For cruciverbalists – professional or amateur, creators or solvers – there’s nothing more satisfying than coming along a clever crossword. “Clever” can mean a variety of different things. More often than not, however, “cleverness” relates to the theme in some way. While a clever crossword leads solvers to an “Aha!” moment, it can lead creators to publication and fame.

One type of crossword theme is so clever, it has its own name: a Schrödinger puzzle. But what is it, and what does it look like? And how popular are they?

Defining a Schrödinger Puzzle

Many of us have heard of the famous thought experiment devised by Erwin Schrödinger and his theoretical cat. It is used to discuss quantum mechanics, but most people understand it in its simplest terms: if you placed a cat in a box with something deadly, you would have no way of knowing whether it’s alive or dead unless someone opened the box. This means the cat is theoretically both alive and dead.

How does that relate to crosswords? A Schrödinger puzzle, then, is a puzzle with answers that could be one answer or another. In this way, the solver has no way of knowing which answer is “right” until they solved the puzzle. That means an unsolved puzzle has two answers for one clue. Joon Pahk suggested the name. Some people also refer to these as “quantum crosswords.”

Keep in mind that this differs from a rebus. In a rebus, multiple letters appear in a single square, sometimes forming an entire word. These letters are not interchangeable, though. The answer requires all the letters.

Famous Examples of Schrödinger Puzzles

There are several famous Schrödinger puzzles, but none more famous than Will Shortz’ favorite created by Jeremiah Farrell and published on November 5, 1996, or Election Day. The GIF below posted by Reddit user chewpendous and shared by the Daily Dot demonstrates the cleverness.

As you can see, the answer to the themed clue, “Lead story in tomorrow’s newspaper (!), with 43-Across” could have been CLINTON or BOBDOLE. It didn’t matter who actually won the election. In fact, solvers who found the BOBDOLE answer called in a misprint. Some who found CLINTON deemed the New York Times presumptuous.

Almost twenty years later in 2016, Ben Tausing’s puzzle created a similar stir. For the first time in New York Times crossword history, the term “gender fluid” appeared. Not only that, it was the theme of the puzzle.

While many wondered if this puzzle was a social or political statement in some way, Will Shortz reportedly said, “No, this puzzle is not a response to anything. It’s just a good puzzle.”

As of this writing, the New York Times has published twelve Schrödinger puzzles. The first and only Schrödinger puzzle not edited by Will Shortz was published on Sunday, February 2, 1988. Created by Ralph G. Beaman and edited by Eugene T. Maleska, nine different squares have more than one correct answer.

Interestingly, it seems Schrödinger puzzles are rising in popularity. Of the twelve published in the New York Times, eight were published in the last decade. Three were published in 2014, and 2018 has already seen two of them.

Creating a Schrödinger puzzle is no small feat, but if a creator can pull one off, odds are high it could appear in the New York Times. If you plan to attempt one, make sure you have the basics down first. Then, think outside of the box for your clues and answers. Or, maybe you’ll want to stay in the box with your favorite cat.