I rarely find that reading fiction makes me upset. Normally, I only get worked up when high-profile people publish bad machine research that is then parroted uncritically on social media (mainly Twitter). Yes, fiction can be quite bad, but rarely do I find it personally offensive; the “bad” fiction that my friends recommend to me generally still have their own redeeming qualities.

But Greg Egan's short story “Didicosm” managed it anyway.

Spoilers ahead.

A standard take on Greg Egan's writing is that the science part of his science fiction is quite good, but the fiction part is comparatively much worse. His skill lies in coming up with interesting alternative physics or integrating interesting math to create an alternative world, but he often struggles to populate the world with characters with satisfying character arcs. “Didicosm” is no exception to this.

The core scientific conceit of the piece is the following: (in reality,) we seem to observe that the universe is flat and spatially unbounded. A natural conclusion (often made in modern cosmology) is that we exist in an infinite, flat universe.

However, this does not necessarily follow. A 3-torus, for example, is locally flat and has no boundary, but of [...]

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First published:
April 23rd, 2026

Source:
https://www.lesswrong.com/posts/EbqJfCz9qvfptNbCQ/an-angry-review-of-greg-egan-s-didicosm

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Narrated by TYPE III AUDIO.