The idea that the speed of light is constant – at 186,000 miles per second – is one of the few scientific facts that almost everyone knows. This constant – c – also appears in the most famous of all scientific equations: e=mc2. However, in recent years, a small group of highly remarkable young physicists has proposed that the central dogmatic belief of modern physics may not be an absolute truth – light may have moved faster in the early life of the universe, it may still move at different speeds somewhere else today. Referring to the history of this heresy and its gradual path toward acceptance, João Magueijo writes as one of the three central figures of the story, introducing the reader to modern cosmology, the implications of VSL (variable speed of light), and the world of physicists. The initial rejection of Magueijo’s ideas begins to give way to a reluctant acceptance that the young men may be right – only the coming years will show the ultimate fate of this ‘dangerous’ idea.