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.
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.
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.
Doesn't sound particularly obvious to me...
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.
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.
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.
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.
> We take over the galaxy or die trying.
Let's first survive on Earth, shall we?
But if you don't understand how we need biodiversity to survive, I guess try to eat ChatGPT or Starship.
[1]. https://en.m.wikipedia.org/wiki/Keystone_species [2]. https://bfi.uchicago.edu/wp-content/uploads/2023/01/BFI_WP_2...
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.
But hey, thanks for steering it in an ad hominem direction.
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?
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.
You: "Looks like bullshit to me." (<- your words~)
Unimpressive.
I just wanted someone to describe a plausible scenario with that outcome due to loss of diversity.
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?
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!)
Your comment could apply to any one commenting on these topics and so I am confused.
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"
If we don't have a very active interplanetary society in 100 million years we're almost certainly extinct.
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 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.
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.
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.
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.
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).
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.
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.
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?
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?
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
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.
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.
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.
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.
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 a loooong time, obviously, but it's not "theoretically impossible"
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).
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.
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.
Famous last words :-)
Humanity doesn't really want to do a project like this, however.
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.
That whole idea is also based on IMO the worst instincts of our race.
For all we know making it past the great filter involves developing an increased empathy for all life.
Great. So don't wash your hands before eating... and don't eat.
It is unlikely life elsewhere won't involve the same fundamental game theory.