"Can you kick a black hole?" "What about electrons?" As a child, quantum-physicist Smitha Vishveshwara pondered such questions with her astrophysicist father, C. V. Vishveshwara (Vishu); decades later, their musings grew into a series of letter exchanges in Two Revolutions: Relativity and Quantum Physics.

The letters between father and daughter lead the scientifically curious reader through these two remarkable branches of physics that dramatically changed our perception of nature. From the subatomic to the astronomical realms, they weave a rich tapestry of scientific insight, history, personal anecdotes, philosophy, and wonder.

The book traces Einstein's tenacious journey in formulating the theory of relativity, in which space and time merge, and gravitation warps spacetime, forming the very fabric of the Universe. The authors reveal how black holes and gravitational waves emerge as bizarre and awe-inspiring constructs within this framework. In the quantum realm, the book mulls over conundrums posed by wave-particle duality, Schrodinger's curious cat, the beautiful dance of electrons in atoms, and entanglement. It explores communities of particles acting in marvelous concert in magnetic resonance imaging, superfluids, and more.

Fate took unforeseen twists while the book was still in the making. In 2016, after decades of work by numerous researchers, the detection of gravitational waves — Vishu's lifelong dream — finally came to pass. Emanating from two spiraling blackholes a billion light years away, the waves' signals even showed hints of Vishu's pioneering predictions on black hole ringdowns from the 1970s. But soon after that glorious culmination, Vishu fell critically ill. Smitha concludes their story by recreating the euphoria of scientific discovery against the intimate backdrop of life and death.