In 1975, Queen, which was rapidly becoming serious in its quest to be the leading hard rock/progressive rock band of the decade, surprised everyone with A Night at the Opera. A work of dazzling production genius and amazing musical invention, it was considered by some to be the Sgt. Pepper album of its era. Stuck amid the album's virtuoso production efforts, such as the multi-layered "Bohemian Rhapsody," was a song that went in exactly the opposite direction: "'39." Written as a solo effort by guitarist Brian May, its instrumentation consisted of a single acoustic guitar and a fretless bass, but what made the song even more uncharacteristic for the band was its subject -- space travel at near-light speeds. Couched as a country-folk singalong-style number, its only obvious progressive attribute being the chorus over the opening bars (which made many first-time listeners mistake it for a Justin Hayward/John Lodge Bluejays-era track), it told the story of a man who sets out on a mission into deep space, travelling near the speed of light, who returns to find his wife and children aged and gone, while he has aged scarcely at all. The tune was catchy, the chorus unforgettable, May's acoustic guitar attack hard and lyrical at the same time, and the song found an even bigger audience when it turned up as the B-side of the Day at the Races single "Somebody to Love" -- it was a favorite singalong number at the Queen concerts that followed, and is captured for posterity in that form on the Live Killers concert album. Along with the Byrds' "5D," cut nine years earlier, "'39" is one of two popular songs that deal with the time and space distortion effects inherent in Einstein's General Theory of Relativity, which probably has less to do with its popularity than a great beat and arrangement, and superb guitar playing.