Headscratchers / Remembrance of Earth's Past

• Liu's theory in the second book caused one big paradox: Who will attack the attacker?
  • If one civilization is either too naive like human, or in do-or-die situation like Trisolarans, and start expanding with a little bit of luck (like not directly run into an enemy, alas poor human), how should other civilizations react? If they keep hiding, this civilization could discover or shoot them one by one. If they launch attacks and destroyed that expanding civilization (or failed), then? Sit back and pretend nothing has happened?

  • Anything a civilization do may expose itself, including, or maybe especially launching "Dark Forest Strike" at other civilization for the star-level or even cosmic-level energy it costs. Even technologically inferior human can somehow lure out and track the Photoid that destroyed a star system, some more advanced civilization are very likely being able to track the ship who launched it, some SUPER advanced civilization WILL locate the launcher's homeworld. And as every advanced civilization have some kind of observation network and ready-to-go WMD, galaxy should be burning then.

  • Liu's explanation in the third book relies heavily on Deus ex machina. A super advanced ax-crazy civilization throwing WMD everywhere and basically every Tuesday? To hell with dark forest, that jerk has set the whole forest on fire!

  • That assumes the attacker cannot sufficiently mask their attacks. One must assume any advanced species living in such a world is very good at stealth kills.
    • Even if the attacks are stealthy, other advanced civilizations will still try to find them. Unless they are completely undetectable then the problem remains.
    • They do try to find them and they are undetectable. When Singer decides to cleanse Trisolaris but realises someone else has beaten him (her? it?) to the punch he follows established procedure to attempt to trace the source. The book notes that “The process soon terminated, and like every other time, yielded no results.” The books very strongly imply that most dark forest strikes are initiated from near light speed capable ships and that these ships are, basically, everywhere. There are at least two in the general vicinity (in cosmic terms) of Earth during the books - the one Singer serves on, the one that destroyed Trisolaris and possibly a third depending on who attacked the star destroyed to confirm Luo Ji's hypothesis in book 2. Given that attacks take several years to reach their target, that the results of those attacks take years more to be apparent to observers light years away and the ships that launch them can get away from the launch point at near light speed, it’s not difficult to see why tracking would be a problem. Even if the launch point could be accurately located the information will be so out of date by the time other species become aware it will be useless unless a civilisation is dumb enough to initiate a strike from its home solar system. The Dark Forest hypothesis depends on two basic assumptions: that intelligent life is far more common than we currently believe and that near light speed travel isn’t that difficult once the theory has been developed (it only takes humanity a hundred years or so to figure it out once sophon lockdown is lifted; two centuries for Galactic Humans who didn’t have the advantage of Tianming’s espionage). If those premises are true everything else follows.
    • If hiding in space is that easy than why doesn't everyone just abandon planets entirely and just live in space full time? It's not like anyone would ever be able to find them in that case if stealth is somehow that powerful?

  • The third book shows that the universe is a remnant of a war too advanced to comprehend. Fundamental laws of physics have been changed, possibly mathematics itself is not working as it used to. It is thus strongly hinted that attackers did get attacked all the time and the galactic war is still ongoing with the various offensive and defensive measures threatening to rip existence itself apart.

• Ultimately, wasn't Rey Diaz right? His plan was basically the same concept as Luo Ji's (ultimately successful) plan, and it was considerably easier and cheaper, to boot. Is the only real difference between the two that Luo Ji kept his secret to the end, or am I missing something?
  • Maybe Rey Diaz's project is not powerful enough. Trisolarans may not need Earth intact. It is possible that all they need is a stable star, but Photoid strike will destroy the sun.
  • I think it's stated by Rey Diaz's wallbreaker that "The Lord doesn't care", because he could never amass the amount of stellar bombs to push Mercury into the sun anyway. (As a non-related comment, the moment I heard his plan is when I truly fell in love with the series.)
  • Ultimately, another reason of "The Lord doesn't care" is that his plan doesn't actually threaten the Trisolaran homeworld.

• Near the end of book three, the death lines on Planet Gray rupture and reduce lightspeed in the system to less than twenty meters per second. Since that's obviously far less than orbital velocity, shouldn't planets Blue and Gray have deorbited into their sun within a few days?
  • It's possible that the speed of light and the gravitational constant are related in some manner such that reducing the speed of light also decreases the apparent force of gravity in a proportional way so that orbits work out the same just at a slower speed.

• How did intelligent, multicellular life even evolve on Trisolaris?
  • Underground, maybe? A chunk of planetary crust would provide excellent protection from most sun-related disasters.

• What is happening with the speed of the two-dimensional collapse in Death's End? The effect is spreading fast enough to engulf the entire solar system in ten days, and is sucking in space fast enough that only lightspeed can escape it, but it takes entire minutes to flatten one of the bunker cities? Surely it should have destroyed a city-sized object in a tiny fraction of a second, unless I missed something important about its spread accelerating massively. May simply be a mistake and a (rare for this series) case of Sci-Fi Writers Have No Sense of Scale?