Silurian Hypothesis • Hacker News Board

Re: Silurian Hypothesis

#61

Post by kadoban » Sun, Feb 12, 2023, 4:43 PM UTC

throwaway4aday wrote: post #37

simonh wrote: post #16

It’s true that only very few individuals would be fossilised and fewer if they found. Nevertheless we do generally find multiple fossils of the same or closely related species. We also find fossils of multiple stages in the evolution of many species. So it seems unlikely to me that we would find zero fossils of a species advanced enough to colonise the entire planet, as we have, nor any of their ancestral species. It…

A fun thought experiment is to imagine what we will do once we leave the cradle of Earth behind. Will we just leave all of our junk here? Make the homeworld a monument to our past? We would know that it wouldn't last, everything decays with time so some would argue it would be a crime not to preserve it and the only way you can be sure to preserve something is by regularly tending to it. I imagine many would argue th…

> A fun thought experiment is to imagine what we will do once we leave the cradle of Earth behind. Will we just leave all of our junk here? Make the homeworld a monument to our past?

It is a fun thought experiment, but humanity is big. Humanity leaving Earth would be extremely more likely to look like a few people hopping on a ship and flying away and everything else stays the same.

For it to look anything like "last one out, turn off the lights" type of thing, energy would have to be truly free and there would need to be a _very_ compelling evacuation scenario. Otherwise there would be a lot of people left behind for social/economic reasons or because they just don't want to leave.

Re: Silurian Hypothesis

#62

Post by kadoban » Sun, Feb 12, 2023, 4:47 PM UTC

jiggawatts wrote: post #49

throwaway4aday wrote: post #35

Earlier quoted context omitted.

Most evidence would be gone after a few million years. Any metal that oxidizes would go first, aluminium included. Concrete would disappear with weathering, earth quakes, and even just by the action of plants. Huge open pit mines or mountain top removal would be weathered away and filled in with sediments. Plastics decompose and chemicals are diluted and dispersed or consumed by microbes. Gold jewelry may last a long…

We’re finding organic remains like skeletons hundreds of millions of years later! Manufactured goods made of durable materials would certainly be just as easy to find. It’s simple logic.

We find _extremely few_ organic remains that got ungodly lucky and are still recognizable after so long.

Most "durable" goods are durable only on human scales of time, and if anything are less likely to survive on longer time scales.

Re: Silurian Hypothesis

#63

Post by puffoflogic » Sun, Feb 12, 2023, 5:41 PM UTC

When discussing the fossil record it's astonishing that no one ever mentions the possibility that an advanced species would intentionally remove all geological and archaeological traces of its existence. Why would they do that, you ask? Well, quite possibly for similar reasons homo sapiens is currently doing the same thing! The environmentalist ideology holds that we must return the planet to a pre-industrial state, as much as possible, and to leave as few non-degradable artifacts as possible. The movement would achieve success precisely when there is no evidence left that humans ever existed.

Re: Silurian Hypothesis

#64

Post by throwaway4aday » Sun, Feb 12, 2023, 8:02 PM UTC

kadoban wrote: post #61

throwaway4aday wrote: post #37

Earlier quoted context omitted.

A fun thought experiment is to imagine what we will do once we leave the cradle of Earth behind. Will we just leave all of our junk here? Make the homeworld a monument to our past? We would know that it wouldn't last, everything decays with time so some would argue it would be a crime not to preserve it and the only way you can be sure to preserve something is by regularly tending to it. I imagine many would argue th…

> A fun thought experiment is to imagine what we will do once we leave the cradle of Earth behind. Will we just leave all of our junk here? Make the homeworld a monument to our past? It is a fun thought experiment, but humanity is big. Humanity leaving Earth would be extremely more likely to look like a few people hopping on a ship and flying away and everything else stays the same. For it to look anything like "last…

It's all about incentives. A huge percentage of the human population has decided to live in cities because they offer a variety of incentives to live there. The transformation isn't complete but if the benefits were even greater then you could eventually see a complete shift.

Who knows what incentives a hyper-advanced civilization might have? Maybe life in space is a million times more appealing than life on a planet for a sufficiently advanced technology level. If estimates are to be believed then the resource wealth of the solar system far exceeds anything contained within the Earth. If you've solved the problems of efficient space propulsion, resource extraction and construction then you would have access to an abundance of everything you need. Space also has a lot more space, enough room for any person or group of people to build whatever they want without annoying their neighbours. It also has more energy both in the form of sunlight and radioactive elements. So yes, maybe energy and matter are nearly free for a true space faring civilization and maybe that's the reason no one would want to stay behind or at least so few that they would leave very little evidence of their presence.

Re: Silurian Hypothesis

#65

Post by aetherson » Mon, Feb 13, 2023, 5:15 AM UTC

simonh wrote: post #59

aetherson wrote: post #38

Earlier quoted context omitted.

So this article: https://www.science.org/content/article/most-species-disappe... says that of modern threatened-but-not-extinct mammal species, we have recorded fossils for 9% of them. For non-threatened extant mammal species, we have recorded fossils for 20% of them. Assuming that's correct, it doesn't seem crazy to imagine that we might not have fossils for a species or it's say 5 ancestors species that existed let…

Considering an extant species is like picking an arbitrary point in the existence of a past species, and excluding all fossils formed after that point. On average that half the fossils. As for threatened species, just a guess, but I’d expect most of those to be likely have relatively small populations to start with and live in constrained habitats, all factors that would tend to mean they would leave a lot fewer foss…

I think you're dramatically overestimating the likelihood that artifacts would survive in recognizable form for millions of years. I do think we can be reasonably sure that there was no advanced technological society let's say 50,000 years ago. But 20M years ago is another story. 5M years might be another story.

Whether you'd find fossils of an advanced technological species at a point in their history when they might have a population of billions seems incredibly contingent on unknowable things about their culture. But the question of whether you'd find fossils of them from their prehistoric period (in which their population would not necessarily be enormous), or of their evolutionary ancestors seems less contingent, and very plausibly you wouldn't.