Humans have always wondered how they might communicate with their descendants—and that desire has surfaced in everything from time capsules to a “John wuz here” tag scribbled on a bathroom door. But to actually leave a message for posterity—say, humans 50,000 years from now—you have to tackle a few complications. One, where will future humans be most likely to find it? Two, what material can stand the test of time? And three, what language or symbols are likely to survive over the next several thousand years?

Those questions swirled in Lorenz Potthast’s mind last year as he researched the topic for his bachelor thesis in integrated design at the University of the Arts in Bremen, Germany. “After all this research, I was kind of depressed,” he says. “It’s not so easy to send a message to the future if you’re really thinking about long term future. You need a lot of knowledge and technology and money.” In the end, Potthast created what he calls a “positive vandalism” machine that uses an Arduino computer and CNC milling to etch messages onto stone, for future generations to see.

To design a solution for communicating with future societies puts you in strange company. The Crypt of Civilization at Oglethorpe University in Atlanta, Georgia, spearheaded by Dr. Thornwall Jacobs in 1936, is often called the first modern time capsule. Dr. Thornwall became fascinated with the idea in 1922 after the excavation of King Tut’s tomb and the many objects buried with him, so he created the Crypt of Civilization, a massive vault of media materials and everyday objects underneath the university that’s meant to be opened in year 8113. More recently, the (now deceased) French artist Jean-Marc Philippe was trying to launch a satellite into orbit containing letters from people today. The satellite, which is supposed to finally launch in January, would return to Earth’s atmosphere in 50,000 years.

Lorenz Potthast

Potthast researched all these guys while considering the best approach for his project. He chose the topic after an earlier project of his, a helmet that creates slow-motion vision for the wearer, received awards and a lot of attention from researchers. “This idea of time and perception kept on following me as an interest,” he says. This time, “I wanted to invest in a longer scale, so maybe not a personal perception but a global scale of perception.”

For the “positive vandalism” machine Potthast decided that the messages should be left in stone, at famous monuments. In the past, the location of buried time capsules has gone missing, so this would prevent the notes from getting lost in the future. And stone has proven itself as a material for the ages: societies have used gravestone markers for burying the dead for centuries. “The idea of gravestones show that human development has always linked the material of stone with immortality. Stone is seen as an indelible material.” Potthast decided other materials, like DVDs or hard drives, aren’t future-proof. “If people were to find a hard drive in a hundred years, they need to be able to get it running again, understand binary code, then need an understanding of the written language, like English.”

Settling on the language for the actual messages is the most dubious part of the project. The meaning of iconography can change drastically or be washed away with time. (For example, the skull and crossbones that we read as poisonous used to be a symbol for rebirth.) After considering that cave paintings from 40,000 years ago still have some current connotations—like the imprints of human hands—Potthast programmed the Arduino with a series of familiar icons, like the envelope symbol for “mail.” “I saw it as a maybe our today’s most present symbols,” he says. Once the CNC milling machine and interface get strapped onto the chosen stone, the user presses a button and it’ll drill the selected icon into the rock (or tree). As with prehistoric paintings, “You cannot really understand what they were trying to communicate, but you can appreciate it. There’s not so much information, but some emotions and some insights into their everyday life.”

The “positive vandalism” machine is a concept, but Potthast says he hopes to get it up and running in the wild soon.