To me the most likely back of the napkin answer to the Fermi paradox is that aliens are elsewhere in time. The Milky Way galaxy is about 100,000 light years across but about 13.5 billion years old. So it’s like 135,000x deeper in the time direction than the distance direction.
We’re in the light cones of all the stars we can see, and as far as we know, we can’t get out of them. If a civilization ended even 100 years earlier than our equivalent “now” in their light cone, we wouldn’t have seen them. And if they became visible even 1 year later than our equivalent “now,” we would not have seen them yet.
We’re proceeding through time at 1 sec per sec and basically if we’re going to see an alien civilization at this point, I think the only way would be if one happens to achieve the necessary technology to be detected while we’re looking at it. If there were existing civilizations that were easy to see, we would have seen them already.
I think it’s far more likely we will confirm alien life first by indirect means, for example spectroscopically detecting free atmospheric oxygen on an exoplanet, or finding tiny fossils on Mars.
This is the L constant of the Drake equation. Probably the hardest to find a value for until we've actually discovered other intelligent life or remains of such. The confounding part of it is that we can only guess at things that may end a civilization so completely that it will never recover. Things like the so called Great Filters, natural extinctions like impact events or gamma ray bursts, or other more speculative things that prevent expansion. The tricky part is that our existence seems to fly in the face of such events so far, is that mere luck or do all forms of intelligent life have enough sense to navigate around these problems? The last and most paradox defining part of the problem is that even if the tiniest fraction of civilizations can evade these filters then they should eventually be everywhere in the galaxy. Assuming the Copernican principle that we are not at a special place in the universe or time then there should have already been ample opportunity for such civilizations to develop and hence Fermi's question "Where is everybody?".
> Great Filters, natural extinctions like impact events or gamma ray bursts
you know what really alarms me? these things are only chances on a very, very short-time scale. they are inevitable, yet no one seems alarmed when meteors come between us and the moon and we dont see it coming until hours beforehand.
sun bursts blowing out the electric grid, nuclear war, antiobotic resistance, crop and animal monoculture, climate change, natural resource depletion... taleb is right. we need an agent of chaos to make anti-fragility valuable. otherwise we learn the lesson the hard way. by dying.
I think people are alarmed, but solutions to these problems are enormously costly and largely fictional. The techniques we have for living in space (or transiting through it) would not sustain us if we lost earth. They are enormously costly[1], which is fine for what we are doing, but we need multiple orders-of-magnitude improvement to be practically interstellar.
On balance, I think we could spend more, but I also think diminishing returns is very real. Giving the wright brothers 100,000 workers to build copies of their planes would not have gotten us to the space shuttle much faster. Ironically, it could have slowed us down because of sunk cost fallacies.
I think your view is skewed. Every single person I've talked to about this as looked at me like they are bored. Of course, here on HN, I've found many like-minded people. That's great, but I think very few humans, especially humans in the power structures that run this planet, care about this issue.
I think that's a pretty healthy reaction, pretty much all of human history took place in an environment where investing time an energy in thinking/caring about "the big picture"/"distant future" would drastically lower your chances of survival. Even today there's still plenty of people who have to worry about having something to eat tomorrow.
We're slowly getting comfortable enough about our immediate situation, leaving room to start thinking on a bigger scale. But I think it takes actual effort to say: "ok brain, I understand our immediate situation is important but I think we've got that covered enough to allow us to start caring about the less immediate problems we might face"
I'm a glass half full guy so maybe it's naive but I think we're actually doing pretty well. Climate change sucks and we're pretty slow to respond but you wouldn't expect a hunter/gatherer to be able to see the importance of fighting it. Our situation is different but the brain isn't all that different when it comes to prioritizing things to spend time/energy on. Obesity is a good example of what happens when you combine ancient instincts with modern situations.
Same thing probably goes for racism. We're advanced enough to know better and responsible for our actions but we're dealing with a brain has evolved mostly during times where trusting other tribes and survival of the fittest were Incompatible. Xenophobia had some evolutionary benefit and now we have to deal with it's existence in a vastly different situation.
Like I said, people should know better and have to be held responsible for their actions and we should never be comfortable with the slow rate of change.
Still I like to remind myself every now and then that its amazing how much progress has already been made changing things that evolution hasn't had time to value yet.
This turned out way longer than I expected but it's something I think about a lot. Hope you don't mind me using your comment to finally put some thoughts into words.
I suspect it's more that we have different definitions of how widely a feeling of alarm should spread before saying this. I agree the absolute number of people who are worried about the problem is small.
I guess I think about it in terms of "what proportion of the population that would be directly involved in solving this problem"? I would suspect that is close to 100%. Anyone involved in space work is aware that we may we wiped out and would not like that to happen. Government leaders are also, I think, aware, but unconvinced that more resource expenditure would be meaningfully helpful. Given how difficult it's been to convince people to deal with a much cheaper & easier problem that is much more obvious and immediate (global climate change) I have trouble critiquing people for being insufficiently zealous about this issue.
I think there's a correlation between the age of politicians and how much they care, and we have far too many old politicians. (I'm old, btw.) We need more young people to get involved and get into positions of power. They have a vested interested in seeing solutions implemented, rather than the current crop who know they'll be dead when the real shit hits the fan and they're just letting things stay as is, because they want to maximize their benefits between now and death.
Related to this age observation, I happened to be listening to a recording of Anand Giridharadas speaking in Seattle about how technocratic, engineering-oriented, "rational" mindsets (like most of the people here, like the people who work at tech-influenced foundations) very often do not understand or apparently don't consider the power component of their policy or solution efforts. Net net, more young people in power and more understanding of the power dynamics in society might go a lot farther in getting the "right thing" done.
To e40's point, sadly, when Anand asked the audience how many would be willing to commit to getting involved in the then upcoming election, it was a small minority despite generous applause at other points in his talk about effecting societal change. And this was for local changes in taxation if I recall correctly. I'm guessing they were mostly "old" and have their life's effort to lose in the latter halves of their expected lives.
This is where technical solutions seeking wide societal traction need a helping hand from that other side of our brains that relate to stories, myths, meaning, and purpose.
> you know what really alarms me? these things are only chances on a very, very short-time scale. they are inevitable, yet no one seems alarmed when meteors come between us and the moon and we dont see it coming until hours beforehand.
That is why Elon is so hell bent on making humanity multi planetary.
Carl Sagan had a similar take. From Pale Blue Dot:
> These are the missing practical arguments: safeguarding the Earth from otherwise inevitable catastrophic impacts and hedging our bets on the many other threats, known and unknown, to the environment that sustains us. Without these arguments, a compelling case for sending humans to Mars and elsewhere might be lacking. But with them—and the buttressing arguments involving science, education, perspective, and hope—I think a strong case can be made. If our long-term survival is at stake, we have a basic responsibility to our species venture to other worlds.
Elon Musk has the same chance of making humanity multi-planetary as the Pharaohs did. We are still far away from any semblance of a chance to do so.
Besides, anything at all that we can imagine hitting the earth (except a gamma ray burst or collision with another planet) would still leave the earth in a better shape than Mars is. It's entirely doubtful that humanity could be self-sustaining on Mars even in principle, it is certainly not possible with known technologies.
For a self sustaining colony on Mars you need to span a huge part of the Martian globe to get access to enough raw materials to build things like the microprocessors required for basic life sustaining devices.
But the more you scale to reach the required resources, the more of those resources you will need - especially when you'll more or less have to tunnel your way everywhere if you don't want everyone to die of cancer in their thirties.
And one of the biggest potential limiters is water: we don't actually know how much water there is on Mars. The reserves we know for sure exist at the poles are somewhat small, and it's hard to say how much of Mars' ancestral oceans froze and how much were boiled away and carried off into space along with the rest of its atmosphere. All of the water is frozen (very hard to extract) and likely full of corrosive salts (very hard to separate). Water used in industrial processes is going to be very hard to recapture, and water that evaporates is likely to be lost forever to space (slowly but surely).
You'll also need massive ecosystems to sustain an industrial chain with 0 access to fossil fuels, since you'll need to be able to produce bioplastics and biofuels in addition to food. Again, you'll consume huge quantities of water to achieve this.
Finally, energy production will be extremely difficult, as solar panels are extremely inefficient, efficient forms of solar require boiling water compounding your water problems (and so does nuclear), and both wind and solar of any kind will have massive dust problems, probably insurmountable with today's technology.
I appreciate the thought you put into this response. You make good points.
>For a self sustaining colony on Mars you need to span a huge part of the Martian globe to get access to enough raw materials to build things like the microprocessors required for basic life sustaining devices.
I don't see any reason that microprocessors are required for basic life sustaining devices. They are certainly convenient and valuable. Even if there were required, a simple microchip fab is a known technology. Expensive but does not require new technology.
An interesting question here is how big such a colony needs to be to be self-sustaining.We have clear answers because our present complex Terran economy assumes a planet wide network of trading industrial economies. Perhaps other, smaller solutions exist but we haven't bothered exploring them here because there is no market for it on Earth. Then again I suspect that as long as Earth has an industrial space faring civilization, there will be continuous trade between Earth and Mars. We might not be able to determine how self-sufficient Mars ever is because trade between Earth and Mars may never be shut off.
>And one of the biggest potential limiters is water: we don't actually know how much water there is on Mars.
I agree with you here and it is important point. If it turns out that extracting useable water on Mars is exceptionally difficult, a self-sustaining Mars colony is much harder to create. However we don't really know how true this is. This degree of uncertainly does not support the statement given earlier that "it is certainly not possible with known technologies."
>You'll also need massive ecosystems to sustain an industrial chain with 0 access to fossil fuels, since you'll need to be able to produce bioplastics and biofuels in addition to food. Again, you'll consume huge quantities of water to achieve this.
Yep, strong agree this is why most of these architectures assume large quantities of usable water. I wonder when we get the answer to this question?
>But the more you scale to reach the required resources, the more of those resources you will need - especially when you'll more or less have to tunnel your way everywhere if you don't want everyone to die of cancer in their thirties.
You tunnel for living spaces, you tunnel for resources, a self-sustaining Mars colony will likely require a sufficient investment to get going. Part of that investment will be in energy used for tunneling. Light weight nuclear batteries and generators. Bootstrapping a self-sustaining Martian colony would be extremely difficult but taking a dependent colony and growing it to a self-sustaining system seems easier.
Probably the longer Earth sustains it, the cheaper it will be to become fully self-sustaining.
>Finally, energy production will be extremely difficult, as solar panels are extremely inefficient, efficient forms of solar require boiling water compounding your water problems (and so does nuclear), and both wind and solar of any kind will have massive dust problems, probably insurmountable with today's technology.
I don't know the science but I would assume wind is out because of the thin atmosphere. Solar might be inefficient but how much electricity do you need? I suspect you want to build farms and living spaces that can survive at least a few days to a few weeks without electricity. Low electricity usage and dependency is probably a critical component of robust martian colony architectures.
You can run nuclear on things other than water. US and Soviet Submarines use liquid metal cooled reactors [0]. Why not run underground breeder reactors on Mars, if something goes wrong collapse 5km of soil on them?
While I think fusion is going to play a big role on Earth, I suspect it won't be well used on Mars for a while due to its inherent complexity and dependence on rare materials.
Human nature, apparently. Just about all large-scale human activities at the moment are predicated on exponential growth. We're nowhere near achieving a long-term stable steady-state here on earth. The odds of achieving that in a vastly more hostile environment are even lower.
Will there be simple jobs on Mars base? Someone to sweep the floor, someone to bake a cake, etc? Will they produce enough value to justify enormous resources to keep them alive in such hostile environment?
And even people with important jobs, they would work maybe 50-60 hours a week, but consume resources 24/7.
On average, the value all humans produce in a week might not be enough to keep them all alive for a week.
Most places where humans are on Earth, if one piece of equipment fails (say the engines fall off of your passenger plane while you're over the ocean), you survive and carry on for at least days. In space or on Mars, you're dead in minutes.
> The tricky part is that our existence seems to fly in the face of such events so far.
We've only been here for a few minutes. We aren't really making any efforts to save the planet or colonize space. It's totally possible that we will wipe ourselves out before our TV and radio signals ever make it far enough to be detected by aliens, even if there are a ton of them out there.
There's the other end of a technology curve, when a civilization ceases use of an outdated piece of technology. In our case humanity is looking for radar because we're currently broadcasting it. Why would anyone continue using radar to communicate within a few years of quantum entangled data processing, capable instantly transmitting data instantaneously across vast distances? There might be a few living that rock star lifestyle of HAM radio operation and messenger pidgeons, but at that moment our civ would go narly completely dark to our sister civ's SETI program. All humanity's existence so far has been nothing but spark swallowed up by the darkness of time. Our use of radio a fart in the wind.
This theory is incredibly type-zero-civ-pocentric. A species capable of interstellar travel will have mastered technologies we can't even comprehend. By the time humanity is able to meaningfully reach across the stars, we'll have spread life across our entire solar system and everything we'd ever need. Unlimited energy from our sun, a lush and verdant Venus and Mars, mining colonies across the solar system producing vast quantities of any desirable element, not to mention an Earth whose biosphere is a shining jewel - perpetually locked-in at peak biodiversity.
Begs the question of what we would ever need from another civ, and furthermore what a similar civilization would ever want from a bunch of squatting troglodytes such as ourselves.
> Begs the question of what we would ever need from another civ, and furthermore what a similar civilization would ever want from a bunch of squatting troglodytes such as ourselves.
The need to fight loneliness and to find a kindred spirit?
That and the fact that civilizations probably only broadcast EM radiation out into the void for a short period of time before they start getting into energy efficiency and switch over to more efficient communication technologies.
Even broadcast emissions aren't detectable at long distances. If you parked an Arecibo-class telescope in orbit around Alpha Centauri the only signals you'd detect coming from Earth would be intentional directional transmissions from an Arecibo-class (or Goldstone class) radar.
Our television and radio broadcasts aren't detectable by an Arecibo-class telescope out much past Jupiter let alone outside the solar system. Even our high powered radar systems wouldn't be detectable out even half a light year from the solar system.
The only civilizations that can be detected with a SETI-like program would be ones intentionally transmitting directional signals. Even then out past a thousand light years even a multi-terawatt (EIRP) signal would be difficult to detect.
Like inverse square law is as unforgiving as the rocket equation. Anyone hand-waving either of those principals is not trying to have a meaningful discussion about interstellar communication or travel, they're just writing about science fiction.
Leaving the serious engineering difficulties involved in a solar gravitational lensing system aside, such a system doesn't necessarily help in picking up just random omnidirectional broadcasts from an ETI.
Say we had an SGL telescope positioned such to image an Earth-sized planet we know is in orbit of Alpha Centauri A. For ease of math we'll say this Earth sized planet is at a distance such the solar constant is the same as Earth. So that's a total power received from the Sun of 1.74x10^17 watts and with the Earth's mean albedo of 0.3 about 5.22x10^16 watts being reflected off into space.
We can use our SGL to image the planet around Alpha Centauri because it's reflecting 52.2 petawatts of sunlight out into space. So it takes the power of a star reflecting off a disc with a cross sectional area of 1.26x10^8 square kilometers for a proposed SGL system to detect and image a planet.
The amount of power an omnidirectional antenna can possibly emit is somewhat less than 52 petawatts. Broadcast antennas output at most a few megawatts EIRP because there's no utility in blasting out hundreds of megawatts for terrestrial transmission. Such broadcasts just aren't going to be detectable even with gravitational lensing from our Centauran neighbors.
Nor are gravitational lenses terribly useful for beacons since you need the right geometry between the sender, star, and receiver to use the lens. You could use lensing to increase the EIRP of your transmission but only at a specific target. Nobody outside the focal plane of the lensing system is going to benefit from the lens.
SGLs are a neat idea and an interesting topic but I don't think they solve many SETI problems.
You look at human civilization and that's exactly what's happened. We started off by broadcasting everything as loud as we could (which isn't very loud) and we've slowly transitioned to signals that are both quieter and don't really survive escaping the atmosphere.
I can't imagine an advanced species wouldn't follow a similar communications path. The only way we detect them is if they specifically target our spot in the sky with focused EM for a very long time, generations! After all, they have no clue when we would be in our evolutionary path.
And for that to happen, the species would have to first find us. Not just find us, find us while we are still listening.
And this is all with the assumption that FTL communication/observation is even a possibility (It likely isn't).
IMO, the simplest answer is that FTL communication and travel is impossible. Advanced civilizations across the galaxy have all come to the same conclusion.
We might be able to explore our own neighboring stars throughout generations but it's unlikely we'll be able to ever send a message to another civilization that will get there while they are listening (without spending huge amounts of power).
But if you pursue an evolution over millions of years, at some point we'll have to miniaturise. Imagine we can make fully conscious silicon - let's say in 200 000 years (6500 human generations). At this point, we'd be tempted little by little to raise them as our intellectual children and find less and less need to make them with sperm and vagina.
After a long while, there might be this great replacement, totally peaceful, that would lead these conscious organisms with a vastly superior intellectual efficiency to probably become very small and self centered and not behave like the territorial monkeys we are. What do you think a massively singular electronic intelligence will think when it notices a planet like ours ? "nuke them all and rape their women" ? This is monkey behavior that we still haven't fully shaken up.
I have heard (can’t remember the source) that radar, especially military radar, continues to be a significant source of artificial-looking EM radiation leaving the Earth, even as radio and TV broadcasts have declined in power.
Short lived on those timescales, yes. But not necessarily short lived in terms of our perspective.
If we imagine that in the last 5 billion years, there have been a good solid 10,000 post-industrial civilizations, and each of those civilizations has lasted 10,000 years (in the post-industrial stage where they're detectable), then that implies that of the last 5,000,000,000 years, 100,000,000 of them have been host to a post-industrial civilization: a given year has on average 0.02 currently present civilizations in it.
Now, this hypothesis does probably imply that significantly interstellar civilizations are impossible, since it seems like if you've colonized say 20 stars, what disaster could possibly end your civilization?
(I think the most likely scenario is that we're the only civilization ever to have developed in the Milky Way. Everything else seems like it assumes a lot of additional stuff.)
I mean, maybe. Honestly hard for me to imagine war actually going on between two interstellar civilizations. But even if it did, it seems like in 99% of all cases, that would leave at least one of the two civilizations still around. We're looking for explanations, in this hypothesis, that leave 98% of all time with no civilizations.
Maybe war between two spacefaring civilizations is too "easy". eg something like: throwing asteroids at ~the speed of light is necessarily a cheap thing to do once you're at that level, and everyone just dies.
Like if on Earth nukes were something everyone could cook up in their backyard in an afternoon, we'd all be gone pretty quick.
> Maybe war between two spacefaring civilizations is too "easy". eg something like: throwing asteroids at ~the speed of light is necessarily a cheap thing to do once you're at that level, and everyone just dies.
The Killing Star[0] and Flying to Valhalla by Charles Pellegrino are based around the idea that it's natural for a species to annihilate all other sentient species. The characters define three rules that an alien species may be operating by.
Rule 1. Aliens will believe their survival is more important than our survival.
Rule 2. Wimps don't become top dogs.
Rule 3. Aliens will assume that the first two rules apply to us as well.
Given the relative emptiness of observed space, im not convinced that a civilization A would try to annihilate all life but would maybe war with others in their light cone who threaten civA goals/expansion. If you can traverse interstellar space you can probably make home most anywhere further reducing the amount of potential conflict.
How likely does it seem that if you can traverse interstellar space, your civilization splinters over time and your potential for internal conflict just grows without bound?
If you can traverse interstellar space you are pretty much required to "live off the land" as you go and especially so once you reach your destination. This means you possess the ability to produce all of the energy, food, material, etc. required for a civilization to exist from what is present in either interstellar space or a solar system. If we put our sci-fi hats on we can imagine a perfect system of recycling and matter conversion that can keep a massive generational ship functioning with the only input being hydrogen scooped from the space it crosses. If you possess that level of sophistication then you really could live anywhere. That gives you plenty of living space with little motivation to pre-emptively attack others.
Spoilers for The Dark Forest and The Remembrance of Earth's Past Trilogy below.
In the book that the OP article is based on, humanity is doing anything and everything to prevent/defend themselves against an alien invasion happening ~400 years in the future. The character who coins "Dark Forest" theory in the book proposes sending a 'spell' (just a signal containing coordinates) to a nearby star, which is then amplified throughout the universe via "Sci-Fi science". This reveals the location of the star, and shortly after the star is destroyed by some comet-sized object moving at the speed of light. It's later revealed that some other civilization listens for broadcasts on every spectrum, decodes them for coordinates, then destroys the ones that seem to have actually been sent by intelligent life.
I thought this made perfect sense - why wouldn't another intelligent species do this if they possess the technology? I personally agree with "Dark Forest" theory and think that we should /never/ make first contact (lest we are destroyed), but if we were to attempt first contact, we should at the very least have a weapon like you described available to us first.
> why wouldn't another intelligent species do this if they possess the technology?
I think the only question we can ask here is "Would we do this if we possessed the technology?". We only have ourselves as an example of intelligent life.
You may be on to something there. Nukes aren't something that you can cook up in your back yard yet but it seems inevitable that at a certain level of technology they will be. The same is even more true for biological warfare.
Society probably only functions below a certain level of technological advancement before everybody dies to an onslaught of engineered diseases.
If the stars are reasonably close together a supernova would do it. Even a relatively distant supernova (like 30-40 light years) would likely render most planets inhabitable for a long time.
But maybe war is a territorial animal's instinct and once we have shaken up a bit more of our animality, we'd understand this makes no sense ?
If we can control resource, exchange knowledge and techniques, and reproduce automatically (for instance if we become small electronic machines rather than the current inefficient chemical process we are), "war" might probably sounds both ridiculous and totally ineffective, both to cull us if we're abstract enough, and to cull potential enemies, probably just as impossible to reach "physically".
OTOH animals evolved those instincts because they worked in the game-theoretical circumstances that competition with other animals.
Perhaps we can shake off many emotional components of war (which would make war an irrational option in many of the cases that our monkey brain would have been dragged into) but that doesn't necessarily mean that war itself would be eradicated
Animals are stuck in local maxima (betrayal in the Prisoner's Dilemma). A more evolved group might discover and be able to reach the global maximum (solidarity in the Prisoner's Dilemma). Imagine if tigers or sharks developed pack hunting, or the octopus became more pro-social.
Also, multi-species symbiotic relationships are quite common in the animal kingdom. It would be surprising if that weren't true at other scales (and if it were limited to the sci-fi trope of "worker species, soldier species, leader species").
I'm not saying it's not possible to find other equilibrium points. I'm just pointing out that there are more fundamental forces at play and it's not just because of our "monkey/animal brain".
Selective pressures that permit the emergence of cooperative behaviour require participating individuals to exhibit a variation in behaviour and those who cooperate result in having a higher fitness in the environment than those who shun cooperation.
The selection effect operates on over the whole population and over times that are longer than the life span of an individual.
An individual that is implementing what ultimately will emerge as the winning strategy, may on average be better off, but it can (and it will) be also often worse off.
Depending whose existence you're optimizing for (individual or species) changes the framing of what is the optimal strategy.
An existential risk for a species changes the framing of what is rational to do quite a lot.
The rocket equation, energy being quadratic with velocity, and the impossibility of perfect efficiency (and, possibly, limits on material properties) constrain speeds.
That means it takes a long time to get between stars. A long time.
Which means if you venture between stars successfully, you're adapted for life in interstellar space. If that's the case, why would you go down the gravity well? There are lots of asteroids and comets to use in Oort clouds and between stars, and those down-well enviroments are hostile.
Climate change is very real and worth addressing, but it's extremely unlikely to wipe out human civilization. It's just going to be costly and kill millions, not billions.
Climate change by itself could be extremely unlikely to wipe out human civilization but it could be the catalyst that sets other events in motion like nuclear war.
I wouldn't say it's extremely unlikely.
Maybe not the primary effects won't kill us. But when nations start to struggle with the primary effects, the resource shortages are going to cause conflict - which will almost certainly lead to wars, with these weapons, which will kill billions.
Can you clarify what you mean by "millions"? The Syrian civil war is estimated to have killed just short of half a million people. The pandemic easily has a global death toll of roughly 4 million people so far. The Chalisa famine of 1783/1784 is estimated to have killed 11 million people. The Spanish flu killed at least 17 million people, though some of the more dramatizing estimates place it closer to 100 million. According to some researchers, climate change is already killing 100,000 a year[1]. So I assume you're not thinking of just seven or eight digits unless you're exceedingly optimistic.
Climate change will make parts of the world inhabitable that are currently populated by humans. It will also result in crop failures, which will cause famines. In some cases formerly native crops will no longer be supported by the changing local climate or farmland may become completely unusable. Potable water will become harder to source. Water contamination is a source of many deadly diseases.
Even if we assume most of the deaths will be concentrated in places like Africa or the Indian subcontinent, the global economy relies on these places for resources and cheap labor. People in ongoing climate catastrophes also don't tend to stay put and die in an orderly fashion, they become refugees or riot against their governments. Things can get politically messy even in the nations next door as humans tend to be uncomfortable with political chaos and mass deaths.
But unlike the Spanish flu, or the potato famine, or COVID, climate change is not a temporary blip that happens and then goes away. If all the carriers of the plague have died, nobody dies from the plague unless they get infected handling the dead. Famines can starve millions to death but once there's another harvest the survivors have food again. Climate change isn't like that. If climate change creates a drought, that's not just a drought, that's now dry season and it will be dry season every year from now.
There are currently 7.8 billion humans. There's absolutely no reason to believe climate change can't kill billions, especially once it's managed to kill the first hundreds of millions.
Keep in mind that it's not about "addressing" climate change. It's not a moldy bathroom tile that you need to clean up or replace before the mold spreads everywhere. It's a fire our entire way of life is fueling every single day. We know what needs to be done to slow it down to survivable levels (or at least levels that are lethal for less than 1% of us) but we can't just pass legislation or appeal to personal responsibility to do that because it involves changes that would be economical suicide for anyone doing it alone. The world economy is playing a game of chicken with each other and nobody is bluffing.
New equilibriums will form. Where it was once one climate, another will be, and the native crops that can no longer live in the first climate will be supplanted by new ones that can survive in the new one. This won’t be the case everywhere, but this sort of adaptation will happen. You’re talking as if everything will remain static except the climate.
Additionally, the entire worlds population at relatively sparse city density (say, Houston) can fit in like 1/3 of the United States.
That isn’t to say that climate change isn’t a big deal. It is one of the biggest deals and quite grave. But you don’t really propose any solutions. What you allude to though won’t happen, that everyone works together to address the issues. My speculation is that if our technology doesn’t progress fast enough, billions will die, but if tech does happen to progress fast enough then that will be mitigated.
That isn’t to say that the world couldn’t use a strong reduction in population. But given that we are causing this, I feel particularly bad for the wildlife whose habitats will be unlivable to them through no fault of their own and not through natural processes.
Civilizations are only detectable for a short period of time. Once they understand physics, they no longer need radio waves or Dyson spheres or to travel through what we call spacetime.
Space and time may be emergent, we don't know, all we do know is that our current model of physics is missing something. Quantum Gravity for example and We don't know what happens inside a black hole either.
Yes, it seems that the Fermi paradox implies that other civs progress beyond what we consider signs of intelligent life. The great filter seems less likely as we get close to colonizing other planets, and then other solar systems.
Yup, to me it implies a darker problem, that FLT is something that can't be surpassed. All civs might advance to that understanding and decide to maybe just occupy nearby solar systems and nothing more.
We may not talk to them simply because it's both incredibly expensive and will yield nothing more than "Yup, we're stuck here, so are you".
Sure, they could, but imagine they are 10,000 light years away. Such a craft would need to travel for a long time before it could communicate back it's findings.
AFA we know we've been insanely lucky up to this point (as earthling life we went past multiple mass extinctions, we got multi-cellular life, multiple brains iterations, a society which still didn't wipe itself out etc)
What makes it more likely for the filter to be ahead of us rather than behind us?
Modern civilization is extremely dependent on fossil fuels. We've already passed peak conventional oil production, and we're now surviving on EXTRAORDINARY technical means of enhanced oil recovery.
If we can't make the complete transition to renewables in the next thirty years, it's game over for a VERY long time. Future civilizations won't enjoy the benefit of Spindletop. Cheap energy sources won't be available near the surface of the crust for another > 50 million years.
We won't go extinct, but it will be the 18th century for a very long time and nobody will leave this rock during that time.
The Great Filter is right here, in front of us, in our lifetimes.
That's a good point. It's pretty easy to construct and maintain fission reactors without fossil fuels. I bet enriching uranium was a snap in the 18th century, too. It will be even easier even getting to the enrichment phase in the future, with accessible ores about 30% as rich as they were when the nuclear age began.
Looking forward to the fleet of electric concrete trucks carrying electrically-manufactured concrete loaded with batteries that were produced with lithium carbonate dug out of the ground by electric excavation rigs.
All of this construction work will also not be disrupted by any social unrest resulting from 3 billion people starving to death because the Haber process no longer has enough cheap feedstock to sustain modern agricultural processes.
Your snark is misplaced. All of the issues you raise apply to any source of energy, including "renewables". The difference is, "renewables" (a) are not controllable, and (b) don't have nearly enough capacity to support a global civilization. And if you're worried about social unrest, by far the best way to ensure it is to refuse to make use of an obvious source of plentiful energy to help maintain and improve people's standard of living, and instead insist on keeping billions of people in poverty in order to satisfy your ideological preconceptions.
Sure eventually, but there's no clear indication if that's 10 years away, 10 billion years away, or a mere technicality as our descendants evolve into something that counts as a separate species.
We're currently undergoing the largest mass extinction event that will easily rank in the top 6 of life on this planet and could possibly compete with the end-permian. What makes you think we could possibly survive? Because we're the cause? Plenty of species in the past that have caused extinction events also perished.
It seems far more questionable to assume we won't risk extinction in the geological near term. The parent is downvoted more out of existential fear rather than an honest assessment of the situation.
I think the parent comment was downvoted because it's not really contributing anything besides pessimism.
As for us, I don't doubt the likelihood of a serious mass extinction, including possibly a severe drop in human population, but I can't see it being so severe as to cause an existential threat to us. No other species on this planet has had the ability to change the environment to suit it, or the ease of mobility to move where they can survive. Short of earth being entirely incompatible with complex life on the surface, I don't see humanity disappearing because of climate change.
I'm talking about much more than climate change. Failure to cooperate, anti-intellectualism, and innate hatred of each other (among other flaws) are what will sink us.
If we don't expand beyond Earth, we've got maybe 700 million years tops, since past then the sun's changes will make multi-cellular life, if not all life, on Earth impossible.
Generalization. Would be interesting discussion with details. Pop is growing. What's your concern - global warming, fertility rates, pollution, nuclear arsenal, running out of resources? Doesn't seem like we are doing that badly and that pop can't drop if get below renewable resource level or adjust to new ways of making energy/food, etc.
Does seem likely that on an extremely long time scale, we need to get multi-planetary, which is "realistic" if we give a reasonable time frame of, say, 10,000 years.
As far as the sun dying, that's beyond even parent point's timeline. This is very things start to get questionable if we never get to even .1 of c (e.g. Project Orion "realistic" estimates). Alpha Centauri is relative close at 4.something ly, but other "potentially habitable/useful" star systems are way out there.
Agreed. The great filter and collapse theory in general are fascinating in theory and can motivate some great positive action but they can't undermine the fact that humans beings are doing better than they've ever done in our history by almost every imaginable metric.
Plus humans are extremely adaptable. Even before we invented agriculture, people had colonized the whole planet, except for Antarctica. It would be hard to kill us all off.
This is a strange claim I see repeated over and over, but it has very little evidence to justify it. The only piece of evidence people present is:
> people had colonized the whole planet, except for Antarctica
This is true of a fairly large number of organisms on Earth.
On top of this humans have only been around for ~200,000 years, that's not long at all. Humans have not survived a single mass extinction event.
So far we've seen humans travel around a planet that has been relatively stable for that period of time. There have been plenty of species that have traveled around with us that didn't even need to rely on extra tools, clothing or the use of energy to survive.
Humans share several vulnerabilities with other megafauna that have all gone extinct. A major one is a fairly long gestation, plus small number of offspring per generation. Human young likewise need tremendous amounts of care and energy to raise to mature adulthood. Additionally human have fairly high energy requirements to support their complex brains.
We've seen exponential rise in human population only because humans have had access to excessive amount of non-renewable, high-energy density sources of energy.
It just happens that humans have lived on a planet that has mostly been within survivable temperature changes, with historic climate changes happening on time scales that lead to easy migration. As you pointed out, the one continent that does not have an environment that supports human life remains empty.
Humans can't survive a wet bulb temperature of 35C. Until just recently we never saw that temperature on this planet. As we see more and more places reach that temperature more often, I suspect we'll see how frail human adaptability is.
In comparison to most other mammals (including the neanderthals), we are pretty awesome at adaption. Probably even better than bacteria, all things considered.
That is because we possess multiple different ways of adapting to our enviroment:
But we don't see the same species of seals or birds everywhere. There are different species which evolved to survive on each continent. Whereas humans are a single worldwide species.
Birds migrate from one place to the other they don’t live on every continent all year round. Even if we take these though (and as the other commenter said they aren’t the same species in every continent) that still leaves a total of 3 out of how many thousands, millions, of multicellular organisms on the planet.
> the fact that humans beings are doing better than they've ever done in our history by almost every imaginable metric.
That's because we have had ready access to insanely abundant high-energy density source of energy.
The non-fossil fuel supported carrying capacity of the planet for humans is estimated to be somewhere around 1 billion people. When the fuel runs out (if we don't cook ourselves first), that will collapse.
It is nothing intrinsic about humans that have lead to our recent success, just access to lots of nearly free energy.
edit: why the downvotes? Is there even anything controversial in these statements? HN's fear of bad news is getting out of hand.
What is your source for the 1 billion estimate? Because that seems completely, non-credibly *low* to me.
I also strongly believe that we could cover all our energy needs with renewable sources within a few decades if we really wanted to (even assuming no significant advances in tech), and this seems mostly non-disputed to me (because that is literally what nation-states are currently planning/doing).
> Is there even anything controversial in these statements?
Yes. Your statements seem not credible to me and you cite no sources.
1 billion is a rough estimate based populations prior to the massive boom in the industrial revolution that saw massive changes in the way agriculture is done. It could easily be 2 billion or so, but definitely not 7.8 billion. You can see the population history here[0.]
To see the powerful impact of fossil fuels on carrying capacity you'll notice there's an important inflection point around 1920-1930. This is because of the advent of the Haber process[1] which allows us to use fossil fuels to create nitrogen based fertilizers.
Lest you doubt the impact of the Haber process just look at trends in corn yield per acre since then [2]. It's truly remarkable. Additional gains there are from other industrialized, fossil fuel driven agricultural process.
The Haber process requires hydrocarbons. In the wikipedia article you can see that it consumes 3-5% of the worlds natural gas production and 1-2% of the global energy supply.
We have completely disrupted the natural nitrogen cycle [4] and so would be unable to produce anywhere near as much food without fossil fuels. Because we have disrupted this cycle it's not even obvious that we could go back to a world of pre-fossil fuel agriculture.
So those are just some bit of information about my claims but let's take a look at yours:
> we could cover all our energy needs with renewable sources within a few decades if we really wanted to... this seems mostly non-disputed to me
This is wildly disputed, and I don't know anyone who credibly believes this without invoking "magic" future technology.
For starters we haven't replaced fossil fuels with "renewables" at all so far. We've just used them to supplement our energy needs. You can see here [4] that global fossil fuel consumption has continued to rise.
Then it is important to separate electricity from the more general subject of energy. Currently only 20% of global energy usage is electricity generation [5]. So even if you replaced the entire grid with renewables over night you would still be missing the vast majority of energy demands.
We currently have no viable pathway for renewable energy in transportation. Alice Friedman has more notes on this than I could ever fit in a comment [6]. Transportation inherently requires high energy density fuels, and outside of passenger vehicles, battery technology does not have the density required for industrial shipping.
It worth looking at our national energy flows to get a good sense of just how little of the energy we use comes from renewables [7].
But even if we look just at the electrical grid, in the US, we have some very obvious problems with "all" our needs. As you probably know, wind and solar are intermittent power sources that requires fossil fuel powered "peaker" plants to provide energy in down times.
This had two problems. One you need energy storage technology that we do not currently have (you cannot use grid scale lithium batters, pumped hydro has geological constraints, molten salts only work with concentrated solar, compressed air requires decommissioned oil field, etc).
The other problem is that even if you had perfect storage you need to now more than double the total energy production so you can fill those batteries.
The should be enough sources for you to get started, but I have feeling I'll still get down votes and "hand wavy" explanations of how it will all work out.
Thanks for explaining how you arrived at your numbers.
> I have feeling I'll still get down votes and "hand wavy" explanations
Let me turn this around: you are getting downvotes (not from me) because your 1 billion population carrying estimate in a post-fossil age is implausible and borderline disingenuous:
1) It assumes that pre-industrial agricultural output is the maximum that our planet can sustain. Which is completely off for a multitude of reasons:
- Genetic improvements to cultivars still fully apply
- Pesticides won't cease to exist
- Automation in harvesting/monitoring also won't go away
2) There is no reason to assume that we're anywhere close to peak sustainable agricultural output, neither in pre-industrial times NOR now.
3) Furthermore, it implies that land utilization, cultivar choice and consumer behavior in general would stay similar/comparable regardless of cataclysmic change in supply/demand (pricing).
Which is obviously wrong: If avocado price went up to 50$/kg then people would just put potatoes on their toast instead, and total agricultural output (in calories) would "inexplicably" increase.
Regarding power:
Renewables (solar/wind) are a perfectly fine source of primary energy. Storage/grid stability does not depend on "technology we do not currently have"--Batteries and inverters are perfectly usable, mature technologies--but right now slapping down natural gas plants is simply cheaper. This is exclusively a matter of price/ROI, and installation could be jumpstarted immediately if there was the political will to pay for it (and thats not blaming politicians exclusively to be clear--average citizen is simply unwilling to pay 1$/kWh right now for residential electricity).
> Renewable energy in transportation
Friedman selfdescribes as "energy sceptic" which is already...unfavorable... to me and after stumbling over "running out of fossils is gonna solve climate change better than anything else" (transcribed), I gave up on the author completely;
Viable pathways are:
- Batteries
- Biofuel
- Fuel cells
- Hydrogen in combustion engines
We literally built all of those already, but same story here: It's less cost efficient than burning diesel right now, so why would anyone do it.
> It assumes that pre-industrial agricultural output is the maximum that our planet can sustain. Which is completely off for a multitude of reasons
I agree it's off because we've done significant damage to the biosphere since industrialization. As I've pointed out we have disrupted the natural nitrogen cycle.
If we where to immediately rewind our population back to 1850 and try to life that lifestyle we would have a much harder time since we have depleted natural resources. We cannot go back because we the earth would not support us the way it once did.
> There is no reason to assume that we're anywhere close to peak sustainable agricultural output, neither in pre-industrial times NOR now.
Our entire current agricultural system relies on fossil fuels, so I agree, where nowhere near close... we're way past.
> Viable pathways are
- batteries: not for commercial transport, the energy density is still way too low. Your battery becomes your cargo. Modern global trade is impossible in a battery based economy. Nobody that is serious on renewables will disagree with this, they will claim that new battery technology is going to solve this.
- Biofuel: require more energy to make they they provide [0]. So again, not only do you need to double the grid to handle intermittent power, you now need to expand it by the total biofuel energy required times 1/efficiency, so we're looking at at least tripling our current power output and trying to do it with only renewables. Please tell me how much silicon and lithium it would take to build a grid that large in that sort of a time span and you'll find it dwarf's annual production.
- Fuel cells: same problem again, currently fuel cells are made with coal or natural gas today 95% of fuel cells are made with natural gas [1]. If you want to switch to electrolysis you come up with the same problem of having to double our current grid power.
- Hydrogen in combustion engines: I'm not sure how this is different from hydrogen fuel cells, but the hydrogen production problem is the same.
Please if you want sources, provide some of your own. Come up with some back of the envelope estimates on the total grid capacity needed to cover 100% of our energy needs. Then do some research on the energy costs to produce solar cells at that scale (or wind farms, hydro is already near full capacity at least in the US).
I know you yourself don't really believe what you are saying. It's based on no research, you have provided no meaningful sources, and even the most die-hard solar/renewable proponents realize that grid scale storage is still an unsolved problems. What you have given are "hand wavy" explanations without sources, exactly as I expected.
And to add the evidence we do have; in the billions of years of life on earth, there has only been <200 years where any species had the will and the way to send deliberate communications into space. Observational evidence suggests that the time span of civilizations existing is vanishingly tiny compared to the vastness of time overall
Is it? I can move all sorts of distances, in different directions, at all sorts of rates. It's surely harder to go certain speeds than others, and in certain directions than others. But to move 1 year in time - I only have one speed and one direction to move.
We’re in the light cones of all the stars we can see, and as far as we know, we can’t get out of them. If a civilization ended even 100 years earlier than our equivalent “now” in their light cone, we wouldn’t have seen them. And if they became visible even 1 year later than our equivalent “now,” we would not have seen them yet.
We’re proceeding through time at 1 sec per sec and basically if we’re going to see an alien civilization at this point, I think the only way would be if one happens to achieve the necessary technology to be detected while we’re looking at it. If there were existing civilizations that were easy to see, we would have seen them already.
I think it’s far more likely we will confirm alien life first by indirect means, for example spectroscopically detecting free atmospheric oxygen on an exoplanet, or finding tiny fossils on Mars.