Question is to people who say if universe is teeming with life, then why is it not visible close by: We don't know how large the universe is. If say life is "teeming" means it's found every 1M Parsec on the size of 10^100M Parsec, wouldn't it be teeming, and yet nothing in our vicinity?
I'm being genuinely curious, not dissing on anyone.
1. Our view of the galaxy is very limited. We know almost nothing about our closest neighbouring solar system, let alone anything further afield
2. And because the distances are so far, we are effectively seeing those distant events hundreds or thousands of years in the past.
3. Where to look? We cannot search everywhere. We can only hope to get lucky that we are searching the right corner of the sky at the right time.
Alien life is completely alien:
4. We can only make assumptions of what to look for. Any sufficiently encrypted signal might genuinely appear like white noise to us.
They might be so advanced that we simply cannot detect them
5. Early communication systems on Earth were noisy in that they were broadcast 365 degrees. Later systems could be targeted, focused in a specific direction. As technology advances, noisy classical methods of broadcasting become less common. This in turn reduces the amount of noisy any extraterrestrial eavesdropper could spot.
And that’s assuming they’re not intentionally “cloaking” themselves. Putting aside Star Trek style fantasy for a moment, there is an advantage to remaining hidden. Whether you’re a predator like a burrowing spider or stealth bomber, or prey like bugs that camouflage themselves as plants; being hidden gives you a massive tactical advantage.
Cloaking probably isnt possible without discovering someway to violate the laws of conservation of energy. Any work done by a system will produce heat hiding the heat signature of an advanced technological society is probably impossible.
Basic technology we have today would have seemed impossible to people not that long ago. I mean they could have easily imagined it, but would have had no reason to believe it to be possible. There's a fun article here [1] where the NYTimes, in response to a failed attempt at flight, claimed that human flight would be basically impossible. Amusingly enough, that article was posted just 9 weeks before the Wright Bros achieved manned flight. After being proven wrong there, they would later go on to claim space flight was impossible. [2]
The point I make here is that there are two possible scenarios here. (1) We've now finally reached the defacto end of revolutionary technology, technology we might imagine yet have no reason to believe could ever really exist. Or (2) we continue on at just another random point in technological development, where our views of today will look as naive as those of the past. And it seems that one of these scenarios is inexpressibly more likely than the other.
Every planet, every rock emits heat (thermal EM radiation) so why can't the civilization willing to forgo most of its potential computing and industrial capacities choose to emit a heat signature indistinguishabe from a rock by observers at other star systems?
If you want to hide your heat signature, and you have the technological means to capture and direct your waste heat, you could simply radiate it towards your system's star. This is assuming you're producing so much heat that it would stand out more from a distance than similar but lifeless planets.
And it's not just the size of the distance we can see, it's the size of the slice of time when we are looking. We've had the tools to sorta-kinda detect life signatures for what, 10-20 years? Maybe we can keep that up for another (at best) 100-1000 years until we destroy ourselves? The universe is on the order of 10^10 years old. Star formation will end ~10^14 years from now The last black holes will evaporate ~10^100 years from now. So our temporal search window is astronomically small, too.
Why do you assume we distroy ourselves? If we can make spacecolonies at somepoint between now and your 1000 year figure why kill ourselves when we can leave for another star. It doesn't even have to be a popular strategy just one that a nonzero number choose to take rather that self distruction.
Seveneves, by Neil Stephenson, discusses the human penchant for self-destruction much better then I can in an HN comment, it is worth a read. In short, though, we cannot, unfortunately, escape our humanity, and pretending we don’t take it with us wherever we go is wishful thinking. As a group, we are ruled by incredibly base instincts that no longer apply to our situation, but they still largely determine our trajectory.
You mean the book where the nations of the world put everything aside to preserve the human species from distruction by space based natural disaster by throwing almost all their resources at various space programs?
Yeah, that one. Where those people then go on with their stupid, petty, political infighting and senseless scheming thereby nearly bringing about the end of human species anyway.
You’ve clearly read the book, I am curious what would drive you to make such an obviously incomplete representation of the story. Being edgy? Contrarian for contrarian’s sake? Since you offer no additional context besides a vague (and uninteresting) insinuation that im somehow wrong, I suspect you are just trolling, smegger001
"We haven't died yet" is the most selection biased evidence you could possibly invent. 10 on a scale of 10.
It also has no predictive value given the nature of catastrophic threats continues to evolve rapidly in quantity and quality, and the elements of past threats (the cold war -> nuclear war), continue to be threats (autocratic regimes -> fighting or planning wars that could become existential to their leaders -> nuclear war).
Given we have a sample size of one, its hard to make argument not based on past experience as that's all we have to go on, and we a reasoning about use of weapons that haven't existed for a century yet it hard to make strong argument either way bit MAD seems to have worked so far and most leaders of nuclear armed States are to egotistical to commit suicide when they are living the good-life at the top and that's what launching WMD s, is its is suicide .
Putting aside the more sociological arguments about (non-)human nature for a second - roughly speaking, technological development = ability to wield greater amounts of energy. The easier it is to put a satellite in orbit, the easier it is land a missile on another country. The easier it is to harness virtually free energy, the easier it is to rain unimaginable destruction on your enemies. Robot workforces enable robot armies (directed by malicious humans, not Skynet)
The more widely accessible a technology becomes, the more damage a single person or faction can do, and therefore the probability of someone causing mayhem tends to 1. And it's basically always less effort to destroy something than (re)create it
We can hope defensive counterparts to all these risks develop at a greater rate, but I don't think that's a given at all
Also remember that from a SETI/Fermi/Great Filter perspective it doesn't matter whether the species completely kills itself off. It could instead just repeatedly reset itself to steam age technology, and therefore never be stable enough for long enough to become seriously spacefaring
Have you not been paying attention to the news? We have a major nuclear power constantly threatening nuclear war, and several very likely conflicts between major nuclear powers.
it's also not only a question of distance but also a question of time. there could be/have been several alien species that would be our next door neighbours but just not at the same time as us.
I'm fairly sure you know this already, but you just described the Fermi Paradox. [1] And the answer to this paradox is that there is no answer, though there are a million hypotheses.
The first exoplanet was only detected in 1988 and confirmed in 2002. These are things we were really really sure were there and are absolutely huge relative to a vital sign. It would be surprising indeed were we to already have found a biosignature given it's got to be a lot harder than finding a gigantic chunk of rock.
I don't know anything about anything but I can imagine a society of bacteria saying the world is teeming with life but they're sadly sitting at the bottom of the ocean in a lava tube and they can't manage to find any life.
If the next "hard step" is aliens going from biological to artificial, how can we be sure what sorts of signals they might leak? We're not even there yet ourselves.
Here are some alternative theories of possible types of life. The thought of silicon-based life swimming in oceans of ammonia or other hydrocarbons fascinates me.
It's super fun to consider, but one problem with ammonia-based biochemistry is that everything would be so cold. In temperatures that are cold enough to liquefy ammonia you just have a lot less energy going around, and life requires energy to thrive. We can see this principle at work on earth where the tropics have the most biodiversity and the interior of Antarctica is almost totally barren of life. So it seems to me that while an ammonia-based biochemistry might be plausible, it may be a sort of evolutionary dead-end where nothing can progress beyond being simple and microscopic.
Or maybe it can at the bottom of an ocean where the pressures are higher and the ammonia is warmer due to geothermal effects...? but then it has no access to energy from the sun, and it's very hard for us to detect something that lives at the bottom of our sea, let alone an extraterrestrial one
This kind of gets to what I was implying. Chemistry is chemistry, and physics is physics. The same elements are available throughout the universe even if they are not all brought together in the same quantities.
I get that it's fun to consider, but things are beyond credulity thinking that chemistry will be different elsewhere in the galaxy. Of course the weasel words "based on our current understanding" are a great way to keep the fun going
It seems like there ought to be a sweet-spot where life will consume the right amount of energy for an environment. Consume too much energy, you starve. Consume too little, you are out-competed by other life forms which consume more, and move faster as a result. But that’s environment-specific, maybe it is possible that ammonia life evolved on a lower-energy planet everybody just moves slower?
If you move slower, you evolve slower. If less energy is available you have fewer organisms, there's less reproduction, therefore there is less evolution and less mutation.
That's why when we drilled down to Lake Vostok we found some single celled life forms that had interesting properties because they'd been cut off from the rest of the world for millions of years, but we didn't find Jules Verne's Lost World. There's just not enough energy down there under the ice to power a lot of biology. The less abundant/accessible energy is, the less probable complex life becomes, regardless of the biochemistry.
I buy that there's a good chance weird things on the complexity scale of bacterium are dotted all over the cosmos, but the big problem is those are functionally impossible for us to study (and even conclusively detect) unless mayyyyybe if they're in our solar system.
In the plank limit maybe. Large-scale "organic" farms speed up evolution 100,000x with the right drug cocktail to circumvent the current legal definitions of "GMO." They aren't pumping 100,000x more energy into the system. Our base rate of evolution is naturally selected for complicated reasons which _involve_ the available entropy supply but aren't simply monotonically dependent on it.
Because there’s nothing out there but swarms of paperclip optimizer ai drones, converting all the universes mass into paperclip fueled war machines for when they encounter a competing paperclip swarm
Regarding alien life and search for it, I have really big problem with concept of Dyson Sphere/Swarm. The moment when human race will be able to build such megastructures, it is very likely that long time before that fusion generators will be about as common as a smart phone and probably with a same size.
Furthermore matter is just condensed energy, so why bother with some wonky immobile megastructure when you can just decay your everyday trash into pure energy.
>> Furthermore matter is just condensed energy, so why bother with some wonky immobile megastructure when you can just decay your everyday trash into pure energy.
True, matter is an energy... however the only known way to convert matter into pure energy is to make it annihilate with antimatter ( akin to electron-positron). We first have to have a good and cheap source of antimatter! And the matter annihilation may still generate a lot of particles/matter - that may be a waste (or not) depending what you do with that further.
A Partial conversion of a matter into energy is also fusion and fission reactions, but they are limited by the difference between source and end element of reaction here https://en.wikipedia.org/wiki/Iron_peak#/media/File:Binding_... - e.g. H2 -> He3, That uses only a tiny portion of matter, no energy that can be extracted from Fe56 (max), and all its close elements are also useless for either fusion or fission energy extraction.
We're closer to building a Dyson swarm today then we are to workable fusion reactors though - as in, we technically have the technology and means to start building one right now - a series of solar-harvesting satellites in Earth-halo orbits beaming microwave power back towards us.
It would be inefficient, but there is no physical reason we couldn't do it.
The other problem is scale: Dyson swarm power levels are orders of magnitude greater then the amount of deuterium in the Earth's oceans. At those sort of levels, you can't use fusion because you don't have the fuel.
Finally, based on what we know there's some real problems with compact fusion: ITER and other big vacuum vessels are because we're at the materials science limits of how strong magnets can be without destroying themselves.
The first problem with microwave beam is that it can be used as a weapon and will be treated as such. So I don't believe it will get over prototype test phase before being banned like nukes. Additionally the further you are going to be from such beam, the less energy you will get from it. So transferring any energy from the Sun will be extremely inefficient endeavor.
Another big problem with nodes in Dyson swarm is heat, or the inability to get rid of it. They need to be close to the star so they can get as much energy as possible so they will heat up by position, but also modulate this energy and transfer it further, which won't happen without loses. So nodes can be constructed on gigawatt output but in reality be able to do fraction of that, otherwise they would fry itself up.
You can use the dyson structure for other things.. there is a (sci-fi'esque) suggestion called a Matrioska Brain I think, where the entire dyson structure is made of computational substrates - it could be conveniently powered by the solar radiation but also by fusion. Given the track of AI and realistic world sims, everything might end up "living" inside one of those structures..
You would have to protect it pretty decently though..
> Matrioska Brain I think, where the entire dyson structure is made of computational substrate
Well let's compare star to the amount of available material in Solar System - I don't think that there is enough material to build one layer, let alone several + protective layer.
protect it... like running more than one instance of everybody so that we still experience continuity when a bolide strikes a compute node? Or like, we build a wall?
Because it's unclear where you'd get the mass for the wall. Seems better to just let the nodes fail sometimes and tolerate the unreliability in a RAID sort of way.
A Dyson swarm does allow you to move the star or sterilise any planet in the galaxy by focusing the light into a “death ray”. So it’s a useful tool to have for more reasons than just energy.
Even if you could refocus all of the sun into a single direction, over stellar distances, wouldn't it have dispersed into nothing more than a bright star? What is the range of a putative Sol death ray?
"Dispersion" as I think you're describing is an artifact of the fact that most light sources radiate spherically, and more focused alternatives simply reflect the edges of that sphere to obtain some focus at larger distances, still radiating off in a 1/r^2 nature eventually.
If you actually take every photon from Sol and point it in a single direction (think "LASER" rather than "mirrors"), the range is infinite, give-or-take the fact that you'll hit some objects on the way, and the intensity is on par with the intensity next to the surface of the sun.
Even laser beams diverge, so that is where my intuition is headed. Plus the engineering implausibility of perfectly aligning every photon to go in the same direction.
I see. If we're willing to suspend disbelief enough to say that we can focus a star in a direction, I think it's reasonable to assume we'll get the rest of the engineering "good enough."
The only hard limits I'm aware of are the engineering (which we're ignoring), and diffraction (which is small, I'll touch on). Diffraction-limited lasers have a wavelength / diameter term in the mix, so the relative increase in beam diameter is miniscule at any reasonable scale (doubling at 650M light years, tripling at twice that, quadrupling at 3x that, and so on linearly). Surface power scales with the inverse of that squared.
The engineering is pretty obviously going to be the dominant term. Even with some lasers we've already created (not to mention more exotic forms of wave propagation), dispersion (diameter) would be on the order of 750x at 1 light year, or ballpark 1.1e2 watts per square metre if I haven't screwed up too much arithmetic, contrasted with the 1.4e3 or so we experience on Earth when measured in a plane normal to the Sun and the roughly 6.3e7 you get on the surface of the sun and the roughly 5.6e4 where no matter your orientation if you didn't have protection or active cooling you couldn't prevent death by overheating just via sweating (that last threshold you hit from this hypothetical laser at 0.045 light years -- a small chunk of the way into the oort cloud).
How much better will we get the engineering between now and then? Who knows, but the math in that regime is _almost_ linear, and if you halve the angle of dispersion you double the distances in question for a given power flux.
Isn't it easier to just use accelerated protons or electrons for this purpose on much more smaller and agile ship, than trying to move a star?
Additional problem with this concept is, that if you will close a star into a sphere, won't it have effect on star itself, like destabilization of fusion process, because of excess energy? For example when star will start burning helium, it will get bigger. If you will prevent the star from getting rid of excess energy, won't it build pressure in the star, so it will start burning helium instead, expands and destroy the Dyson sphere in the process? Then after pressure decreases, it will go back into being a normal hydrogen burning star again.
Power output of a fusion reactor scales with something like the fourth power of the radius, IIRC. I don't think they're going to be able to build a reactor the size of their sun, so capturing that energy still seems pretty useful for large-scale efforts, like moving ships between star systems at near light speed.
1. Being able to take your power source with you, so it also works behind nearest asteroid is even more important
2. Having your own source, so not to be dependent on one megastructure, because it is a single point of failure and single point of control of civilization.
I understand it would be super interesting to find biological processes similar to earth like life similar to our light, water & dioxide cycle (im sure there's a name for it)
But sometimes it sound like many people think that's the only way life can start, yet we have no idea how it really works. Also on earth there are organisms in the deep sea that have completely different biology. We might find life, even sentient one, in places we haven't thought to look.
I'm on the more pessimistic side of this argument. Lots of very smart people have thought about this, and really the only element that is able to form complex molecules besides carbon is silicon, and there are good arguments as to why it's a much worse basis for life. And if you have carbon-based life forms, you will have water and CO2.
In any case, it is just way more likely than any other form and makes absolutely the most sense to look for this first.
Sure, you can always say that we don't know what we don't know, but the periodic table of elements is finite and complete, and we are pretty sure that chemistry doesn't change across the universe. I realize I'm fighting an uphill battle in my position, because it's hard to prove the non-existence of things, so you will always be able to say "whatever, maybe you didn't think of everything", and it's true, but I have a hard time seeing how life can be anything but carbon-based. If you have more insight besides what resembles a god of the gaps, I'd be very interested.
Yeah that make sense, but still very much earthlike biology perspective. I mean almost everyone here also believes in digital intelligence at some point.
Are there elements that are more stable under high pressure or heat? Or opposite?
> Yeah that make sense, but still very much earthlike biology perspective.
What does that mean? The parent’s point was that this isn’t just a matter of looking for what is already familiar, but a matter of through the lens of what affordances the elements have and therefore what, in principle, is likely or even possible, to the best of our physical/chemical knowledge.
There’s a rational middle ground between parochialism and anything goes.
Worth noting that even "digital" doesn't mean "not carbon". The current likely end-state of electronics is likely moving from silicon back to carbon due to abundance and durability.
People are working on diamond-based semiconductor devices, and organic-transistors are built experimentally all the time (nothing commercial but it's an area of active research).
An advanced bit of nanotechnology that could self-repair would likely consist of a computer chip which fabbed up replacement organic components for itself and could transport and replace them in-situ, even if it was still just a computer otherwise being digital - after all, that's how our cells do it.
Sillicon is actually significantly more common, so relative abundance isn't a good reason to use carbon. Carbon would be used because it performs better
Maybe in earth's crust, but on a galactic scale carbon is more common.
But they're both one of the most common elements either way, so I think other properties would be more important.
The way the GP comment describes carbon-based technological life made out of transistors doesn't sound like the metabolize carbon to CO2 or would require a lot of water, though, which are two important markers when searching for life.
I would argue abundance based on CO2 being a fairly common gas and "easily" processed. Silicon in silicate minerals is common, but it's much harder to crack out of them.
I'm up for it, but since you are the one who proposed we could have unimaginable forms of life, and I'm coming up short, I'm relying on you (or anyone who holds your position) here to be the creative one.
What's more likely is finding carbon-based life of opposite chirality from the left handed kind native to Earth. This would make life from each planet fundamentally incompatible with each other in numerous surprising ways.
Doesn't this depend on the STP of the alien environment? It seems plausible that planets that are a few hundred degrees warmer might benefit from silicon based life, no?
Kind of a tangent but I'm really interested in why statements like:
> if you have carbon-based life forms, you will have water and CO2.
..can lead to statements like:
> it is just way more likely than any other form
I totally agree on the observation, but what is fascinating to me is why a deductive statement can be considered to indicate likelihood in probability. It seems there is a bit of abductive reasoning going on behind the scenes which neither the deductive logic or inductive probability can really capture on their own.
I don't see that particular statement "leading" to the second statement. You quoted very selectively and didn't quote the part that is the reason why I believe carbon-based to be much more likely, i.e. the fact that silicon is such a bad candidate and that no other molecule allows complex chemistry. Maybe that helps with your fascination. Obviously I skipped all the actual arguments, but they are easy to find by the interested reader in standard literature.
You're right. Absolutely, completely correct. There's almost certainly other ways life can start. Other processes that can result in intelligence. Other paths of technological development.
The issue, as I understand is, is that all of those are completely unknown. We have absolutely no useful idea of how to look for wildly different life in places we haven't thought to look.
What we do know with certainty is that Earth's chemistry can result in life. We do know that it can result in intelligence. We do know what paths our technological development took. We even have some idea what these things might look like from afar. All together, we have exactly one data point that lets us search for similar data points.
Are there other, different world, with different life? Very possibly. We humans are well aware of this. We just don't have a way of knowing if we've found anything. So as a matter of managing limited resources, there's a tendency to stick to what we know can work.
It may just be a failure of the imagination, but on the face of it the only chemistry that could feasibly make organisms is organic chemistry. That's not because it's Earth's chemistry, but because carbon is a very useful lego brick. This leaves us looking for alternatives beyond chemistry, something like Douglas Adams's "sentient shade of blue", except imaginable and not nonsense. So your certainty about this is ... staunch, let's say.
I'm doing my best to tell this user that their imagination is possibly on to something, but mostly this is a waste of energy. I'm exaggerating the realistic possibilities to help them feel good about themselves because it makes it easier to sneak in the idea that this is not a useful or productive line of thought.
The approach of "Smart people have thought of that, there are very few chemically useful alternatives" is the kind of thing that entrenches a person in their insistence that this is just a wide-scale failure of imagination. Witness their comment about "earthlike biology perspective". They want to believe a wider, weirder universe is possible. As a rule, it helps people feel heard to tell them they're right about something.
So yes. I'm going to present it as a staunch certainty that something else is possible but currently unknowable, invisible, and irrelevant. I'm doing this in the hopes that the message gets through that this is not simply parochialist arrogance at work, from which they might nobly dissent.
>but on the face of it the only chemistry that could feasibly make organisms is organic chemistry.
First order life, but what about second order?
If I make a complex 'mechano-computer' that can reproduce itself, how exactly is that different from life? Now it looks like the universe doesn't have any direct way to go to silicon based life, but indirection over carbon based life first seems very possible.
"on earth there are organisms in the deep sea that have completely different biology": Not sure what you mean by that. There are bacteria that metabolize different things than what the bacteria up here metabolize, but they (and we) all use DNA, and with a couple exceptions they use the same codons to encode the same amino acids and start/stop. As far as anyone knows, that coding is completely arbitrary, i.e. the codons could have been entirely different. The fact that they are not entirely different implies a common origin.
You don't have to look for oxygen etc that are the signs of earth-like lifeforms. I have no idea what prohects like this look for specifically, but any kind of thermodynamic disequilibrium that shows up in the atmospheric makeup of a planet is potentially a sign of life. Free oxygen is a very good candidate, but not necessarily the only one.
The most probable candidate for now is Europa with an incoming NASA mission [0]. Because within the solar system among the 3 potential candidates to host life in an ocean under thick ice sheet. Maybe we will find traces of old life on Mars. IMHO, the only other way to have confirmation is to recieve a "hand-crafted radio signal".
That would be bad news. I hope we never have proper confirmation of independently arisen life out there (or, worse, intelligent life out there.) It would imply the Great Filter is likely to be ahead of us, so humanity would likely be doomed.
It shows no such thing. The Fermi paradox is fun but it explodes into such a massive tree of possibilities that are all untestable that it’s just that… fun.
It could be that as we explore the universe we find a ton of microbes but few or no other nearby complex lifeforms with any form of intelligence. This would imply that Earth is a special environment for fostering stable complexity, in which case the great filter is still behind us.
BTW there are reasons to think Earth might be special: it’s got this nice magnetic field, a huge moon that reduces bombardment, a thick radiation shielding atmosphere, volcanic activity enough to replenish that atmosphere and the landscape, a reasonably stable climate, is not tide locked to its star (as many planets likely are), and orbits a friendly star that doesn’t throw tantrums and blast us with gamma rays. (The sun appears to be a cute fuzzy waggy little puppy as stars go.)
I believe a survey of planetary systems showed that the gas giants were more common closer to the stars (hot Jupiters), and they tended to eject the rocky inner planets. Our solar system might be exceptional because of Saturn preventing Jupiter from migrating inward.
Also the collision of Earth with the other body that eventually formed the Moon, as violent and destructive as it was when it happened, may been a big reason why the Earth is tectonically active (which also is the reason for the magnetic field, which helps keep our atmosphere intact) and the presence of the Moon also gives us tidal forces which may have been necessary for abiogenesis, The collision of such a large object at the right time of planetary evolution may have been a low probability event.
OTOH, alternatives have bene proposed. The moons of the "hot Jupiters" could get similar benefits as the Moon and the remnants of the collision gives Earth In particular, it is known that the moons of Jupiter experience substantial tidal forces.
I don't think so. We already know there is a filter for our race. The sun is one terminus, sometime after the earth is uninhabitable to human life (due to ecology). So there's nothing to lose but some time.
If we run into another intelligence it is strong evidence we haven't made it past the Great Filter. Sure, you can choose to believe the opposite, but that's pure wishful thinking.
That makes no sense to me. If there wasn't a great filter we would expect to find more intelligent life, if there were we would expect a much smaller probability of intelligent life.
If an event makes an observation less likely then conversely such an observation also makes that event less likely, not the other way around.
The thing that has to be explained was why Earth was left alone for 4.55 billion years so we could evolve. Something prevented intelligences from colonizing it and exploiting it (and everywhere else we can see in the universe, as far as we can tell). That thing is called the Great Filter. Its existence is not in question, since we evolved. If we run into ETs that means intelligence must be extremely common (and mobile, since we ran into it) so the filter has to be very VERY effective.
The most benign Great Filter would be in our past, if life or intelligence is very difficult for the universe to create. If it's not in our past, it's in our future, and it's going to clobber us with almost no chance of escape (after all, if we're not special, we have no better chance than any of the potentially vast number of ET civilizations it has already hit.)
There was an interesting interview of Lee Cronin on Lex Fridman's podcast a while ago.
For anyone unfamiliar, Assembly Theory is based on the idea that the more structurally complex something is, such as a molecule, the less likely it was created by chance, and the more likely it was created by an assembly factory of sorts, one type of which is life in it's potentially diverse forms.
I was never very impressed by assembly "theory" (what are its testable predictions?)... If we find a refrigerator floating in space I don't need an Assembly Theorist to tell me there's some intelligent/intentional process behind it.
Seriously, what is it other than a potent source of pop sci clickbait?
I think assembly theory is most useful to define a spectrum of complexity.
Sure, a refrigerator requires intelligence, whereas loose carbon atoms do not.
What about everything in between? Methane? Complex hydrocarbons? Pointy sticks? Things that look like crude tools?
It’s about defining a metric that can measure complexity across a wide range of things you might encounter, to help estimate the odds that it was produced by something simple yet alive, or something complex and alive, or something alive but not very smart, or something kinda smart, or something super smart, etc
Take something far simpler, the methane molecule. If you find it in the atmosphere of a planet then most likely it was formed within the last 10 to 20 years. There has to be some form of process creating it. This holds true for any short time frame molecules. Now, there could be a non-biogenic source for these, but when you find something like this it points to an active planet.
The essential prediction is that complex things are made by some sort of repeatable assembly process/factory, not by chance (with increased confidence when multiple copies have been seen). There is an idea of an "assembly index" for objects (e.g. molecules) as a measure/bound of how many steps they took to assemble - the level of complexity.
There is also a prediction (or definition?) that things with a high assembly index are produced by some form of life, so if one can measure the assembly index of molecules and find ones of high index/complexity, then this indicates they were created by some form of life, and so this can be used as a test for life without having to make any assumptions of it being like life on earth (and therefore only looking for biosignatures of life we know of).
Assembly theory seems most interesting when applied to molecules, although it's not limited to that in scope. There are constraints on how complex molecules are formed in terms of what reacts with what, as well as some intuitive measure of complexity in terms of their size and variety of components and atomic bonds.
One thing that Lee Cronin has discovered/noted is that mass spectrometry can be used as a crude way to measure complexity of molecules, and hence give an idea of their "assembly index", since different chemical bonds have different fingerprints in terms of how they absorb energy (diff. frequencies of UV or IR light absorbed in the mass spec.).
There's a couple of different applications of this use of mass spectroscopy as a proxy for assembly index that Cronin mentions in his interview with Lex Fridman, which do seem to provide some proof of it's predictions of high assembly index being an indicator of life, and relative assembly index and indicator of which came first.
1) NASA, wanting Cronin to prove the value of this as a potential life-detector, gave him a variety of unlabeled organic and inorganic samples, and Cronin was able to classify them all correctly based just on their mass spec. signatures.
2) By analyzing a variety of biological samples, again via his mass spec. technique, Cronin was able to reconstruct the evolutionary tree of life in agreement with other ways of doing this. He goes into a little detail on the Lex interview, but it sounds complex and he does not fully describe the technique/analysis.
> If we find a refrigerator floating in space I don't need an Assembly Theorist to tell me there's some intelligent/intentional process behind it.
Isn't that the point? What you find obvious about a refrigerator is precisely because it's complex in a way that you understand.
I mean, the problems with the theory are pretty obvious. Anything complex is a matter of how you measure complexity. A common earth object is obvious because we can easily categorize the complexity and recognize it.
It seems strange to me that life is the default assumption instead of "new chemical process for creating phosphine/whatever that we weren't aware of before." The latter seems to me like it would require far fewer assumptions
Are there any trickle down technologies or scientific discoveries making the search itself worthwhile? In terms of an economic development perspective?
I think your comment is sarcastic, but Poe's Law in the age of $ > all makes it impossible to tell. If it's genuine I'd only emphasize that the point of money is to be able to do great things. GDP doesn't matter whatsoever, but the betterment of lifestyles and civilization that it's supposed to* correlate against does. And discovering a species, regardless of how simply or complex, on another planet would be one of the greatest discoveries and achievements in human history, with immense scientific and philosophical value.
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* - kind of funny, but the reason GDP was invented was a local jurisdiction claiming it was being overtaxed. But needless to say the reason countries obsess over it today is not to try to reduce their tax burden.
Genuine question. I do not doubt that pursuing the question would be worthwhile. However given how far off we are from achieving this aim, does the effort itself provide value elsewhere from the diffusion of innovation in the same way the Apollo program is said to have done.
Let me turn the question around on you. Imagine the Apollo program somehow provided no value whatsoever beyond what it achieved - putting a man on the Moon. Would it have been worth it to do it? To me, the answer there is undoubtedly yes. The whole point of all the 'value' in existence is to achieve these great things.
Without these great achievements, I'm not even entirely sure the direction our species has taken could be argued to be good. Declining fertility, urban cityscapes that feel increasingly dystopic, working vastly more than even hunter-gathers did (or do), and more. But to what end? There needs to be some payoff to go down this road. For one who is not into consumerism, the only payoff I can see is in these great milestones that probably could not be achieved without going down this path we've chosen.
If someone proposed to use all of our resources to discover life outside of Earth, we would probably agree that's not the best use of our resources.
But this means there's an upper bound to the cost we're willing to bear. Which leads to the question, how much resources should we devote to finding life outside of Earth? The answer to that question is, yes, dependent on the expected economic outcome of finding extraterrestrial life.
Absolutely in that sense the ends justify the means. I was just wondering what we can get from the means themselves given how far off achieving that end appears.
Is this a joke question? Imagine if we discovered an alien civilization that had a population of trillions - if they subscribed to our SaaS app, the scaling and network effects would be insane.
Let’s just hope it’s not the “dark forest” theory that’s correct, although it would make a lot of sense to me assuming the universe is teeming with life.
Three Body Problem is a lot of fun, but if you are that concerned by it you should seek out the broader Fermi Paradox dialogue which does not favor this solution, and not just because it's unwanted. Isaac Arthur's Fermi Paradox Compendium on youtube is probably a good place to start and I'm pretty sure his Dark Forest video covers the major points. In any case, I have them here too:
If the universe is teeming with alien life, why isn't it here? It looks like it will take millions of years to colonize the galaxy but the likely variation in emergence/evolutionary timelines is some decent fraction of billions of years (considerably more than 4 billion years, the starting gun is metallicity not the formation of Earth). In particular, if there is highly capable space-faring life at Alpha Centauri, why haven't they probed their neighboring star system in a billion years even though it was completely trivial to do so relative to subsequently displayed technological feats?
Also: it's really hard to configure the rules of a Dark Forest so that the optimal strategy is "hide" rather than "grow, grow, grow -- and hope you grow fast enough by the time it matters," and it's spectacularly hard to make that so universal across all aliens that none of them "wins" and colonizes the galaxy per the previous paragraph.
Finally, Cixin Liu had to break the speed of light to make his story work (and then carefully avoid the implications to #1 and #2 above, which both get worse if c is no longer a constraint). I am all for doing what it takes to tell the story, and even more delighted by his deeper exploration of this concept further down the line, but one must remember to adjust the likelihoods of it all according to the likelihood of the premise, which seems quite low according to our present understanding.
This is a nit pick and doesn't change your argument, but Alpha Centauri would not have been our neighboring star system for a billion years. Stars move relative to each other in our stellar neighborhood at about 30 km/s, or one light year every 10,000 years.
Yep, good reminder! Of course, as you point out, it doesn't change the argument because probing (or simply direct observation, if they must hide) would still be trivial, both at larger distances when we weren't quite neighbors and on the shorter timescale when we were. Trivial next to mustering an interstellar invasion fleet on the turn of a dime, at any rate. Besides, if they were itching for a fight then the original "decent fraction of billions of years" timeline still applies to the question of "why didn't they grow and colonize?"
The most likely theory is that the universe is much like it appears to be and the speed of light is an absolute barrier, and that in practice means that interstellar civilizations never form, because it's simply far, far too expensive and difficult.
If alien civilizations lasted indefinitely, that wouldn't be a barrier, but in the one sample of a civilization we have, we are consuming our resources and generating waste at an exponentially increasing rate, and will crash and burn leaving us without the quadrillions of "dollars" it would take to even start colonizing the stars.
Kurzgesagt has many videos on this topic. In one video, they point out we may actually be in the right place at the right time and could be one of the first civilizations. This seems egocentric at first, but if you consider how chaotic the early universe has been and how relatively calm things are in the last billion years, it does make sense.
Also, I learned recently that we don’t have as much time with Earth as I originally thought. We have a few hundred million years to figure out how to colonize other planets or live in space before Earth becomes radically different and potentially unlivable. I imagine most civilizations get snuffed out like this.
The past survival of livable conditions on Earth is no guarantee they will persist for very long in the future. There's observer selection bias to consider. For example, the O2 level in the atmosphere could drop below that needed to sustain higher life. As I understand it, there's been no feedback mechanism identified that stabilizes O2 at current levels, so the persistence of adequate oxygen over the last 500 million years could just be an unlikely accident.
In the absence of burial of photosynthesized materials atmospheric O2 will disappear in a few million years as reduced materials are exposed by geological processes and then oxidized. So, the time constant for O2 fluctuations is rather short.
If and when we spread into the galaxy, we may find many planets where livable conditions were snuffed out before intelligence could arise. In our own solar system, both Mars and Venus may have been more habitable than Earth earlier in the history of the solar system, but now are forever ruined.
> We have a few hundred million years to figure out how to colonize other planets or live in space before Earth becomes radically different and potentially unlivable.
Hmm... at the rate we are going, big parts of the Earth (a big slice around the Equator) may well become unlivable for human beings in a couple of decades.
I get the idea that it won't mean that the Earth will be unlivable for all organisms, but from what we know, a sufficiently advanced civilization only needs a couple hundred years to destroy itself.
And AI is likely a binary outcome. It’s either very good for us or not, and it won’t take a million years to figure out which. We were in caves not long ago.
Very little to no evidence that continuously increasing intelligence will maintain the status quo indefinitely, on a scale of at least thousands of years. The odds of us not either populating the galaxy or utterly owning ourselves are vanishingly small. What is the middle ground that you think is likely, and what things have to happen for that to be true? Why is it more likely than one of the extremes?
It's so interesting that our intuitions are vastly different on this. You and I both just can't believe that our default case isn't obvious.
I personally think "recency bias" is to blame for the "we'll muddle through" case. Life is great and the weather is fine, and there are no asteroids or globally impacting volcanoes, and we haven't had a civilisational collapse in a good while, and nukes didn't kill us, so the current state is pretty locked in indefinitely, despite massive technological change that we have zero chance of predicting the outcomes of.
That's an unstable equilibrium at best. We take over the galaxy or die trying.
Well we are pretty capable of predicting, right now, that our civilization is very likely to collapse in the next few decades because we can't seem to address the climate/biodiversity problems (which are consequences of the abundance of fossil fuels that will end soon).
Loss of keystone species[1]. Say, if bees went extinct, our agriculture would come crashing. We still rely on other organisms for a lot of important, sometimes poorly understood until too late[2] functions that sustain our civilization.
If bees went extinct, it would affect none of the essential crops we grow. Grains are wind pollinated, not insect pollinated.
More generally, I'm sure extinctions would wreak havoc on wild ecosystems. But we grow food by explicitly destroying wild ecosystems, replacing them with monocultures. Crops seem to grow just fine anyway.
I think it's a bit telling/alarming that you seem to be "okay" with monocultures and mass extinctions because we don't seem to be affected (at the moment).
This discussion is about the claim it causes civilization to collapse, not whether I'm okay with it. But hey, thanks for steering this in an ad hominem direction.
Which you steered there because you wanted to be nitpicky about the biodiversity issue, where what I originally said was that civilization is likely to collapse because we can't seem to address the climate, biodiversity and energy problems.
But hey, thanks for steering it in an ad hominem direction.
I'm not allowed to question a statement that loss of biodiversity could cause civilization to collapse in the next few decades? Really?
This is an objective statement about facts out in the world, and as such it is completely acceptable to ask how this position was reached. I questioned it because it looked like bullshit to me. You don't think bullshit should be called out?
The statement was that the climate change, biodiversity loss and energy crisis could cause civilization to collapse in the next few decades. You cherry-picked "biodiversity" there.
I was merely pointing out the irony that you complain about somebody steering the discussion somewhere while you actually did that in the first place.
To start, remember that in the 50s and 60s, the Gros Michel banana went extinct due to a blight that killed the entire strain because it was genetically homogeneous (there's the lack of biodiversity you asked for), and now what we see in supermarkets is the Cavendish.
Now, imagine if instead of a fruit, a blight did similar devastation to rice. But not just any of the 22 species of rice grown, no, let's get rid of one of the two that's predominantly consumed across the world.
One rice species fails and everyone relying on it as the staple carbohydrate/energy source in their diet is at risk of famine. Rice is what allowed Asia to become the most populated continent. Wheat can't compare. The diversity of grains humanity enjoyed in prehistory was already whittled down before this imaginary scenario started. Even if you rush in aid from around the world, even if you drop everything trying to figure out ways to successfully replace the lost rice strain with one of the others, people need to eat every day. There will be a starvation event, period.
There have been plenty of events that dropped population throughout history and it's always rebounded, like Black Death. COVID really messed up supply chains for a while. But losing an important strain of rice forever isn't a temporary setback like a disease. Civilization now is so complex that permanently losing a staple crop and population to starvation has a very real risk of undermining infrastructure to the point that there's not a critical mass of either physical or knowledge workers that can keep things running, especially if people are fighting over scraps, fleeing a breakdown of social order, or retreating into their family home hoping to weather the storm. Cascades are bitches.
And the world already has heightened tensions in other areas, Russia v Ukraine, Israel vs Hamas, Iran, China, India and Pakistan. Plus with other resources like oil and water already hotly contested, and the need to keep face against geopolitical rivals, could lead to all sorts of strange things. If China is particularly devastated by a loss of rice, would Xi be desperate enough to move into Siberia for more resources, or finally poke the Spratley Islands hard enough for them to ignite? If India's particularly plagued, maybe Pakistan will take advantage of that? The US will find itself drawn in. How long until someone is driven to use the football?
And, here's an extreme example: what if all biological matter on Earth was human? You think we could handle the "biodiversity loss" well?
The Kurzgesagt videos on these sorts of topics are interesting and entertaining, but they're often very speculative — they can rely heavily on unique but unproven theories, unprovable philosophical questions, or even just interesting sci-fi premises.
They're definitely informative and interesting within a given scope of discussion — it's good to ask interesting questions and explore what different answers might look like, because it helps us to push the boundaries of our mental models of the universe. But some of the videos — particularly the ones on Boltzmann brains or solutions to the Fermi paradox — are a lot closer to "here's an interesting thought experiment" than "here's something that's likely to be the case in our universe".
(Although they're usually very explicit when they do dive into this sort of speculative territory, and they also do a lot of videos which aren't in this vein at all — this is no slight on Kurzgesagt and the people who enjoy watching them!)
Yeah, I didn't want my comment to be a criticism of Kuzgesagt - like you say, they're usually very upfront when they do their more speculative videos. But I think sometimes people see the Kuzgesagt name and are like "oh, that's the informative science videos, this must be true", whereas a lot of the Fermi paradox stuff is closer to speculative fiction in nature than some of their other videos.
I've seen at least one "physicist reacts" video to this that tl;dw's to: "seems reasonable, would obviously require a lot of technological advancement and work"
I am always surprised by how people tend to completely ignore the scale of the universe. People get excited by claims to "go back to the Moon, then Mars, then who knows?", but the truth is that given our current understanding of the world, sending humans on another solar system is theoretically impossible. Just look at those distances: we just can't, period.
Of course, we may discover new fundamental physics that would change that. But that's a fundamental problem, not an engineering problem. Instead of wasting money and energy on the engineering required to send humans to Mars (which is an artistic performance at this point), we should pay fundamental physicists to attempt to revolutionize our understanding of the world (wishing them luck) and spend those resources into something that is actually important for life: preserving life on Earth.
Right now we as a civilization are failing to survive on Earth. It seems reasonable to consider that other civilizations may have the same problems.
I agree. The only way to colonize other solar systems is using some sort of cryogenic technology or generation ships. And even then, no one alive will ever witness the ship arriving at the destination. Which, to me, raises the question why you should even do this. There is no benefit. Just for the solace of knowing that there is a chance your species might survive the demise of your civilization? That's not much considering the immense cost. Civilizations that do this must have some strong biological urge or have founded a suitable religion that compels them to colonize other solar systems.
That's not even considering secondary colonies. The time it takes for the passengers of a generation ship to start a new civilization and gather the resources to launch another generation ship is mind boggling. They have to ensure not to lose any knowledge or the will to colonize more solar systems. By the time they've done this a few times, it's probably not even the same species anymore.
The "time it takes for the passengers of a generation ship to start a new civilization and gather the resources to launch another generation ship" is minuscule compared to the time to make the journey in the first place. Here's a Kurzgesagt video that essentially proposes using our solar system itself as our "generation ship" and getting from one star to the next would take on the order of a hundred thousand years, while the time to set up to travel that way seems reasonable to create in tens of thousands, or even thousands, of years.
>Which, to me, raises the question why you should even do this. There is no benefit. Just for the solace of knowing that there is a chance your species might survive the demise of your civilization? That's not much considering the immense cost.
For the people on the generation ship, it can be a good deal. If the ship is large enough and comfortable enough, it can be a better lifestyle than many people live today.
> If the ship is large enough and comfortable enough, it can be a better lifestyle than many people live today.
Surely if it is comfortable enough, nobody is even remotely considering sending poor people there, right?
Then again: what about improving life on Earth instead? Because if you look out there, it's great (at least in those places that humans have not completely destroyed).
>Then again: what about improving life on Earth instead?
Because it's politically impossible.
Your question is like going to a prison full of psychopathic murderers (not just regular murderers, but the ones who really like murdering) and asking them why they can't just be normal, good citizens.
It’s not theoretically impossible, it’s just really hard. If we go fast enough, we can even do it within the current lifespan of a human (from the perspective of that human).
Well, it starts with "assuming we had something we don't have (i.e. the capability to accelerate at 1G for 100 years)"...
I meant it's theoretically impossible with the theory that we have now. Of course if we make breakthroughs in the theory, then the theory will change and it may become possible.
But SpaceX going to Mars is not exactly revisiting this theory. They are just having fun with the current state of the theory, which says that they won't bring humans further, period.
I don't mean to be nitpicky, but you specified the difference between a theoretical impossibility and an engineering impossibility in your parent comment. I assume the reply is just referring to the fact that technically getting to a star system within the 10s of light-years away is an engineering feat, not a break-the-known-rules-of-the-universe feat. I don't take it that they're actually claiming it's a realistic feat that may be accomplished soon.
Sure, I guess I shouldn't have used the word "theoretically". My point was that with our current knowledge and capabilities, it is completely unrealistic to consider it remotely possible to achieve such a thing. We are orders of magnitudes more likely to disappear as a civilization in the short term than to achieve any kind of meaningful space travel.
Continuous acceleration to relativistic speeds is impossible without magic. Reasonable drives require impossibly enormous amounts of fuel. Antimatter drives require impractically enormous amounts of fuel.
Relativistic speeds require too much energy, too much reaction mass, and too much fuel. None of the reaction drives are good enough. It would only be possible with magic reactionless drive, and magic source of power.
>People get excited by claims to "go back to the Moon, then Mars, then who knows?", but the truth is that given our current understanding of the world, sending humans on another solar system is theoretically impossible. Just look at those distances: we just can't, period.
1. Colonizing and exploiting the resources of our star system is mostly separate from traveling to other star systems. We can do one and never do the other.
2. It's not impossible at all. It's just an engineering problem: we could build large "generation ships" and send those to other star systems if we really wanted to. No, this isn't the same as traveling to other systems in your lifetime and returning, but it is possible for humans to travel to other stars.
>we should pay fundamental physicists to attempt to revolutionize our understanding of the world (wishing them luck) and spend those resources into something that is actually important for life: preserving life on Earth.
Fundamental physicists can't help you with this project. We already know the fundamental physics we really need for this. The problem is social and economic and governmental. If you want to preserve life on Earth, you have to get humans to live in a way that's more compatible with the biosphere, but humans don't want to do that.
Sure, it's obviously an enormous challenge and totally beyond our current capabilities, but my point is that it's not at all impossible, it's just a matter of priorities. Humanity could do it if they really wanted to. The physics aren't that hard or in the realm of sci-fi. (I'm not sure the resulting ship would survive, but that's another matter. They'd really need to make many of such ships to make sure at least one survives the trip.) It would require developing significant capabilities for space-based construction of course, which means mining operations in space, manufacturing, etc., none of which we currently possess, so it's not even something that could be done in a decade like the Apollo moonshot, but if humanity really wanted to do this, it could be done in a century I think.
Humanity doesn't really want to do a project like this, however.
I expected to be downvoted! It's a grim idea, that this is there is and there isn't some huge prize of "a whole galaxy" a thousand years down the line.
I would have resisted it when I was a kid, myself.
About fifteen years ago, I made an attempt to figure out how much it would cost to set up a self-sustaining colony on Mars. My target was a Mars that could make its own pressure suits because terraforming would take centuries and making your own pressure suits is a precursor to that.
I realized that you had to essentially re-invent almost every industrial process humans have today, from baking to smelting steel, because all of them rely on unlimited, free air, and large quantities of cheap water.
You need to recreate most of the chemical industry, just to create new computer chips, each one of which relies on hundreds of chemical compounds available at very very high purities and affordable prices.
After a lot of work, I was unable to come up with a figure. My best guess was $3 to $30 quadrillion dollars, if it were even possible!
And all of that to have a bunch of miserable real estate in a cold, dark, arid, lifeless, airless, radioactive desert characterized by fine, abrasive, statically charged, poisonous dust. Antarctica is nicer in every way - much warmer, much brighter, has breathable air, endless quantities of water, etc - and yet no one lives there.
If you're trying to calculate "how much it would take" for a project that size, it seems silly to try to calculate in dollars. What you want to consider is how many people it would take: what population would you need, with reasonable bootstrapping equipment, to establish a self-sustaining colony on Mars?
I'll hand-wave away whether Mars has the necessary resources (I suspect it actually doesn't, but that's just a guess) so if we assume that Mars has the raw materials we need, and is just lacking an atmosphere, then it seems likely (just spit-balling here) that a million people could get the job done, or to be conservative, ten million. For comparison, North Korea has something like 25 million -- they're not as isolated as a Mars colony would be, but they're also not organized well.
If we really want to translate that back into dollars, it seems unlikely that we should budget over a billion dollars per person, but maybe?
> so if we assume that Mars has the raw materials we need, and is just lacking an atmosphere, then it seems likely (just spit-balling here) that a million people could get the job done
Hmm... I don't get how it seems likely that a million people could get the job done. I mean really, we are destroying the conditions necessary for our survival on Earth. It's not like we know how to survive in a place (Earth) that just requires us to change nothing. Why would we be able to survive in a place (Mars) that requires us to create from scratch the very conditions we can't seem to maintain on Earth?
I'm not sure I understand your point. I'm not an expert, but "conditions necessary for our survival" == about 7 things in (rough) order of immediacy:
1. Breathable air
2. Survivable temperature
3. Shelter from solar radiation
4. Drinkable water
5. Food
6. Energy to support the previous 5
7. Raw materials to support the previous 6
I postulated the 7th item, so let's take the previous 6 in order:
1. We know how to generate breathable air and keep it under pressure. We do this in nuclear submarines.
2. We know how to insulate habitats. We cope with a roughly equivalent temperature at Antarctica.
3. We know how to protect against solar radiation. We (somewhat) do this at the ISS, and we have plans to do it on lunar base.
4. We know how to produce water as long as we have raw materials to work with.
5. We can grow food in pretty much any environment we ourselves can survive in.
6. We can generate power in almost any environment if we have raw materials.
We are not "destroying the conditions necessary for our survival on Earth." -- we are significantly changing the environment on Earth, that is true, but not such that we will all die. Has any credible person presented evidence for that outcome?
I guess my point is that though we know how to make a few humans survive in space (with constant support from the Earth) and we may know how to make a few humans survive on Mars without constant support from the Earth, I am not at all convinced that we know how to make millions of people survive on Mars.
Take point 6 for instance: power. One of the biggest problems we currently have on Earth is that we don't know how to replace fossil fuels, and fossil fuels are not unlimited. It's currently unsolved, and it will impact our lives heavily in the next few decades.
> We are not "destroying the conditions necessary for our survival on Earth."
We are, most definitely. Where the air humidity is saturated (so take a strip around the Equator), if the air temperature goes higher than the skin temperature, we can't regulate our own temperature anymore (by sweating). So we can't live outside without life support.
If we reach an average increase of 4 degrees, then 1/3 of the world population will be located in places where humans cannot survive outside without life support. And right now we are most definitely going for those 4 degrees.
Now you may not care because you don't live around the Equator, but... imagine a world where 1/3 of the population must relocate in order to... regulate their body temperature properly. And I am not even talking about the impact on agriculture in the rest of the world where you can still regulate your body temperature (because at some point you need to eat). In such a world, if you are lucky enough to be in a livable location in terms of temperature, you may just not have food. Definitely global instability and wars.
Not everyone will die, but you have to realize that everybody will be affected greatly.
Fossil fuels are becoming less and less necessary to human life, and we have solar and nuclear in pretty reasonable shape to make synthetics as long as we have the raw materials.
Sorry, I took "destroying the conditions necessary for our survival on Earth" to mean in general, as in universally. We're certainly not doing that.
Just as a rough guess something like 15 percent of the land surface of the Earth is near-completely inhospitable to humans, and we're increasing that by 1-3% per century? (both guesses) I don't find it difficult to imagine 1/3 of the earth's population relocating over the course of a few centuries.
I'm an optimist, but I think "everybody will be affected greatly" is pessimistic. Technology and affluence make up for a great deal of negative environment (check out the growth around Phoenix) and the world is becoming more affluent.
> Fossil fuels are becoming less and less necessary to human life
This is completely wrong. We can't even build renewable infrastructure without fossil fuels right now, by very far. Without fossil fuels, today, big cities simply die because food doesn't get there anymore. Are you seeing electric trucks coming along? I mean not in a pitch for VCs, but in a realistic way, at scale?
> as long as we have the raw materials.
Ever checked the status of raw materials on Earth? :-)
> I don't find it difficult to imagine 1/3 of the earth's population relocating over the course of a few centuries.
You vastly underestimate climate change. Problems are starting right now, and the time scale is rather decades than centuries. Not to mention that it's not "planned relocation" where we organize it over a few centuries: when people start moving, they will move massively. At that point it will result in global instability and wars. Imagine whole countries emigrating... with their military.
> but I think "everybody will be affected greatly" is pessimistic.
From my point of view, not even realizing that we have a problem now is making things worse (because we need to act really badly).
That's my point: it's clearly extremely difficult (much harder than surviving on Earth), and it's still infinitely easier than going in another solar system.
The vast majority of people won't go to Mars, but will pay the consequences of climate change, biodiversity loss and fossil energy. Still not only nobody cares, but many keep dreaming about Mars.
> but the truth is that given our current understanding of the world, sending humans on another solar system is theoretically impossible. Just look at those distances: we just can't, period.
Of course it's theoretically possible. We couldn't do it at relativistic speeds, but that's hardly necessary. We could even do it with chemical propulsion (especially if the Oberth effect were exploited by close solar/stellar flyby). Granted, the trip would take a long time, the scale of the vehicles would be very large, and the humans who arrived would not be the ones who left.
It depends on what time scale you're talking about. Here's a Kurzgesagt video that describes how to do it over the course of millions of years: https://www.youtube.com/watch?v=v3y8AIEX_dU
That's a loooong time, obviously, but it's not "theoretically impossible"
Sure, but it assumes technology we don't remotely have. Maybe I should not have used the word "theoretically" here. It's just ridiculous to seriously consider it at this point.
It is nice to think about it, of course. But I just don't get how people support wasting so many resources into sending people to Mars where it's basically useless (though exciting, I get it!) and we have much bigger problems to solve on Earth (e.g. the survival of our species in acceptable conditions).
If you have silicon/AI/computer-based intelligence, then it's a lot more durable in space and lasts a lot longer. That's a totally different ballgame. You don't even need habitable worlds, arguably what would be valuable is asteroids since you don't have gravity wells.
200 year transits isn't a big deal then. They could tolerate the G-forces of an Orion pulse nuclear ship a lot better too. That's 1960s tech, if you have some antimatter collectors in space (my idea for a starship-based startup, how valuable is antimatter?), then you get to have even more fun.
Orion can do .1c with fission. One of the big problems was getting it off the ground and the fallout was unacceptable.
BUT, with starship doing 150-250 tons, that means 8 flights for a 4,000 ton low-end orion, or ... a lot more for the high end 1,000,000 ton orion.
The astronomers, who reported the finding on Monday in a pair of papers, have not collected specimens of Venusian microbes, nor have they snapped any pictures of them. But with powerful telescopes, they have detected a chemical — phosphine — in the thick Venus atmosphere. After much analysis, the scientists assert that something now alive is the only explanation for the chemical’s source.
Later in the same article
On such worlds, “as far as we can tell, only life can make phosphine,” Dr. Sousa-Silva said. She has long studied the gas, on the theory that finding it being emitted from rocky planets that orbit distant stars could be proof that life exists elsewhere in the Milky Way.
The actual publication abstract[1]
...If PH3 ’s presence in Venus’ atmosphere is confirmed, it therefore is highly likely to be the result of a process not previously considered plausible for Venusian conditions. The process could be unknown geochemistry, photochemistry, or even aerial microbial life, given that on Earth phosphine is exclusively associated with anthropogenic and biological sources.
Which reads to me like a, "We saw something funny" result.
it sometimes is a bit sad to realize we will probably never confirm the existence of intelligent life forms somewhere else in the universe.
Given the size of the universe, billions of galaxies, and each galaxy having billions and billions of stars, life obviously exists somewhere else, and we can safely say it exists in many places and intelligent life forms have emerged and have built civilizations somewhere else.
Given the age of the universe, it's highly probable that other intelligent life forms have built civilizations way more advanced than the human civilization.
Most of human scientific and technological progress happened in the last 200 hundred years.
We can only imagine what a society with a 100 000 years head start would look like. I can't imagine what the human race will look like and will be able to do in 10 000 years.
Our galaxy has a 100 000 light years diameter, even if an advanced civilization somewhere in the galaxy, on a planet 20 000 light years away had invented radio 10 000 years ago, we still wouldn't be able to detect it. By the time we detect it, who knows what technological progress they'd made by then.
I tend to think that the answer to the Fermi paradox is that the universe is so big.
Even if we could travel at the speed of light, the universe would still be huge and we would probably not be able to detect other intelligent life forms / civilizations.
EDIT:
Oops, looks like i got this Proxima Centauri distance a bit off :-) Updated the comment to remove this error, as the main point still stands.
Yeah, not sure where the other figure came from. There is literally a project to build unmanned craft to visit Proxima Centauri sometime in the next 50 years or so: https://en.wikipedia.org/wiki/Breakthrough_Starshot
I'm being genuinely curious, not dissing on anyone.