'A gem of a book' Carlo Rovelli, author of Seven Brief Lessons on Physics 'A unique and beautifully written masterpiece' Max Tegmark, author of Life 3.0 Could there be a civilization on a mote of dust? How much of your fate have you made? Who cleans the universe? Through more than fifty Koans - pleasingly paradoxical vignettes following the ancient Zen tradition - leading physicist Anthony Aguirre takes us across the world from Japan to Italy, and through ideas spanning the age, breadth and depth of the Universe. Using these beguiling stories and a flair for explaining complex science, he covers cosmic questions that giants from Aristotle to Galileo to Heisenberg have grappled with - from the nature of time to the origin of multiple universes to the meaning of quantum theory. Playful and enlightening, Cosmological Koans invites the reader into an intellectual adventure of the highest order, giving us what Einstein called 'the most beautiful and deepest experience' anyone can have - a sense of the mysterious.