About the author Dipanjan Rai Chaudhuri, born in Kolkata in 1944, read Physics at Presidency College in the turbulent late sixties and early seventies, while breathing philosophy, politics and literature. Over the years, he alternated between physics and political activism -earning a PhD from London, spending a term in prison, teaching and publishing research papers in physics and also working with the Association for Protection of Democratic Rights. This strange mix led VS Naipaul to feature Dipanjan in one of his books, India: A Million Mutinies Now. He has published two volumes of poetry in Bengali, several books on the political economy of West Bengal, and books on science for children. He writes prolifically on current affairs, both in Bengali and English. He retired as Professor and Head, Department of Physics, Presidency College, in 2004, but continues to demystify physics for school children. In his spare time, apart from writing, he is involved, along with his students, in the education of children in the slums of Kolkata.