ENERGY NEVER STOPS radiating through space, or on Earth. For more than a decade, hundreds of millions of samples from the never-ending deluge of protons, nuclei, and other atomic debris have collected in the International Space Station’s cosmic ray bucket—an instrument called the Alpha Magnetic Spectrometer. Here at home, cloud chambers—like those used by CERN, the Switzerland-based European Organization for Nuclear Research—illuminate the universe’s invisible cosmic storm.
In March 1951, longtime Popular Science contributor Kenneth M. Swezey treated space enthusiasts and DIYers to a step-by-step guide to making a cloud chamber, using a peanut butter jar. “The secret of any cloud chamber is a supersaturated vapor,” Swezey wrote. “As atomic particles dart through this vapor, they condense molecules in their path, leaving visible droplets—like vapor trails of high-flying aircraft.”
The first cloud chamber was devised by physicist Charles Thomas Rees Wilson in 1895 to reproduce the airborne puffs and study their behavior. By 1910, he’d begun spying the trails of charged particles, which ionized the supersaturated air and caused water droplets to form. At about the same time, physicist Victor Hess determined that charged particles, which he dubbed cosmic rays, were entering Earth’s atmosphere from space, a discovery that earned him a Nobel Prize in 1936.
Despite their ubiquity, the origins of those celestial sparks remain a mystery, although supernovas and ordinary stars like our sun are suspected to be prime sources. Beams of energy collide with atoms in Earth’s upper atmosphere, spawning charged subatomic particles like pions, muons, electrons, and positrons, whose ionized trails show up as spindly lines in cloud chambers. Radiation here on Earth also generates cosmic rays.
When Swezey offered up his home chamber in the 1950s, its use seemed somewhat practical. Fears of nuclear war, spurred by the worsening Cold…
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