The first half of the 1930s saw a curious foreshadowing of the Space Race of the 1950s and 1960s: the Stratosphere Race. It came about because Auguste Piccard, a Swiss physicist, became curious about the upper atmosphere. Since the air became too thin to breathe above four miles or so, Piccard invented a pressurized capsule to maintain a breathable air pressure, and on May 27, 1931 Piccard and his assistant Paul Kipfer set a record by rising up 9.8 miles in a balloon. The following year, on August 18, Piccard and Max Cosyns flew to a height of 10.4 miles. This touched off an international competition between the United States and the Soviet Union to reach the highest altitude, which formed the background for Amelia Reynolds Long's story "Cosmic Fever", published in the February 1937 issue of Astounding Stories.
When Long wrote her story in 1936, the altitude record was held by the U.S. Army Air Corps' Explorer II, which reached an altitude of 13.7 miles on November 11, 1935 while manned by Captain Albert Stevens and Captain Orvil Anderson. Long's hero, Pat Marsh, plans to fly his balloon up to an altitude of 60 miles, more than four times as high, in order to study cosmic rays.
Cosmic Rays had been discovered by a balloon-borne researcher named Victor Francis Hess in the Austro-Hungarian Empire in 1912. Hess found that radiation levels increased the higher he rose into the atmosphere, leading him to conclude that the radiation was coming from outer space. Hess's observations were confirmed by Robert A. Millikan of CalTech in 1925, and it was Millikan who named the phenomenon "cosmic rays". Millikan thought the rays were just that: electromagnetic radiation, but in 1930 Arthur Compton of the University of Chicago proposed that they were subatomic particles. Piccard agreed with Millikan, and in her story Long also assumes that cosmic rays are, like sunlight, a form of radiation.
Long also assumed that, like sunlight, most cosmic rays were reflected by the Earth's atmosphere, and that as one rose higher above the Earth, the energy from cosmic rays would grow stronger until they would heat Pat Marsh's balloon hundreds of degrees when it rose above the stratopause. As evidence she cited Piccard's ascent in 1931, when he reported his gondola growing uncomfortably warm. However, Piccard's experiences actually contradicted Long. For his 1931 flight he had painted his gondola half white and half black, and had installed a mechanism that would allow him to rotate it to regulate the temperature. The mechanism became jammed, though, with the black side of the gondola facing the sun, and that caused the temperature rise. On his later flight in 1932, when he rose even higher, Piccard reported that the temperature in the gondola fell below freezing, and during their flight in 1935 Stevens and Anderson found their gondola becoming even colder. However, as science fiction writers frequently did (and do), Long was willing to fudge the facts in order to consider an unusual idea: the idea that cosmic rays were energetic enough to drastically heat objects in space. In effect, Long predicted that outer space would turn out to be one big microwave oven.
As it turned out, the balloon altitude record set by Stevens and Anderson remained in place for 21 years. They had reached the upper limit of what could be accomplished with the available technology, and it wasn't until November 8, 1956 that a manned balloon flew higher. By that time, though, Arthur Murray had already broken the Explorer II altitude record on May 28, 1954, reaching 16.5 miles in the experimental jet aircraft Bell X-1A. The current record for a manned balloon flight was set on May 4, 1961 when Commander Malcolm D. Ross and Lieutenant Victor A. Prather, Jr. flew in the USN Strato-Lab V to a height of 21.5 miles.
It also turned out that Millikan and Piccard were wrong, and Compton was right, about the nature of cosmic rays, which are indeed subatomic particles. Most cosmic rays are deflected by the Earth's magnetic field rather than its atmosphere, and the launch of Sputnik I on October 4, 1957 demonstrated that they would not, in fact, cook an object in outer space.
The American Institute of Technology, the research institute that built Pat Marsh's first two unmanned balloons, and of which Professor Roy Anthony was a member, was an invention on Long's part, though the name was used for real by a truck driving school founded in Phoenix, Arizona in 1981.