concerns only the last few million years of hominid activity.

How will asphalt and concrete appear in the geological record? Would it not be identifiable? If we can recognize fossilized bones, a future civilization should civilisation able to recognize concrete with steel rebar inside, no?
Post reply on HN