Paradoxes are notoriously hard to understand but in his book, ‘Paradox; The Nine Greatest Enigmas in Science’, Jim Al-Khalili attempts to describe and explain some of the most common problems that are thought of as paradoxes. This is done on the whole successfully, with Khalili explaining some of the most difficult concepts in modern physics, such as elements of Einstein’s Theory of Relativity, in a way that is relatively easy to understand, although rereading is often required.
One ‘paradox’ that I particularly enjoyed reading about was Olbers’ paradox. This is one way to prove that the universe had a beginning. It starts with a seemingly simple question: why does the sky get dark at night? When this questions different theories were put forward to explain why the night sky wasn’t brighter than the day’s sky as light should be coming from stars in all directions. Some scientists thought that the darkness was the wall of the universe, others thought that the further away stars were too faint to see with the naked eye. The conundrum can only be resolved when you consider the possibility that the universe had a beginning (when the problem was solved the big bang was only a theory, as it still is). The universe is expanding and so the light that is travelling from the most distant stars has not reached us yet and the stars themselves are travelling further away from us. Therefore light does not reach us from all directions, and the night’s sky is dark.
‘Paradox’ is a very good and very interesting physics book and it is mostly understandable. Some passages do need to be reread in order to grasp some of the more complex theories and concepts but the language is both clear and simple. I would recommend this book to almost anyone who wants to learn more about physics in order to broaden their knowledge, rather than just learning in the classroom. Having said this I would recommend having a basic knowledge of quantum physics, even if it is just knowing what Schrödinger’s cat is.