Harrison, Harry. "Run from the Fire"
Summary: A man from our world aids others in timelines where the sun is about to go nova, including one where Europe is feudal and Iriquois run North America.
Published: In Epoch (eds. Robert Silverberg and Roger Elwood), Berkley/Putnam's 1975 (0399114602) and Berkley 1977 (0425033155); Catastrophes (eds. Isaac Asimov et al.), Fawcett 1981; and Time Wars (eds. Charles G. Waugh and Martin H. Greenberg), Tor 1986 (0812530489, 0812530497).
Original in: English.
Translation: German by Jürgen Buerger as "Flucht vor dem Feuer", in Faszination der Science Fiction (eds. Isaac Asimov, Martin H. Greenberg, and Charles G. Waugh), Bastei-Lübbe 1985 (3404240685).