Nuclear waste can remain deadly for thousands of years. Plutonium-23, an isotope used in nuclear weapons production, has a half-life of more than 24,000 years. By contrast, some of the earliest human writing emerged only 5,000 years ago. This presents a challenge of near-eternal proportions: How do you create a label that will convey danger to someone thousands of years in the future—someone who probably won't share any common culture or language with you?
In 1990, the Waste Isolation Pilot Plant called for artists, linguists, writers, and others to develop a marker system that could last for 10,000 years, Roman Mars reports this week in his excellent design podcast 99% Invisible. The plant is the U.S.'s only permanent underground repository for radioactive waste generated from weapons manufacturing and power plants, and the idea was to create a marker system that would alert future generations to the danger of waste decaying below the ground.
Think of how much language changes in just a few hundred years. The Middle English works of Chaucer bear a passing resemblance to today's English, but still require a hefty vocabulary lesson for contemporary readers. Beowulf, written in England sometime in the 11th century, requires complete translation.
Even symbols change meanings over time. The skull and crossbones, widely recognized as a symbol of danger now (albeit one that decorates baby clothes) once symbolized rebirth. The fallout shelter symbol means nothing if you can't read the words. How do you convey that a waste storage site isn't the fun-to-explore variety of danger, but real, death-by-radiation-poisoning danger?
At the 1990 panel, one landscape architect suggested installing giant spikes around the site, so that people would be afraid of it. But the best (or maybe just weirdest) solution proposed actually came from an earlier task force convened in 1981 discuss the proposed Yucca Mountain Nuclear Waste Repository in Nevada. Two philosophers, Françoise Bastide and Paolo Fabbri, suggested we use color-changing cats. From 99% Invisible:
Bastide and Fabbri came to the conclusion that the most durable thing that humanity has ever made is culture: religion, folklore, belief systems. They may morph over time, but an essential message can get pulled through over millennia. They proposed that we genetically engineer a species of cat that changes color in the presence of radiation, which would be released into the wild to serve as living Geiger counters. Then, we would create folklore and write songs and tell stories about these "ray cats," the moral being that when you see these cats change colors, run far, far away.
Cats are always the answer.
Listen to the whole thing here.