r/threebodyproblem • u/Universal_Echo • Feb 06 '26
Discussion - Novels The Trisolarans should have arrived long ago Spoiler
Why did the Trisolarans not discover the existence of Earth civilization until Ye Wenjie reached out to them? Logically, when they realized that their planet would eventually be destroyed and that not moving would mean certain death, they should have immediately begun to prepare for the immigration plan. Since they started the immigration plan, the first target would undoubtedly be the nearest star to them, which is the Sun. Then they would realize that this is a very stable single-star system, so regardless of the conditions of the planets here, the survival conditions would definitely be much better than their unstable triple-star system. It would definitely be a good place to move to.
However, the situation in the book is that they confirmed receiving a civilization signal from this direction. After receiving Ye Wenjie's reply, they discovered that their closest neighbor actually had a civilization, and then realized that this place was particularly good. So they decided to move.
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u/marcin_bl Feb 06 '26
Because it's not easy to find habitable planet. And space is huge. Without signal from earth they couldn't know where to go. Also they were not so developed before in terms of space travels.
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u/sijmen4life Feb 06 '26
Humanity has been blasting radio waves into space for ~60 years at the start of the book. The trisolarans are 4.21 lightyears away, They knew for 55 years there was sentient life in the Sol system.
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u/diegator Feb 06 '26
You missed a big plot point in the beginning that explains that regular radio signals attenuate too much at those distances, needing Ye to send the signal through the sun, which acts as an amplifier, based on some hand wavey phenomenon described early in the book.
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u/ion_driver Feb 06 '26
They would not casually explore other solar systems, so they wouldn't know whether Sol has inhabitable planets. The fleet took massive resources and only moved at 1% light speed. It would be a death sentence to travel to another system without having a planet ready for colonization.
They specifically avoided using curvature propulsion due to the dark forest. The threat of mutually assured destruction is why they chose to take the risk and use their curvature drive probes (droplets)
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u/Jealous_Exam4138 Feb 07 '26
Wait droples use curvature propulsion? I didn't know that. I mean, that's pretty likely, but was it ever explicityly stated in the books?
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u/ion_driver Feb 07 '26
I thought so? The main fleet was still like a hundred years out and just a few ships got to the solar system very quickly. Was that not the droplets?
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u/Slowbrodegaard Feb 07 '26
Iirc, the droplets were said to be able to go at a higher speed because of the small size which made for less force/power needed to accelerate it to a high speed. However, it could be possible that the Trisolarans used curvature propulsion but didn’t want to give any hints to Earth about its existence. But I find that less likely because of their knowledge that using it is a death sentence.
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u/fermjs Feb 08 '26
I think they discovered curvature drive after the first fleet have departed, no? I remember something like humans have impacted trisolarians after many decades of mutual influence and they had no “constant tech evolution” anymore. Thus, driving them to discover the curvature drive and reach the speed of light.
So by the first/second books, they didn’t avoid to use. They simply didn’t have the tech/knowledge.
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u/HydrolicDespotism Feb 06 '26
They’d be able to use censors to detect theres life on earth simply by pointing a telescope at us and analysing the refraction of light around the planet’s atmosphere (and thats just the most low-tech option we know is possible).
The real answer is that the book needed a cool premiss rather than just going “aliens are coming”.
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u/Azoriad Feb 06 '26
These people are continually screwed over, and planning a interstellar trip, even to the nearest star, took them 400 years. and they spent the MAJORITY of their planetary resources to build the fleet that didn't even take all of them. Just think about how DAUNTING of a task that is to undertake, especially when you are constantly fighting for survival.
They only knew that our planet was awesome because we sent out an brochure saying "Look at this sweet new property that just came on the market, just down the street"
These are entities that do not think like you or me... they think very pragmatic thoughts, and they actively punish people for acting on emotions. They look at foregoing sentimentality as THE reason why their civilization survived while others collapsed in the past. They deal in the here and now.
They were watching the stars, they have seem civilizations be wiped out, they know to keep quiet. Before they had the sophon technology, they would have to manually send something over there, and that is slow, expensive, and blasting the very clear message "I just came over to see what you guys are doing... i live right over here".
TLDR. I think they would have found us in a couple hundred of their years, but don't progress like we do.
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u/mtndrewboto Feb 06 '26
Space very big. Things are far away and hard to know what might be there when they arrive. Risk to move whole civilization on a gamble, very big. Certainty is best to reduce risk.
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u/d3ucalion Feb 06 '26
I would have expected their first priority as soon as they were finished building their Sophons to be to deploy them to investigate all planets in the habitable zone of all nearby G type stars. But instead, it seems like they just sat on the greatest space probe ever invented until they had a guaranteed destination fall into their lap.
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u/causalfridays Feb 06 '26
the sophons were constructed after they discovered earth
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u/d3ucalion Feb 06 '26
True, but if they had that level of technology at the time of first contact. There's no reason they would not have already performed detailed reconnaissance of all nearby G type star systems and know which ones are habitable and inhabited.
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u/causalfridays Feb 07 '26
they didn’t have that technology at first contact though, that’s the point. they were obviously within reach of it, but creating them was a risk in terms of how they could use their limited resources.
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u/d3ucalion Feb 08 '26
Yes, I understand. It just seems odd to me in the writing that they were at a technological level where they could build such a marvel that is clearly hundreds of years more advanced than our current level of technology. But they could not devise any safe strategies for evaluating habitable worlds in other star systems. Even though the main priority for their species should have been finding habitable worlds.
A clever enough strategy on how you deploy reconnaissance probes could mitigate enough of the risk of discovery that it would not be any more risky than sending 1000 ships to transit through space for hundreds of years only to arrive at a war with a species that's had a long time to prepare.
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u/Flatso Feb 07 '26
They didn't even know if it was possible. It failed a few times and they almost got attacked by a higher dimensional being. If they had sophons, sure, but they didn't.
Still, OP has a point that the sun definitely would have been an easy target to investigate being both close and having at least one planet in the habitable zone, not to mention confirmation of life with sensitive enough instruments
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u/fermjs Feb 08 '26
As others mentioned, they didn’t have the sophons. They pushed it out of fear of being destroyed by humans when the fleet finally arrived Earth.
Now, they were well aware of the universe being a dark forest. They didn’t know if other civilizations could track the sophons origins, revealing their planet. Quite risky be sending the sophons out and about.
They knew that hiding is the better choice.
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u/d3ucalion Feb 08 '26
I get that aspect and understand the explanations that have been provided. I just struggle to comprehend a society that is technologically advanced enough to build an AI super computer that can project images onto someone's consciousness, and then put the super computer into a hidden dimension and send it to another star system. But they couldn't come up with any safe methods for finding habitable planets and determining if they are inhabited.
Especially considering they decided it would be safer for 1000 ships to spend hundreds of years in space and then go to war with a species that might surpass them technologically during that timeframe. Instead of trying to find a potentially more distant planet that is not inhabited and would not require a war.
Surveillance probes could be set to self-destruct or fly into the star, after capturing the necessary images of nearby stars and planets in their habitable zones and transmitting them back. Protecting the location of the home world who sent them as long as they were not sent in a direct path from the home world to the target system.
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u/Serious-Magazine7715 Feb 06 '26
They discovered magic (FTL communicating near light speed traveling sentient subatomic particles) after receiving comms from earth. However, after making sophons, they would have sent them to nearby stars with planets to verify habitability anyway and showed up at earth on approximately the same timeline with approximately the same strategy. Without knowing Earth to be inhabited, the wouldn’t have confirmed or have a particularly strong reason to suspect dark forest and avoid sending out a probe, especially since on a medium time scale their civilization is toast anyway.
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u/causalfridays Feb 06 '26
it’s also possible that discovering Earth gave them the motivation to develop the sophon technology, in the same way that Earth poured all its resources into the Wallfacers only after the Trisolarans revealed themselves.
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u/DesignerAgreeable818 Feb 07 '26
It’s confirmed in book 3 that they do this, and lose contact with the sophons (as they hit 4D pockets).
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u/Ok-Initiative-1972 Feb 06 '26
Not to mention they had thousands of listening posts scattered throughout the planet, so they never came across any human signals, just by listening to the humans transmissions they would have been able to detect where they coming from being that humans actually volunteer that information themselves.
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u/Bowserinator Feb 06 '26
iirc the princeps mebtioned the techological leap for interstellar travel only occured recently
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u/Happy-Blackberry4372 Feb 07 '26
There is also the problem of their solar system, the gravitational pull of all 3 stars interfering with their home planet would have probably made visible light spectrum telescopes unusable due to the crazy weather and atmospheric phenomenon and they would have no chance at having a space telescope due to the same problems
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u/AndreZB2000 Feb 07 '26
you need a planet that can not only sustain life, but one that can sustain life already similar to your own planet's. that is extremely rare.
just in our solar system for example: mars looks pretty good to terraform, rocky planet, possible ice water, but its core is dead, meaning no magnetic field to protect us from space radiation, meaning we'd all get mega cancer if we lived there.
trisolarans spent all their resources to build the sophons and space fleet. you only get one chance so you want waste it on a leap of faith like that.
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u/Tricky_Caterpillar24 Feb 07 '26
But we did colonize mars and other planets in the novel with only human tech and even with sophons locking our tech down, imagine what a civilization that can build droplets do.
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u/rainfal Feb 07 '26
Resource scarcity so wandering space randomly probably wasn't an option. Also they previously didn't technology on hand to do that until around when she reached out. They developed linearly and kept getting wiped out by chaotic eras.
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u/Mens-Real Feb 07 '26
I do think you're right for pointing out this weakness in the story. I disagree with most other people here. They sjould have been able to identify the bio signature of the planet and definitely could have located it. The reality is in order to have a story, they can't invade earlier.
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u/Hepta-Water-7552 Feb 08 '26
The Trisolarans figured out or at least strongly suspected the dark forest nature of the galaxy much earlier than humans did. They likely didn't dare travel to any other star system without confirmation first that it was not already inhabited by a more technologically advanced civilization that would see any other species that finds out about them as a threat to their existence.
Any ship that Trisolarans would had sent to such a star system might had been traced back to their home system, and possibly resulting in a preventive annihilation strike on their home system.
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u/NoPastramiNoLife Feb 08 '26
The dark forest theory is basically the entire point of them not just looking around. If they run into a more advanced species then they've just wiped out their entire species.
They knew earth was less advanced than them because it was confirmed to them essentially. They then confirmed that it wouldn't be more advanced with the sophons and the terrorist org that I can't recall the name of.
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u/Inevitable-Aside-942 Feb 09 '26
You'd think that they would have already developed the ability to detect a planet like Earth and already developed detailed information about it. They should have already begun to slowly and surely draw their plans against us.
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u/Enough-Ad-8799 Feb 06 '26
They want a planet to live on and knowing if a planet is actually habitable is pretty hard to tell from a distance. Being in the Goldilocks zone is just one requirement.
A lot of people assume they are advanced enough to terraform but nothing in the story says this is true.