Slate ponders how to communicate the danger of radioactive waste to the far future. The problem is, if they can't read English, or recognize the radiation trefoil, anything you do sounds more likely to intrigue future anthropologists than to warn them off:
Even if future trespassers could understand what keep and out mean when placed side by side, there's no reason to assume they'd follow directions. In "Expert Judgment," the panelists observe that "[m]useums and private collections abound with [keep out signs] removed from burial sites." The tomb of the ancient Egyptian vizier Khentika (also known as Ikhekhi), for example, contains the inscription: "As for all men who shall enter this my tomb ... impure ... there will be judgment ... an end shall be made for him. ... I shall seize his neck like a bird. ... I shall cast the fear of myself into him." It's possible that the vizier's contemporaries took Khentika at his word. But 20th-century archaeologists with wildly different religious beliefs had no reason to take the neck-cracking threat seriously. Likewise, a scavenger on the Carlsbad site in the year 12,000 C.E. may dismiss the menace of radiation poisoning as mere superstition. ("So I'm supposed to think that if I dig here, invisible energy beams will kill me?") Hence the crux of the problem: Not only must intruders understand the message that nuclear waste is near and dangerous; they must also believe it.
The report's proposed solution is a layered message--one that conveys not only that the site is dangerous but that there's a legitimate (nonsuperstitious) reason to think so. It should also emphasize that there's no buried treasure, just toxic trash. Here's how the authors phrase the essential talking points: "[T]his place is not a place of honor ... no highly esteemed deed is commemorated here." Finally, the marker system should communicate that the danger--an emanation of energy--is unleashed only if you disturb the place physically, so it's best left uninhabited.
As for the problem of actually getting these essentials across, the report proposes a system of redundancy--a fancy way of saying throw everything at the wall and hope that something sticks. Giant, jagged earthwork berms should surround the area. Dozens of granite message walls or kiosks, each 25 feet high, might present graphic images of human faces contorted with horror, terror, or pain (the inspiration here is Edvard Munch's Scream) as well as text in English, Spanish, Russian, French, Chinese, Arabic, and Navajo explaining what's buried. This variety of languages, as Charles Piller remarked in a 2006 Los Angeles Times story, turns the monoliths into quasi-Rosetta stones. Three rooms--one off-site but nearby, one centrally located, and one underground--would serve as information centers with more detailed explanations of nuclear waste and its hazards, maps showing the location of similar sites around the world, and star charts to help intruders calculate the year the site was sealed. According to 1994 estimates, the whole shebang would cost about $68 million, but that's just a ballpark figure based on very incomplete data.
Proposals for the "earthworks" component demonstrate that the whole project of communicating with the future is really a creative assignment, more dependent on the imagination than on expertise. What'll really scare off 210th-century tomb raiders? The report proposes a "Landscape of Thorns" with giant obelisklike stones sticking out of the earth at odd angles. "Menacing Earthworks" has lightning-shaped mounds radiating out of a square. In "Forbidding Blocks," a Lego city gone terribly wrong, black, irregular stones "are set in a grid, defining a square, with 5-foot wide 'streets' running both ways. You can even get 'in' it, but the streets lead nowhere, and they are too narrow to live in, farm in, or even meet in."
I know I'd want to get to the heart of the mystery if I came across any of those setups.