[ajuc]

My problem with the series is the premise that invasion of another star system is worth it.

With all the resources Trisolarians put into colonization of Earth, and all their superior technology - they could've made space habitats that had perfectly safe orbits around whichever star they prefer, and put all of their citizens on them.

What's the point of risking mutual destruction by hunter in the dark forest (and we know they were afraid of it since the start), if you can create habitats in your own star system, or choose any nearby uninhabited star system if the 3-body-problem is really making it impossible to put these in your own system (and realistically - it wouldn't be so bad, just make a dyson swarm around the whole system.

[lsadam0]

Invading our Solar System was worth the risk for Tri-Solaris. Because of the Dark Forest nature of the universe they could not just pick a star where they thought there was no life, as life there could just be especially good at hiding. When they found earth they found a luxurious planet containing a race which was ignorant of the true state of the universe and technologically incapable of doing anything about it anyway. On top of all of this, our solar system was very close by :). Their own star system was hellish compared to ours, they needed to leave.

The final book in the series does a good job showing why Earth was a good option for them. Tri-Solarians knew far more about Earth than they could reliably determine about most nearby star systems.

[ajuc]

If you're afraid that a planet will have life, then why choose a planet where you are sure there is life?

They were betting their existence on a species they knew already uses MAD as a basis for its' survival not figuring out that it could use MAD to defend themselves.

Their system was interesting, but ultimately not much worse than ours, once you leave the planet. And they have to leave the planet anyway.

Once you have nanomaterials allowing cheap access to space - putting your population in space habitats is cheap and easy. We could do it now, if we had space elevator. The cost of materials and energy is negligible compared to invasion of another star system. Especially with such conveniently storeable population :)

> Tri-Solarians knew far more about Earth than they could reliably determine about most nearby star systems.

There's nothing stopping them from figuring it out. You don't have to invade a system, you can send a stealthy probe. I would assume in their circumstances it would be a wise thing to do if they really don't want to live in space further away from the center of gravity of their star system.

Besides, if the dark forest is so important - why invade Earth at all and play with fire? You can kill everybody on Earth without bothering to show up or sending any warnings. Send a big meteor their way or make a deadly disease that looks like flu, infect everybody, and on set date kill all hosts. Much cheaper, and no risk of ceasing to exist.

What they did in the books was very risky and wasteful for no good reason.

[lsadam0]

Spoilers Ahead!

> betting their existence on a species they knew already uses MAD

If ant colonies depend on MAD for continued existence, it means nothing to us. This example was used multiple times throughout the series. They didn't even make a singular bet on Earth. The invasion was just one avenue they chose for survival.

> You don't have to invade a system, you can send a stealthy probe.

In the dark forest of the three body universe you could send a probe, but you learn nothing if it finds no life in a system. The only reliable, actionable information a probe can provide you is if life is found. Finding an absence of life just as easily means that the life in the system is so far advanced beyond you that you cannot detect it. It would be far riskier to bet your future on a system in which you found no life. Not to mention that you are making a huge gamble on the stealthiness of said probe. The probe could be the very thing that makes you the target of a dark forest strike. Earth already appeared safe, so why take further action that carries real risk of notifying some other civilization that you exist? You can't be reliably stealthy because some other race can be technically beyond you.

> Send a big meteor

Earth was an un-imaginable eden to Tri-Solaris, it's made clear that they wanted the planet intact.

> or make a deadly disease that looks like flu

This requires a much longer timeline as multiple trips are required to carry out the plan. The Tri-Solarans were facing a very real threat of extinction that made a shorter plan worth the risk. It's made very clear that they did not wish to exterminate humanity.

Earth was valuable because in all probability the rest of the universe did not know it existed. Given that you are saying they were stupid for not building space habitats, you must not be aware of what actually happened to the Tri-Solarans :). Besides, those space habitats present their own form of danger to their inhabitants. Actually, the danger they pose is worse than existing on a planet.

[ajuc]

> If ant colonies depend on MAD for continued existence, it means nothing to us.

But we're not an ant colony to them, we're already using technology that can be used for MAD (sending signals through the sun), and they know it from the start.

> Earth was an un-imaginable eden to Tri-Solaris, it's made clear that they wanted the planet intact.

As far as I understand every planet in the system was heaven for them, the orbit was important. Which is stupid, because you can make anything follow a circular orbit around some star.

> This [flu] requires a much longer timeline as multiple trips are required to carry out the plan.

Why? They have their stealth probe (don't remember how it was called), they can take a look at a spanish influenza or something and pimp it up a little. At worst they then need to send like 1 gram at almost light speed the conventional way - still much easier and faster than sending the armada.

> Given that you are saying they were stupid for not building space habitats, you must not be aware of what actually happened to the Tri-Solarans :).

They were destroyed because their coordinates were broadcasted. As they should expect from the start messing with civilization that broadcasted "hello".

> those space habitats present their own form of danger to their inhabitants. Actually, the danger they pose is worse than existing on a planet.

How? They aren't any less stealthy than sattelites, tv, or radio.

[lsadam0]

* More Spoilers *

> But we're not an ant colony to them

Tri-Solaris technologically stomps humanity throughout the series. Humanity was ignorant of the dark forest, and Tri-Solaris knew that. Further, they're able to suppress the Sun's broadcast capability. From their vantage point there was no feasible way for humanity to become aware of the dark forest. Their misunderstanding of humans is a central plot point. By every single measure Tri-Solaris had the advantage in a massive way.

> Why? They have their stealth probe

It was not stealthy. Humanity literally saw the probe pull ahead of the fleet and knew the probe was coming 50+ years before it arrived. Sometimes hiding behind an asteroid or planet is not stealth.

> They were destroyed because their coordinates were broadcasted.

No, the Tri-Solaris civilization still existed near the end of the universe. Their planet was destroyed, but they lived on as a space faring species.

> How? They aren't any less stealthy than sattelites, tv, or radio.

Do you recall what light-speed capable ships do to the fabric of the universe?

[ajuc]

> Humanity was ignorant of the dark forest, and Tri-Solaris knew that

Tri-Solaris knew only what their sect was aware of, not what everyone on Earth thought. Also - they were somehow aware of the dark forest, would be very naive to think others can't discover it on their own. They were clearly considering it a real threat, because they tried to stop him and reacted so quickly when the guy staring at the wall did the experimental star demolition.

> Humanity literally saw the probe pull ahead of the fleet and knew the probe was coming 50+ years before it arrived.

Wasn't it only seen because they were already looking there? I might misremember something.

> Further, they're able to suppress the Sun's broadcast capability.

Only after the girl is chosen as the person to hold MAD button, IIRC. At that point the decisions on invasion were made centuries ago. Counting on that happening would be crazy.

> Do you recall what light-speed capable ships do to the fabric of the universe?

Not really, I ignored most of that 3rd book technobabble because it was unphysical. They were destroying universe and making it 2d or something?

Anyway, why should it matter? Habitats are supposed to orbit somewhere pleasant, like any dumb rock would do, not move at light speed.

> No, the Tri-Solaris civilization still existed near the end of the universe. Their planet was destroyed, but they lived on as a space faring species.

My bad, don't remember everything from the book. Still - this only proves my point - it's possible, so they should have done that from the start. They were never in "existential danger", just lazy (but still somehow happy to spend lots of resources, effort, and risk to live on Earth).

[magduf]

This is exactly my problem with the whole idea of alien invasion. The technological resources needed to traverse star systems are so huge, and even then it's very unlikely any life-bearing planet will be all that habitable for your particular biology (the life there will have evolved for the conditions on that planet, which might very well be toxic for you). If you have such resources, it should be much easier to just build yourself some O'neal cylinders, or even terraform some more conveniently-located planets.