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The Milky Way is probably full of dead civilizations

livescience.com

31–40 of 62 posts

Re: The Milky Way is probably full of dead civilizations

#31

It seems equally likely to me that conditions in the Universe just weren't amenable to life until relatively recently. Radio waves take time to travel; there could be many civilisations out there whose signals haven't had time to reach us. If that's the case, we're just the first intelligent civilisation to evolve in our immediate vicinity.

> It seems equally likely to me that conditions in the Universe just weren't amenable to life until relatively recently.

It's at least 4b years old on earth, that's not "relatively recently"

We've been technologically capable for less than 200 years, that's nothing in the grand scheme of things.

We could have just missed them by a few millions years and we would have no ideas at all. There might be 10 ancient Egypt tier civilisations out there right now that might develop radio tech by the time we're extinct or back to low tech.

Re: The Milky Way is probably full of dead civilizations

#32

This paper doesn't account the possibility of a civilization to spread itself and to fill eventually the whole galaxy. But in such case it's practically impossible for such civilization to extinct. Since we see no intelligent signatures everywhere, it's certain that no such civilization was formed in our galaxy.

It’s not really possible to say that it is certain given we haven’t looked very hard or for very long. We don’t even know if there’s life in nearby places like Enceladus.

Re: The Milky Way is probably full of dead civilizations

#33
post #32

This paper doesn't account the possibility of a civilization to spread itself and to fill eventually the whole galaxy. But in such case it's practically impossible for such civilization to extinct. Since we see no intelligent signatures everywhere, it's certain that no such civilization was formed in our galaxy.

It’s not really possible to say that it is certain given we haven’t looked very hard or for very long. We don’t even know if there’s life in nearby places like Enceladus.

We don't need to look hard. If interstellar travel is possible and someone in our Galaxy have developed it in the past, the whole Solar System including Earth should be already colonized.

Re: The Milky Way is probably full of dead civilizations

#34
Maybe the question to ask is:

"Can advanced beings evolve beyond the need for civilization?"

Future Star Trek episode:

The crew arrives at what appears to be a completely lifeless planet, and sees the empty buildings of a futuristic city...

Crew member: "These warlike people must have annihilated themselves... nuclear war with advanced energy devices that penetrate buildings with high energy radiation, that leave the buildings but destroy all life..."

Beings in light bodies (who suddenly appear out of nowhere!): "No, it's totally cool -- all of us are still alive! We simply evolved beyond the need for civilization!"

Dumbfounded crew member (whose sociologic theory about civilizational collapse is now proven utterly and completely wrong!): "Oh..."

:-)

Re: The Milky Way is probably full of dead civilizations

#35
post #25

What continues to vex me is the tedious inevitability with which hypothetical extraterrestrial civilisations are assessed through the narrow prism of human failings – namely, self-destruction and aggression. Intelligence, a term we are so fond of bandying about, encompasses a spectrum of attributes, yet it is fundamentally anchored in two core tenets: logic and reason. An entity truly in possession of such faculties…

You make several good points.

I would push back on the idea that alien civilizations might somehow be more enlightened so as to avoid internal conflict altogether. Unless they were artificially designed by a creator who explicitly factored out these traits, they likely also evolved from primitive beginnings. If we know anything from our single sample of living organisms is that competition and survival play a key role in driving evolution. Even if their planet had ample resources for everyone—which can also be said about Earth—those resources might not be accessible to everyone equally. This would inevitably lead to hoarding, tribalism, and conflicts. Besides, physical resources aren't the only cause for conflict. If they're social creatures, relationships, hierarchies, and politics also play a role.

So all of these things would be embedded in their organisms even after they've evolved to a technological civilization, just like they are in ours. Therefore it is not difficult to imagine that they would also struggle to balance their use of technology with their nature to distrust each other. I don't think this is a human-centrist viewpoint, but one we observe from nature itself. However limited that may be, it's the only place we can draw any kind of conclusions from. Thinking otherwise is interesting, but the realm of science fiction.

Re: The Milky Way is probably full of dead civilizations

#36
post #29

Earlier quoted context omitted.

The radius of the observable universe is 45.7 billion light-years. The universe is approximately 13.8 billion years old. Primates evolved only six million years ago. So let's be charitable and say it took only 13 billion years for a lifeform capable of transmitting radio waves to evolve. Unless I'm missing something, if we're listening for ETs, we would only have visibility into a sphere with a radius around 1/45th t…

The article calls out that « the probability of life emerging based on known factors peaked about 13,000 light-years from the galactic center and 8 billion years after the galaxy formed ». A hypothetical civilisation may well have emerged with a head start of five billion years – a span of time sufficiently vast to allow for profound advancement, assuming favourable conditions and uninterrupted development. However,…

i can't help thinking the galaxy would be symmetrical with earths, like petals round a flower, being at the same stage of development as each other.

Re: The Milky Way is probably full of dead civilizations

#37
post #22

Earlier quoted context omitted.

From a technological point of view, the main distinctive feature of humans has not been the use of tools, which is relatively widespread among animals, but the control of fire. The control of fire is what has enabled humans to produce and use new classes of materials that all other living beings are unable to make, e.g. ceramics, metals, glasses, cements, thermoplastics and thermosets, various kinds of crystals, incl…

> From a technological point of view, the main distinctive feature of humans has not been the use of tools, which is relatively widespread among animals, but the control of fire . > The control of fire is what has enabled humans to […] … on Earth with an iron-nickel core and an oxygen rich atmosphere, with easy access to vasts of low energy density organic material (dead trees) and higher density energy source (coal)…

The native metals are either too soft for being used for tools (Cu, Ag, Au) or too hard to be possible to forge (platinum-group metal nuggets, which were the material originally named "adamant" by the Greeks, before the Indian diamonds became known after the expedition in India of Alexander the Great).

Native metals have always been used only as jewels, before it became possible to melt them, in order to make hard alloys, e.g. copper-arsenic or copper-antimony, and later copper-tin.

The exception has been meteoric iron (i.e. Fe-Ni-Co-Ge alloy), which is hard enough to be useful (because it is an alloy), but that could never be an abundant resource. Moreover, meteoric iron cannot be forged without heating it. Cutting and polishing it like you do with stones is very difficult, but possible. However, such a method of using it does not provide the main advantage of metals, of enabling the creation of complex shapes by plastic deformation. Had it not been possible to forge meteoric iron by heating it in fire, nobody would have bothered with attempts to make knives out of it, instead of using stone tools.

Using concentrated light instead of fire would work, so such an invention could be imagined on a planet where the atmosphere could not provide fire, like on Earth. However this is not something that could be invented by aquatic animals, because they would have to invent first means to make chambers empty of water where materials could be heated in such a way. Such a succession of inventions, including adequate pumps, is extremely implausible because their utility would not appear until all the necessary techniques would exist. It would be far more plausible for aquatic animals to first develop means to live outside the water, and only then make such inventions, in an environment where they are much easier.

While there are bacteria that can reduce some metal ions, e.g. of copper, silver or gold, to the corresponding metal, they do not do this for producing a metal, but for removing poisonous ions from their environment by sequestering them into the insoluble metal. On Earth, living beings have either a complex structure or chemical versatility, never both. It seems likely that this constraint would also exist elsewhere, so one should not expect intelligent beings that are able to reduce metal ions into metals by their body physiology. In any case, the pure metals produced in this way, like also the native metals precipitated in abiotic conditions, are useless for making tools, without being able to heat them to high temperatures for making alloys and for controlling their polycrystalline structure. The same applies to metals that would be produced by electrolysis.

Fire using air is the source of heat originally used by humans on Earth. Any other available source of strong heat could have replaced it in the history of another planet. The point is that to ascend to the level of human technology any living being must acquire the capability of processing materials at temperatures very different from their ambient temperature. None of the techniques of producing metals at the ambient temperature is sufficient for being able to make useful things out of them. The same for other classes of materials, e.g. semiconductors or glasses.

One could imagine an extremely advanced technology where one would be able to make a big object by putting an atom after another in just the right place. That could work at ambient temperature and produce anything. Even if such a technique were possible, I find it impossible to believe that any living beings could become capable to develop it without first passing through the stage where a lot of material transformations can be made only at high temperatures and/or high pressures.

Re: The Milky Way is probably full of dead civilizations

#39

I read a paper a long while back that used purely numerical arguments to first show a common rate in the growth of complexity across biological and non-biological systems under similar conditions. It then plotted this exponential growth backwards in time, showing that life's origins were prior to the formation of earth by about 1.5 billion years. No guesswork, it was quite solid; the same math applied to human techno…

Obligatory: https://xkcd.com/605/

That paper used a horribly faulty logical argument because it has been well known for quite a while that most of the time evolution is quite slow, but there are short bursts of rapid change. For example: https://en.wikipedia.org/wiki/Cambrian_explosion

See: https://en.wikipedia.org/wiki/Punctuated_equilibrium

Re: The Milky Way is probably full of dead civilizations

#40
post #22

Earlier quoted context omitted.

> From a technological point of view, the main distinctive feature of humans has not been the use of tools, which is relatively widespread among animals, but the control of fire . > The control of fire is what has enabled humans to […] … on Earth with an iron-nickel core and an oxygen rich atmosphere, with easy access to vasts of low energy density organic material (dead trees) and higher density energy source (coal)…

The native metals are either too soft for being used for tools (Cu, Ag, Au) or too hard to be possible to forge (platinum-group metal nuggets, which were the material originally named "adamant" by the Greeks, before the Indian diamonds became known after the expedition in India of Alexander the Great). Native metals have always been used only as jewels, before it became possible to melt them, in order to make hard al…

The plausible scenarios I have outlined concern the seeding and emergence of a civilisation in the absence of terrestrial fire – a detail that, whilst seemingly minor, is foundational to the argument. Given sufficient time, such a civilisation could, through alternative pathways, achieve technological maturity without reliance on combustion. That is the crux of the matter.

Moreover, fire – as it is understood on Earth – is not merely a product of an oxygen-rich atmosphere. It is inextricably tied to the cyclical processes of organic growth and decay specific to this biosphere. To assume that such a mechanism is universal is a failure of both imagination and scientific rigour. It is patently unreasonable to presume that alien worlds capable of hosting life would replicate the precise biochemical and atmospheric conditions of this planet.

One might as well expect a symphony to be performed identically by instruments fashioned from entirely different matter – and yet remain surprised when the melody diverges.

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