In 2006, artist Ben Rubin created the San Jose Semaphore which is installed on top of the Adobe headquarters building in San Jose, California. The Semaphore consists of four orange LED circles with diametric lines that shift every 7.2 seconds, displaying a looping encrypted message.
The first puzzle the Semaphore transmitted was solved in weeks. But the second puzzle was unsolved for nearly five years.
Until Jimmy Waters, a high school math teacher from Powell, Tennessee, decided to tackle it, spending a month of his summer vacation on the problem.
First, Waters assigned numeric values to each circle’s position and configuration. When Waters graphed the result, he realized that the wave-like pattern looked like a visualization of an audio file.
But what was the message contained in that audio file?
According to the Knoxville News Sentinel, Waters’ hometown newspaper, Waters “searched online for a way to turn numbers into sound and found a script using the programming language, Julia.”
After converting the file and adjusting the frequency, Waters recognized Neil Armstrong’s voice from the first broadcast from the moon.
In recognition of Jimmy Waters’ work, Adobe gave Powell High School a year’s worth of Adobe software and two 3D printers, and flew Waters to San Jose to meet Ben Rubin.
Mr. Rubin is now working on a third puzzle to challenge would-be decoders.