All You Zombies is a short story by Robert Heinlein, which outlines a rather bizarre time travel paradox. Here is an outline of the paradox with a few key moments missing.

  1. Jane is dropped off at an orphanage in 1945.
  2. Jane grows up lonely and dejected not knowing who her parents are.
  3. In 1963, Jane falls in love with a drifter, becomes pregnant with his child. The drifter disappears immediately thereafter.
  4. During childbirth, there are complications. The doctor discovers ___________, and in order to save Jane's life, the doctor ____________.
  5. A few weeks later, Jane's baby (A healthy baby girl) is kidnapped from the hospital.
  6. Losing ones parents, lover and only child has a devastating effect on Jane. Scorned by fate, Jane rejects society and becomes a drunkard.
  7. In 1970, Jane stumbles into a bar, and tells the sad tale to a sympathetic bartender.
  8. The bartender, who is a respected member of the time-travelling guild, offers Jane a chance to seek revenge on the drifter who ruined Jane's life.
  9. The bartender takes Jane back to 1963, where Jane ______________.
  10. The bartender hops forward in time _______(length of time), and __________.
  11. The bartender returns to 1963 and picks Jane up. The two of them return to 1970.

The Puzzle:

Fill in all the blanks (So that there is a paradox) and answer the following questions:

  • What becomes of Jane after 1970?
  • What is the paradox?


The 4th blank is: 9 months

NOTE: If you are familiar with the paradox or have read the short story, don't answer the question right away.. Not much of a puzzle if you know the paradox.

  • 1
    $\begingroup$ I know it and loved it (a riddle in itself, what is IT? lol) But yeah. Pretty cool. Didn't know it came from a short story. $\endgroup$ Apr 28 '15 at 21:59
  • $\begingroup$ Must be some version of the grandfather paradox? $\endgroup$ Apr 28 '15 at 22:02
  • $\begingroup$ Yeah! The short story is a fun and easy read. Can be easily found online if you're interested. $\endgroup$
    – knrumsey
    Apr 28 '15 at 22:03
  • 1
    $\begingroup$ There is no paradox. A self-caused chain of events is mathematically valid. Never mind that our human minds think there must be a paradox here. $\endgroup$
    – Joshua
    Jun 11 '15 at 20:36
  • 1
    $\begingroup$ For anyone not aware of it: there is a movie based on this story called Predestination. I remember it as pretty good. $\endgroup$
    – Mark
    Sep 20 '18 at 8:01

Here are my thoughts on this


The doctors discover that she has both sets of genitals? And cuts off the male parts


Jane, now a man falls in love with a woman (Quite sure it's Jane)


From the hint, it's 9 months first then the bartender takes Jane's child away from the mother ( 9 months is the normal gestation period), then travels through time and drops the child at an orphanage in 1945.

And finally

After 1970, Jane grows old and opens a bar

So the paradox is

Jane is the woman, the child, the drifter and the bartender.


Note: I feel like this puzzle is really just asking for specific trivia from a written piece. I could just as easily fill in the blanks as below, with the same level of satisfaction that the answer is correct.

During childbirth, there are complications. The doctor discovers the baby is breached, and in order to save Jane's life, the doctor performs an emergency c-section.

The bartender takes Jane back to 1963, where Jane loses her nerve and decides to go watch a movie instead.

The bartender hops forward in time 9 months and steals the baby that he conceived with the younger Jane, returns to 1945 and drops it off at an orphanage with a name tag "Jane".

What becomes of Jane after 1970?
She accepts her fate and her life takes a positive turn. She later adopts a cat and spends the rest of her days quilting for the locals.

What is the paradox?
No paradox, just coincidence. The bartender initially had no conversation with Jane in the original set of events; he decided to go to 1963 all on his own and knock up a stranger. This first stranger was not necessarily an orphan or named Jane. After stealing the baby, he travelled around for a few more weeks, only to realise that babies are a lot of work. It was during a stop he made briefly in 1945 that he decided he no longer had the patience for the child, and dropped her at an orphanage with the name tag reading "Jane". This baby becomes the protagonist in our puzzle. Her own baby is dropped at the same orphanage by the same time traveller, but in this timeline, there are now two (different) babies named Jane.

Who is the bartender?
A member of the time-traveller's guild.

  • $\begingroup$ Well if you haven't created a paradox, then you clearly haven't solved any form of the puzzle. It's certainly not asking for trivia. It requires just a little bit of thought, to realize what the paradox could be, at that point filling in the blanks is a straightforward challenge. $\endgroup$
    – knrumsey
    Apr 28 '15 at 23:15
  • $\begingroup$ After your edit, you have filled in the fifth blank (minus the word 'again') correctly. You're definitely on the right track, but the paradox is more bizarre and involved than even that. See the new hint in the puzzle statement. $\endgroup$
    – knrumsey
    Apr 28 '15 at 23:51

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