Steins;Gate/Headscratchers

• Seeing this is a Time Travel story, Mind Screw like this is to be expected. In the final episode what happened after The Other Okabe sent the D-Mail to Daru (as shown in episode 1) when Our Okabe faked the death of Kurisu? Our Okabe told The Other Okabe to live out the most important 3 weeks of his life without altering the past. However, how could the other Okabe accomplish that when he would have sent the D-Mail and cross the 1% Divergence to the Beta world line.
  • It works like this: Okabe initially sets events in motion by seeing Kurisu's body and sending a D-mail that she was killed, which jumps him into the Beta world line. After he manages to return to the Alpha world line, he can't directly save Kurisu because it would create a paradox. If he never saw Kurisu's body, he would never shift to the Beta world line and therefore never obtain the motivation he needed to save Kurisu in the first place. After future Okabe sends the D-mail, he most likely shifts to the Steins Gate world line's future as well.
• Why is Okabe the only one with the Reading Steiner? No one ever tried to explain it over the course of the series.
  • It's rather vaguely implied that others might possess Reading Steiner, but would be dismissed as crazy, especially if you believe the WMG that Okabe is a paranoid scizophrenic. Plus, they don't have D-mail or Time Leap to take advantage of, so anything they say would most likely be taken as insane babbling.
  • Or only the people who used the D-mail can activate the Reading Steiner for that world line. In fact, Rumiho and Moeka sent their own D-mail to their past self. This theory seems plausible for the former, but ambiguous for the later.
  • When I first saw Moeka "making photos to have proofs about what happened to her" I thought she has such ability too
• How did Rumiho and Ruka remember vividly the events of the original timeline when Okabe brought it up to them? Mayuri was only able to connect the pieces from different timelines as dreams. While Kurisu was unable to make any connection at all. This seems to have the signs of a Plot Hole, not a particularly bad or blatant one though and it plays rather nicely to the plot. It was never thoroughly explained more than little fragments from different timelines are stored deep in someone's heart.
  • It could just be explained as repeated contact with somebody that posseses Reading Steiner, which can help unlock certain memories from past world lines.
  • Assuming that there exists actually only one world and switching world line changes world to another possibility (so this is not Okabe's conscience moving from one parallel world to another, the whole world morphs), the memories of people are actually rewritten, and the rewrite is not perfect. Also this is cool and sentimental.
  • Kurisu, of all people, explained how this could happen in a world where the many-worlds theory stands (even though she kind of made it up on the spot so that Okabe wouldn't be so sad about killing her.)
• What exactly happened to the information from the 2000 John Titor that Nakabachi stole for his paper in the first episode? The very first D-Mail that Okabe sent out only went back a week, yet somehow it erased all of the information from the 2000 John Titor, when he was talking to the 2010 John Titor in the second episode. And on the same vein, in the first episode, why did Kurisu drag Okabe out of the conference room and ask him what he wanted, if in no instance (even in the final episode) did Okabe ever confront her beforehand?
  • The Butterfly Effect, as explained over the course of the series. D-mail after D-mail affect the divergence number, which in turn alter the timelines. And yes Future Okabe did meet with past Kurisu.
    • Looks like there are two types of time travel: the ones that change the world line (D-mails and time leaps) and the ones that not (John Titor's material time travel). There were no John Titor in 2000 because in Alpha timeline he traveled to 2010, not 2000. Let me develop the idea: material time travel should preserve world stability, it cannot change events that already happened, so if you decide to travel to past, this world should already contain traces of your intervention (which you don't made yet in your 'conscience timeline'). Remember John Titor and SERN Z-Program part 4. Tl;dr: the cause and effect are both in one world line, though effect may precede cause. But when you perform information time travel, it changes the world line: the cause lies in one, and effect in another. Thinking about what happens in the world line where you came from (or sent D-Mail) could lead to Fridge Horror (do you disappear? nothing happens? the whole world line disappears?). In the destination world line some unexplainable effects do appear (there were no event of sending of first D-Mail in the Alpha timeline, only receiving).
    • A much, much simpler explanation: Titor was coming from the future. Therefore, even a change in 2010 could affect whether or not Titor arrived in 2000.
  • Actually, it's rather simple. Okabe sending that first D-mail, changed the future from World War 3 to SERN's Dystopia. It changed Titor's origin, motivation for time traveling, as well as the creator of the time machine. Which made all the difference.
• Wait, if each world line has the You Can't Fight Fate events, then how did SERN take over the world by altering the past?
  • Significant changes to the world line could be made only during key points (like invention of time machine in 2010); otherwise only minor changes will be caused. After SERN got time machine, they could choose between any of alpha_0 .. alpha_n timelines in further 'divergence points'.
• If Kurisu had a paper on a feasible time machine at the beginning of the series, why does she present such an air of total disbelief in time travel at the same point in the story?
  • Okabe jumped to the Alpha world line. It is possible that she does not have it there.
    • This might be a wrongful assumption of mine, but I thought "Rintaro Okabe finds the corpse of Kurisu Makise in 2010" is the divergence point, i.e. there is no difference between the alpha and beta timelines before that point.
    • It is a wrongful assumption, as proven by the fact that John Titor never visited 2000 in the alpha timeline. Because of the existence of time travel, changes in the future affect the past until a Stable Time Loop is achieved.
• Why did the 0 before the decimal point on the Divergence Meter go out in the Faris ending, where Okabe saves both Mayuri and Faris' father?
  • Probably because it wasn't designed to display negative values.
• If Russia got the key to building a time machine why would SERN take over? Russia would be the one with a time machine, and they aren't members of SERN. What gives?
  • They don't. In the Beta World Line Russia sets in motions the events for World War III and in the Alpha World Line Kuriso never loses her research to her father and Russia doesn't obtain that information. Instead, SERN finds the secret to time travel.
• How come the worldline didn't change on the second d-mail (Daru: Okarin is hentai)? Granted, it's completely stupid in content and was designed to be ignored after viewing, but it should still have a tiny effect because having seen a stupid mail <> having not seen a stupid mail.
  • D-mails can be ignored and have no effect, as Moeka demonstrated. Besides...really, what effect, however small, was "Okarin is hentai" supposed to have, anyway?
    • Should've went further through the game before asking. Some changes are so small that it doesn't even register on a six-digit-after-decimal basis.
• Regarding Ruka's ending in the VN, and why events don't happen as in other routes: Why wasn't Mayuri killed by the Rounders in the Ruka ending? In that same vein, why was the lab not raided, and why wasn't Okabe picked up by SERN like the other timelines? I can understand them finally having no reason to kill Mayuri, but earlier in the route I believe Daru reported she had been killed. Perhaps they could've ransacked the lab at a later date, but why don't the apprehend Okabe? The last cg reveals he's been with Ruka for at least 9 months, and I'm pretty sure they're still in the alpha timeline.