“On the first Sunday of 1969 Robert Barry went to Central Park with four capsules of radioactive material in his pocket. He had ordered them from a scientific supply catalog, choosing an isotope of his namesake, barium-133, the only one of twenty-two known isotopes of the element that does not dangerously decay within seconds or minutes. He walked to the Great Lawn behind the Metropolitan Museum of Art and, in two locations there, inconspicuously buried the capsules. He then snapped a quick photograph at each of the sites, leaving behind what he called 0.5 Microcurie Radiation Installation.
With a half-life of slightly more than ten years, the barium isotopes continue to decay. So unless they have been unearthed, they are emitting a faint but charged bit of energy, like an invisible signal from a dying star, unbeknownst to the ballplayers, dog walkers, and picknickers on the grass above.” —Peter Eleey, Thursday