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.
