Time travel makes my brain go “eek.” This is a compliment. Not many things make my brain do backflips and somersaults. Time travel is an impossible concept I cannot understand because it is inherently incomprehensible. Therefore, I love it.

This review contains spoilers, so if you’ve never read this, you might want to stop now and allow yourself to be surprised.

I first read this story by Robert Heinlein long ago as part of a compilation of his classic short stories. After all these years, it remains on the top of the heap of time travel tales. I couldn’t remember its title, so it took me a while to find it. It is called “All You Zombies.”

In a strange infinite loop, a baby girl is mysteriously dropped off at an orphanage in Cleveland in 1945. “Jane” grows up lonely and dejected, not knowing who her parents are, until one day in 1963 she is strangely attracted to a drifter. She has a brief passionate relationship with him and becomes pregnant.

The stranger disappears.

During a weird and complicated birthing, Jane’s doctors discover she actually has two complete sets of sex organs. With her life on the line, the doctors change her from female to male. Jane is now a man. Then …. a mysterious stranger kidnaps her baby leaving Jane a man and childless.

Depressed, lost, he becomes a drunk and a drifter. He eventually, meets a young woman in a bar, who he impregnates during a brief affair. The story contains even more complexities, involving the Time Corps and a bartender. Throughout, everything continues moving forward and backward in time.

Read it, and get your own brain in a twist.

The story is a paradox, impossible yet structured with its own internal logic that you can neither reject nor accept. At which point, my brain goes “Eek!!” Jane is everyone. Everyone is Jane. She is her family: tree, trunk, branches and roots.

I found this amazing diagram on the Heinlein Society’s web page. They have lots of other cool stuff too and if you’re a fan, take a look. You won’t be disappointed.

The circular logic combined with the impossibility of the sequence where the same person is mother, father, and child forever in an infinite loop — the snake eating its tail — is deliciously mind-blowing. You can get it for your Kindle from Amazon for $1.25, or as part of an anthology of Heinlein short stories. There are several listed on Amazon, new and used.

Heinlein did much of his most creative writing in these early short stories. His later novels are better known today, especially Stranger In a Strange Land. The short stories have been forgotten by many people, but are well worth your time. Most were written for the science fiction fanzines — newsprint magazines that were the primary outlets for sci-fi until the genre broke into mainstream literature in the 1960s. Not only Heinlein, but all the classic great science fiction authors started their careers writing for the fanzines.

I’ve read many hundreds of time travel books and stories over more than 50 years of loving science fiction. But this one, this story, has stuck firmly in my brain as the ultimate paradox where the past, present, and future come together.

All You Zombies is my favorite for good reason. It’s unforgettable. I promise you will never forget it either.