The Time-Lapsed Man
Brown, Eric, "The Time-Lapsed Man." Interzone 24 (Summer 1988). Collected The Time-Lapsed Man and Other Stories. 1990. Rpt. New York: Tor, 1990. Text available on line as of 18 March 2019.
During flux, traveling as he "mind-pushed his boat between the stars," Thorn and others of his profession feel "one with the vastness of the nada-continuum. [***] Some Enginemen he knew, in fact the majority of those from the East, subscribed to the belief that in flux they were granted a foretaste of Nirvana. Thorn’s Western pragmatism denied him this explanation. He favoured a more psychological rationale – though in the immediate period following flux he found it difficult to define exactly a materialistic basis for the ecstasy he had experienced." The down-side, as it develops in the story, is that after fifty shifts in flux, one by one Thorn's senses lapse into the past.
Cf. and contrast "Awareness of being, without object or subject Nirvana" in Ursula K. Le Guin's "Vaster than Empires and More Slow," especially in the original version of the story (New Dimensions 1 1970), with her description of the experience of NAFAL space travel (Nearly As Fast As Light).
Cited and briefly discussed (and highly recommended) in Stephen Baxter's "The Technology of Omniscience: Past Viewers in Science Fiction.
RDE, Initial Compiler, 18Mar19