W. W. Norton & Company in United States Quantum: Einstein, Bohr, and the Great Debate About the Nature of Reality is a science history book written by Manjit Kumar.

He describes Einstein, Bohr and the "Great Debate about the Nature of Reality" that played out over a number of years, particularly at the Fifth Solvay International Conference on electrons and photons in 1927, where the physicists met to discuss the then newly formulated quantum theory.

It narrates the life of some eminent physicists and their work and also gives a view of the environment of science at that time.

It tells the life stories of Bohr, Einstein, Planck, Rutherford, Schrödinger, and others.

Quantum was number 1 on the Hindustan Times top 10 science books you should read in 2012.