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Comment by mekkkkkk | Hacker News Reader

There's a lot of talk about the great filter this, and the great filter that. Even if life is abundant, what gives you the impression that civilization level intelligence would be? Out of all the species that ever roamed the earth, only a single one has reached this point. Perhaps it's an absolutely incredible fluke or glitch in our biology that is one in a [insert astronomical number].

It's tempting to think something in the lines of "oh but if it happened here in our little shitty solar system, it can't be very special". But that's more or less the anthropic principle.

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100% this.

Unfortunately people still think very teleologically, as if nature works in a progressive fashion towards some structured end; this tendency is deep in western thought all the way back to Plato (and probably beyond), and it's all over science fiction.

The core observation is that organisms with an ability to model the Universe, even if imprecisely and in a tiny space-time neighborhood, increases the chances of survival. See the ubiqutous living beings with a nervous system. The hypothesis is that increased precision and/or size of the prediction bubble is correlated with survival fitness, which, in the limit, gives raise to beings with a God-like ability to predict the Universe. It's a relatively simple inductive argument.

Even if it is true that "in the limit" increased foresight implies increased fitness, it doesn't necessarily follow that being with God-like foresight exist.

That said, IMO there's a lot of things that could confound the usefulness of increased foresight. After a certain point (which humanity has likely passed) foresight is not a particularly visible measure of fitness except in those rare extinction events that require significant cooperation to survive. I suppose that even given that foresight is the most valuable trait for long-term survival of a species, it's very rare that it is selected for beyond a certain point because the events that it allows a species to survive are too rare to be selected against.

The hypothesis also makes a huge assumption: that if intelligent civilizations were common, they would be detectable by us. The radio waves emitted by our own civilization don't go that far (compared to the distance between stars) before becoming nearly indistinguishable from background noise.

Also, they’re dying. Earth is probably less noisy now that 50 years ago.

Why is that the case?

As I understand it, the most visible stuff would be TV signal and over the horizon radar. TV signals have gotten less powerful, over the horizon radar is less of a big deal than it used to be. In another 50 years, will terrestrial TV, or any high power terrestrial radio, be a thing at all?

It’s wasteful to spend the power to broadcast up into the sky when no viewers are up there; more focused directional transmitters, more sensitive receivers which allow lower power signals, more information sent over cable and fibre optic and undersea transmission lines and point-to-point satellite, more microwave and laser links compared to spam-everywhere radio broadcasts.

On the other hand, stars are extremely wasteful. A technological civilization will, eventually, encase their sun in an energy extracting Dyson swarm. So why isn't the sky full of dim uniform-distribution infrared blobs?

Would they still be detectable? Or could they capture enough energy that the stars would be barely noticeable, like trying to find a brown dwarf?

I followed Tabby's Star news for a while (star that showed massive dips, speculation was that it is a dyson sphere being built).

Most scientists believe that even if the star is encased in Dyson sphere that there would be excess infrared emissions as the sphere would need to vent heat. It would be hotter than surrounding space and thus visible.

They are thus trying to detect such stars with higher mass and IR excess than expected, but so far there are not many candidates.

You cannot simply absorb all the energy of the star and never emit it. The waste heat has to go somewhere. An efficient Dyson sphere would still emit lower energy infrared radiation in a way that would be detectable from out space-based observatories.

Because there's no other intelligent life out there.

You know that. But it bears mention, for others following along, that rampant artificial intelligence or similar does not count as a great filter candidate, because it would be just as visible as the life it's replacing.

That doesn't leave a lot of fast-acting filters that could still be in our future, to be honest. Nuclear war? Sure, but we've avoided it too long for that to be a good one either.

Artificial intelligence would necessarily have different physical needs than biological life. We can expect even our own AI to be a bit alien to our ways of thinking. Alien created AI would be completely alien to us. With different needs and different motivations, what evidence do we even look for, and if it is pervasive, how do we know we aren’t looking right at it?

It would still exist in the same universe subject to the same laws of thermodynamics, and would still extract energy from fusion stars in a way that leaves an unmistakable technology signature.

It would be subject to the same laws, barring novel physics (like extracting energy from dark matter or some other process we don't yet understand). But a single AI could be smarter than 10 billion humans and consume less energy, need less space, and not care about expanding out into the stars. They could coast around their host star indefinitely and when they eventually needed to leave (which could be never), they could store energy and make a long, slow trek to another star. Imagine trying to find an asteroid-sized object in interstellar space.

>Nuclear war? Sure, but we've avoided it too long for that to be a good one either.

75 years is an infinitessimal blip of time in cosmic terms.

One must assume either the aliens aren't there, or that the idea is not worth it for reasons we haven't discovered yet. Maybe planetside fusion power is just more efficient. Maybe they can harvest energy from black holes or something.

Such observation supposes that our timeline matches theirs (taking into account the delay due to lightspeed). We weren't capable of such observation until about a few decades ago, other civilization could have existed and vanished billions of years ago, or billions of years in the future, or are so distant that they're outside of our obserable universe (if they ever was within it).

Or energy is not such a big deal anymore once you've reached a certain stage of technological advancement, so it's not the right criteria.

Civilizations won’t go extinct once there are interstellar, thanks to the speed of light balkanizing any such civilization, and thereby providing redundancy.

> A technological civilization will, eventually, encase their sun in an energy extracting Dyson swarm.

I always wonder, when I read this and similar claims, how on earth the tone of 100% certainty is justified. It seems pure bluff.

I have wondered about this too. I suppose the reasoning is that every solar system has a massive source of energy in the middle of it, and that mega civilizations would be stupid to not utilize it.

Sounds probable, but I can see many possible reasons not to bother. Not to mention it is speculating about technology so far ahead of our own that it seems silly. 50's predictions of rocket belts and nuclear powered cars come to mind.

> 50's predictions of rocket belts and nuclear powered cars come to mind.

These are different kind of predictions. Rocket belts could work, but they don't make economic sense and there's a strong safety argument against it. It's the same reason we don't have flying cars either.

Nuclear-powered cars could have worked; the failure wasn't predicting technology or its feasibility, but that nobody figured out humanity will collectively go insane and irrationally refuse to develop use of nuclear energy.

Dyson spheres are a pretty obvious thing to do - every star is a free, self-maintaining fusion generator that just wastes almost 100% of its output. So the argument is really that when a civilization's need for energy gets larger than what can be supplied by burning whatever stuff they have on their planet, the next obvious step is their star. Barring some magic tech breakthroughs like pulling energy from "subspace" or whatever, you have a rather solid argument that's essentially: "as long as life is not limited from growing, it will eventually start blotting out the sun it orbits".

The 50s analogy is only to point out how we like to extrapolate contemporary technical understanding into the future. The envisioned dyson spheres I've seen look like our current understanding and use of photovoltaics extrapolated in the same way.

I don't disagree that the core idea of harnessing the suns energy seems likely. As the parent poster said, it's just the absolute confidence that people seem to have on the subject that's a bit curious.

Maybe breakthroughs in energy generation will make it not worth the effort? Maybe becoming interstellar makes it obsolete since the energy requirements for a given civilization are spread thinner? Maybe there are other ways to harness the solar energy that would not show the same signs as we predict? Maybe civilizations trend to energy efficiency instead of just increased usage?

Maybe not.

It’s quite rooted in game theory:

https://wiki.lesswrong.com/wiki/Basic_AI_drives

The above link is about AI, but it could apply to any alien species just as well.

Any organism living in a thermodynamic universe and subject to competition and evolutionary pressures will develop instinctual drives that align with resource acquisition, replication, and survival. As the above link details this surprisingly holds true even when you remove evolution and consider designed minds.

Even if a hypothetical civilization didn’t care about resource acquisition, replication and survival, they’d be out-competed by one which did. So where is that civilization’s ever expanding sphere of Dyson clouds?

Unless the super advanced aliens fear they live in a dark forest and decide not to paint huge Dyson Sphere bullseyes on their backs.

There are a lot of problems with the dark forest hypothesis, the most critical for this purpose being that it is not a stable outcome. A civilization with the capability to create a Dyson sphere and harness the power of an entire star could easily defeat any invader attracted to their presence. E.g. with gamma-ray lasers that fry anything and everything that might be hostile.

Even with the most advanced technology we can imagine, you can't expect to be able to detect a neighboring civilization, cross the gap between stars with an invading fleet, and arrive with enough power to overwhelm defenses every single time. Local development of solar system resources is inherently an exponential process, whereas mustering of interstellar resources is quadratic. A potential dark forest / wolf entity (I much prefer Alastair Reynolds over Liu Cixin) would have to arrive right within the (cosmically brief) window of opportunity in which a developing civilization announces its presence but before it achieves Type II status on the Kardashev scale. Statistically, someone will eventually be lucky enough to avoid the wolves long enough to get that far, and then they'd have the capability to defend themselves from any plausible enemy.

Where are the Dyson spheres of those civilizations?

The authors referenced at the above link don't use that seemingly unwarranted tone of certainty. I can't see anything in Omohundro's papers of anything like the same flavour, and Bostrom's conclusion is the sensible-sounding

It should be emphasized that the existence of convergent instrumental reasons, even if they apply to and are recognized by a particular agent, does not imply that the agent’s behavior is easily predictable. An agent might well think of ways of pursuing the relevant instrumental values that do not readily occur to us. This is especially true for a superintelligence, which could devise extremely clever but counterintuitive plans to realize its goals, possibly even exploiting as-yet undiscovered physical phenomena. What is predictable is that the convergent instrumental values would be pursued and used to realize the agent’s final goals, not the specific actions that the agent would take to achieve this.

I’m not what you’re picking up on other than academic prose. The very quote you give is very certain that convergent intermediate goals would be pursued.

Especially when the Earth is getting effectively zero of the sun's energy now, and humanity is so incapable of harnessing even that minuscule amount, that killing off their entire planet is still a much talked about possibility.

Some proportion of civilizations would develop to the point that their signals are detectable to us (this is a parameter in the Drake equation). Since we haven't detected anyone, there must be some problem in reaching that point.

Unless:

1) The Drake Equation is wrong and its difficult to detect advanced civilizations.

2) We have detected other civilizations but we haven't recognized their signals properly.

3) We have detected other civilizations and the government is concealing it from us.

4) The UFO footage released recently by the Pentagon is proof of detection.

IANAA, but I have always wondered if dark matter / energy is an explanation for 2)

Our planetary system (formed 4.5B years ago) is comparatively late to the game. The waves from older civilizations should have been everywhere by now. If they were expansionist, they should have even collonised the whole Galaxy long ago.

If I remember the argument by Bostrom correctly, finding life would increase the probability that one or possibly a number of great filters are further up in the evolutionary development of life, as a corollary this would mean a higher likelihood that such filters still lie ahead of us.

Bostroms original article was about how finding intelligent life would be concerning. He even goes into detail about how a great filter could be somewhere in the evolutionary steps between simple life to complex, intelligent, civilization-building life.

My point is that the "omg great filter confirmed" is a bit premature, and is a misunderstanding of the argument.

EDIT: Re-reading your comment, maybe this isn't contradictory to your point. Finding out that there is an abundance of life does indeed eliminate at least one major candidate great filter. I'm not sure that would somehow move the odds of a real one being ahead of us though.

It's not about intelligent life per se; rather the more advanced life we find, the more concerning for the future it would be, as the likelihood of a great filter being located ahead of us increases, precisely because we haven't been able to detect more advanced life forms than us. Another interesting consideration is the Dark Forest, of course.

I dug out the section in Bostrom's paper:

"What has all this got to do with finding life on Mars? Consider the implications of discovering that life had evolved independently on Mars (or some other planet in our solar system). That discovery would suggest that the emergence of life is not a very improbable event. If it happened independently twice here in our own back yard, it must surely have happened millions times across the galaxy. This would mean that the Great Filter is less likely to occur in the early life of planets and is therefore more likely still to come.

If we discovered some very simple life forms on Mars in its soil or under the ice at the polar caps, it would show that the Great Filter must exist somewhere after that period in evolution. This would be disturbing, but we might still hope that the Great Filter was located in our past. If we discovered a more advanced life‐form, such as some kind of multi‐cellular organism, that would eliminate a much larger stretch of potential locations where the Great Filter could be. The effect would be to shift the probability more strongly to the hypothesis that the Great Filter is ahead of us, not behind us. And if we discovered the fossils of some very complex life form, such as of some vertebrate‐like creature, we would have to conclude that the probability is very great that the bulk of the Great Filter is ahead of us. Such a discovery would be a crushing blow. It would be by far the worst news ever printed on a newspaper cover."

Thank you for digging that up! It makes a lot of sense, Nick is a wise man. I still feel like it's incredibly hard to quantify just how much a difference a discovery like this (if it indeed turns out to be microbial life) would make.

It took evolution on earth four billion years to result in a single civilization-capable species. The potential of filters along the way seem incomprehensible. And four billion years is a meaningful timespan even in astronomical terms.

And the intelligence part is also like an elephant in the room. Even given vertebrate creatures with nervous systems, we've had those for hundreds of millions of years. The secret sauce for advanced civilization is still only possessed by a single species, and not even it understands how it happened. How do you map a transition like that on a linear timeline of filters?

There are many candidates for the Great Filter, in fact what you are proposing (it's unlikely to evolve civilization-level intelligence) is one of them.

So you are saying, we are special for real? :)

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