Science Fiction Books/Scifi novel + a short story
Butch Malahide wrote at 2013-01-25 08:50:37
"The Men Return" is a classic, but I don't think it fits the description very well. Two stories that fit better: "The New Reality" by Charles L. Harness; "Matter's End" by Gregory Benford.
Butch Malahide wrote at 2013-01-27 00:36:46
Here are lists of publications where those two stories can be found, from the ISFDB:
"The New Reality" by Charles L. Harness:http://www.isfdb.org/cgi-bin/title.cgi?41114
"Matter's End" by Gregory Benford:http://www.isfdb.org/cgi-bin/title.cgi?41164
"The New Reality" is almost surely the story the asker is looking for: it is quite a bit older and more famous than "Matter's End", and it contains actual dialogue about the idea of a formerly-flat earth (couldn't find anything like that skimming the other story):
"I maintain that their information was substantially accurate. I maintain that at one time in our history the earth was flat--as flat as it is now round, and no one living before the time of Hecataeus, though he might have been equipped with the finest modern instruments, could have proved otherwise. His mind was _conditioned_ to a two-dimensional world. Any of us present, if we were transplanted to the world of Hecataeus, could, of course, establish terrestrial sphericity in short order. Our minds have been conditioned to a three-dimensional world. The day may come a few millennia hence when a four-dimensional Terra will be commonplace even to school children, they will have been intuitively conditioned to relativistic concepts." He added slyly: "And the less intelligent of them may attempt to blame our naive three-dimensional planet on our grossly inaccurate instruments, because it will be as plain as day to them that their planet has four dimensions!"