The Singular Universe and the Reality of Time: A Proposal in Natural Philosophy is a book about cosmology, philosophy of time, metaphysics and scientific naturalism by the American theoretical physicist Lee Smolin and the Brazilian philosopher Roberto Mangabeira Unger.

[1][2][3] The book discusses a number of philosophical and physical ideas on the true role of time in the Universe.

[4] You might expect a book co-authored by Smolin and Unger to be an exchange about science and human values—something, perhaps, in the region of the 1930 dialogue between Einstein and the polymath Rabindranath Tagore.

But The Singular Universe and the Reality of Time is not that kind of thing: it is a big and daunting book, harder to read than recent works by either author.

The first section, by Unger, includes among other things an exploration of the global, irreversible and continuous attributes of time, followed by an analysis of proto-ontological assumptions.