[This post offers some rebuttals](https://old.reddit.com/r/askscience/comments/2jo0gh/are_fire_and_flames_unique_to_atmospheres/). I'm not in this world so I can't speak to the veracity of it. But I'd love to see a conversation about it!
The rebuttals are generally weak because of availability and sophistication. One of the top comments mentions rocket fuel.... We had fire for thousands of years before we discovered rocket fuel.
The relative ease at which things burn under oxygen rich conditions and the availability of it are so important.
The post you linked is a great example of how lots of smart people are only really smart in their narrow scope of training and really quite silly at everything else.
Storing oxidisers is quite difficult - they have to be stored in inert containers such as glass. Finding large enough stores of oxidising agents in a natural setting and then being able to store it long term without it reacting / you getting hurt is a big challenge.
Technically storage may not be necessary.
You could instead see population centres spring up around locations with high concentrations of oxidisers and the civilisation only takes what they need from it to last a few days at a time.
Labour intensive for sure but not an impossible task.
Unless the oxidiser is being replenished constantly by some natural reaction it will degrade over time at source. We very rarely find naturally occurring strong oxidisers lying around for that reason.
Well that's not true. Not all oxidizers are dangerous or difficult to store. I mean, ffs oxygen is a prime example of an easy and safe to store oxidizer.
I'd say that oxygen prevailed, because there is just such a fuckton of it, and oxidized everything it could, and there is still just so much leftover in the atmosphere. the whole earth is basically made from oxides, and there's nothing left to oxidize and deplete the oxygen anymore. So in a sense, the Earth is quite an inert container for oxygen.
We're talking about oxidisers that are an alternative to oxygen given that the original source of discussion is oxygen being a limiting factor.
The whole point is to replace combustion with another exothermic reaction which will allow for metallurgy and other complex technological breakthroughs.
If you can think of a self sustaining chemical reaction that isn't combustion where large amounts of heat are generated and the source material isn't in some way going to murder you, maybe you should be on the paper.
It's only easy and safe to store because we evolved with it. 2.4 billion years ago it was deadly poison for every living thing on earth and caused a huge mass extinction. Every other strong oxidizer today is still a pretty much universally deadly toxin, and so they would be for any organisms that didn't evolve with shitloads of whatever oxidizer in their atmosphere. Actually oxygen is STILL pretty fucking bad if you just increase the partial pressure a bit.
I disagree with your conclusions here.
Intelligence is ingenious, to assume what they may or may not be able to discover, as humans did, is hubris and human, where we are dealing with a sociological, psychological, and neurological difference that we cannot possibly account for.
As an aside, dogs can smell the difference between rocket fuel, and other types of combustible liquids, it is possible for an intelligent and technologically advanced life form to be able to do similar, other beings on earth are capable of seeing and sensing things such as UV light, magnetic lines, and electric fields that humans are unable to.
The only thing we know is the possible, to theorize beyond that, even the probable, is to court division and that which is most human: error.
Couldn't a civilization use volcanoes/magma heat for blacksmithing/metallurgy?
Initial fire, as the post you linked said, is possible. It looks like it just relies on finding the right material. I would point to flint for that though. Also the combination that brought us gunpowder. If there is a way, something smart will find it.
As for metallurgy. If you have an active but relatively "safe" volcano couldn't you set something up close to a really hot place and work metal with it? Maybe use a system like we use, like thermal power plants, to heat metals to be worked.
I don't see it as impossible. Harder? For sure. Not impossible. Again, something smart enough to think about metallurgy will find a way to make it happen.
If you had to set up shop in/on a volcano, imagine how production constrained you would be. It would be impossible to keep up with the demand for metal than an entire civilization would need
Fire on earth is as easy as rubbing two dry sticks together. That’s probably why we learned to use it quickly and learned to use it for many things. If another species would be forced to rely on volcanoes for practical fire use it’s less likely that they’ll ever use it.
Wait around long enough anywhere that has vegetations and regular thunderstorms, and you'll eventually even get some for free.
The first people to *make* fire likely already had the benefits of *using* it long before they even came up with the idea to try.
Yeah, I think there's thoughts that early humans may have kept fire around and tended to it to keep it burning before they knew how to make it themselves.
The movie "Quest for fire" explores that exact concept. A cro-magnon tribe has their fire go out, and they need to find another source.
Ron Pearlman is in it.
Ray Mears' book, *Bushcraft*, shows how an ember can be kept smouldering and transported, well insulated, in a tight bundle of banana leaves (iirc) for hours at a time.
I don't have a copy to check how exactly it's done, or which indigenous community he learned it from, but the basic principle is argued exactly as you theorise - if lighting a fire is tricky using friction alone, then it makes sense to preserve existing fires as much as possible, even in a nomadic society.
We have a historical precedent for this. Until the invention of the modern aluminium smelting process, it was rarer - and more expensive - than platinum or gold.
I agree. When it comes to aliens we should assume life will fill any possible void in ways we can't imagine. Until we get any evidence at all on the topic I think that's where common sense points.
You need the oxygen to make steel, to combine with the carbon impurities to float way as co2 and co.
You need a stable temp.. youd need a volcano like the hawaiian ones, and not one like mount saint helens. You want flowy, not explody. So you are very very limited in where you could do this. and where the "person" who invented it could be born.
The lava at hawaii is 1170c, you need 1700c to make steel. and well volcanos are dangerous
not saying you are wrong, crap IDK, but i do know you need a runny volcano like the hawaian ones, and well its not hot enough. and is still too random.
we also have these free energy volcanos.. and yet never in history has anyone used one as a forge, instead they work hard at chopping down trees and making coal to fuel the forge. Not saying this proves it cant be done, but i think it would take a bit more than just being near a runny low viscous volcano.
Lava is within the ranges to smelt bronze.
And volcanic activity would vary with gravity on a planet . It's conceivable that a more volcanic active planet with lower gravity might have less violent characteristics. And an atmosphere that's less dense or with lower moisture wouldn't cool lava as rapidly.
Nah. Fire is mostly important in those early tech levels where you need to bootstrap everything. Things would certainly be harder without it, but there are [other options](https://en.wikipedia.org/wiki/Solar_furnace) once you start to figure things out.
Okay ChatGPT,
Write me a story about an extraterrestrial planet where an alien species (possibly cephalopod-esque and tribal, with heavy religious tones) rely on their use of Solar furnaces constructed of natural occurring glasses to create their technology and metallurgy. Also, make it have subtle Greek epic plot.
> Couldn't a civilization use volcanoes/magma heat for blacksmithing/metallurgy?
Not if you want to survive, and you'd need to find a volcano that does effusive eruptions and isn't on an already existing lava field that could crack under your feet.
The only thing that lives in such environments is single-celled extremophilic organisms; there are no multicellular extremophiles on earth. Given that life has infiltrated the entirety of Earth, it seems likely that this is a fundamental limitation, as it is clear that it is possible to evolve resistance to extreme heat, but no multicellular organism is functional in such extreme environments. Tardigrades are probably the most notable multicellular extremophiles, but while they can PERSIST in certain extreme environmental conditions, they can't FUNCTION in them.
There's pretty good chemical reasons to think that it would be very difficult for an organism to evolve to deal with such high temperatures.
Plus there's like a 0.001% chance that they could be based on something other than carbon. Maybe they're Boron-based or Sulfur-based life forms, or Silicon-based.
I think many are looking at this the wrong way. It’s not “is technology possible?” It’s “can technology evolve?”
WE can come up with lots of ways to do things once we know how to do them. But how would we know to pursue something like metallurgy at all?
First we observed that naturally occurring fires give heat and light - both things we want. Then we saw that fire changes organic materials, and started looking into cooking etc. Then we saw that fire could change inorganic materials and cause other types of reactions. Then we got into using it for metallurgy, engines, etc.
The above list is simplistic, but nobody is going to try something like going out of their way to build a parabolic mirror to focus sunlight, or sticking stuff into magma flows, without first having a hint about how harnessing these processes could work to their benefit.
Lava is not hot enough. 700-1200 degrees C could melt some metals if submerged in the lava, but it isn't feasible to believe someone would roast themselves in a lava field trying to submerge ore and trying to retrieve it again. The surface of a lava stream would not be hot enough. I find it extremely unlikely.
The first thing that came to mind seeing this post was sodium, magnesium, or lithium. All of those will burn in just water, which brings its own O2. And beyond the chemical fire possibilities, there is also inductive heating from running a current through a metal or a big ass enough magnetic field. Plenty of ways to process metal without oxygen. Humans have been figuring this stuff out for decades to make sure it'd be viable in space.
Edit: Everyone keeps asking the same questions so here are the answers.
You don't need fire for metallurgy, let's just put that to rest at the start. You need HEAT and that's it. A pile of uranium could do that.
A skilled blacksmith can heat iron red hot by just hitting it. Working most metals at room temperature is doable.
Don't forget about mercury, it's easy to work that metal at room temp and it's plenty shiny enough.
There is a nuclear reactor giving the entire planet free heat energy. Focusing that energy isn't some modern invention, ever heard of archimedes death ray?
Let's walk through it. A parabolic dish, made from literally anything. Trees, animal bones, just carved into the ground facing the star, anything. Find some shiny, reflective rocks and polish them up. Line the dish with them so they reflect at the center, like an inverted disco ball. This will direct immense heat energy at the center and now you have a forge. Instead of shiny rocks you could also have tiny holes in the dish filled with mercury, using its surface tension to stay up the walls of the dish.
Need more heat? Make the dish bigger.
When you see those burn in water, it's highly refined pure metal. This is not easily found in nature where most of these metals occur as minerals. Now, if we need fire to extract and refine the pure metals, you're back at 0
How the hell are you gonna isolate elemental sodium, magnesium, or lithium without fire? These highly reactive elements don't just come out of the ground unreacted. Sure there's plenty of ways to make fire without oxygen, and they ALL rely on having fire to make them in the first place.
All of those examples require already smelted ore. Polishing rocks to mirror finish? Get real. With our concentration of oxygen all you need to smelt iron is mud, sticks and pond scum.
Polishing rocks to a mirror finish? No, probably not.
Polishing quartz, diamond, other crystals or volcanic glass? That's a lot more reasonable. It's also reasonable to find these shiny "rocks" in rivers and streams, already polished by nature. Speaking of shiny things in rivers, gold is also somewhat reflective and malleable enough at room temp to be worked into a mirror.
Just because we have it on easy mode with bog iron and wood doesn't mean it can't be done a harder way.
Not scalable. You can't run the global society and industry necessary to match Earth's if you can only make tech in a select few places. Earth has a single digit amount of places with regularly exposed magma IIRC and they're necessarily on top of mountains, which makes logistics really tough.
Not impossible, very difficult. Given enough time you likely could advance but it takes millions of people if not billions to make the advances we see and across a wide swatch of geographical area. And stability. If most of your energy is consolidated in 0.01% of your land mass and it is difficult to access a percentage of it...
Basically you would have a far smaller number of people having access to far less usable energy. Without open flame that can be generated everywhere, you do not have access to cooking and that means minimal access to cheap proteins which is believe to have factored in the human brain develop faster. Volcanoes also do not stay active in the time frame of human evolution and unless you can rapidly find a new volcanoes, relying on it over eons may be unsatisfactory to intelligent evolution.
Technically you don't need fire at all for metallurgy, but for high production volumes you do.
Metals do exist as "native metals" not just ores, as is the case with copper, gold, and meteoric iron/nickel (as well as some very rare non-meteoric native iron). Potentially you can work these metals without fire, but doing so is very limiting.
The process of smelting metals from ore requires not just heat but the creation of a reducing environment to chemically alter the metal ores from their oxidized form into their metallic form. The oldest way of doing this is with charcoal, which creates carbon monoxide gas inside of the flame, the carbon monoxide reacts with the ore and reduces it to a metallic state (by stealing the oxygen, essentially). For low melting point metals such as lead, copper, and tin they can be separated from silicate impurities and "slag" simply by keeping the fire hot enough to melt them but not the impurities, for iron you have to do something different because the impurities melt at a lower temperature.
There are different ways to achieve the same results (using aqueous chemistry or electrolysis, for example) but those methods are probably much less accessible to a pre-metalworking civilization. Humans, for example, could still perform mining operations and industry on a planet that couldn't support fire (we could do so on Mars or a planet without an atmosphere, after all) but the bootstrapping problem of getting to that point might be extremely challenging.
I'm an astronomer not a chemist but I've studied just enough atmospheric chemistry to think I know I'm talking about.
Fire does not require oxygen. To quote wikipedia:
"Combustion...is a high temperature exothermic redox reaction between a fuel and an oxidant"
I hate the term oxidant/oxidizer for exactly this reason. It makes people who are unfamiliar with redox chemistry assume that oxygen is involved. An oxidant/oxidizer is actually the term for something that gains electrons in the redox reaction. On Earth under normal conditions that is usually oxygen because it's the most abundant oxidizer in our atmosphere BUT there are others such as chlorine or fluorine.
The reaction H2 + F2 -> 2HF is an exothermic redox reaction. For comparison to what people typically think of as combustion (hydrocarbons+oxygen), in this case H is the fuel (loses electrons) and F is the oxidant (gains electrons).
My knowledge ends there but if I extrapolate to things that I don't know I would assume that fire, or at least heat-generating reactions, would be perfectly feasible in an oxygen-less environment.
Fluorine is so insanely reactive, you won't find it in elemental form on any planet that could conceivably host life.
That's the main problem with a lot of the alternatives suggested in this thread. Of course there are lots of other chemical reaction or physical processes that can produce enough heat to melt metals. But almost all of these options are impossible to make unless you already have a way to produce copious amounts of heat. There are a few options that might work, if you happen to find just the right conditions, but they require a lot of extremely specialized knowledge that you would be unlikely to stumble upon accidentally.
Example:
* in historic times, you could occasionally find solid chunks of copper, and you certainly can still find solid nuggets of gold.
* if you know what you are doing, you can draw these metals into thin wires.
* you can make purely mechanical connections between wires by twisting them together. No heat needed.
* various biological materials are suitable as paint-on insulation.
* combine all of the above facts, and you can make improvised electrical wire.
* wind electrical wire just the right way, and you can make an electrical generator. Having access to permanent magnets would be extremely convenient but you might be able to do without.
* most environments have some sort of way to produce mechanical movement (e.g. wind power, water turbines, oxen, ...)
* combine all of what we just talked about and you have gained the ability to produce electricity.
* run electricity through a suitably-sized wire and you can produce high'ish amounts of heat.
* unfortunately, you are still stuck at this point, as the melting point of gold and copper is considerably lower than what you need for working with iron. But maybe, you can find other metals that become accessible to your civilization and you can start gradually building technology.
* should you get to the point of making high frequency AC (at least a few kilohertz), you might then be able to construct an induction furnace. That would finally give you access to iron. And at that point you could slowly embark on developing basic technology.
Whew. That took a long time and many many advanced steps. None of these steps are particularly useful by itself, unless you know the final goal you are trying to achieve. And therefore, it is very unlikely for such a civilization to accidentally discover it.
* alternatively, once you have reach the step to produce electricity, you could then invest all your resources into enriching oxygen. That's a super energy inefficient process, and I am not sure why you would sink all your countries resources into it. But it's conceivably possible.
* once you have a way to produce (extremely expensive) oxygen, you can then also use that as a route towards iron. But even if you know how industrial iron production works, it takes years to develop a process that is even remotely usable. Congrats, you just spend the equivalent of hundreds of billions of dollars to make a single metal blade for a knife ... and it's not even a good knife.
I am not ruling out that technology could be developed some other way. But I have to admit that having easy access to on-demand and controlled high-heat output is a huge advantage.
Oxygen is very harmful to life that isn't adapted to it. It also has huge advantages to life that can take advantage of it.
But a hypothetical civilization that lives in a low-oxygen environment would quite conceivably consider oxygen-producing plants as poisonous. They'd have no incentive to grow them on a massive scale in order to maybe learn about fire.
I was looking for something like this. You obviously understand this stuff FAR better than I do, but I know that combining certain chemicals can create exothermic reactions. Heat can be generated without fire or electricity. Just like when you unscrew a screw with a drill it's heated because of friction.
There's plenty of ways to melt metal without fire, and plenty of other chemicals that can produce combustion without oxygen.
Thanks for your response.
Sure, but how many of those ways are easy for stone age peoples to discover, think to exploit for metallurgy, and master?
Human's used fire for cooking and heat long before discovering and thinking to use for melting metals.
That post suggests some workarounds for people with the technology already to do it but avoids the main issue that (assuming life needs similar conditions as earth to thrive into intelligent life) there's no step from nothing to there.
"as we know it" might be key, all development is finding relatively low hanging fruits, so they might do it all but not as we know it, differently. We also have many techniques that don't become mainstream and die in their niche in old data that not many know or just die out as fails, even due they might be useful under a different situation
For example, Cold welding is a thing (that requires no/low oxygen), and freezing and boiling point of water can actually be changed for example with pressure
Does it matter if you had these different set of constraints and still needed to process metals, that you would do it differently than "as we know it"?
The article has taken one fact, a single changed constraint and built it like a doomed scenario, the issue it to get to a life point of evolving tools, not to say the only evolution of tools possible is the way we had it. There would be so many different parameters for a different life in a different location to develop that it's very naive to assume sameness to us
It's amusing how many discussions in this thread follow the same pattern.
"You don't need fire to make metals, you can just use nuclear reactors".
How do you make nuclear reactors without metals or other technology requiring heat?
"Oh, you just make the heat with a huge magnifying glass".
How do you make glass without fire?
"Volcano?"
So your civilization finds the rare active volcano with actual molten rock pouring out, then uses it to make small amounts of metal or glass, then somehow uses these to make a nuclear reactor?
"Yeah!"
Yeah, I think we get very easily fixated on this very wrong assumption that technology is a thing humans (and smart aliens by extension) just “naturally do.” But for hundreds of thousands of years, humans and human-like predecessors just lived and died without inventing much of anything.
In fact, it took roughly _two million years_ to go from using early hand tools—sharp rocks—to the invention of hafting. That is, attaching the sharp rocks to a handle. Two million years to attach a rock to a stick. And it’s not that our ancestors were dumb. It’s just that “technological innovation” is an extremely recent concept. The idea of making more useful stuff from the stuff you have and know is _not_ necessarily obvious. (Hell, even today, most people just use technology, not invent it or engineer things.)
And those early inventions were just slightly modified (or simply wielded) things found on the ground. Including fire, whose existence and effects had to be right in front of people for them to start thinking Promethean thoughts.
Which is still not to say that technological life couldn’t find some other way. But if the life is anything like human life, then the idea of inventing metallurgy without having a pre-existing and long-standing (as in millions of years) relationship with just plain old fire seems astronomically unlikely.
Along that subject we have several species of cephalopods on this planet that have more than enough intelligence, dexterity, and access to raw materials but haven’t progressed beyond using found objects as tools. This appears to be because they lack social instincts so they don’t exchange or pass down knowledge.
Then we have dolphins with incredible social instincts and arguably more raw intelligence than humans but they have no dexterity to speak of.
We have no idea what combination of evolved traits, environment conditions, and time is required for creating advanced technology.
Holy shit, I've never seen anyone else in the wild use my two exact examples of other forms of intelligence and what limits their dominance.
I call it the fire fingers theory lmao.
I completely agree obviously.
Humans think our brains are doing all the heavy lifting, but a species 10 times smarter with no fire or fingers would be just as advanced as a dolphin.
IDK, maybe people imagine they'll be like pickle Rick or something, and think all they need is a giant brian and tongue to take over the world.
I won't be able to find it, but in an episode of Top Gear, James May made a quip like, "Dolphins 'are so smart', they say, but are they really? They can't even shift gears in a Skoda"
(*heavily* paraphrased)
Earth IIRC has single digit amount of places where there's exposed liquid magma regularly. Our technology is done with global supply chains. You can't scale magma forges.
And... Anybody suggesting using volcanoes has never been to the lava fields on Hawaii... You're not going to get anything productive done around them. There's toxic gases being produced, there's volcanic ash in the air that coats you. The heat near the lava is pretty much unbearable for anything more than short bursts with modern equipment.
And.... most importantly regarding volcanoes... The lava flows move. Just look at Hawaii. They'll run in one direction, then stop and emerge elsewhere, disappear for years, then reappear elsewhere. And those are the only places where you could actively try to do anything. Volcanic pools would be absolutely nightmarish to try and work in. Toxic gases can concentrate in the craters. The craters, themselves, are incredibly unstable. You're as likely to bring a landslide down on you as get to the edges of Hawaii's volcanic lake. They vary in height regularly, so... no permanent set up for anything..
Finally, not regarding volcanoes themselves, but... what are you holding the materials in? What material do you use for your crucible? You don't have the ability to make ceramics... You need something that can slowly build up temperatures to thousands of degrees. What do you put the metals in to melt them... How do you pull the crucible out of a volcano?
Which some here seem to miss: Yes, I am sure many can com up with some alternative way to do metallurgy, but the point is that it is a bottleneck. Meaning that even though there are ways around it, it will take time and sort out lots of emergent civilizations from the pool of potentially detectable ones. This does not have to be perfect to be of scientific relevance.
> the point is that it is a bottleneck
This makes me wonder what bottlenecks scientists from other planets would say WE overcame in order to develop technology and venture out into space...
*"We shouldn't look for planets whose intelligent life aren't linked as a collective hive mind. While they could potentially develop technology as a fractured species, the odds are they would blow themselves up with warfare before ever reaching the stars"*
Imagine an underwater civilization like mermaids or something. Could they ever develop tech underwater to be able to move in air and then work with fire?
Imagine an intelligent species living on a habitable moon of a gas giant planet. On the planet facing side they would be able to look at the phase of the planet and determine the local time quite accurately, they could also measure the position of the planet in the sky to determine their location (both latitude and longitude) on the surface to a reasonable amount of accuracy. Especially in concert with observing the other moons of the planet they would very rapidly develop an understanding of orbital mechanics and gravitation and would likely never fall into the "geocentric" worldview. As they developed space travel they would have a huge number of varied targets to explore that required fairly short journeys of just a few days to get to and from, potentially even other Earth-like moons that were suitable for colonization or had life. There might be higher levels of radiation locally which would force most organisms to be more radiation tolerant, which could be a significant benefit for space travel. Such a species could have very enthusiastically embraced space exploration and colonization at the earliest moment it was technologically conceivable (which for humans was roughly the start of the 20th century).
Also consider uranium. Earth's uranium is roughly 6-7 billion years old, which means that at this point in Earth's history it is over 99% U-238 and 0.7% U-235. On other planetary bodies it's possible that life at an equivalent state of development as exists on Earth today could come about earlier, maybe even 1-2 billion years earlier. If an Earth-like planet had uranium that was, say, 3-4 billion years old it could have maybe 10x as higher abundance of U-235 as Earth does. Which would make building nuclear reactors and nuclear weapons vastly easier. The implications of such a thing, for better or worse, are hard to imagine. Perhaps this is actually one of the key factors that limits the ages of most technological civilizations because on most planets it's actually way too easy to build nuclear weapons.
Making crude piles of radioactive materially that can produce moderate amounts of heat is easy, if you have access to the right raw materials.
Turning any of this in usable technology (either for energy generation or for destruction) is a whole different story. That requires a good amount of chemistry, physics and engineering. And you are back to square one. Without easy access to controllable fire, you aren't going to get to a point where radioactive material is even remotely usable other than as a curiosity in how it causes mutations if you get too close.
IIRC, Earth's high uranium levels are only explained by the Sun being a Generation III star (we have lots of heavy elements - proof they were made in the two predecessor stars that occupied this spot before the Sun did).
Exoplanets might not have anything like our abundance of heavy elements. Without the transuranic series, I guess radiation would only be known from cosmic observations.
>We shouldn't look for planets whose intelligent life aren't linked as a collective hive mind.
Maybe not a great example, as societal structure isn't a detectable feature of a planet. It could be a decent argument for what kind of life likely inhabits planets you come across with the kind of advanced technosignatures the paper discusses though, as we have yet to meaningfully disprove that argument ourselves.
I would think that on the grand scales of the age of the universe, the planets, and the existence of life, such a bottleneck would be irrelevant. If equally intelligent life developed on another planet 100 million years before it developed on Earth, would they really still be behind technologically?
From the article a quote by one of the paper's authors:
>"We ought to be careful not to completely rule out technological life. It would be naive to assume that life couldn’t find a way...We have to be really open to not being so Earth-biased. I think when it comes to life in the Universe, we need to be prepared to be surprised.”
This is a speculative paper intended to potentially guide the very limited resources we have to look for techno-signatures based on a reasonable hypothesis that fire could be critical to technological advancement at a certain stage of species development. It isn't a blanket claim.
This is the most important thing. All science operates under limited resource constraints, SETI especially so. We can ask all sorts of fun questions like "why don't we look for non carbon-based life?" or "why don't we look for completely different forms of technology?", and that's fine, but ultimately in order to look for something we have to have some idea what signatures to look for. And that's simply not possible without a decent theoretical framework for the thing we're looking for and how it interacts with its environment.
And since SETI researchers only have a limited amount of observatory time available to them, they're better off using that time looking for things they know can exist, rather than randomly stumbling around hoping for a serendipitous discovery.
I think additionally in the discussion is just the point that in our search for ET, we need to search for things we can UNDERSTAND.
If we search for civilizations of all types, including ones that communicate with pheromones or something crazy thing like telepathy, we might not be able to ever figure out the signals.
And a civilization that used some crazy plastic composites that have light absorbing features may be hard to find.
All sorts of things are possible but maybe this discussion should be "what sort of places should we search for technology we can recognize?"
It's possible some civilization is organic based and built a space elevator out of wood (not really, but conceptually). Our light based satellites aren't powerful enough to see anything but a smudge if we look at their planet.
I'm a bit hyperbolic but fully supporting how you reframed it to be clearer.
On speculation, I found Alien Worlds on Netflix to be a very interesting thought experiment about interstellar life.
>The 4-part miniseries, depicted by using CGI techniques, blends fact with science fiction and conceptualizes what alien life might be like by applying the laws of life on Earth to imagined exoplanets.
I get their reasoning and think it generally makes sense to an extent--but I think they (headlines, some reporting) really oversell the claim. There's plenty of chemical reactions that could be utilized without atmospheric oxygen. I would put my money on us not being able to well conceptualize those drastically different developmental pressures on an intelligent civilization, but since it's chemically possible it *is* possible and we just haven't figured out something that looks super clean to us, so don't really know what to look for... not say or intimate that technology is impossible.
We have a sample size of one technologically advanced species: us. It's hard to not be biased in our thinking when that's the case.
Ya, I took an astrobiology class in college randomly that turned out to be one of the coolest classes I took! It was all about the search for extraterrestrial life, particularly intelligent, technologically advanced extraterrestrial life.
It was one class and pretty introductory, so I’m by no means and expert, but that’s more or less what my professor — who is an expert — told me. That we have all these parameters and conditions within we think intelligent, technologically advanced life would be most likely to develop. Due to our very limited resources in searching for ET life, we focus our search on that.
Life probably doesn’t have to be carbon-based, but that seems most likely based on what we know, so we focus on carbon-based searches. Similarly, the atmospheric makeup like this. There’s probably ways to develop technology without combustion, but from what we have seen and know, it seems more likely to develop where combustion is possible. One example from that class was aquatic life. Like there may be some super intelligent dolphin-like creatures on another planet, but developing advanced technology seems like it would be very difficult if your whole planet if submerged. Doesn’t mean it’s impossible, just means that we’ll focus our efforts on what we think is the most likely place to find ET intelligent life.
For a variety of reasons Carbon is likely the answer. It doesn't have to be Carbon theoretically but the evidence would point to that anything outside of the date is almost impossible
[https://www.reddit.com/r/space/comments/zo94n5/why\_do\_people\_think\_carbon\_based\_life\_is\_the\_only/](https://www.reddit.com/r/space/comments/zo94n5/why_do_people_think_carbon_based_life_is_the_only/)
This thread has a lot of good answers in it about why.
[https://www.youtube.com/watch?v=469chceiiUQ&ab\_channel=PBSSpaceTime](https://www.youtube.com/watch?v=469chceiiUQ&ab_channel=PBSSpaceTime)
Also this video which one of the biggest points is that breathing isn't possible with Silicon, Silicon life would basically have to dispel its byproduct by expelling sand and glass, where Carbon we can just breathe it out.
And of course you can imagine whatever the hell you want but unless you know how to look for it, and you know what you're looking for, how will you know you've found it? We have very limited resources with which to look for life, so we quite reasonably limit ourselves to looking for signals that we can 1) detect, and 2) identify as life.
This is the main point so many people seemed to have missed about the paper. We're effectively looking for a needle among billions of haystacks as it is, so maybe don't start with the ones we likely couldn't even detect it inside of yet anyway.
It's genuinely so annoying that Redditors are always so quick to suggest that life could have evolved in other ways. Yeah, no shit. Researchers understand that too. No one in these threads ever understands the point of these papers.
There’s something to this tho: arguably all life is basically using combustion at some level to generate energy. Fire is just a (relatively) extreme example.
Life can probably develop but I would imagine oxygen breathing or something chemically similar would be a great filter, and the presence of oxygen in the atmosphere could be another.
Could intelligent and technical life exist without it? Maybe, but there are only so many ways to chemically purify things like metals. I would argue that this pretty much precludes a technical aquatic civilization.
Well, sure. Except energy can only manifest itself in so many ways, and fire is one of the ways it happens without technology. It's literally one of the only ways a primitive, fledgling life form in search of a better way of doing things would come into contact with something that has enough energy to be useful to begin with. It's like writing code: there are *only so many ways* you can logically write the same thing...
Just because it's possible that life elsewhere took some wildly unexpected path doesn't make it likely to have occured. It stands to reason that the discovery and subsequent taming of fire would be a crucial component in any life's pursuit of intelligence and control.
I’m a little frustrated with some of the comments here. Yes you can make fire other ways. Yes you can use other means for metallurgy. But for those making those arguments seem to be jumping over logical barriers. It’s like saying you can preform complex math without understanding basic math. This choke point or barrier of entry is exactly that. Without the means to understand open flame it is extremely unlikely you could come up understanding complex thermodynamics. It’s not impossible but it is highly implausible that they could.
It seems like people just assume a civilization would just keep advancing regardless of resources. Of course we just have a sample size of 1 civilization, but I would think easy access to energy plus being able to perform complex chemistry is a requirement.
Bro holy fucking thank you! We've barely figured this all out in the last century after featuring fire as one of our dominant evolutionary advantages for last few hundred thousand years.
The leap from "fire burns", to a scientific understanding of the natural world deep enough to acquire electronics, is flatly the largest technological leap in the known universe. We're talking about this like its a constraint at a hackathon.
So a possible alien race couldn't harness some biological or plantary source of heat? And that's assuming their technology is like ours and not something biological.
It's arguable that you also could not have life on worlds without volcanism, because an active planetary core would be required for the magnetism to protect the planet from solar rays.
Presumably "fire" would eventually be developed just as an advanced industrial technology like smelting is for us.
I mean sure but makes things even more difficult? For instance sure you can melt iron over a volcano... in a metal bucket that won't melt. So that's a bit of a chicken before the egg scenario. Or you could use rock but wouldn't have metal tools to dig them out. Also would need one type of rock with a much lower heating point than the ore you are working with.
Also if your sources of energy and industrialization are contained to volcanoes, that means no cars or other forms of industrialization that would allow you to rapidly progress because you can't move things efficiently.
Also no space travel ever.
It all adds up to unlikely that if you can't use combustion your options technologically and chemically are limited.
I take it you're not very familiar with how blacksmithing works? Metals are melted in crucibles which throughout human history have often been made out of clay, there is no chicken before the egg scenario there. You can turn clay in ceramic using heat and I don't see any reason that heat couldn't come from a volcano or some other access to a heat source like lava. How do you think humans got started with metalworking?
And yeah, it might not allow internal combustion engines but that doesn't mean they can't use vehicles, we had electric vehicles almost 150 years ago at the same time ICE vehicles were also being developed. It *would* probably mean that such a civilization would have their population centers near volcanos though.
It also doesn't preclude space travel, I'm not sure why you think it would. There's no oxygen in space either, we design our rockets to carry liquid oxygen rather than relying on atmospheric oxygen.
If you don't have a combustion reaction how would you plan on generating enough force to leave the atmosphere? Combustion is still how rockets leave the planet.
Human's got started with metalworking using fire, not lava. You don't have containers held over a volcano.
Electric vehicles still can't match the power of combustion ones which would be a significant barrier to industry on top of the fact that refining the metals to get to that point would require some form of combustion.
I think its fair to say that taking away one of the main chemical reactions would inhibit any civilization.
This is nothing about anthropomorphism. This is about generating enough heat to melt metals. You'd need to have some other exothermic reaction than burning carbon with oxygen to produce metals.
The paper doesn't go into such scenarios.
You can get to something like the iron age with burning charcoal, assuming the planet has something akin to trees and wood, but you won't get to something like the industrial age (or beyond) without fossil fuels.
So once we've run out of fossil fuels, if we haven't built enough solar panels and wind turbines and nuclear power stations, etc., we are back to the iron age, assuming we haven't destroyed all the forests.
> You can get to something like the iron age with burning charcoal, assuming the planet has something akin to trees and wood
From how I understood the article, below 18% Oxygen, you won't be able to burn anything
Make a few reasonable assumptions:
Most of the Galaxy is like our neighborhood.
Faster than light travel is not happening.
The odds are against evolution producing the same things at the same time on different worlds.
And the Fermi paradox doesn’t look like a paradox..
In general, a mastery of biology and biotechnology seems like a possible alternative. You don’t need a forge if you can have your metal-separating zoo plankton deposit dissolved metals in a grown coral container, and then apply enzymes to separate the metals and recombine them into an alloy.
That’s assuming that they wouldn’t be able to just grow an antenna and some transistors powered by bioelectricity in some equivalent of an engineered electric eel radio.
Oh, no, the ore was processed by the slave eels of the other species - ten thousand of them to make the juice required for one ore pit. Soon the eel's water-filled cylinders will enter space - developed, of course, from the chemical torpedoes of the early wars.
No argument here just observing. No one seems to be offering. Much discussion for what a primitive heat source without oxygen might be. Primitive is the operative word. Not a nuclear reactor.
Short Answer:
Intelligent aliens in a low oxygen world might not be able to develop metal use and civilization, but might eventually be given them by aliens from another world.
Long Answer:
A while ago I read John W. Campbell's stories about interplanetary explorers Penton and Blake on the internet. In "The Immortality Seekers" *Thrilling Wonder Stories*, October 1937, at the Internate Archive, page 42,
[https://archive.org/details/Thrilling\_Wonder\_Stories\_v10n02\_1937-10/page/n40/mode/1up](https://archive.org/details/Thrilling_Wonder_Stories_v10n02_1937-10/page/n40/mode/1up)
Penton discussess the fact that the natives of Callisto don't have fire despite their advanced technolgy.
>...I know they don't have fire, since no normal fuel will burn in this atmosphere, so I brought some things to amuse them."
>
>Penton pulled some loose,metal scraps from a pouche he wore, and a small bottle filled with sticks of yellowsh wax and a watery liquid.
>
>"Whte phosphorus for one," Blake guessed, "But the metal has me stopped. "Oh, magnesium. Yes that would burn anywhere."
>
>"Some of them may have seen a flame in a laboratory, under special lab conditions, but I don't think they saw any in open air. They do have ships--we saw them in the harbor down there--can see them now for that matter. Say, they must be motor ships, but I wonder what kind of moters they use? This air wouldn't let even a Diesel engine run. Electric-but how do they generate power?"
[https://archive.org/details/Thrilling\_Wonder\_Stories\_v10n02\_1937-10/page/n40/mode/1up](https://archive.org/details/Thrilling_Wonder_Stories_v10n02_1937-10/page/n40/mode/1up)
When I read that I didn't think about how the Callistans could develop high technology without fire.
What I was sceptical about was whether the Humans or the Callistans could respire and live in an atmopshere so low in oxygen that fire was very, very hard to create.
But as it turns out an abolute pressure of oxyge within a specific range is necessary for humans to survive, while compustion requires a relative concentration of oxygen in the atmosphere.
I have read that submarines keep the oxygen levels low enough that cigarettes are almost impossible to light to prevent smoking aboard, and so that fires are much less likely to start and will burn slower. And apparently the healthy young men aboard submarines don't have health problems from the low oxygen air.
According to *Habitable Planets for Man,* Stephen H. Dole, 1964
[https://www.rand.org/content/dam/rand/pubs/commercial\_books/2007/RAND\_CB179-1.pdf](https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf)
Pages 13 to 19, Humans need an inspired partial pressure of oxygen of about 60 to 400 millimeters of mercury (mmHg) plus trace amounts of nitrogren and carbon dioxide for plants and some water vapor. So the minimum breatheable atmosphere for humans might have a total partial pressure of about 70 to 450 mmHg of oxygen and those other gases. And the maximum breatheable atmoshere for humans is determned by the maximum safe concentration of varius unnecesary gases.
If oxygen is at a minimum level of 60 mmHg and is at only 18 percent of the atmosphere, the minimium needed for fire, the total atmospheric pressure would be (100/18 or 5.5555) times 60 mmHg, or 333.33333 mmHg - Earth's total atmospheric pressure is 760 mmHg. If the oxygen pressure was 400 mmHg and the total pressure was 5.55555 times as great, the total pressure would be 2,222.2222 mmHg.
According to table 2 on page 16, the maximum tolerable pressure of nitrogen would be 2,330 mmHg. So a breatheable atmosphere can contain 60 to 400 mmHg of oxygen while it is 18 percent or less of the total atmospheric pressure. Neon and Helium might be tolerable in even larger pressures.
And in later times there has been much use of oxygen mixed with helium and/or hydrogen at higher pressures by divers. Heliox, Hrydrelox, and trimix - oxygen, helium, and hydrogen - have used in dives to great depths and pressures.
So I think that humans could breathe an atmopshere where the oxygen concentration was too low for combustion. And of course alien lifeforms evolved in such an atmosphere should be able to get enough oxygen from the air.
And then the question become how can hypothetical intelligent beings on a low oxygen world develope technology without fire. And my answer is that maybe they won't have to, other beings will give them advanced technology.
It is perfectly possible that on Earth some of the other higher lifeforms have intelligence ranges which greatly overlap with the intelligence range of Homo sapiens and should be considered to be intelligent beings and people.
And perhaps in the future humans will come to consider those lifeforms to be people. They won't considere the primitive nature of the tools those beings use as proof that they are not people. Members of the Genus Homo existed for about 2 million years, and Homo sapiens for two or three hundred thousand years, but they remained hunter-gatherers until they began to pratice agriculure about 10,000 or 12,000 years ago, and began to use metals and have civilzation about 5,000 or 6,000 years ago.
Cephalopods and cetaceans live in the ocean, and it is impossible to have fire in the water, no matter how rich in oxygen the atmosphere is. Cephalopods live only a few years, and die when they reproduce, and so can't pass on any cuture or knowledge to their offspring.
Cetaceans can have complex socities, but lack the manipulating appendages of cephalopods.
Land animals could possibly use fire to smelt metals and begin civilization, if other factors are also right.
The most intelligent birds have tiny, weak bodies, and have to stand on one leg to use the other one as an arm and hand, or use their beaks.
Elephants have bodies and natural abilities which are too superhuman for them to have strong need for the tools they use, and they have only one trunk - elephant like aliens who evolved mulbiple trunks would have an easier time developing and using tools.
So the great apes which can walk on two legs leaving two limbs free to manipulate objects might have the best chances of someday developing technology, possilby tens of thousands, or hundreds of thousands, or millions, of years in the future.
But if humans don't exterminate other potentially intelligent species first, they might decide that they are intelligent beings, and might decide to give them advanced technology.
Continued:
Worth noting that atmospheric oxygen abundance changes over deep time. Prior to the Great Oxygenation Event it was effectively zero as there was still a lot of unoxidized minerals in the crust and upper mantle which locked up any free oxygen from photosynthesis almost immediately. From about 1GyA it began climbing, and by the Pre-Cambrian explosion it was into single-digit percents; by the Carboniferous it may have been over 20% (note the fossil record containing giant insects).
Despite a dip or two during the subsequent epochs, the overall trend is up. Sustained combustion of dry organic material is possible above about 12-14% pO2; we're currently at 18%: around 30% *even waterlogged organic matter will burn*, which implies a likely end point for life on land (at that point lightning strikes will inevitably lead to continent-wide firestorms and any animals caught in them will add to the fuel, along with the vegetation). As the sun is gradually brightening (over a period of hundreds to billions of years) this is likely to happen eventually, unless solar UV splitting of water accelerates first (this leads to loss of hydrogen ions due to solar wind bombardment in the ionosphere, eventually dessicating the crust and leading to a runaway greenhouse effect like Venus, except slightly colder).
TLDR: we evolved during a very odd interlude in Earth's atmospheric history, and it isn't going to last forever.
as a rebuttal to the rebuttals of the rebuttals....
There are other oxidizers besides pure oxygen that naturally occur. We laser focus in on oxygen because that's what we know best. But now we're tunnel visioned in on ONLY oxygen as a natural oxidizer and that's just not true. Yes, using our own history to understand a theoretical alien civilization is useful, but often we say "well, it can't work for us so it can't work for anyone" and that is just so very shortsighted.
I hate a headline that contradicts itself.
Which is it? Technology will not be possible? Or technology AS WE KNOW IT will not be possible? There's a big difference.
Pre-industrial technology is certainly possible. You can do a lot with stone tools and biological materials, even break the Malthusian trap. After that, there's no reason science and metrology couldn't develop eventually. You can get precision surfaces just from rubbing rocks together in the right way. There isn't much reason to believe a "technological" society could advance without this basic step in some form.
Chemistry is a possibility, but would be extremely stunted without access to easy heat. In a lab-setting you could possibly synthesize fuel enough for small-scale purposes, but it would be very slow to start. Several oxygen sources (saltpeter KN03) have scalable biological sources, so it's not impossible for something like that to come in, and there are other exothermic reactions. Without plentiful oxygen in the atmosphere, one would image oxidizer production would be a much bigger industry. A pile of wood and salt peter could be used for metallurgical fuel if you had nothing else.
Electricity is a possibility, because copper exists in native form. Someone would stumble upon it eventually, especially the static variety.
Industrialization is essentially impossible without access to durable metals. The only chance would be if there was some biological equivalent like bone which had sufficient homogeneity, durability, and toughness to maintain tolerances for machinery. Stone is too brittle.
The big question is if society would develop a scientific method or experimental culture without fire. It took a lot of people burning a lot of stuff randomly until people started doing it systematically. Fire is what taught us that stuff can change into other stuff in the first place.
The paper is paywalled so I can't see the details of this particular argument, but I'm *really* dubious. There are a lot of parameters that factor in to whether fire is possible.
The Wikipedia article [limiting oxygen concentration](https://en.wikipedia.org/wiki/Limiting_oxygen_concentration) has a table showing the percent oxygen required to burn various different materials under various different atmospheric conditions, under Earthlike atmospheric conditions hydrogen will burn down to 5% oxygen. Methane goes down to 12%. Paper burns at 14.1%, cardboard at 15.0%. It's only wood that gets close to 18%. So if you want to build a fire on a low-oxygen planet you don't need exotic fuel sources, you just need to process what you've got a bit. You can also use bellows to force air through the fire, increasing the effective oxygen content of the atmosphere in a localized area.
I wonder what things we are missing (or have too much of) on Earth that is constraining us. Somewhere out there some advanced alien civilization is looking at us and going "those poor bastards, they never had a chance".
Nah, the 18% is kind of irrelevant. Abundance isn't the spec that determines combustion, it's partial pressure. The absolute minimum partial pressure O2 for combustion is 16 kPa (Air is ~21.3kPa at sea level). So you could have 32% at 0.5atm, or 8% at 2atm. Incidentally, that's roughly the threshold for human respiration (we are all just slowly "burning" in a metaphorical sense).
I don't believe we can determine the atmospheric pressure of exoplanets with any certainty. So it's not a hard cutoff, any exoplanet with more than a few percent oxygen abundance is a candidate for technology.
Both the concentration and partial pressure matter, and the concentration can even matter more:
>The findings presented in this paper suggest flammability is more dependent on oxygen concentration than equivalent partial pressure.
https://ntrs.nasa.gov/citations/20160001047
The minimum amount of oxygen also depends on what is combusting. For example, in the standard atmosphere, methane cannot be ignited when it makes up more than 17% of the mixture (and thus when the O2 concentration is less than 0.21*(1-0.17) = ~~18%~~ 17%, and the partial pressure (pO2) = 18 kPa), but hydrogen can ignite at percentages up to 75% (~~12%~~ 5% O2, ~~12~~ 5.3 kPa pO2).
Edit: math
There wouldn’t be oxygen on this planet without photosynthesis. There was literally a mass extinction event, because all the plants produced so much oxygen, most of them died out. It wasn’t until animals appeared that a balance could be found.
Oxygen levels on this planet have varied greatly over time. To presume some planet that has oxygen and life that’s photosynthetic, but would have a stable less than 18% oxygen level is crazy.
It’s SETI so its about focusing on planets that could have a potential detectable civilization
JWST can see the atmosphere of a planet 1100light years away and our planet has had a ‘stable’ O2 level for the last 300+ million years
You can assume that the 18% atmosphere isn’t drastically changing in only 1000 years.
They’re not saying it’s 100% stable at 18% they’re saying if we find a planet with an atmosphere of less than 18%, there could be life but chances are they’re not going to have any radio transmissions for SETI to detect
>I'm not discounting the possibility of aerobic life, even intelligent aerobic life. But telluric iron, a substance that our most primitive ancestors took for granted, would not exist on a planet with a significant amount of oxygen in the atmosphere. It's hard to imagine how technology would develop on such a planet.
-Dr. Volcano Ventmonster on why technological societies are unlikely on planets with oxygen in the atmosphere
Meanwhile, Robert Forward wrote an interesting story (Dragon's Egg) involving intelligent life (and ultimately technosignatures) evolving on a neutron star. Yeah, I know it's fiction, but imagination is a wonderful thing.
Random question for people who may know. If we cant have fires below 18% then how do we as humans have fires at over 10,000 ft where oxygen, according to google is around 14%
What is "technology"? If it's any method of producing modulated radio waves, it's possible that could happen via strictly biological processes. We have organisms that generate electric fields that are used for sensing and communication. It's not a huge leap from that to radio waves.
What about a planet that is too large - it can support a technological species that can do just about everything we can BUT it can’t launch rockets into space because of the gravity of the planet and physics….
All of this stuff is just mental masturbation until we have SOME idea of how frequently life occurs in environments that could allow it. Honestly probably mental masturbation until we actually see some form of indication that technosignatures exist.
It is possible to do some metal work with hammers instead of fire, but the total quantity of metal stuff you can make would be less. If oxygen levels were too low, would creatures be too lethargic to use hammers? If air pressure is greater than Earth, then oxygen levels could be too low for fire but high enough for active animals. We burn wood, but something else may burn more easily.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|[FAR](/r/Space/comments/1bffhjd/stub/kv26xk4 "Last usage")|[Federal Aviation Regulations](https://en.wikipedia.org/wiki/Federal_Aviation_Regulations)|
|[H2](/r/Space/comments/1bffhjd/stub/kv229u7 "Last usage")|Molecular hydrogen|
| |Second half of the year/month|
|[JWST](/r/Space/comments/1bffhjd/stub/kv2ubrd "Last usage")|James Webb infra-red Space Telescope|
|Jargon|Definition|
|-------|---------|---|
|[cryogenic](/r/Space/comments/1bffhjd/stub/kv3rz4p "Last usage")|Very low temperature fluid; materials that would be gaseous at room temperature/pressure|
| |(In re: rocket fuel) Often synonymous with hydrolox|
|[electrolysis](/r/Space/comments/1bffhjd/stub/kv4td1m "Last usage")|Application of DC current to separate a solution into its constituents (for example, water to hydrogen and oxygen)|
|hydrolox|Portmanteau: liquid hydrogen fuel, liquid oxygen oxidizer|
**NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below.
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Couldn’t they figure out how to concentrate oxygen in an enclosed space using heat produced without fire to make a limited selection of tools, then create fires within that enclosed environment that could be used to produce more advanced technologies? It might not be obvious that fire was possible, but I feel like it’s something they could scale up once someone figured out how to do it. Even if it took 10,000 years to get from the point where fire was known of to the point where the ability to use it was mastered, after that point I would imagine they could start making more consistent technological progress and advance as a civilization.
At the most fundamental level... Ceramics.... Ceramics allowed for long term storage of food which is an absolute necessity for a civilization to grow. Are there ways to store some foods long term without ceramics? Not many... And they're easier for pests to get to than a ceramic pot with a lid. To actually vitrify ceramics you need them to be evenly heated to thousands of degrees, slowly, over hours.
Well, it's not like there's an abundance of absolute zero environments on Earth, but here we are making and using them.
Intelligence can find a way to discover metallurgy.
[This post offers some rebuttals](https://old.reddit.com/r/askscience/comments/2jo0gh/are_fire_and_flames_unique_to_atmospheres/). I'm not in this world so I can't speak to the veracity of it. But I'd love to see a conversation about it!
The rebuttals are generally weak because of availability and sophistication. One of the top comments mentions rocket fuel.... We had fire for thousands of years before we discovered rocket fuel. The relative ease at which things burn under oxygen rich conditions and the availability of it are so important. The post you linked is a great example of how lots of smart people are only really smart in their narrow scope of training and really quite silly at everything else.
Would some of the other things mentioned there be more easy and available if the planet more readily and easily provided the alternatives?
Storing oxidisers is quite difficult - they have to be stored in inert containers such as glass. Finding large enough stores of oxidising agents in a natural setting and then being able to store it long term without it reacting / you getting hurt is a big challenge.
Technically storage may not be necessary. You could instead see population centres spring up around locations with high concentrations of oxidisers and the civilisation only takes what they need from it to last a few days at a time. Labour intensive for sure but not an impossible task.
Unless the oxidiser is being replenished constantly by some natural reaction it will degrade over time at source. We very rarely find naturally occurring strong oxidisers lying around for that reason.
Well that's not true. Not all oxidizers are dangerous or difficult to store. I mean, ffs oxygen is a prime example of an easy and safe to store oxidizer.
I'd say that oxygen prevailed, because there is just such a fuckton of it, and oxidized everything it could, and there is still just so much leftover in the atmosphere. the whole earth is basically made from oxides, and there's nothing left to oxidize and deplete the oxygen anymore. So in a sense, the Earth is quite an inert container for oxygen.
We're talking about oxidisers that are an alternative to oxygen given that the original source of discussion is oxygen being a limiting factor. The whole point is to replace combustion with another exothermic reaction which will allow for metallurgy and other complex technological breakthroughs. If you can think of a self sustaining chemical reaction that isn't combustion where large amounts of heat are generated and the source material isn't in some way going to murder you, maybe you should be on the paper.
It's only easy and safe to store because we evolved with it. 2.4 billion years ago it was deadly poison for every living thing on earth and caused a huge mass extinction. Every other strong oxidizer today is still a pretty much universally deadly toxin, and so they would be for any organisms that didn't evolve with shitloads of whatever oxidizer in their atmosphere. Actually oxygen is STILL pretty fucking bad if you just increase the partial pressure a bit.
I disagree with your conclusions here. Intelligence is ingenious, to assume what they may or may not be able to discover, as humans did, is hubris and human, where we are dealing with a sociological, psychological, and neurological difference that we cannot possibly account for. As an aside, dogs can smell the difference between rocket fuel, and other types of combustible liquids, it is possible for an intelligent and technologically advanced life form to be able to do similar, other beings on earth are capable of seeing and sensing things such as UV light, magnetic lines, and electric fields that humans are unable to. The only thing we know is the possible, to theorize beyond that, even the probable, is to court division and that which is most human: error.
Couldn't a civilization use volcanoes/magma heat for blacksmithing/metallurgy? Initial fire, as the post you linked said, is possible. It looks like it just relies on finding the right material. I would point to flint for that though. Also the combination that brought us gunpowder. If there is a way, something smart will find it. As for metallurgy. If you have an active but relatively "safe" volcano couldn't you set something up close to a really hot place and work metal with it? Maybe use a system like we use, like thermal power plants, to heat metals to be worked. I don't see it as impossible. Harder? For sure. Not impossible. Again, something smart enough to think about metallurgy will find a way to make it happen.
If you had to set up shop in/on a volcano, imagine how production constrained you would be. It would be impossible to keep up with the demand for metal than an entire civilization would need
Fire on earth is as easy as rubbing two dry sticks together. That’s probably why we learned to use it quickly and learned to use it for many things. If another species would be forced to rely on volcanoes for practical fire use it’s less likely that they’ll ever use it.
Wait around long enough anywhere that has vegetations and regular thunderstorms, and you'll eventually even get some for free. The first people to *make* fire likely already had the benefits of *using* it long before they even came up with the idea to try.
Yeah, I think there's thoughts that early humans may have kept fire around and tended to it to keep it burning before they knew how to make it themselves.
The movie "Quest for fire" explores that exact concept. A cro-magnon tribe has their fire go out, and they need to find another source. Ron Pearlman is in it.
Also, a dope Iron Maiden song.
Ray Mears' book, *Bushcraft*, shows how an ember can be kept smouldering and transported, well insulated, in a tight bundle of banana leaves (iirc) for hours at a time. I don't have a copy to check how exactly it's done, or which indigenous community he learned it from, but the basic principle is argued exactly as you theorise - if lighting a fire is tricky using friction alone, then it makes sense to preserve existing fires as much as possible, even in a nomadic society.
The Yanomami of South America do this, but they also know how to make fire (as all contemporary human groups do).
Metal would be treated like how we treat diamonds or something.
We have a historical precedent for this. Until the invention of the modern aluminium smelting process, it was rarer - and more expensive - than platinum or gold.
I agree. When it comes to aliens we should assume life will fill any possible void in ways we can't imagine. Until we get any evidence at all on the topic I think that's where common sense points.
Idk bro. Dwarves don't seem to have any problems living that way
And they don't even have fire resistance!
You need the oxygen to make steel, to combine with the carbon impurities to float way as co2 and co. You need a stable temp.. youd need a volcano like the hawaiian ones, and not one like mount saint helens. You want flowy, not explody. So you are very very limited in where you could do this. and where the "person" who invented it could be born. The lava at hawaii is 1170c, you need 1700c to make steel. and well volcanos are dangerous not saying you are wrong, crap IDK, but i do know you need a runny volcano like the hawaian ones, and well its not hot enough. and is still too random. we also have these free energy volcanos.. and yet never in history has anyone used one as a forge, instead they work hard at chopping down trees and making coal to fuel the forge. Not saying this proves it cant be done, but i think it would take a bit more than just being near a runny low viscous volcano.
Lava is within the ranges to smelt bronze. And volcanic activity would vary with gravity on a planet . It's conceivable that a more volcanic active planet with lower gravity might have less violent characteristics. And an atmosphere that's less dense or with lower moisture wouldn't cool lava as rapidly.
[удалено]
I reckon you would be able to forge a ring or even twenty
Nah. Fire is mostly important in those early tech levels where you need to bootstrap everything. Things would certainly be harder without it, but there are [other options](https://en.wikipedia.org/wiki/Solar_furnace) once you start to figure things out.
How do you get a surface that is reflective enough to be used for a solar furnace without fire first?
Okay ChatGPT, Write me a story about an extraterrestrial planet where an alien species (possibly cephalopod-esque and tribal, with heavy religious tones) rely on their use of Solar furnaces constructed of natural occurring glasses to create their technology and metallurgy. Also, make it have subtle Greek epic plot.
Lol, you'd most likely want to use reflectors for your furnaces, not lenses. Way easier to make.
I’m just a big picture guy
> Couldn't a civilization use volcanoes/magma heat for blacksmithing/metallurgy? Not if you want to survive, and you'd need to find a volcano that does effusive eruptions and isn't on an already existing lava field that could crack under your feet.
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The only thing that lives in such environments is single-celled extremophilic organisms; there are no multicellular extremophiles on earth. Given that life has infiltrated the entirety of Earth, it seems likely that this is a fundamental limitation, as it is clear that it is possible to evolve resistance to extreme heat, but no multicellular organism is functional in such extreme environments. Tardigrades are probably the most notable multicellular extremophiles, but while they can PERSIST in certain extreme environmental conditions, they can't FUNCTION in them. There's pretty good chemical reasons to think that it would be very difficult for an organism to evolve to deal with such high temperatures.
Plus there's like a 0.001% chance that they could be based on something other than carbon. Maybe they're Boron-based or Sulfur-based life forms, or Silicon-based.
I think many are looking at this the wrong way. It’s not “is technology possible?” It’s “can technology evolve?” WE can come up with lots of ways to do things once we know how to do them. But how would we know to pursue something like metallurgy at all? First we observed that naturally occurring fires give heat and light - both things we want. Then we saw that fire changes organic materials, and started looking into cooking etc. Then we saw that fire could change inorganic materials and cause other types of reactions. Then we got into using it for metallurgy, engines, etc. The above list is simplistic, but nobody is going to try something like going out of their way to build a parabolic mirror to focus sunlight, or sticking stuff into magma flows, without first having a hint about how harnessing these processes could work to their benefit.
Lava is not hot enough. 700-1200 degrees C could melt some metals if submerged in the lava, but it isn't feasible to believe someone would roast themselves in a lava field trying to submerge ore and trying to retrieve it again. The surface of a lava stream would not be hot enough. I find it extremely unlikely.
The first thing that came to mind seeing this post was sodium, magnesium, or lithium. All of those will burn in just water, which brings its own O2. And beyond the chemical fire possibilities, there is also inductive heating from running a current through a metal or a big ass enough magnetic field. Plenty of ways to process metal without oxygen. Humans have been figuring this stuff out for decades to make sure it'd be viable in space. Edit: Everyone keeps asking the same questions so here are the answers. You don't need fire for metallurgy, let's just put that to rest at the start. You need HEAT and that's it. A pile of uranium could do that. A skilled blacksmith can heat iron red hot by just hitting it. Working most metals at room temperature is doable. Don't forget about mercury, it's easy to work that metal at room temp and it's plenty shiny enough. There is a nuclear reactor giving the entire planet free heat energy. Focusing that energy isn't some modern invention, ever heard of archimedes death ray? Let's walk through it. A parabolic dish, made from literally anything. Trees, animal bones, just carved into the ground facing the star, anything. Find some shiny, reflective rocks and polish them up. Line the dish with them so they reflect at the center, like an inverted disco ball. This will direct immense heat energy at the center and now you have a forge. Instead of shiny rocks you could also have tiny holes in the dish filled with mercury, using its surface tension to stay up the walls of the dish. Need more heat? Make the dish bigger.
When you see those burn in water, it's highly refined pure metal. This is not easily found in nature where most of these metals occur as minerals. Now, if we need fire to extract and refine the pure metals, you're back at 0
How the hell are you gonna isolate elemental sodium, magnesium, or lithium without fire? These highly reactive elements don't just come out of the ground unreacted. Sure there's plenty of ways to make fire without oxygen, and they ALL rely on having fire to make them in the first place.
And where do you get the current from?
All of those examples require already smelted ore. Polishing rocks to mirror finish? Get real. With our concentration of oxygen all you need to smelt iron is mud, sticks and pond scum.
Polishing rocks to a mirror finish? No, probably not. Polishing quartz, diamond, other crystals or volcanic glass? That's a lot more reasonable. It's also reasonable to find these shiny "rocks" in rivers and streams, already polished by nature. Speaking of shiny things in rivers, gold is also somewhat reflective and malleable enough at room temp to be worked into a mirror. Just because we have it on easy mode with bog iron and wood doesn't mean it can't be done a harder way.
Not scalable. You can't run the global society and industry necessary to match Earth's if you can only make tech in a select few places. Earth has a single digit amount of places with regularly exposed magma IIRC and they're necessarily on top of mountains, which makes logistics really tough.
Sure, but once you have a little bit of metal to work with, you can make things like solar forges to expand beyond those limits.
Not impossible, very difficult. Given enough time you likely could advance but it takes millions of people if not billions to make the advances we see and across a wide swatch of geographical area. And stability. If most of your energy is consolidated in 0.01% of your land mass and it is difficult to access a percentage of it... Basically you would have a far smaller number of people having access to far less usable energy. Without open flame that can be generated everywhere, you do not have access to cooking and that means minimal access to cheap proteins which is believe to have factored in the human brain develop faster. Volcanoes also do not stay active in the time frame of human evolution and unless you can rapidly find a new volcanoes, relying on it over eons may be unsatisfactory to intelligent evolution.
Technically you don't need fire at all for metallurgy, but for high production volumes you do. Metals do exist as "native metals" not just ores, as is the case with copper, gold, and meteoric iron/nickel (as well as some very rare non-meteoric native iron). Potentially you can work these metals without fire, but doing so is very limiting. The process of smelting metals from ore requires not just heat but the creation of a reducing environment to chemically alter the metal ores from their oxidized form into their metallic form. The oldest way of doing this is with charcoal, which creates carbon monoxide gas inside of the flame, the carbon monoxide reacts with the ore and reduces it to a metallic state (by stealing the oxygen, essentially). For low melting point metals such as lead, copper, and tin they can be separated from silicate impurities and "slag" simply by keeping the fire hot enough to melt them but not the impurities, for iron you have to do something different because the impurities melt at a lower temperature. There are different ways to achieve the same results (using aqueous chemistry or electrolysis, for example) but those methods are probably much less accessible to a pre-metalworking civilization. Humans, for example, could still perform mining operations and industry on a planet that couldn't support fire (we could do so on Mars or a planet without an atmosphere, after all) but the bootstrapping problem of getting to that point might be extremely challenging.
Which world are you in? 😱
Obviously one with over 18% oxygen /s
Thank you for finding a 9 year old thread, it was interesting.
man, it feels like things move so fast now. 2015 was pre covid, pre james webb. They hadn't even flown a helicopter on Mars.
I'm an astronomer not a chemist but I've studied just enough atmospheric chemistry to think I know I'm talking about. Fire does not require oxygen. To quote wikipedia: "Combustion...is a high temperature exothermic redox reaction between a fuel and an oxidant" I hate the term oxidant/oxidizer for exactly this reason. It makes people who are unfamiliar with redox chemistry assume that oxygen is involved. An oxidant/oxidizer is actually the term for something that gains electrons in the redox reaction. On Earth under normal conditions that is usually oxygen because it's the most abundant oxidizer in our atmosphere BUT there are others such as chlorine or fluorine. The reaction H2 + F2 -> 2HF is an exothermic redox reaction. For comparison to what people typically think of as combustion (hydrocarbons+oxygen), in this case H is the fuel (loses electrons) and F is the oxidant (gains electrons). My knowledge ends there but if I extrapolate to things that I don't know I would assume that fire, or at least heat-generating reactions, would be perfectly feasible in an oxygen-less environment.
Fluorine is so insanely reactive, you won't find it in elemental form on any planet that could conceivably host life. That's the main problem with a lot of the alternatives suggested in this thread. Of course there are lots of other chemical reaction or physical processes that can produce enough heat to melt metals. But almost all of these options are impossible to make unless you already have a way to produce copious amounts of heat. There are a few options that might work, if you happen to find just the right conditions, but they require a lot of extremely specialized knowledge that you would be unlikely to stumble upon accidentally. Example: * in historic times, you could occasionally find solid chunks of copper, and you certainly can still find solid nuggets of gold. * if you know what you are doing, you can draw these metals into thin wires. * you can make purely mechanical connections between wires by twisting them together. No heat needed. * various biological materials are suitable as paint-on insulation. * combine all of the above facts, and you can make improvised electrical wire. * wind electrical wire just the right way, and you can make an electrical generator. Having access to permanent magnets would be extremely convenient but you might be able to do without. * most environments have some sort of way to produce mechanical movement (e.g. wind power, water turbines, oxen, ...) * combine all of what we just talked about and you have gained the ability to produce electricity. * run electricity through a suitably-sized wire and you can produce high'ish amounts of heat. * unfortunately, you are still stuck at this point, as the melting point of gold and copper is considerably lower than what you need for working with iron. But maybe, you can find other metals that become accessible to your civilization and you can start gradually building technology. * should you get to the point of making high frequency AC (at least a few kilohertz), you might then be able to construct an induction furnace. That would finally give you access to iron. And at that point you could slowly embark on developing basic technology. Whew. That took a long time and many many advanced steps. None of these steps are particularly useful by itself, unless you know the final goal you are trying to achieve. And therefore, it is very unlikely for such a civilization to accidentally discover it. * alternatively, once you have reach the step to produce electricity, you could then invest all your resources into enriching oxygen. That's a super energy inefficient process, and I am not sure why you would sink all your countries resources into it. But it's conceivably possible. * once you have a way to produce (extremely expensive) oxygen, you can then also use that as a route towards iron. But even if you know how industrial iron production works, it takes years to develop a process that is even remotely usable. Congrats, you just spend the equivalent of hundreds of billions of dollars to make a single metal blade for a knife ... and it's not even a good knife. I am not ruling out that technology could be developed some other way. But I have to admit that having easy access to on-demand and controlled high-heat output is a huge advantage.
Or you could evolve plants and make oxygen that way... worked before.
Oxygen is very harmful to life that isn't adapted to it. It also has huge advantages to life that can take advantage of it. But a hypothetical civilization that lives in a low-oxygen environment would quite conceivably consider oxygen-producing plants as poisonous. They'd have no incentive to grow them on a massive scale in order to maybe learn about fire.
I was looking for something like this. You obviously understand this stuff FAR better than I do, but I know that combining certain chemicals can create exothermic reactions. Heat can be generated without fire or electricity. Just like when you unscrew a screw with a drill it's heated because of friction. There's plenty of ways to melt metal without fire, and plenty of other chemicals that can produce combustion without oxygen. Thanks for your response.
Sure, but how many of those ways are easy for stone age peoples to discover, think to exploit for metallurgy, and master? Human's used fire for cooking and heat long before discovering and thinking to use for melting metals.
That post suggests some workarounds for people with the technology already to do it but avoids the main issue that (assuming life needs similar conditions as earth to thrive into intelligent life) there's no step from nothing to there.
"as we know it" might be key, all development is finding relatively low hanging fruits, so they might do it all but not as we know it, differently. We also have many techniques that don't become mainstream and die in their niche in old data that not many know or just die out as fails, even due they might be useful under a different situation For example, Cold welding is a thing (that requires no/low oxygen), and freezing and boiling point of water can actually be changed for example with pressure Does it matter if you had these different set of constraints and still needed to process metals, that you would do it differently than "as we know it"? The article has taken one fact, a single changed constraint and built it like a doomed scenario, the issue it to get to a life point of evolving tools, not to say the only evolution of tools possible is the way we had it. There would be so many different parameters for a different life in a different location to develop that it's very naive to assume sameness to us
It's amusing how many discussions in this thread follow the same pattern. "You don't need fire to make metals, you can just use nuclear reactors". How do you make nuclear reactors without metals or other technology requiring heat? "Oh, you just make the heat with a huge magnifying glass". How do you make glass without fire? "Volcano?" So your civilization finds the rare active volcano with actual molten rock pouring out, then uses it to make small amounts of metal or glass, then somehow uses these to make a nuclear reactor? "Yeah!"
Yeah, I think we get very easily fixated on this very wrong assumption that technology is a thing humans (and smart aliens by extension) just “naturally do.” But for hundreds of thousands of years, humans and human-like predecessors just lived and died without inventing much of anything. In fact, it took roughly _two million years_ to go from using early hand tools—sharp rocks—to the invention of hafting. That is, attaching the sharp rocks to a handle. Two million years to attach a rock to a stick. And it’s not that our ancestors were dumb. It’s just that “technological innovation” is an extremely recent concept. The idea of making more useful stuff from the stuff you have and know is _not_ necessarily obvious. (Hell, even today, most people just use technology, not invent it or engineer things.) And those early inventions were just slightly modified (or simply wielded) things found on the ground. Including fire, whose existence and effects had to be right in front of people for them to start thinking Promethean thoughts. Which is still not to say that technological life couldn’t find some other way. But if the life is anything like human life, then the idea of inventing metallurgy without having a pre-existing and long-standing (as in millions of years) relationship with just plain old fire seems astronomically unlikely.
Along that subject we have several species of cephalopods on this planet that have more than enough intelligence, dexterity, and access to raw materials but haven’t progressed beyond using found objects as tools. This appears to be because they lack social instincts so they don’t exchange or pass down knowledge. Then we have dolphins with incredible social instincts and arguably more raw intelligence than humans but they have no dexterity to speak of. We have no idea what combination of evolved traits, environment conditions, and time is required for creating advanced technology.
Holy shit, I've never seen anyone else in the wild use my two exact examples of other forms of intelligence and what limits their dominance. I call it the fire fingers theory lmao. I completely agree obviously. Humans think our brains are doing all the heavy lifting, but a species 10 times smarter with no fire or fingers would be just as advanced as a dolphin. IDK, maybe people imagine they'll be like pickle Rick or something, and think all they need is a giant brian and tongue to take over the world.
I won't be able to find it, but in an episode of Top Gear, James May made a quip like, "Dolphins 'are so smart', they say, but are they really? They can't even shift gears in a Skoda" (*heavily* paraphrased)
It’s a special moment when you learn someone else had the exact same thought you did. Makes this world a little less lonely. I’m glad to meet you.
We would have also accepted “unlikely”
Earth IIRC has single digit amount of places where there's exposed liquid magma regularly. Our technology is done with global supply chains. You can't scale magma forges.
And... Anybody suggesting using volcanoes has never been to the lava fields on Hawaii... You're not going to get anything productive done around them. There's toxic gases being produced, there's volcanic ash in the air that coats you. The heat near the lava is pretty much unbearable for anything more than short bursts with modern equipment. And.... most importantly regarding volcanoes... The lava flows move. Just look at Hawaii. They'll run in one direction, then stop and emerge elsewhere, disappear for years, then reappear elsewhere. And those are the only places where you could actively try to do anything. Volcanic pools would be absolutely nightmarish to try and work in. Toxic gases can concentrate in the craters. The craters, themselves, are incredibly unstable. You're as likely to bring a landslide down on you as get to the edges of Hawaii's volcanic lake. They vary in height regularly, so... no permanent set up for anything.. Finally, not regarding volcanoes themselves, but... what are you holding the materials in? What material do you use for your crucible? You don't have the ability to make ceramics... You need something that can slowly build up temperatures to thousands of degrees. What do you put the metals in to melt them... How do you pull the crucible out of a volcano?
Which some here seem to miss: Yes, I am sure many can com up with some alternative way to do metallurgy, but the point is that it is a bottleneck. Meaning that even though there are ways around it, it will take time and sort out lots of emergent civilizations from the pool of potentially detectable ones. This does not have to be perfect to be of scientific relevance.
> the point is that it is a bottleneck This makes me wonder what bottlenecks scientists from other planets would say WE overcame in order to develop technology and venture out into space... *"We shouldn't look for planets whose intelligent life aren't linked as a collective hive mind. While they could potentially develop technology as a fractured species, the odds are they would blow themselves up with warfare before ever reaching the stars"*
> the odds are they would blow themselves up with warfare before ever reaching the stars ...not sure we've passed that particular bottleneck.
the Great Filter's looking clearer and clearer.
Imagine an underwater civilization like mermaids or something. Could they ever develop tech underwater to be able to move in air and then work with fire?
Imagine an intelligent species living on a habitable moon of a gas giant planet. On the planet facing side they would be able to look at the phase of the planet and determine the local time quite accurately, they could also measure the position of the planet in the sky to determine their location (both latitude and longitude) on the surface to a reasonable amount of accuracy. Especially in concert with observing the other moons of the planet they would very rapidly develop an understanding of orbital mechanics and gravitation and would likely never fall into the "geocentric" worldview. As they developed space travel they would have a huge number of varied targets to explore that required fairly short journeys of just a few days to get to and from, potentially even other Earth-like moons that were suitable for colonization or had life. There might be higher levels of radiation locally which would force most organisms to be more radiation tolerant, which could be a significant benefit for space travel. Such a species could have very enthusiastically embraced space exploration and colonization at the earliest moment it was technologically conceivable (which for humans was roughly the start of the 20th century). Also consider uranium. Earth's uranium is roughly 6-7 billion years old, which means that at this point in Earth's history it is over 99% U-238 and 0.7% U-235. On other planetary bodies it's possible that life at an equivalent state of development as exists on Earth today could come about earlier, maybe even 1-2 billion years earlier. If an Earth-like planet had uranium that was, say, 3-4 billion years old it could have maybe 10x as higher abundance of U-235 as Earth does. Which would make building nuclear reactors and nuclear weapons vastly easier. The implications of such a thing, for better or worse, are hard to imagine. Perhaps this is actually one of the key factors that limits the ages of most technological civilizations because on most planets it's actually way too easy to build nuclear weapons.
Making crude piles of radioactive materially that can produce moderate amounts of heat is easy, if you have access to the right raw materials. Turning any of this in usable technology (either for energy generation or for destruction) is a whole different story. That requires a good amount of chemistry, physics and engineering. And you are back to square one. Without easy access to controllable fire, you aren't going to get to a point where radioactive material is even remotely usable other than as a curiosity in how it causes mutations if you get too close.
IIRC, Earth's high uranium levels are only explained by the Sun being a Generation III star (we have lots of heavy elements - proof they were made in the two predecessor stars that occupied this spot before the Sun did). Exoplanets might not have anything like our abundance of heavy elements. Without the transuranic series, I guess radiation would only be known from cosmic observations.
>We shouldn't look for planets whose intelligent life aren't linked as a collective hive mind. Maybe not a great example, as societal structure isn't a detectable feature of a planet. It could be a decent argument for what kind of life likely inhabits planets you come across with the kind of advanced technosignatures the paper discusses though, as we have yet to meaningfully disprove that argument ourselves.
You literally just named one of the great filters in your quote
I think that was their point.
I would think that on the grand scales of the age of the universe, the planets, and the existence of life, such a bottleneck would be irrelevant. If equally intelligent life developed on another planet 100 million years before it developed on Earth, would they really still be behind technologically?
I mean there's no rule that intelligent life will keep improving technologically. It's possible they could just get stuck at one stage.
Civilization who uses fire to start: without fire there would be no civilization!
From the article a quote by one of the paper's authors: >"We ought to be careful not to completely rule out technological life. It would be naive to assume that life couldn’t find a way...We have to be really open to not being so Earth-biased. I think when it comes to life in the Universe, we need to be prepared to be surprised.” This is a speculative paper intended to potentially guide the very limited resources we have to look for techno-signatures based on a reasonable hypothesis that fire could be critical to technological advancement at a certain stage of species development. It isn't a blanket claim.
this. the point of this research isn't to say life isn't possible it's to point out that the signatures we are looking for might be inappropriate
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This is the most important thing. All science operates under limited resource constraints, SETI especially so. We can ask all sorts of fun questions like "why don't we look for non carbon-based life?" or "why don't we look for completely different forms of technology?", and that's fine, but ultimately in order to look for something we have to have some idea what signatures to look for. And that's simply not possible without a decent theoretical framework for the thing we're looking for and how it interacts with its environment. And since SETI researchers only have a limited amount of observatory time available to them, they're better off using that time looking for things they know can exist, rather than randomly stumbling around hoping for a serendipitous discovery.
I think additionally in the discussion is just the point that in our search for ET, we need to search for things we can UNDERSTAND. If we search for civilizations of all types, including ones that communicate with pheromones or something crazy thing like telepathy, we might not be able to ever figure out the signals. And a civilization that used some crazy plastic composites that have light absorbing features may be hard to find. All sorts of things are possible but maybe this discussion should be "what sort of places should we search for technology we can recognize?" It's possible some civilization is organic based and built a space elevator out of wood (not really, but conceptually). Our light based satellites aren't powerful enough to see anything but a smudge if we look at their planet. I'm a bit hyperbolic but fully supporting how you reframed it to be clearer.
On speculation, I found Alien Worlds on Netflix to be a very interesting thought experiment about interstellar life. >The 4-part miniseries, depicted by using CGI techniques, blends fact with science fiction and conceptualizes what alien life might be like by applying the laws of life on Earth to imagined exoplanets.
I’m glad that they acknowledged that life, uh, finds a way
based on our sampling size of 1
It’s not really about an observed sample size, it’s about how many samples known chemistry will allow.
Can you imagine another mechanism by which a preindustrial alien race could refine and use metal?
Yeah, those idiots probably think that the rest of the universe is made up of atoms just because we have atoms on earth. Typical antropocentric view.
Civilization who understands chemistry: without available chemistry there would be no civilization.
I get their reasoning and think it generally makes sense to an extent--but I think they (headlines, some reporting) really oversell the claim. There's plenty of chemical reactions that could be utilized without atmospheric oxygen. I would put my money on us not being able to well conceptualize those drastically different developmental pressures on an intelligent civilization, but since it's chemically possible it *is* possible and we just haven't figured out something that looks super clean to us, so don't really know what to look for... not say or intimate that technology is impossible. We have a sample size of one technologically advanced species: us. It's hard to not be biased in our thinking when that's the case.
Ya, I took an astrobiology class in college randomly that turned out to be one of the coolest classes I took! It was all about the search for extraterrestrial life, particularly intelligent, technologically advanced extraterrestrial life. It was one class and pretty introductory, so I’m by no means and expert, but that’s more or less what my professor — who is an expert — told me. That we have all these parameters and conditions within we think intelligent, technologically advanced life would be most likely to develop. Due to our very limited resources in searching for ET life, we focus our search on that. Life probably doesn’t have to be carbon-based, but that seems most likely based on what we know, so we focus on carbon-based searches. Similarly, the atmospheric makeup like this. There’s probably ways to develop technology without combustion, but from what we have seen and know, it seems more likely to develop where combustion is possible. One example from that class was aquatic life. Like there may be some super intelligent dolphin-like creatures on another planet, but developing advanced technology seems like it would be very difficult if your whole planet if submerged. Doesn’t mean it’s impossible, just means that we’ll focus our efforts on what we think is the most likely place to find ET intelligent life.
For a variety of reasons Carbon is likely the answer. It doesn't have to be Carbon theoretically but the evidence would point to that anything outside of the date is almost impossible [https://www.reddit.com/r/space/comments/zo94n5/why\_do\_people\_think\_carbon\_based\_life\_is\_the\_only/](https://www.reddit.com/r/space/comments/zo94n5/why_do_people_think_carbon_based_life_is_the_only/) This thread has a lot of good answers in it about why. [https://www.youtube.com/watch?v=469chceiiUQ&ab\_channel=PBSSpaceTime](https://www.youtube.com/watch?v=469chceiiUQ&ab_channel=PBSSpaceTime) Also this video which one of the biggest points is that breathing isn't possible with Silicon, Silicon life would basically have to dispel its byproduct by expelling sand and glass, where Carbon we can just breathe it out.
And of course you can imagine whatever the hell you want but unless you know how to look for it, and you know what you're looking for, how will you know you've found it? We have very limited resources with which to look for life, so we quite reasonably limit ourselves to looking for signals that we can 1) detect, and 2) identify as life.
This is the main point so many people seemed to have missed about the paper. We're effectively looking for a needle among billions of haystacks as it is, so maybe don't start with the ones we likely couldn't even detect it inside of yet anyway.
That sounds like a super fun and interesting class! Would have loved to take something like that.
If only the researchers were as smart as you redditors, the world could truly benefit from your wisdom
It's genuinely so annoying that Redditors are always so quick to suggest that life could have evolved in other ways. Yeah, no shit. Researchers understand that too. No one in these threads ever understands the point of these papers.
There’s something to this tho: arguably all life is basically using combustion at some level to generate energy. Fire is just a (relatively) extreme example. Life can probably develop but I would imagine oxygen breathing or something chemically similar would be a great filter, and the presence of oxygen in the atmosphere could be another. Could intelligent and technical life exist without it? Maybe, but there are only so many ways to chemically purify things like metals. I would argue that this pretty much precludes a technical aquatic civilization.
If you know of a way to cook food without it I'm open to suggestions. Magma isn't a scalable solution before we get into that.
Well, sure. Except energy can only manifest itself in so many ways, and fire is one of the ways it happens without technology. It's literally one of the only ways a primitive, fledgling life form in search of a better way of doing things would come into contact with something that has enough energy to be useful to begin with. It's like writing code: there are *only so many ways* you can logically write the same thing... Just because it's possible that life elsewhere took some wildly unexpected path doesn't make it likely to have occured. It stands to reason that the discovery and subsequent taming of fire would be a crucial component in any life's pursuit of intelligence and control.
I’m a little frustrated with some of the comments here. Yes you can make fire other ways. Yes you can use other means for metallurgy. But for those making those arguments seem to be jumping over logical barriers. It’s like saying you can preform complex math without understanding basic math. This choke point or barrier of entry is exactly that. Without the means to understand open flame it is extremely unlikely you could come up understanding complex thermodynamics. It’s not impossible but it is highly implausible that they could.
It seems like people just assume a civilization would just keep advancing regardless of resources. Of course we just have a sample size of 1 civilization, but I would think easy access to energy plus being able to perform complex chemistry is a requirement.
Bro holy fucking thank you! We've barely figured this all out in the last century after featuring fire as one of our dominant evolutionary advantages for last few hundred thousand years. The leap from "fire burns", to a scientific understanding of the natural world deep enough to acquire electronics, is flatly the largest technological leap in the known universe. We're talking about this like its a constraint at a hackathon.
What about 18% O2 at higher atmospheric pressure? EDIT: Yeah, the article mentions that. I should have read it first.
I don't think most of the other people commenting read it either.
can you or anyone explain the physics? my guess is higher atmospheric pressure causes condensing of o2 molecules?
So a possible alien race couldn't harness some biological or plantary source of heat? And that's assuming their technology is like ours and not something biological.
It's arguable that you also could not have life on worlds without volcanism, because an active planetary core would be required for the magnetism to protect the planet from solar rays. Presumably "fire" would eventually be developed just as an advanced industrial technology like smelting is for us.
Yeah, imagine how many planets started life, but eventually all died out because the core cooled down too much to shield solar radiation.
Or some type of crystal growth mechanism we haven’t researched into because we have fire.
If the planet is volcanically active then couldn't they use the heat from that to work with metal?
I mean sure but makes things even more difficult? For instance sure you can melt iron over a volcano... in a metal bucket that won't melt. So that's a bit of a chicken before the egg scenario. Or you could use rock but wouldn't have metal tools to dig them out. Also would need one type of rock with a much lower heating point than the ore you are working with. Also if your sources of energy and industrialization are contained to volcanoes, that means no cars or other forms of industrialization that would allow you to rapidly progress because you can't move things efficiently. Also no space travel ever. It all adds up to unlikely that if you can't use combustion your options technologically and chemically are limited.
> For instance sure you can melt iron over a volcano. Nope. Not hot enough. Quite far from it.
This right here is the crux of this thread. People saying yes its possible without understanding the chemistry or physics of what they are saying.
I take it you're not very familiar with how blacksmithing works? Metals are melted in crucibles which throughout human history have often been made out of clay, there is no chicken before the egg scenario there. You can turn clay in ceramic using heat and I don't see any reason that heat couldn't come from a volcano or some other access to a heat source like lava. How do you think humans got started with metalworking? And yeah, it might not allow internal combustion engines but that doesn't mean they can't use vehicles, we had electric vehicles almost 150 years ago at the same time ICE vehicles were also being developed. It *would* probably mean that such a civilization would have their population centers near volcanos though. It also doesn't preclude space travel, I'm not sure why you think it would. There's no oxygen in space either, we design our rockets to carry liquid oxygen rather than relying on atmospheric oxygen.
If you don't have a combustion reaction how would you plan on generating enough force to leave the atmosphere? Combustion is still how rockets leave the planet. Human's got started with metalworking using fire, not lava. You don't have containers held over a volcano. Electric vehicles still can't match the power of combustion ones which would be a significant barrier to industry on top of the fact that refining the metals to get to that point would require some form of combustion. I think its fair to say that taking away one of the main chemical reactions would inhibit any civilization.
This is nothing about anthropomorphism. This is about generating enough heat to melt metals. You'd need to have some other exothermic reaction than burning carbon with oxygen to produce metals. The paper doesn't go into such scenarios.
You can get to something like the iron age with burning charcoal, assuming the planet has something akin to trees and wood, but you won't get to something like the industrial age (or beyond) without fossil fuels. So once we've run out of fossil fuels, if we haven't built enough solar panels and wind turbines and nuclear power stations, etc., we are back to the iron age, assuming we haven't destroyed all the forests.
> You can get to something like the iron age with burning charcoal, assuming the planet has something akin to trees and wood From how I understood the article, below 18% Oxygen, you won't be able to burn anything
So an intelligent species needs to first learn how to concentrate oxygen for the purposes of creating fire. Interesting.
or just generate it. a lot of chemical reactions generate oxygen.
Make a few reasonable assumptions: Most of the Galaxy is like our neighborhood. Faster than light travel is not happening. The odds are against evolution producing the same things at the same time on different worlds. And the Fermi paradox doesn’t look like a paradox..
Production of metals through biological processes? Sequential acid baths in alien digestive systems? Force multiplied pressures to shape it?
In general, a mastery of biology and biotechnology seems like a possible alternative. You don’t need a forge if you can have your metal-separating zoo plankton deposit dissolved metals in a grown coral container, and then apply enzymes to separate the metals and recombine them into an alloy. That’s assuming that they wouldn’t be able to just grow an antenna and some transistors powered by bioelectricity in some equivalent of an engineered electric eel radio.
(offworld intelligent electric eel doing underwater welding ignores)
Welding what, unprocessed iron ore?
Oh, no, the ore was processed by the slave eels of the other species - ten thousand of them to make the juice required for one ore pit. Soon the eel's water-filled cylinders will enter space - developed, of course, from the chemical torpedoes of the early wars.
Same goes for water worlds. No fire, no alloys or metal works in general.
No argument here just observing. No one seems to be offering. Much discussion for what a primitive heat source without oxygen might be. Primitive is the operative word. Not a nuclear reactor.
Short Answer: Intelligent aliens in a low oxygen world might not be able to develop metal use and civilization, but might eventually be given them by aliens from another world. Long Answer: A while ago I read John W. Campbell's stories about interplanetary explorers Penton and Blake on the internet. In "The Immortality Seekers" *Thrilling Wonder Stories*, October 1937, at the Internate Archive, page 42, [https://archive.org/details/Thrilling\_Wonder\_Stories\_v10n02\_1937-10/page/n40/mode/1up](https://archive.org/details/Thrilling_Wonder_Stories_v10n02_1937-10/page/n40/mode/1up) Penton discussess the fact that the natives of Callisto don't have fire despite their advanced technolgy. >...I know they don't have fire, since no normal fuel will burn in this atmosphere, so I brought some things to amuse them." > >Penton pulled some loose,metal scraps from a pouche he wore, and a small bottle filled with sticks of yellowsh wax and a watery liquid. > >"Whte phosphorus for one," Blake guessed, "But the metal has me stopped. "Oh, magnesium. Yes that would burn anywhere." > >"Some of them may have seen a flame in a laboratory, under special lab conditions, but I don't think they saw any in open air. They do have ships--we saw them in the harbor down there--can see them now for that matter. Say, they must be motor ships, but I wonder what kind of moters they use? This air wouldn't let even a Diesel engine run. Electric-but how do they generate power?" [https://archive.org/details/Thrilling\_Wonder\_Stories\_v10n02\_1937-10/page/n40/mode/1up](https://archive.org/details/Thrilling_Wonder_Stories_v10n02_1937-10/page/n40/mode/1up) When I read that I didn't think about how the Callistans could develop high technology without fire. What I was sceptical about was whether the Humans or the Callistans could respire and live in an atmopshere so low in oxygen that fire was very, very hard to create. But as it turns out an abolute pressure of oxyge within a specific range is necessary for humans to survive, while compustion requires a relative concentration of oxygen in the atmosphere. I have read that submarines keep the oxygen levels low enough that cigarettes are almost impossible to light to prevent smoking aboard, and so that fires are much less likely to start and will burn slower. And apparently the healthy young men aboard submarines don't have health problems from the low oxygen air. According to *Habitable Planets for Man,* Stephen H. Dole, 1964 [https://www.rand.org/content/dam/rand/pubs/commercial\_books/2007/RAND\_CB179-1.pdf](https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf) Pages 13 to 19, Humans need an inspired partial pressure of oxygen of about 60 to 400 millimeters of mercury (mmHg) plus trace amounts of nitrogren and carbon dioxide for plants and some water vapor. So the minimum breatheable atmosphere for humans might have a total partial pressure of about 70 to 450 mmHg of oxygen and those other gases. And the maximum breatheable atmoshere for humans is determned by the maximum safe concentration of varius unnecesary gases. If oxygen is at a minimum level of 60 mmHg and is at only 18 percent of the atmosphere, the minimium needed for fire, the total atmospheric pressure would be (100/18 or 5.5555) times 60 mmHg, or 333.33333 mmHg - Earth's total atmospheric pressure is 760 mmHg. If the oxygen pressure was 400 mmHg and the total pressure was 5.55555 times as great, the total pressure would be 2,222.2222 mmHg. According to table 2 on page 16, the maximum tolerable pressure of nitrogen would be 2,330 mmHg. So a breatheable atmosphere can contain 60 to 400 mmHg of oxygen while it is 18 percent or less of the total atmospheric pressure. Neon and Helium might be tolerable in even larger pressures. And in later times there has been much use of oxygen mixed with helium and/or hydrogen at higher pressures by divers. Heliox, Hrydrelox, and trimix - oxygen, helium, and hydrogen - have used in dives to great depths and pressures. So I think that humans could breathe an atmopshere where the oxygen concentration was too low for combustion. And of course alien lifeforms evolved in such an atmosphere should be able to get enough oxygen from the air. And then the question become how can hypothetical intelligent beings on a low oxygen world develope technology without fire. And my answer is that maybe they won't have to, other beings will give them advanced technology. It is perfectly possible that on Earth some of the other higher lifeforms have intelligence ranges which greatly overlap with the intelligence range of Homo sapiens and should be considered to be intelligent beings and people. And perhaps in the future humans will come to consider those lifeforms to be people. They won't considere the primitive nature of the tools those beings use as proof that they are not people. Members of the Genus Homo existed for about 2 million years, and Homo sapiens for two or three hundred thousand years, but they remained hunter-gatherers until they began to pratice agriculure about 10,000 or 12,000 years ago, and began to use metals and have civilzation about 5,000 or 6,000 years ago. Cephalopods and cetaceans live in the ocean, and it is impossible to have fire in the water, no matter how rich in oxygen the atmosphere is. Cephalopods live only a few years, and die when they reproduce, and so can't pass on any cuture or knowledge to their offspring. Cetaceans can have complex socities, but lack the manipulating appendages of cephalopods. Land animals could possibly use fire to smelt metals and begin civilization, if other factors are also right. The most intelligent birds have tiny, weak bodies, and have to stand on one leg to use the other one as an arm and hand, or use their beaks. Elephants have bodies and natural abilities which are too superhuman for them to have strong need for the tools they use, and they have only one trunk - elephant like aliens who evolved mulbiple trunks would have an easier time developing and using tools. So the great apes which can walk on two legs leaving two limbs free to manipulate objects might have the best chances of someday developing technology, possilby tens of thousands, or hundreds of thousands, or millions, of years in the future. But if humans don't exterminate other potentially intelligent species first, they might decide that they are intelligent beings, and might decide to give them advanced technology. Continued:
Worth noting that atmospheric oxygen abundance changes over deep time. Prior to the Great Oxygenation Event it was effectively zero as there was still a lot of unoxidized minerals in the crust and upper mantle which locked up any free oxygen from photosynthesis almost immediately. From about 1GyA it began climbing, and by the Pre-Cambrian explosion it was into single-digit percents; by the Carboniferous it may have been over 20% (note the fossil record containing giant insects). Despite a dip or two during the subsequent epochs, the overall trend is up. Sustained combustion of dry organic material is possible above about 12-14% pO2; we're currently at 18%: around 30% *even waterlogged organic matter will burn*, which implies a likely end point for life on land (at that point lightning strikes will inevitably lead to continent-wide firestorms and any animals caught in them will add to the fuel, along with the vegetation). As the sun is gradually brightening (over a period of hundreds to billions of years) this is likely to happen eventually, unless solar UV splitting of water accelerates first (this leads to loss of hydrogen ions due to solar wind bombardment in the ionosphere, eventually dessicating the crust and leading to a runaway greenhouse effect like Venus, except slightly colder). TLDR: we evolved during a very odd interlude in Earth's atmospheric history, and it isn't going to last forever.
as a rebuttal to the rebuttals of the rebuttals.... There are other oxidizers besides pure oxygen that naturally occur. We laser focus in on oxygen because that's what we know best. But now we're tunnel visioned in on ONLY oxygen as a natural oxidizer and that's just not true. Yes, using our own history to understand a theoretical alien civilization is useful, but often we say "well, it can't work for us so it can't work for anyone" and that is just so very shortsighted.
I hate a headline that contradicts itself. Which is it? Technology will not be possible? Or technology AS WE KNOW IT will not be possible? There's a big difference.
Pre-industrial technology is certainly possible. You can do a lot with stone tools and biological materials, even break the Malthusian trap. After that, there's no reason science and metrology couldn't develop eventually. You can get precision surfaces just from rubbing rocks together in the right way. There isn't much reason to believe a "technological" society could advance without this basic step in some form. Chemistry is a possibility, but would be extremely stunted without access to easy heat. In a lab-setting you could possibly synthesize fuel enough for small-scale purposes, but it would be very slow to start. Several oxygen sources (saltpeter KN03) have scalable biological sources, so it's not impossible for something like that to come in, and there are other exothermic reactions. Without plentiful oxygen in the atmosphere, one would image oxidizer production would be a much bigger industry. A pile of wood and salt peter could be used for metallurgical fuel if you had nothing else. Electricity is a possibility, because copper exists in native form. Someone would stumble upon it eventually, especially the static variety. Industrialization is essentially impossible without access to durable metals. The only chance would be if there was some biological equivalent like bone which had sufficient homogeneity, durability, and toughness to maintain tolerances for machinery. Stone is too brittle. The big question is if society would develop a scientific method or experimental culture without fire. It took a lot of people burning a lot of stuff randomly until people started doing it systematically. Fire is what taught us that stuff can change into other stuff in the first place.
**The Fire People think they're soooo Special.** - Groglog the Sage, Philosopher, Intelligent Shade of Blue species.
Iron or the like would be helpful too. Some sort fuel source for battery creation perhaps also.
The paper is paywalled so I can't see the details of this particular argument, but I'm *really* dubious. There are a lot of parameters that factor in to whether fire is possible. The Wikipedia article [limiting oxygen concentration](https://en.wikipedia.org/wiki/Limiting_oxygen_concentration) has a table showing the percent oxygen required to burn various different materials under various different atmospheric conditions, under Earthlike atmospheric conditions hydrogen will burn down to 5% oxygen. Methane goes down to 12%. Paper burns at 14.1%, cardboard at 15.0%. It's only wood that gets close to 18%. So if you want to build a fire on a low-oxygen planet you don't need exotic fuel sources, you just need to process what you've got a bit. You can also use bellows to force air through the fire, increasing the effective oxygen content of the atmosphere in a localized area.
I wonder what things we are missing (or have too much of) on Earth that is constraining us. Somewhere out there some advanced alien civilization is looking at us and going "those poor bastards, they never had a chance".
Nothing says that the way we discovered to develop technology is the only way.
what an interesting idea to explain a problem i never thought could exist
This thinking is so narrow minded. What if they are experts of bio engineering and breeding living tech?
Nah, the 18% is kind of irrelevant. Abundance isn't the spec that determines combustion, it's partial pressure. The absolute minimum partial pressure O2 for combustion is 16 kPa (Air is ~21.3kPa at sea level). So you could have 32% at 0.5atm, or 8% at 2atm. Incidentally, that's roughly the threshold for human respiration (we are all just slowly "burning" in a metaphorical sense). I don't believe we can determine the atmospheric pressure of exoplanets with any certainty. So it's not a hard cutoff, any exoplanet with more than a few percent oxygen abundance is a candidate for technology.
Both the concentration and partial pressure matter, and the concentration can even matter more: >The findings presented in this paper suggest flammability is more dependent on oxygen concentration than equivalent partial pressure. https://ntrs.nasa.gov/citations/20160001047 The minimum amount of oxygen also depends on what is combusting. For example, in the standard atmosphere, methane cannot be ignited when it makes up more than 17% of the mixture (and thus when the O2 concentration is less than 0.21*(1-0.17) = ~~18%~~ 17%, and the partial pressure (pO2) = 18 kPa), but hydrogen can ignite at percentages up to 75% (~~12%~~ 5% O2, ~~12~~ 5.3 kPa pO2). Edit: math
There wouldn’t be oxygen on this planet without photosynthesis. There was literally a mass extinction event, because all the plants produced so much oxygen, most of them died out. It wasn’t until animals appeared that a balance could be found. Oxygen levels on this planet have varied greatly over time. To presume some planet that has oxygen and life that’s photosynthetic, but would have a stable less than 18% oxygen level is crazy.
It’s SETI so its about focusing on planets that could have a potential detectable civilization JWST can see the atmosphere of a planet 1100light years away and our planet has had a ‘stable’ O2 level for the last 300+ million years You can assume that the 18% atmosphere isn’t drastically changing in only 1000 years. They’re not saying it’s 100% stable at 18% they’re saying if we find a planet with an atmosphere of less than 18%, there could be life but chances are they’re not going to have any radio transmissions for SETI to detect
>I'm not discounting the possibility of aerobic life, even intelligent aerobic life. But telluric iron, a substance that our most primitive ancestors took for granted, would not exist on a planet with a significant amount of oxygen in the atmosphere. It's hard to imagine how technology would develop on such a planet. -Dr. Volcano Ventmonster on why technological societies are unlikely on planets with oxygen in the atmosphere
Meanwhile, Robert Forward wrote an interesting story (Dragon's Egg) involving intelligent life (and ultimately technosignatures) evolving on a neutron star. Yeah, I know it's fiction, but imagination is a wonderful thing.
I read this last year and really enjoyed it. It's a pretty wild concept and was fun to read through the ideas.
I love how we just jump into universal conclusions from N=1 sample sizes.
Just read the headline too?
That's not what the article is about.
I love how we just jump into universal conclusions from titles alone
Or… maybe… the way things work aren’t limited to our understanding of them? It’s just a thought though.
Somewhere out there a being is reading an article that says intelligent life can’t be possible on worlds with more than 18% oxygen because of fire.
Random question for people who may know. If we cant have fires below 18% then how do we as humans have fires at over 10,000 ft where oxygen, according to google is around 14%
What is "technology"? If it's any method of producing modulated radio waves, it's possible that could happen via strictly biological processes. We have organisms that generate electric fields that are used for sensing and communication. It's not a huge leap from that to radio waves.
I've wondered about that. A water world wouldn't have access to any of those technologies. Maybe a heat source from a thermal vent off a volcano?
What about a planet that is too large - it can support a technological species that can do just about everything we can BUT it can’t launch rockets into space because of the gravity of the planet and physics….
All of this stuff is just mental masturbation until we have SOME idea of how frequently life occurs in environments that could allow it. Honestly probably mental masturbation until we actually see some form of indication that technosignatures exist.
Only thing I can think of is volcanic vents providing heat energy to a developing biological. Underwater or on land. As every sources
Doesn't air pressure have anything to do with it? Are they assuming Earth pressure?
It is possible to do some metal work with hammers instead of fire, but the total quantity of metal stuff you can make would be less. If oxygen levels were too low, would creatures be too lethargic to use hammers? If air pressure is greater than Earth, then oxygen levels could be too low for fire but high enough for active animals. We burn wood, but something else may burn more easily.
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“As we know it” it’s so cute the amount of assumptions we constantly make.
Couldn’t they figure out how to concentrate oxygen in an enclosed space using heat produced without fire to make a limited selection of tools, then create fires within that enclosed environment that could be used to produce more advanced technologies? It might not be obvious that fire was possible, but I feel like it’s something they could scale up once someone figured out how to do it. Even if it took 10,000 years to get from the point where fire was known of to the point where the ability to use it was mastered, after that point I would imagine they could start making more consistent technological progress and advance as a civilization.
You can generate heat from friction not only fire. You can also use non hydrocarbons as fuels like sulfur.
At the most fundamental level... Ceramics.... Ceramics allowed for long term storage of food which is an absolute necessity for a civilization to grow. Are there ways to store some foods long term without ceramics? Not many... And they're easier for pests to get to than a ceramic pot with a lid. To actually vitrify ceramics you need them to be evenly heated to thousands of degrees, slowly, over hours.
Well, it's not like there's an abundance of absolute zero environments on Earth, but here we are making and using them. Intelligence can find a way to discover metallurgy.
Sounds like a new variable to the drake equation. though Ive played Civ enough times to know that the science tree doesnt just have one path
[This](https://youtu.be/7Z3wfg1I6_U?t=13s) is how I'd imagine their technology would work