In 140 pages, two masterly popularisers present 140 explanations of the biggest questions in physics – in the form of 10 or so tweets per page. They set themselves the challenge of boiling down what is essential on each subject into sentences of 140 characters, and the results are both entertaining and brilliantly informative. Not a word is wasted. The reader is not patronized and learns something on every page. If only all science writing could be so precise and so economical. Only science writers of a very high calibre could achieve such compression. Marcus Chown – 'the finest cosmology writer of our day' (Matt Ridley) – has known the Dutch writer Govert Schilling for twenty years. Schilling pioneered this very swift form of explanation in a Dutch newspaper, and suggested to Chown that they collaborate on bringing it to a wider audience. Tweeting the Universe is unlike any other science book.