Some thoughts on the Fermi paradox

[Richard W]

I demur. I think a plague of Belters is entirely possible. Planets, though, will be dead-end gravity wells that you don't want to get trapped on.

[rotting bones]

zompist: I agree with your point about the age of the universe. I disagree with your point that older civilizations are either wiser or command more respect. Pre-spacefaring civilizations were just as prone to collapse as we are. The Chinese developed the most sustainable of the ancient civilizations, and Europeans did the exact opposite of learning from the Chinese and following their customs. (e.g. https://en.wikipedia.org/wiki/Boxer_Rebellion#Aftermath)

Really, the only people the Chinese managed to convince were the Koreans, a tiny tributary state, and the Vietnamese, who were under Chinese rule on and off for a thousand years. Japan was considerably Sinified, but I've read Christian writers whose attitudes were closer to Chinese tradition than, say, the author of Hagakure. Tibeto-Burman peoples developed wholly different paths instead of following China's lead.

Also, I don't know if dolphin vocal apparatus has any bearing on their potential as theoretical physicists.

PS. I watched the opening of Star Trek: Enterprise when people were discussing it in Ephemera. Any thoughts on how humans interacted with the Vulcans as a prediction of our interactions with older galactic civilizations?

[linguistcat]

humans, dolphins, elephants and some bird species are all arguably sapient, and dolphins may be more intelligent than we are since they can mimic our languages but we can't mimic theirs. We got lucky in that we evolved both high intelligence and a body type suitable for handling tools. It may well be, in fact, that it's harder to evolve hands than to evolve high intelligence. but elephants can grasp tools with their trunks, so it's possible that any animal that evolves intelligence will at least do what it can with the anatomy it has. dolphins are out of luck since they live in the worst possible environment for any species that wants to modify its environment. ...

I'd like to point out that even dolphins use tools. Very simply tools like using sponges as nose guards, but still tools. So I think we can at least suggest that any intelligent species (in the way we would recognize) will develop tool use, even in aquatic environments or others that hinder making and/or using tools.

[Moose-tache]

The Chinese developed the most sustainable of the ancient civilizations, and Europeans did the exact opposite of learning from the Chinese and following their customs.

I think things might have gone differently if the Han Chinese had teleporters and ray guns while the Celts were painting themselves blue and riding chariots. The gap between civilizations millions of years apart in development is bound to be greater than the gap between any agricultural societies on Earth.

I'm inclined to agree with Zompist's assumption that places like Earth might be deliberately avoided. Not because aliens are space-hippies, but because it may be a more valuable resource if left undisturbed. If aliens who have met all their material needs find an inhabited planet, surely the greatest treasure it can offer is informational. Earth's value as a data point would be compromised if it were colonized.

[zompist]

zompist: I agree with your point about the age of the universe. I disagree with your point that older civilizations are either wiser or command more respect. Pre-spacefaring civilizations were just as prone to collapse as we are. The Chinese developed the most sustainable of the ancient civilizations, and Europeans did the exact opposite of learning from the Chinese and following their customs.

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.

The logic isn't airtight, of course. Maybe civs stagnate for millions of years. Or maybe they have no reason to care about newcomers.

[zompist]

On dolphins: Larry Niven wrote some stories about the dolphins being "Handicapped", and humans very nicely give them mechanical arms.

But Niven was pretty clueless about biology. I think most biologists would consider that a poor way to think about dolphins-- as some kind of failed primate.

[Raphael]

Obligatory Onion piece:

https://www.theonion.com/dolphins-evolv ... 1819565718

[rotting bones]

Moose-tache: I agree that a spacefaring civilization that can get to us probably wouldn't be interested in our resources. They can probably spin anything they need from star dust.

I disagree that newer civilizations couldn't possibly develop stronger weapons than older ones. The strength of your weapons depends on how much you're willing (and able) to invest in their development.

PS. Regarding the first point, I don't think people are complaining that aliens aren't here yet. The main problem is that we don't see gigantic artificial structures anywhere in the universe. (Edit: Also, there are no transmissions.)

[dɮ the phoneme]

PS. Regarding the first point, I don't think people are complaining that aliens aren't here yet. The main problem is that we don't see gigantic artificial structures anywhere in the universe. (Edit: Also, there are no transmissions.)

Yes, I think people are putting undue focus on alien "conquest" of Earth and such, when that's really not the question at hand. There are all kinds of reasons a spacefaring alien species, even if they had the capability, might not attempt to "conquer" Earth --maybe Earth doesn't have anything they need or want, or maybe it isn't worth the effort, or maybe they're so biologically different from us that the human concept of "conquest" isn't applicable. It's easy to think up hundreds of eminently plausible reasons why we're not subjects of the galactic empire or whatever, so I don't see it in need of very much explaining.

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. If human-like intelligent life is at all common in the universe, it should show up pretty clearly in our radio telescopes. The lack of visible large-scale structures like Dyson spheres is another problem, though I see it as less so: the technological barrier to entry is higher and we don't even really know if such structures are feasible in practice.

My favored explanation is twofold:

1) We're just not looking hard enough. There are a lot of frequencies to check and the sky is very large. Maybe we're getting 24/7 alien TV but we haven't noticed cause it's coming in from directly above the south pole on some obscure frequency band nobody's checking.

2) Notice that I said "human-like" intelligent life. If 90% of the life in the universe is some form of self-replicating plasma crystal, then they may not use a form of communication that we're even on the lookout for at all.

[rotting bones]

Apart from the relatively young age of the universe, remember that the farther we look, the more we gaze into the past. The same goes for radio transmissions.

If high tech aliens want resources, I think it would be more profitable to mine stars and asteroids than conquer inhabited planets. If you want a little dirt, why go out of your way to dig up an anthill? Now, if the aliens wanted a whole block of solar systems, and ours just happened to be one of them, that would be a different matter.

[rotting bones]

2) Notice that I said "human-like" intelligent life. If 90% of the life in the universe is some form of self-replicating plasma crystal, then they may not use a form of communication that we're even on the lookout for at all.

I would be more worried about false positives than false negatives. The method we use to analyze the artificiality of radio signals is based on entropy. Apparently, there is a physically reductive definition of what "order" signifies. There is no reason to think that would change for other forms of life. The worries come from the other direction. We once thought pulsar transmissions were from aliens. The presence of order is not sufficient to infer life.

1) We're just not looking hard enough. There are a lot of frequencies to check and the sky is very large. Maybe we're getting 24/7 alien TV but we haven't noticed cause it's coming in from directly above the south pole on some obscure frequency band nobody's checking.

Our data comes from space telescopes. Do you know specifics about what directions they are pointed at?

[dɮ the phoneme]

Our data comes from space telescopes. Do you know specifics about what directions they are pointed at?

All I know is that, both in radio and optical astronomy, the northern hemisphere is significantly better surveyed than the southern hemisphere. This is partly for practical reasons (most of the southern hemisphere is water, where it's hard to build telescopes), and partly for political reasons. Large portions of the sky are not well studied.

[rotting bones]

All I know is that, both in radio and optical astronomy, the northern hemisphere is significantly better surveyed than the southern hemisphere. This is partly for practical reasons (most of the southern hemisphere is water, where it's hard to build telescopes), and partly for political reasons. Large portions of the sky are not well studied.

Looks like there are radio telescopes in Antarctica: https://en.wikipedia.org/wiki/List_of_r ... Antarctica

This page confirms that radio waves can penetrate the atmosphere without interference: https://imagine.gsfc.nasa.gov/science/t ... ries1.html

But I still haven't found which directions space telescopes are pointed at.

PS. Well, here's some of the data from Hubble anyway: http://hla.stsci.edu/hla_faq.html#HLSP I'm not going to go through it right now.

[zompist]

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.

[rotting bones]

2. My understanding is that transmissions from Earth would be very hard to detect past a few light years.

15 light years for current technology and 250 light years for proposed technology in 1979. Source: https://history.nasa.gov/CP-2156/ch5.4.htm

We now have space-based radio interferometry. The first dedicated radio observatory was sent to space in 1997.

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.

That's because our world closes in on itself more and more like an IC chip. If a civilization has more moving parts, I would expect it to send the more general broadcasts. The more volume it occupies, the higher I would expect their intensities to be.

[Richard W]

Two-way interstellar communication will have to by FTL courier, or just conceivably by quantum entanglement as a single link. (I get confused as to whether that entanglement could work.) If there were anything like Star Trek's subspace communications, we don't know how to detect it.

[Ares Land]

Re: Dyson spheres

The search for Dyson spheres is fairly recent: most Google hits will bring up papers from the last two years.

A paper of interest here: https://www.essoar.org/doi/abs/10.1002/ ... 10503901.1
The full search will include 10^7 - 10^8 objects. Although there 2 to 4x10^11 stars in the Milky Way, so as they say, it's still peanuts compared to the infity of space.

That being said... while the Dyson sphere is a fun thought experiment, but it's not terribly clear why anyone would need one.

Re: radio waves.
If civilizations tend to switch to fiber optic and WiFi like we do, that meansThat's a pretty short window. That's a pretty short window. we need to catch their emissions in a crucial window of a century or two. Given that sentient species could have evolved at pretty much any time in the past billion years or two (and that's conservative)... it's a lot, lot worse than finding a needle in a haystack.

[Ares Land]

Two-way interstellar communication will have to by FTL courier, or just conceivably by quantum entanglement as a single link. (I get confused as to whether that entanglement could work.) If there were anything like Star Trek's subspace communications, we don't know how to detect it.

Apparently, nope, quantum entanglement wouldn't work. (For complex reasons that honestly I can't remember, it can't be used to transmit information.)

Though of course your general point still stands. It's entirely possible that advanced telecommunication relies on something we can't detect.

[rotting bones]

The problem with fiber optic is that you know in advance who the recipient will be. In a rapidly expanding civilization, that is not always possible.

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

FTL and subspace don't exist as far as we know. I don't even know what subspace is supposed to be. Quantum entanglement ensures the coordinated measurement of two particles separated by arbitrary distances, but the specific state measured is still random, so it can't be used to send a message.

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.

[Ares Land]

The problem with fiber optic is that you know in advance who the recipient will be. In a rapidly expanding civilization, that is not always possible.

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.
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.)

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

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

FTL and subspace don't exist as far as we know. I don't even know what subspace is supposed to be. Quantum entanglement ensures the coordinated measurement of two particles separated by arbitrary distances, but the specific state measured is still random, so it can't be used to send a message.

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!)