Some thoughts on the Fermi paradox

[rotting bones]

Uh? This post is being sent by fiber optics and yet I can't be certain of who will read it! Or even when, and how.

The IP address registered at verduria.org will receive it, of course. Then the server will send it to clients who request it.

I don't quite see what a rapidly expanding civilization would have to do with it. (Running a fiber optics cable is simple. Assuming we're colonizing Mars or something, setting up a focused communications laser to Earth is a trivial problem compared to the task of actually living there.)

I'm imagining moving targets. Eg. You send an SOS to all shuttles in your vicinity. If the vicinity is larger, then the intensity of your signal must be greater to travel greater distances.

How do we know in advance there's someone with the proper equipment 24,000 light years away?

Within 24,000 light years.

The point is, scientific advances a million years from know are in the category of unknown unknowns. We just don't know what means of communication would be theoretically available.
(Ah, yes, that's the catch with quantum entanglement. Thanks!)

PS. Interesting coordination is still possible with entangled particles. Eg. You can decide in advance that if the spin of both particles are up, both parties will go left. Otherwise, they'll go right. Andy Weir has a short story where a casino installs its first quantum computer. The computer salesman's wife advises him to entangle a qubit in advance so they can measure it and know what the lottery number will be.

PS. One control qubit or all the lottery number qubits. I don't remember. Probably the second one.

[Richard W]

If we're sending signals on purpose, we could expect them to be received 24,000 light years away by the year 2000.

Do you mean by 26000?

[rotting bones]

Don't know. Google turns up this paper: http://citeseerx.ist.psu.edu/viewdoc/do ... 1&type=pdf

It says:

As a closing thought, in 1977 a high power, directional signal was sent from the Arecibo observatory towards the globular cluster M13. If technologically advanced beings onone of the 300,000 stars in that cluster happens to be listening towards the direction of Earth at the exact time that the message arrives with an instrument of adequate size andsensitivity, then we could expect a reply as early as 50,000 AD given that the cluster is at a distance of 24,000 light years. Why target such a distant group of stars? First,because it is distant, all stars in the cluster will lie along the narrow beam path. Second, because it is so far away, it is unlikely that any Independence Day-like aliens will arriveon Earth anytime soon as a result of the transmission. Selfishly, it would appear that humanity expects everyone else to do all the talking; for now, we'll just listen.

Although the signal was sent in 1977, the paper is dated to the year 2000. It could be what I'm thinking of.

[Ares Land]

I'm imagining moving targets. Eg. You send an SOS to all shuttles in your vicinity. If the vicinity is larger, then the intensity of your signal must be greater to travel greater distances.

Oh, OK! But you can do that with a fairly low intensity these days, I think. And it's most likely to be exceptional in nature, and so dismissed as random noise. It's not terribly useful to broadcast a SOS that can be heard halfway across the solar system, whoever hears you is most certainly unable to change course to meet you.
If you need regular communication with ground control a focused signal is a better use of energy, I think.

By the way, I'm pretty sure we could pick up something with our SETI programs. But the fact that we haven't found any doesn't really call out for special explanation, I think.

It'd be interesting to recheck the Drake equation once we get better at detecting rocky exoplanets and have better models of planetary formation. If you could get a better idea of how many planets in the habitable zone to expect in SETI's hearing range, we'd have a better idea of whether it's weird or not not to hear anything.

[rotting bones]

Oh, OK! But you can do that with a fairly low intensity these days, I think. And it's most likely to be exceptional in nature, and so dismissed as random noise. It's not terribly useful to broadcast a SOS that can be heard halfway across the solar system, whoever hears you is most certainly unable to change course to meet you.

For a civilization that spans a significant portion of a galaxy?

If you need regular communication with ground control a focused signal is a better use of energy, I think.

What if new colonies are always popping up and you are broadcasting instructions, news and entertainment to them?

It'd be interesting to recheck the Drake equation once we get better at detecting rocky exoplanets and have better models of planetary formation. If you could get a better idea of how many planets in the habitable zone to expect in SETI's hearing range, we'd have a better idea of whether it's weird or not not to hear anything.

Yes, and we're still extrapolating from one data point. We should really drill under icy moons to see if there is chemosynthetic life in the water.

PS. To give an example for the first point, I'm imagining a biosphere failing very slowly, so it transmits an SOS. The decentralized network makes a decision to send materials to the habitat, etc.

[zompist]

What if new colonies are always popping up and you are broadcasting instructions, news and entertainment to them?

As technologies mature, they usually get more efficient. And broadcasting is very inefficient!

Mostly from Stross, I get the idea that the cool actually-possible communications tech is a comm laser: intensely high power, but directed very narrowly. Even a widespread interstellar civ would probably save loads of energy by just beaming messages to individual stars, not the whole sky.

Even for your SOS call, it would seem smarter to narrowcast to a known point than just broadcast in all directions.

[rotting bones]

If you know who the closest node is, then narrow beams would be the most efficient. However, note that models for studying distributed algorithms assume that each node communicates with all neighboring nodes. This may sound inefficient, but remember two points: 1. Random radio leakage from earth can be detected from a distance of 250 light years using technology proposed in 1979. We're not even a Type I civilization yet. 2. We're talking about the power output of a Type II civilization here. What makes you think broadcasting is a big deal to these people?

PS. Maybe I'm not being clear why I think the nodes do not know the location of the closest node in the network. I'm assuming the light speed limit holds, and the civilization is creeping across the galaxy anyway using a distributed planning mechanism: https://en.wikipedia.org/wiki/Distributed_algorithm However, if the light speed barrier has been broken, then all terrestrial analogies apply, and directed beams are a good idea.

[kodé]

I think the timing bit mentioned on the first page (I think by zompist) is really the biggest part here. If there are other sapient civilizations in our (relative) vicinity, it’s unlikely that they have less than tens of millions of years on us. Hundreds of millions of years is likely.

We’ve only been around as a species for a hundred THOUSAND years, give or take. The technological differences between now and 100kya are staggering. Hell, the technological differences between now and 1kya are staggering!

Even if increase in technological prowess slows to a relative crawl, if human civilization is still around in another hundred thousand years and hasn’t sent itself back into a permanent Stone Age, the technology of our progeny will be unimaginable. Multiply this by 100 or 1000 and there’s zero chance we could fathom such technology—again, even at a relative crawl.

A sapient civilization tens of millions of years our senior would be unimaginable to us. If they exist, and it is possible for one sapient civilization to see another, they already have. I think existence is pretty much guaranteed by how freakin HUGE the universe is: some podunk planet in some galaxy has birthed sapient civilization tens of hundreds of millions of years ago. The possibility of seeing or interacting is a bigger question, but if it’s possible, I think it’s been done. And, since such a senior sapient civilization (so many sibilants) would have unfathomable technology, then if they wanted us not to see them, we can’t.

I think the weakest part in my argument is technological advance… this could just be a thing of young sapient civilizations. However, even if a civilization reaches a plateau relatively early on, they’ll still be light years (ha, not sorry) ahead of our faintest dreams.

/ramble

[rotting bones]

OK, but on the scale we're talking about all these civs are the same in age. A civ that's lasted a million years is likely to be pretty fearsome.

Maybe, but when they give you advice, how can you be sure that they know better, and they're not just taking advantage of your gullibility?

kodé: I think you're confusing scientific research with technological development. Although it's unlikely that the light speed limit will be crossed, there is still a lot of scientific research to be done in fields like materials science. Technology is the application of scientific research to build practical solutions to our problems. We have so far applied only a fraction of the research that could make our lives better. Even if scientific research plateaus in many fields, one civilization can still greatly surpass another in the practical applications of science.

PS. Actually, both particles being spin up is not how entanglement works IIRC. If one is spin up, the other would be spin down.

PPS. Also, It's not that we have applied a fraction of the research so much as we have applied all of the research to only a fraction of the problems they could solve.

[KathTheDragon]

PS. Actually, both particles being spin up is not how entanglement works IIRC. If one is spin up, the other would be spin down.

Entanglement only correlates quantum states - it doesn't say anything about what those states must be. That depends on how the entanglement is set up. For any state you could measure, there is an entangled state where you can measure it.

[WeepingElf]

What is in need of explaining is why we don't see any obvious alien radio signals (or transmissions more generally). It really doesn't take that much technologic prowess, certainly not galactic empire level, to start emitting a continuous block of radio transmissions out into space in every direction. Humans have been doing it for a century by pure accident.

There's a few problems with this.

1. We tend to concentrate on whatever humans have been doing in the last century or two. Maybe broadcasting is just not a very common or long-lasting thing.
2. My understanding is that transmissions from Earth would be very hard to detect past a few light years.
3. I recall reading that we used to broadcast straight out into space a lot more than we do now. We use more directed radio sources now, or just enclose them in wires.

Indeed. Civilizations more advanced than us will be less noisy than we are, I think, because they have replaced broadcasting and radar by more efficient technologies which are harder to detect from interstellar distances. It is already beginning here and now.

I also think that the Kardashev scale ought to be tossed because it mistakes energy consumption for progress. It tells a lot that it is from the 1960s Soviet Union, which had the highest per-capita energy consumption ahead of even the US, and was proud of that. Of course, that was not because of prosperity, but because of an excessive predominance of heavy industry, especially armament industry, and of course obsolete inefficient technology which was also badly maintained, leading to excessive waste of energy and other resources.

An interesting book relevant to this discussion is Contact with Alien Civilizations by Michael Michaud, which points out many reasons why alien civilizations are probably harder to detect than commonly assumed.

[rotting bones]

Entanglement only correlates quantum states - it doesn't say anything about what those states must be. That depends on how the entanglement is set up. For any state you could measure, there is an entangled state where you can measure it.

If you're saying the measured state is an entangled state, that seems removed from the context of trying to use the entanglement to send a message. This is because we'd have already completed the measurement by the time the particles were in the required state, right? Normally, if the particles became entangled through interaction, wouldn't they end up in opposite states by conservation laws? On the other hand, it seems trivial to use quantum gates to entangle qubits so that they are in a superposition of states, but end up with the same value when measured. This is confusing to me. How exactly are these gates constructed?

Indeed. Civilizations more advanced than us will be less noisy than we are, I think, because they have replaced broadcasting and radar by more efficient technologies which are harder to detect from interstellar distances. It is already beginning here and now.

I also think that the Kardashev scale ought to be tossed because it mistakes energy consumption for progress. It tells a lot that it is from the 1960s Soviet Union, which had the highest per-capita energy consumption ahead of even the US, and was proud of that. Of course, that was not because of prosperity, but because of an excessive predominance of heavy industry, especially armament industry, and of course obsolete inefficient technology which was also badly maintained, leading to excessive waste of energy and other resources.

An interesting book relevant to this discussion is Contact with Alien Civilizations by Michael Michaud, which points out many reasons why alien civilizations are probably harder to detect than commonly assumed.

There is an alternative proposed to the Kardashev scale based on how close a species is to merging with its environment: https://arxiv.org/pdf/2005.13221.pdf 1. I'm using the Kardashev scale only as an indicator of power output, not as a scale of progress. As far as I'm concerned, the Type II civilization may well be a rogue AI that's turning the galaxy into paper clips. 2. I have given reasons to think that increased energy output is what will work in a decentralized Type II civilization without FTL. 3. Broadcasting messages won't inflict any additional damage to the civilization's "natural environment" other than noise pollution over radio frequencies. 4. I don't believe in the inevitability of progress. Whatever works in a given situation just works. 5. I don't believe that merging with your environment is an indicator of progress.

[Raphael]

An interesting book relevant to this discussion is Contact with Alien Civilizations by Michael Michaud, which points out many reasons why alien civilizations are probably harder to detect than commonly assumed.

Hm, sounds interesting. Perhaps I'll check it out.

[rotting bones]

Google to the rescue!

Regarding entanglement, we start with 2 qubits in |0>, apply the Hadamard transform to them: https://ieeexplore.ieee.org/document/5612120 and then apply CNOT to one qubit: https://arxiv.org/abs/1803.04105 controlled by the other.

So from what I understand, if you do nothing but entangle two identical particles, they end up in opposed states. But if you alter the waveform, you can change the relationship between their measurements.

Or maybe all this is my sleep deprivation talking.

[zompist]

PS. Interesting coordination is still possible with entangled particles. Eg. You can decide in advance that if the spin of both particles are up, both parties will go left. Otherwise, they'll go right.

This has been bugging me... How does this differ from rolling dice, writing the result on two pieces of paper, sealing them in two envelopes, and sending one in each spaceship?

(I don't mean "how does it differ in methodology"; I mean "how does it differ in results". What does quantum entanglement do that low-tech methods can't, in terms of coordinating behavior?)

[rotting bones]

This has been bugging me... How does this differ from rolling dice, writing the result on two pieces of paper, sealing them in two envelopes, and sending one in each spaceship?

(I don't mean "how does it differ in methodology"; I mean "how does it differ in results". What does quantum entanglement do that low-tech methods can't, in terms of coordinating behavior?)

Quantum information is subject to the no-cloning theorem. Until one particle is measured, the laws of nature guarantee that no force in the universe can decide whether both parties will go left or both parties will go right.

[Moose-tache]

"Captain Splashworth, we must call off the search."
"I can't believe it, Lieutenant McFlipper. They should be out there."
"We pointed our ear-holes in every direction. It's time to admit defeat."
"But maybe other intelligent life doesn't communicate in a series of low-frequency flicks? Or what if their clicking sounds can't be heard as far because they click in the air instead of water."
"Listen to yourself! Air instead of water? Non-clicking sounds? Face facts. If there were other dolphin-level intelligences in the universe, they would be immediately obvious from the loud 'ee-ee-eee' noises they make while doing back flips for tourists."
"I guess you're right, Lieutenant. We are truly alone."

I've always thought it was sad and pathetic that we think intelligent life is scarce because we can't watch the galactic equivalent of I Love Lucy by pointing our TV antennae at Alpha Centauri. Broadcasting is stupid, signals decay, and alien communication is likely to be hard to distinguish from noise the first time we hear it.

[rotting bones]

We know that dolphin communications are ordered. Researchers were working on it a few years ago. I can't remember the details, but they mentioned something about human and dolphin languages belonging to different classes in computational complexity theory, though the implications were unknown. Back then, their data wasn't available online.

And how else are species going to communicate other than by electromagnetic radiation (light, radio) or vibrations induced in the surrounding medium (sound, tremors)? Once you know the signal, it's either ordered or not. If it's ordered, it's generated by life or not.

PS. And yes, order is objective: https://en.wikipedia.org/wiki/Negentropy

PPS. Technically, I suppose they could also communicate by handing each other substances or objects. The point is, that would kill the range of that form of communication. Galactic civilizations are the kind of life we're looking for, not seed pods communicating by chemical cues.

[rotting bones]

And if you hate broadcast despite the reasons I have given, consider that human communication is also a form of broadcast. For that matter, so is communication by chemical cues. Would humans have been as effective if our medium of communication was more directed? Eg. What if we had to speak by bioluminescent flashes? I would say "like fireflies", but fireflies broadcast their signals within their range of interest too. If you think of it like that, you can easily see the problems with not knowing the angle of the node you want to speak to.

PS. Although I admit that human communication has both broadcasting and directed components.

[zompist]

This has been bugging me... How does this differ from rolling dice, writing the result on two pieces of paper, sealing them in two envelopes, and sending one in each spaceship?

(I don't mean "how does it differ in methodology"; I mean "how does it differ in results". What does quantum entanglement do that low-tech methods can't, in terms of coordinating behavior?)

Quantum information is subject to the no-cloning theorem. Until one particle is measured, the laws of nature guarantee that no force in the universe can decide whether both parties will go left or both parties will go right.

That doesn't answer the question. What does this allow you to do that the two envelopes can't?