You’ve seen it in record bins. You’ve seen it represented as a 500×500 pixelated image on iTunes and Amazon. You’ve seen it on T-shirts, coffee mugs, dorm room walls, and on refrigerator magnets. But you probably don’t have the first clue about all of the science behind the cover of Joy Division’s seminal debut album Unknown Pleasures. Thankfully, Scientific American decided to take a break from running articles about particle physics and the effects of climate change to explain it to the rest of us dullards.
As the piece describes, the image on the album cover is a stacked plot, or a data visualization of a pulsar. Radio astronomer Harold D. Craft Jr. originally created it for his 1970 Ph.D. dissertation Radio Observations of the Pulse Profiles and Dispersion Measures of Twelve Pulsars. A pulsar is a rapidly rotating neutron star, or a star that erupted into a supernova, leaving behind a small dense core that is pressed so tightly by gravity that its protons and electrons combine together to create neutrons. Pulsars generally carry the same mass as our sun, but are very dense and have a diameter of around 20 kilometers.
Along with a high degree of density, pulsars also have a very strong magnetic field. The article explains, “As the star rotates, it emanates a radio beam, generated by the combined effect of the magnetic field and the rotation, which sweeps periodically through the surrounding space, like a lighthouse beacon.” As visualized in a two-dimensional form, the radio beam would look like a perfectly rounded bell curve, but due to interferences through space like hot spots, solar wind, and internal variations in the cone of emissions, the stacked plot ends up looking far more jagged and craggy.
So the Unknown Pleasures album cover is actually very much like the music within: a singular moment in time captured and recorded for posterity and future examination.