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Comment by mithametacs | Hacker News Reader

Building something that isn't Turing-complete is surprisingly-hard once it's complex enough.

If basal intelligence is present in diverse computational structures, then weak intelligence is everywhere.

If weak intelligence is everywhere, Earth-like planets are everywhere, ... where are the aliens?

Personally, I blame game theory. Too many agents too smart in one place, you get conflicts, and eventually someone breaks an atom apart in your direction.

Or do you need emotions to have conflict? Are there basal emotions?

I'm usually not worried about AI uprisings, but I do believe in the possibility of conflict.

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>Building something that isn't Turing-complete is surprisingly-hard once it's complex enough

The most basic computational device that is studied is the (deterministic) finite automaton, which corresponds to regular languages (regex, although actual implementations are usually way more powerful). If you add a stack (to count parenthesis basically) you have context-free (CF) languages, which correspond to the syntax of most programming languages. Add a second stack and you're already Turing-complete (TC).

If you know that, you can add any extra-power to your machine that is strictly less than a second unbounded stack, and you get a new language class! For a example, a second n-bounded stack. If you do so you will easily get an infinity of language classes. The point is, are they interesting? In particular, the language classes we focus on have some good properties that most arbitrary classes tend to lack.

The Chomsky hierarchy has context-sensitive languages in between CF and TC, but it is already not a very natural class so I've never seen it discussed anywhere, even in complexity theory research --which focuses a lot more in getting links to computability theory or subtle distinctions between deterministic and non-deterministic classes (most famously P vs NP). For the latter, studying analogs of the complexity classes on restricted models of computations is an interesting approach since Turing machines are difficult to work with.

In natural language processing, mildly context-sensitive languages (which sit between context-free and context-sensitive) have seen some study and use, because context-free languages fall short to model certain phenomena but context-sensitive are overkill (and not even polynomial to process).

> If weak intelligence is everywhere, Earth-like planets are everywhere, ... where are the aliens?

A species needs more than raw intelligence to create technology. They also need:

1. Dexterity: dolphins and ravens are intelligent, but they have no fine motor manipulators, so there is no way to build technology.

2. Reasonably high bandwidth communication: other primates are intelligent, social and dextrous, but don't have sophisticated language for precise and expansive communication.

3. Social inclinations leading to building cultural knowledge across generations: octopuses are intelligent, are reasonably dextrous, and their colour changing ability could possibly be used for reasonably moderate bandwidth communication, but they are largely solitary creatures.

There are probably even a couple more.

Edit: come to think of it, I think a species that builds technology would need to have all of the above features and feature some distinct physical disadvantages in order to drive them towards compensating by developing tools and knowledge to survive. For instance, humans are physically quite weak compared to other primates.

Can't make fire under water either.

Sure you can, it's just harder.

They potentially have access to hydrothermal vents for energy though.

Sodium metal has entered the chat (Potassium and loads of other materials were too busy playing call of duty to be bothered)

????

All species are full of technologies, one more exotic than the next. We have a hard time replicating it and we don't understand how it all works.

What we have is an insanely fast research, design and construction process.

But nothing as simple as a competitive pump on the horizon. Trees be laughing at us.

> If weak intelligence is everywhere, Earth-like planets are everywhere, ... where are the aliens?

Most certainly outside of our light cone.

It took 4 billion years for this planet to produce intelligent life that can send out radio signals. If we were to wipe ourselves out, it would be another half a billion years for another intelligent species to appear on this planet (probably? - using Cambrian explosion as a benchmark FWIW).

We've been emitting radio signals for a century so far, and mayyyyybe we'll last another 1000 years before we blow ourselves up? This is something we can only conjecture about at this point.

But just for the sake of argument, let's say that a post-radio-emissions intelligent species lasts 10,000 years. This means that our light cone must match up to a 10,000 year period in a planet's 4b year history (or 500m year repeat) TODAY, in order for us to detect anything at all. The chances of that are vanishingly small. And they're certainly not going to visit us a mere 100 years after we began emitting detectable signals.

It's not just a problem of space; it's a problem of time (and timing).

Why isn't at least one species expanding across the cosmos though? The light speed limit isn't really much of a hurdle for cosmic timescales.

The guy on cool worlds YouTube channel (Department of Astronomy, Colombia) has argued that we're still in the early days. The conditions for intelligent life in the galaxy hasn't been around for that long.

Perhaps there is, but once again it would have to be visible from our light cone in order for us to even be capable of detecting it. Even with a civilization of 100,000 or even a million years that's still tiny and highly unlikely to happen within a timeframe that intersects with our small window of awareness.

And even if these aliens have cracked FTL travel, who's ever going to find our little planet on the ass end of some mediocre galaxy, with an EM emissions bubble that has only covered 100 light years so far? Needle in a haystack.

Hmm, let's say there's 100 billion stars in our galaxy and one billion habitable planets. Assuming we are average, half, or 500 million have civilizations older than ours. We could assume some sort of distribution where we could say 10% are older than a million years. So 50 million civilizations older than a million years in the milky way. In a million years moving at 0.1c you move 100,000 light years, or across the whole galaxy.

They could have been here already before modern humans even existed.

Seeing how it took earth 4 billion years to figure out how to get inhabitants to set foot on another stellar body the rise of intelligence may be the unlikely event here.

Perhaps it's much more likely to have happened elsewhere in the galaxy 4 more billion years from now. If I remember correctly, stars with our particular properties haven't been around for too long.

I recommend looking into cool worlds lab since you seem to like inferring from the numbers.

We've set foot on only 1 other stellar body.

Luna is sort of made from the Earth. And it's so close that Earth has a stronger pull on it than Sun.

So we have set foot on another stellar body, sure. But we also... kind of haven't.

And then we had to retreat from it anyway. Homo sapiens, hunter champions, arrived at an uninhabited body and were outmatched.

Way to go, smartest species we know of. You've done jack shit.

Maybe interstellar colonization is just never gonna be worth it?

We could already colonize Antarctica, or the sea-- those are easier to reach, supply and colonize than other planets, but we are not trying.

Most of our past exploration/settling efforts happened because there was some gain to be had; it seems quite plausible (if somewhat bleak) to me that interstellar travel could just remain pointlessly expensive regardless of technological progress.

> We could already colonize Antarctica, or the sea-- those are easier to reach, supply and colonize than other planets, but we are not trying.

On the other hand - we were and still are present on the Antarctica, have a permanent base on the South Pole etc.

It may simply not be worth it. Outside of sheer curiosity, there are two reasons I can think of to leave your own solar system. One is overcoming resource scarcity. But interstellar space is extremely hostile to anything that isn't a cloud of dust and there are no resources available for thousands if not millions of years. If you've developed technology already to overcome the need for resources and are hardened to endure conditions for that span of time, you may overcome the resource limits of your own solar system anyway.

The second reason is to escape the death of your own sun. That takes long enough that far fewer lifeforms would be expected to even face that challenge compared to resource scarcity. If you manage to sustain a high-level civilization that can overcome resource scarcity and conquer the challenges of interstellar travel for the billions of years it takes a star to die, maybe you can simply prevent that death by technological means we could not possibly foresee or understand?

Those are hand-wavy answers, but this is sort of the problem. We're imagining near god-like beings here and asking why they don't behave the way humans have historically behaved with respect to exploring and colonizing remote parts of our own planet. The analogy breaks down at some point and we have no idea what beings capable of that kind of thing would even want to do.

Even our best sci-fi imagines answers that are pulled out of imaginary asses but frankly no less plausible than anything else anyone here will come up with. The builders of the expanse series expanded to a few hundred systems but then simply didn't need to expand any further. They figured out how to stop fusion and star-aging and tapped into energy sources from other universes (then got killed off anyway, but seemingly would not have kept expanding). The monolith aliens of the space odyssey series evolved into a non-material form that was actually here the whole time but we had no means of detecting them.

In half a billion years our sun will start the end of its life cycle and boil away all oceans on earth. So life as we know it will end then. But intelligent life probably won't take so long to evolve again and we have several species today who have enormous potential if they only manage to evolve usage of tools somehow. We are where we are today to a large part because of our prehensile extremities.

I think you might be off by an order of magnitude. The sun is expected to begin the death process (and therefore swell into a red giant) in 5 billion years, not 500 million years.

> using Cambrian explosion as a benchmark

I think that's wrong. And thinking of it like that provides another possibility:

The dinosaur era was a local maximum that couldn't develop human-like intelligence and technology. Then around 65 million years ago, Earth got "reset" and broke us out of the local maximum. Only after that did life have a chance to develop in a different direction and end up as us.

Seems at least possible to me that life is quite abundant, but local maximums that can't develop intelligence/technology might be more common than we think and it's easy to get stuck there. Earth just got lucky.

Extending your logic (which is convincing), we, too, could be a local maximum and a form that is relatively low on the “cosmic intelligence scale”, if there is such a thing and if it is linear-ish.

Conversely, it can be amazingly rare to break out of these local maxima.

For instance, it took 60 million years from the first trees until the appearance of the right fungi able to decompose the lignin in wood. (Coal deposits arose because trees from the Carboniferous Period had nothing to make them rot). If you think about it, that's a very long time for a very small amount of evolution.

Equally, as I understand it, all life on Earth has a common ancestor, and therefore a single origin. So life only started here once. And therefore is exceedingly rare.

>where are the aliens?

It's probably a Plato's Cave situation. You're chained there, staring at flickering shadows on the wall asking, "Where are the aliens?".

Which is to say, the dimension that must be traversed in order to meet the aliens is an invisible one.

Are you wondering why Conway’s Game of Life or the C++ type system isn’t trying to communicate with us from beyond the stars?

Beyond the stars, a static void. Ions, but no aliens.

Till one day SETI finds a 5k line template compilation error!

Rejoice! We are not alone! Aliens have to deal with C++ too!

Where is it written that intelligent beings must create the means for interstellar communication, or any technology at all?

Imagine a planet with highly intelligent whales who have no way to manipulate their environment (hands) and no need to.

Every organism manipulates their environment in some way. The ones that can manipulate it in a way that allows them access to more resources than the others will out compete the ones who don't.

Still hard to smelt metal if you live in the ocean.

That's why genetic mutations happened and they grew hands and started smelting on land.

This happened.

Evolution doesn't really work like that. It's just a low bar that everything has to cross from time to time. Being a specialist, very advanced hunter is in no ways better than a dumb jellyfish that spawns billions of offsprings.

Experience on earth that they eventually evolve hands.

That's because there's land here, but what about a planet with only water, or just not enough land.

But maybe water-surface-only (no land surface) is unlikely

There would still be enough earth like planets with land.

Why would water prevent the evolution of hands? Lots of sea creatures have claws.

The sea is also not all that different from an atmosphere with a higher density in principle, we live "under-air".

Looking at this planet, it's less likely to happen.

Maybe high density (water) makes tools less useful, and thus hands less useful,

since you cannot move a tool particularly fast under water, compared to on land.

I suppose you've tried throwing a stone underwater -- compare with throwing on land.

From this seems to follow, that creatures with human like intelligence, are less likely to appear, if the density of the liquid or gas surrounding them, is too high. (Dolphins are bright but not that bright.)

That is incorrect, dolphins are unlikely to evolve hands and humanoids evolved hands before they became intelligent (probably to grab branches). It was very lucky that a good brain evolved in a body that already had hands.

> very lucky that a good brain evolved in a body that already had hands.

The other way around: hands adds evolutionary pressure towards becoming more intelligent. (The ones that understand how to use their hands and tools better...)

The lack of knowledge.

Dolphins do have organs with which they pick up things like rocks or shells and they are able to give them to each other.

They use their sexual organs as "hands"! Both males and females.

In the tree of life brains are correlated much more strongly with locomotion than with hands. The moment you need to do (inverse) kinematics to plan an immediate action, and to plan sequences of motions, and to plan a hunting or fleeing strategy, is what put pressure to evolve brains, static lifeforms can be very complex and have complicated genomes, but brains you wont find in them...

If elephants were carnivores, with their trunks, they would have evolved efficient methods to hunt, and would probably be the dominant species on the earth landmass surface.

All this without hands.

The fact that they are vegetarian gave us the chance to do that evolution ourselves.

> If weak intelligence is everywhere, Earth-like planets are everywhere, ... where are the aliens?

Someone has to be first (in our speed-of-causality bubble), maybe it's us?

Doesn't that seem even less likely? Not only do we exist but we're the first?

No, it actually seems to be the most likely explanation. The universe is so young yet. It's just a cosmic blip of time since the current generation of stars has began forming.

Not without more information.

We don't know how long it takes to evolve our level and kind of intelligence, nor if intelligence like ours implies successful expansion such that it could eventually be noticed from the kinds of distances we can sense with our tech, nor how fast it would actually expand.

If the first in any light cone dominates that light cone, expanding at a high fraction of c, then almost everyone starts off thinking they're the first.

We may be the first in our own light cone, and that light cone may be just about to start intersecting with that of a galaxy where every star has been completely Dyson'd by a Kardeshev 3 civilisation.

If the civilisation is two million years older than us, that galaxy could even be the Andromeda galaxy.

> Or do you need emotions to have conflict?

Microbes and insects have massive conflicts.

emotions are just a form of intelligence that's calcified over evolutionary time. each one of our emotions can be linked with survival and/or reproduction.

The Fermi paradox can be answered in so many ways, and is tied to questions like what is the purpose of life and the universe.

Beyond the existence of a single person (such as myself, or you) what do we exist to do?

Is it to learn the universe? (Curiosity) Is it to decrease entropy locally in order to increase it globally? (Spend energy) Is it to increase complexity? (Do interesting things, foster maximum diversity?)

For example, if the purpose is indeed curiosity, maybe all we will need is one Dyson sphere in order to understand the universe. We could have a dozen super intelligent life forms in our galaxy alone and probably wouldn't notice them. Basically would just look like a quiet black hole the size of a star.

In my opinion, life is just self-replicating tumbleweeds of matter that drift towards local spaces with high energy. The ideal "shape" of these tumbleweeds is gradually approximated via the algorithm of evolution, filtering out the tumbleweeds that fly too close to the sun and so on. Intelligence becomes an emergent property of these optimal shapes, but intelligence doesn't change the outcome, broadly speaking, they still drift towards local spaces with high energy.

Individual organisms will live their life perusing energy, with every breath, with every meal. Even super organisms, such as a nation, will (attempt to) peruse energy in the form of a thriving economy, which influences the energy allocation of the organisms that make it up.

Even absent these tumbleweeds, high density matter (high energy) will literally bend space, and attract other matter to itself through gravitational force. It's entirely different than what I've already discussed, yet intuitively similar?

How does this apply to the fermi paradox? Maybe the idea that the algorithm of evolution will eventually lead to life self-propagating across the universe is flawed. Maybe the spirit of exploration is not universal. Maybe the the simple fact that interstellar travel and communication is energy inefficient is enough to explain the aggregate effect we are seeing?

it sounds like your take is the entropy one, but with a caveat that dark energy prevents Indefinite growth.

I find the most interesting possibility: - life finds a way - life gets too smart - life kills itself - life finds a way

I thought Dyson sphere will emit enormous radiation anyway? Like how do you convert photons into electricity and use that electricity afterwards with 100% efficiency? Is it even theoretically possible? There should be lots of heat emitted as infrared light.

Hard to fathom what engineering a civilization like that might be capable of, maybe it would emit extremely hard to detect radio noise.

A dyson swarm is nothing difficult to achieve. All you need is the ability to put satellite into orbit. That's the minimum. The other part is mass manufacturing them.

How much energy and material is needed to manufacture, launch, position, maintain, and then leverage a Dyson swarm?

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