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Comment by ivan_gammel | Hacker News Reader

> And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived.

If dark forest theory is right, alien civilizations may stay undetectable by hiding biological signatures of their worlds.

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The dark forest theory makes for a great book premise, but it probably doesn't apply in real life simply because the distances are so far.

The universe is not a forest. It's a gigantic, empty ocean. The next, dangerous tribe is not lurking behind a bush 2 meters away, but is sitting on an island that's so far away it will take centuries to go there, if it is possible at all

Isn't that the point of the dark forest theory? It's not the fact that there is a dangerous tribe behind a bush it's more that you don't know if they're dangerous or not so you have to err on the side of caution - because you don't know if they're doing the same.

It's the whole chain of suspicion theory that it's safer to shoot first and then ask questions later because the speed you can communicate is the same speed you can mount an attack.

Yes, but the next bush is dozens of light years away. The analogy breaks down because the distances are different in quality.

The only reason why this becomes such a problem in the Three-Body-Problem is the existence of magic in that universe. Thinking protons, instant communication, folded dimensions, easy interstellar travel, it's all interesting speculation inspired by physics, but incompatible with our actual universe.

Those things are just sci-fi glitter absence of which doesn’t invalidate the theory.

Why does the distance change the dynamic? So what if the species trying to exterminate you are 500 light years away, you think they should ignore it ? Maximum travel speed of an extermination weapon in 100,000 years of of science may very much be impressive or even magical by today’s standards

The distance completely changes the dynamic. If I tell you there's a crazy axe murderer in your house, you should be afraid. If I tell you there's a crazy axe murderer on Venus, how afraid are you?

And unless we are completely wrong about physics, the maximum speed of a weapon will be the same as it today - very close to 1c.

How do you know it's incompatible with the actual universe instead of our current understanding of the universe?

Take us for example, we're communicating instantly (for practical purposes) using thinking machines - how would that not seem like magic to someone thousands of years ago?

My point is, we don't know what the tribe have behind the bush. It's the equivalent of the Mayans wondering what's over that hill and then finding the Spanish with gunpowder, horses, and steel armour.

The only reason why we can't out sentient protons folded out of 28 microdimensions into our 3 macrodimensions is the same reason we can't rule out that our universe is actually the works of a giant hand puppet player called Zquaarx.

The problem is just - if any of what happens in 3BP was to actually happen, we would not have to be a little wrong (like Newton was in regard to celestial mechanics) but so wrong that it doesn't even make sense to apply what we know at all.

This is, by the way, the exact point of the first part of the first book: physicists discover that all off the known physics are completely wrong.

Of course, the risk is, thinking that centuries is a long time may be merely a human, and not a universal, trait.

Time does not matter. Space-faring civilizations can adapt their pace of life to the communication and exploration speeds or even live at multiple speeds. They are likely energy and resource-bound: within the same theory Dyson sphere is a risk, so they can only consume a fraction of locally available energy to remain unnoticed - meaning that it’s not the distance but energy consumption that will limit them.

Dark forest theory is wrong. Staying undetectable is always inferior to both staying undetectable and safely deploying varyingly detectable decoy targets at safe distance to probe the situation and gather intelligence.

Deploying decoy target requires more advanced technology (space travel) than hiding the signature (we may be able to do it long before we reach another star). I don’t think this is a good argument. Let’s say, some civilization decides to invest in decoy. It needs to shine brightly, the energy footprint is huge, a lot of work has to be done to transform the entire system. Then what? If there’s a hostile player, capable of destruction, they research and destroy the target, and start surveying the neighborhood. You cannot just build a decoy on another end of the galaxy, right? The further you have it, the more complicated is the task. And then you can only hope that the time left will be enough to collect enough energy (even if you have the tech) for defense.

Dark forest theory is about very advanced civilisations not engaging with anything around them. Limited resources are not an issue in this case. You can easily just do everything in parallel with AI or other automated control system, using stars as energy sources, including spawning whole decoy civilisations at different stages of development. Because we see so many stars we know nobody is running out of energy yet.

And the evidence of that is what? What is the mechanism behind that? How is it testable?

This is what annoys me about this field. It is just magical thinking and baseless speculation. Random ideas get given names like "dark forest theory" like they are deep and consequential.

What you said is the only consequence of that "theory", because that "theory" is literally just the idle speculation that "alien civilizations may stay undetectable by hiding biological signatures of their worlds."

It’s game theory, mathematics. Let’s say every player has 3 actions: do nothing, expose yourself and destroy the player you aware about. Your goal is survival. If you expose yourself in this game and there’s at least one player choosing „destroy“ action, you loose.

Now, of course there’s a question of applicability of this model: 1. are there other players? (if the game started, we won’t know until we observe destruction event - but that’s falsifiability) 2. do they have means to destroy you? (we may find out) 3. do they have motivation to destroy you? (we may find out) 4. can you protect yourself against unknown level of technology? (we may find out).

This theory meets scientific criteria, it’s just that those criteria require level of technology that we may not reach in thousands of years.

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