On the master palindromist, Barry Duncan.

A Toynbee tile fragment found at a rest stop off I-95 in 2006, photograph by Steve Weinik

The film Resurrect Dead: The Mystery of the Toynbee Tiles just won the U.S. Documentary Competition Directing Award at the Sundance Film Festival, and so we asked puzzlemaker Eric Harshbarger to give us a look at the mystery behind the tiles.

Though these modern days of the 21st century are filled with many puzzles, there seem to be few true mysteries anymore. As a professional puzzle designer and follower of puzzle hunts, I have personally witnessed how drastically the connectivity and community of the internet, the power of Google, and the sheer volume of information readily available to all makes the solving of many brainteasers almost trivial. Throw in the fact that most puzzle memes, alternate reality games, and online mysteries invariably end up just being marketing campaigns for soon to be released (and too often forgotten) films or television series, and one begins to wonder if any modern day, genuine mysteries truly are left.

The existence of the “Toynbee Tiles” might be just such a mystery. This world-spanning puzzle does not involve a musty old map from a remote archeological find. It is not written in an ancient language that few can read. It is not trying to get you to by a ticket to an upcoming summer blockbuster. And it is not giving up its answers easily.

Rather, these linoleum plaques which have been embedded in the asphalt roadways of major cities throughout the world for over two decades are a true conundrum of the present day. They are written in English (though proper grammar and syntax are often lacking), they are fairly easy to access (if you know where to look), and they have attracted the attention of many puzzle enthusiasts in the age of the all-knowing World Wide Web. However, despite all of this, no one really knows what the hell is going on.

I first became aware of the existence of Toynbee Tiles after reading an article on MetaFilter back in 2002. However, since I lived far away from Philadelphia and the other major cities where these cryptic signs were appearing (Pittsburgh, Cleveland, St. Louis, etc), I had to satisfy my curiosity with webpage clicks and URL addresses. Undoubtedly, I was not the only person to be intrigued by the mystery around this time, for the period from 2002 through 2009 saw an increase in the number of new tiles that appeared far and wide.

Director Jon Foy documents a copycat tile in downtown Philadelphia in 2010, photograph by Steve Weinik

Were these new tiles the work of the original creator? No doubt there are copycat Toynbee tilers out there now (“House of Hades” is one movement that is making its own tiles, and there’s even a how-to video on MAKE Magazine’s website). The meme has spread, but it is far from passé. Google may spit back over tens of thousands of results for a “toynbee tiles” query, but that does not mean the mystery is solved.

There are suspects: a Philadelphia resident, James Morasco, is often thought to be the originator of these plaques — possibly in an attempt to proliferate his conspiracy theories, or maybe to advance a theory promoting exploration, colonization, or “resurrection” of humanity on the planet Jupiter. But Mr. Morasco passed away in 2003, and hundreds of tiles have cropped up since then. Most of the signs still refer to Stanley Kubrick’s film 2001: A Space Odyssey, the historian Arnold J. Toynbee (after whom the tiles get their name), and the fifth planet from our Sun; but the tone of the inscriptions, their sizes, and the format of their letterings has varied greatly at times. And, oddly, after several years of great proliferation of the tiles, very few new plaques were laid in 2010.

Producer Colin Smith uncovers a Philadelphia tile in 2007, photograph by Steve Weinik

Trying to uncover a motivation for the tiles’ existence will quickly lead one down a rabbit hole populated with science fiction writers (Clarke, Bradbury), playwrights (David Mamet’s short play 4 A.M. may have something to do with all of this), and radio personalities. The tiles may have begun to spring up as early as 1980, but even today, over thirty years later, little is known for sure.

Probably the most extensive investigation of the tiles takes the form of the new documentary film, Resurrect Dead: The Mystery of the Toynbee Tiles, by Philadelphia-based filmmakers Justin Duerr, Jon Foy, Colin Smith, and Steve Weinik. Duerr is a well known musician and artist of the Philadelphia underground scene, and with that city being the epicenter of Toynbee activity, he is also an expert on the tiles. In 2005 (five years after meeting Duerr) Foy started a film project about the plaques, and six years later the work was finally complete. The research for the film took the documentarians around the United States where they visited about one hundred of the Toynbee sites. They even uncovered a previously unsighted tile placed at a rest stop off Interstate-95.

After hundreds of hours of filming and editing, Colin Smith (one of the producers, writers and co-stars of the movie) thinks at least some of the mystery behind the tiles might be elucidated. “Yes, we definitely think we are closer,” he told me through an email interview, “I’m not going to say that we are ready to close the book, because we are not, but we’ve come up with some pretty huge and very satisfying finds. The mystery persists nonetheless.”

Steve Weinik, the film’s associate producer and co-star, agrees: “For the first time, really ever, the movie establishes a solid timeline and explains the motivation and ideas behind the tiling campaign. We’ve made a strong case for who/what/when/where/why/how. In addition to all that, the movie is driven by a more universal personal story, which is told beautifully and wraps up nicely.”

Having personally been interested in this oddity for nearly a decade now, I was ecstatic to hear that a documentary on the subject had been filmed. And the fact that it just took top prize in the U.S. Documentary category at the 2011 Sundance Film Festival should encourage other puzzle enthusiasts that regardless of how many of the Toynbee secrets the movie resolves, it will be, indeed, very enjoyable to watch. And, of course, the mystery of the tiles themselves will likely continue to intrigue and mystify for many more years to come.

I’ve done my best to make the wording as precise and unambiguious as possible (after working through the explanation with many people), but if you’re confused about anything, please let me know. A word of warning: The answer is not simple. This is an exercise in serious logic, not a lateral thinking riddle. There is not a quick-and-easy answer, and really understanding it takes some effort.

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Related:

• Classic Computer Science Puzzles
• William Wu’s Riddles
• Newcomb’s Paradox
• 13 Balls problem: One of the hardest interview questions
• World’s hardest Sudoku puzzle

I prefer to think of programming languages as utilitarian tools for real world problems. They let me accomplish pragmatic (and often prosaic) goals. PHP is about as unsexy a language as you’ll ever find, but does that matter when it’s the technology driving the current Boardwalk and Park Place of the web world? I’m not a fan of puzzle questions in interviews; I’d rather have potential developers give me a presentation or write a reasonably useful program in the real development environment they’ll be using on the job. Solve all the puzzles you want, but the only one we’re getting paid to solve is the customer’s problem.

That said, many fundamental computer science concepts can be summarized well in puzzle form, which aids tremendously in teaching and learning these key concepts. Here’s a quick list of the classic computer science puzzles that I remember from my university days

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This is an archive of problems I’ve been collecting since the Spring of 2002. They come from many places, including word of mouth, college courses, books, and job interviews for hi-tech positions. Many are even written by members of our own forum community. These carefully chosen puzzles will demand you to think in creative ways you perhaps normally would not. In fact, some will seem outright impossible at first … but once you crack them, the epiphany can be truly rapturous!

• Link (via Neatorama)

A highly superior being from another part of the galaxy presents you with two boxes, one open and one closed. In the open box there is a thousand-dollar bill. In the closed box there is either one million dollars or there is nothing. You are to choose between taking both boxes or taking the closed box only. But there’s a catch.

The being claims that he is able to predict what any human being will decide to do. If he predicted you would take only the closed box, then he placed a million dollars in it. But if he predicted you would take both boxes, he left the closed box empty. Furthermore, he has run this experiment with 999 people before, and has been right every time.

What do you do?

On the one hand, the evidence is fairly obvious that if you choose to take only the closed box you will get one million dollars, whereas if you take both boxes you get only a measly thousand. You’d be stupid to take both boxes.

On the other hand, at the time you make your decision, the closed box already is empty or else contains a million dollars. Either way, if you take both boxes you get a thousand dollars more than if you take the closed box only.

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• As suggested, you should read the entire essay here.
• You can follow the discussion here.

One of the most classic puzzles involving balls is figuring out the odd one out using common balance. There are many levels of puzzles based on the same concept for different levels of interviews – Simple ones for phone interviews to the most gruelling 1 hour hard work needing hard ones.

Problem space
The general problem is you will be given n balls and one of them is either heavier or lighter and you are asked to find out the minimum number of weighings using a common balance required to find out the odd one out.

• Link (via reddit)

It’s times like these that the internet makes me most happy. When respectable online publications publish entertaining and interesting stories about the world’s hardest Sudoku puzzle, you’d at least expect them to give you a link to it, or a picture of it. Oh, yes, you guessed it. They don’t. But I couldn’t find it anywhere! So I undustriously hunted, and eventually found the secret formula hidden away in an ASCII-like tomb of Sudoku knowledge.

• Link (via reddit)