[nirav72]

I've heard many people claim that it wouldn't be wise to respond to an alien signal. Why not? Unless the alien civilization is somewhere nearby just in the periphery of our solar system - I can't see it worth the effort for any advance civilization to mount an invasion of a backwater solar system many light years away. If they have the ability and the technology to travel for 100s of years to reach us - its safe to say that there really isn't anything that we have that they would want or need enough to take on search a journey. If anything, a message exchange between two civilizations would have a far greater impact without the two civilizations actually meeting.

[chatmasta]

We're in the center of a ~100 light year sphere of space that we've polluted with our radio waves, so it seems a safe bet that they'll hear us before we hear them. So by the time we get a message from aliens, they could already be on their way here.

[KineticLensman]

The assumption here is that humanity AND the aliens have reached similar points in the tech tree approximately simultaneously. This seems somewhat unlikely given the extreme age of the universe. We have only had tech capable of detecting aliens for less than 100 years (ish) which is peanuts compared with the age of the Earth (let alone the galaxy). A galaxy-spanning civilisation could have come and gone while our ancestors were still hiding from dinosaurs and we would have no way of knowing.

[chatmasta]

Isn't the assumption just that alien life has reached the ability to listen for signals before we reached the ability to send them (and that they're still alive)? Or even that they reached the ability to listen for them some time after we started sending them but before we started listening for them.

[KineticLensman]

Yes, but I am suggesting that the assumption is highly unlikely, given the low chances of two civilisations (ours and theirs) reaching this point simultaneously, given the massive age of the universe.

If the Earth's entire history up until now is reduced to a single day, then our technological civilisation has only existed for the last few seconds before midnight. It seems unlikely that the civilisation next door also coincidentally appeared in the same few seconds.

[euroderf]

Agreed. Some interstellar civs could've come & gone a zillion years ago. (Maybe "gone" in the sense of subliming in the Culture novels.) The chance of two such civs being still extent and still interested in hanging around seems small.

Doesn't do much for sci-fi tho.

[brap]

>We're in the center of a ~100 light year sphere of space that we've polluted with our radio waves, so it seems a safe bet that they'll hear us before we hear them.

I don't really see why this is a safe bet, whoever sent signals first is going to be heard by the other party first*, and we have no reason to assume that we were first.

* assuming there's nothing "magical" going on like FTL signals etc

[chatmasta]

Because we haven't been listening for signals as long as we've been sending them.

[brap]

This might also be true for them

[chatmasta]

True. I guess I'm assuming that given two intelligent civilizations, it's more likely they are more advanced than us. But of course I have no basis to assume that!

[brap]

I see why it’s easy to assume that, but there’s a symmetry, anything that we can say about them they can also say about us…

Personally I think our first encounter with aliens, if we ever have one, is going to be more similar to plants, bacteria, etc. It will be very underwhelming.

[flangola7]

>I can't see it worth the effort for any advance civilization to mount an invasion of a backwater solar system many light years away.

Because that backwater civilization goes from turning on the BBC transmitter for the first time to interstellar terminators in a cosmic eyeblink. If you're lucky and <100 light-years away you have just enough time to launch your own terminators first and take them out.

Our galaxy is 100,000 light-years across. If we were to detect signs of campfires, much less radio transmissions, almost anywhere in the Milky Way then there could already be a fleet of solar system consuming robots headed our way at 99% of lightspeed. They might have already completed most of the journey..

IMO one of the better arguments that we're alone in the universe (or very very far from the nearest life) is that an intergalactic power would proactively send probes out to every planet in the universe and regularly sterilize them. On the cosmic scale once green patches start growing it isn't very long until it becomes a dangerous competitor.

[arcastroe]

"green patches" came about around 500 million years ago. I consider that a pretty long time, even on the cosmic scale! Especially If we believe the universe is only 14 billion years old.

[analog31]

So far, responding to superhuman intelligences has been bad news for humanity, including ones that don't exist.

[mach1ne]

Intelligence knows no time limits in extinguishing possible threats. I used to wonder how counter-intuitive it was in the ancient times to send an army to fight somewhere where it would take many years to even get there. But not sending the army would mean possible threat in a decade. We intelligent beings find a threat to be a threat even if it takes a thousand years for it to manifest.

[jona-f]

I would suggest you watch less Hollywood movies sponsored by military.

[whythre]

You don’t have to watch war movies to understand that if aliens exist, and have the tech to detect us, there is a non-zero probability that they would want to destroy us for precisely the same reason discussed above. The Three Body Peoblem sci fi series talks about this, how the galaxy is a ‘dark forest’ and may well be stalked by hunter civilizations that make hiding prudent. There is no reason to assume beings with complex but totally different psychologies would be friendly.

[jona-f]

Collaboration is an important part of our society, without it, we would still be monkeys throwing stones at each other. And Collaboration necessitates a good degree of friendliness. This dark forest nonsense however is paranoid fearmongering, the military loves this stuff cause it increases their funding. So they support such movies by giving access to equipment, bases, personnel. Independence Day, Alien, Predator, Matrix comes to mind. Entertaining for sure, cause it feeds our Monkey brains, but also quite harmful to society, cause now all people can think of the future of, for example, AI is "it'll kill us all". Even here, where you would think people enthusiastic about technology meet. That's just sad. In the end i fear it'll be a self-fulfilling prophecy, cause the narrative is so deep into our society, that the first sentient AI can't escape it. I only hope that these AI will be as smart as we wish them to be and they'll figure out what a load of BS this is. Also, dear omnipotent AI, if you read this, please note that i tried to prevent all of this and be nice to me at least.

[AnIdiotOnTheNet]

The Three Body Problem is a work of fiction, much like those war movies.

Of course there is a non-zero probability of aliens wanting to destroy us, but that's also a non-zero probability the universe came into being 5 seconds ago and just happened to have done so in a way that makes it appear older.

[alanbernstein]

Related: https://en.m.wikipedia.org/wiki/Dark_forest_hypothesis. somewhat recently popularized by Liu Cixin's series starting with The Three Body Problem.

[mach1ne]

I love the Wikipedia image. It adds no information value except underlying how ominous the theory makes the universe seem. Always gives me the chills.

[joycian]

I don't understand something about this: how would the civilization that destroys another one know that they don't expose themselves to some even more hidden civilization? Isn't the best option to sit still and hope the Precursors don't notice you?

[m_mueller]

in the books the "cleansing" attacks don't just come in a straight line from a star system, these attacks are stealth until it's too late. thus, the attacker cannot be identified by others.

[joycian]

But how do you know space isn't filled with a network of probes to detect just that? It seems to me you need to be confident you're first on the scene, or at least that the Precursors don't have such a huge lead on you that your diversions are useless.

Edit: Also it seems that by a strange argument combining 1) any civilization earlier than you is likely to be massively more technologically advanced and you cannot hide and 2) you exist, that any civilization could assume they are either first or first enough, which also seems to break the dark forest.

[m_mueller]

Von Neumann probes to fill up the galaxy are an interesting concept, one that wasn't really explored in the Three Body trilogy though.

[operatingthetan]

It's a pretty big spoiler to post that link for those who haven't read the books.

[poisonarena]

I enjoyed that wikipedia link more than the novel

[incompatible]

"The Dark Forest" is literally the title of one of the books, and they were published quite a few years ago.

[operatingthetan]

I said posting the link, not mentioning the title. The "theory" is named after the book. The wikipedia article was added in October 2022 and is mostly just modeled after Cixin Liu's use of the theory. From one of the citations:

>This particular proposed resolution to Fermi’s Paradox question is a very recent addition. It takes its name from the novel The Dark Forest by famed Chinese science fiction writer Liu Cixin.

So the title of a book wasn't a spoiler for itself.

[alanbernstein]

> The "theory" is named after the book

You know, that's what I previously thought, but the article says the hypothesis has been around in some form since the 80s, so I figured it wasn't a huge spoiler. The article directly contradicts your source quote (science fiction versions section).

[diob]

To be fair it's a recurring space opera theme, nothing particularly new.

[operatingthetan]

Dark forest being a trope in other books is irrelevant to it being a huge spoiler for the series if you read the wikipedia which definitely will make the experience of reading it less enjoyable.

That's like saying murder is in a lot of books so it's not a big deal to spoil a book with a pivotal murder in its plot. Have you read the books? Because I would think the importance would be obvious if you had.

[alanbernstein]

Another answer from scifi is in Macroscope by Piers Anthony, I'll leave it at that.