From Gernsback to Campbell
One leading influence on the creation of the Golden age was John W. Campbell, who became legendary in the genre as an editor and publisher of science fiction magazines, including Astounding Science Fiction, to such an extent that Isaac Asimov stated that "...in the 1940s, (Campbell) dominated the field to the point where to many seemed all of science fiction." Under Campbell's editorship, science fiction developed more realism and psychological depth to characterization than it exhibited in the Gernsbackian "super science" era. The focus shifted from the gizmo itself to the characters using the gizmo.
Most fans agree that the Golden Age began around 1938-39, slightly later than the Golden Age of Detective Fiction, another pulp-based genre. The July 1939 issue of Astounding Science Fiction  is sometimes cited as the start of the Golden Age. It included "Black Destroyer", the first published story by A. E. van Vogt, and the first appearance of Isaac Asimov ("Trends") in the magazine. Science fiction writer John C. Wright said of Van Vogt's story, "This one started it all." The August issue contained the first published story by Robert A. Heinlein ("Life-Line").
Robert Silverberg in a 2010 essay argued that the true Golden Age was the 1950s, saying that “Golden Age” of the 1940s was a kind of "false dawn". "Until the decade of the fifties", Silverberg wrote, "there was essentially no market for science fiction books at all"; the audience supported only a few special interest small presses. The 1950s saw "a spectacular outpouring of stories and novels that quickly surpassed both in quantity and quality the considerable achievement of the Campbellian golden age", as mainstream companies like Simon & Schuster and Doubleday displaced specialty publishers like Arkham House and Gnome Press.