Cover art
Brown, Fredric. What Mad Universe. Bantam 1954.

Brown, Fredric. What Mad Universe
Divergence: 1903 CE
What if: An inventor working on a sewing machine inadvertently discovered a space warp drive.
Summary: The editor of Surprising Stories finds himself in a parallel universe where 50 years of spaceflight has resulted in a New York right out of the stories his magazine published.
Comments: Allohistorical content is not particularly strong, but the story is one of the first to advance the idea of multiple parallel worlds.
Published: Dutton 1949; Bantam 1950, 1954; SFBC 1977; Easton 1986; Grafton 1987 (0586071636).
— Included in Martians and Madness, NESFA 2002 (1886778175BUY).
— Originally in Startling Stories, September 1948.
Original in: English.
Translation: French by Jean Rosenthal as L'univers en folie, Rayon 1953, Denoël 1970 (2207501205).
Translation: German by Rainer Eisfeld as Das andere Universum Möwig 1958.
Translation: German by Werner Gronwald as Das andere Universum, Heyne 1970.
Translation: Polish by Zbigniew A. Krolicki as Ten zwariowany wszechswiat, Alfa 1990 (8370014127).
Translation: Italian by Adria Mandrini as Assurdo universo, Mondadori 1953, 1990.