In brief, it is a gem of a novel. Shevek, the protagonist, is what we would call a mathematical physicist—though there is little math as such in the text. Devoted to the anarchic principles of his world, Anarres, Shevek specializes in reconciling the two branches of temporal theory. Sequency represents the progression of time, from which new and free societies—like Anarres—can evolve. Simultaneity represents solidarity of the future with the past, and that includes the capitalist world of Urras. (Ironically, Anarres is a moon of Urras, to which the anarchists were allowed to emigrate.) The idea is that both in personal and political life, one does not simply shed one's past. Shevek returns to Urras for the sake of developing his physics, regarded with suspicion by his ideologically limiting world.

Ursula K. Leguin does a beautiful job of presenting Sequency and Simultaneity as complementariy theories in theoretical physics, while subtly making clear that they point metaphorically to the reconciliation of continuity (fidelity to family, to country) with progress. She succeeds in making theoretical issues into urgent personal metaphor: the only other work I know of that succeeds as well is Michael Frayn's Copenhagen.

The Dispossessed is about the inner and outer journey of a physicist, Shevek, on a far away planet. The mathematics & physics content is vague and mostly fictional. It is important to the story that Shevek has a superior ability to think and reason, but it would not break the story for him to be a master chemist instead.

This classical SF book follows, in alternate chapters, both the life of the physicist Shevek and his adventures as a visiting scholar to a nearby planet. Shevek is a theoretical physicist, and we're shown how his interest in mathematics develops early in life and how physical intuition, mathematical analysis and philosophical insights have to come together for a new theory to be born.
[This book was] important to me in my journey to become a mathematician.