Barrier to Yesterday
by Bob Shaw
The story revolves around tribes who migrate to follow the sun around a slowly rotating
world. I don’t understand what the title refers to, but it is not time travel.
— Michael Main
He seemed to think it was a privilege to live on a world whose spin had almost stopped,
stretching the days and nights into years so that it was useless even to go underground.
“Barrier to Yesterday” by Bob Shaw, in Nebula Science Fiction #16, March 1956.