13.8

John Gribbin is one of the most engaging and informed of popular science writers who also has a very good grasp of the history of science and biographies of its principal characters, which makes this a highly readable account of the history of cosmology. He sets out what he calls the most important factor in his introduction, namely the agreement between quantum theory and relativity theory that separately give right answers to the question of the age of the Universe - 13.8 billion years, just older than the ages of the stars it contains, as should be the case; they are just a little bit younger than the universe. Gribbin takes the reader on a tour of how we know the ages of stars and the age of the Universe using a number of different methods. One of the most interesting episodes is seeing how early indications of the Big Bang theory were missed by researchers originally committed to the Steady State theory. He still finds it mind-blowing that only 5% of the Universe is formed of the matter with which we are familiar, 25% of cold dark matter and the rest is a form of dark energy. He concludes that the finding that the age of the Universe is just slightly older than the stars is both the ultimate truth of science and the ultimate proof that science is the best way to understand how the world works.