Uchronia

Mercier's resort to uchronia, on the other hand, initiates a new paradigm for utopian literature not only by setting action in a specific future chronologically connected to our past and present but even more crucially by characterizing that future as one belonging to progress and thus linked causally if not immediately to the reader's time.

This uchronia actually exerted some influence in its time, converting many readers to socialism because they wanted to live in the world of Bellamy's vision.

Alternate or alternative histories—uchronias or counterfactuals, to employ yet two other terms—have gone through a boom-and-bust cycle lately, accruing both merits and demerits. […] S.M. Stirling falls into none of these pitfalls. In fact, his new book is simply the best uchronia in years.

For Portelli, uchronia comprises 'that amazing scene in which the author imagines what would have happened if a certain historical event had not taken place'.