The God Equation tells the story of how physics reached this point. Kaku explains how gravity pushes rather than pulls, and tackles curious questions such as: why is the night sky black if it is filled with stars? He elucidates esoteric mathematics with graspable, real-life illustrations, and explains how breakthroughs in theoretical physics have had a tangible impact on human experience: the laws of motion were the rudiments of the Industrial Revolution; the power of earthquakes and volcanoes comes from the weak nuclear force.
This is a general problem that will be familiar to regular readers of popular physics, the obligatory whistle-stop tour of increasingly complex theories that is necessary to then get to the really really complex theories. For connoisseurs of the genre, Kaku does it well. General Relativity is dispatched with a metaphor about funfair carousels, quantum mechanics is covered through the prism of an argument between Bohr and Einstein, light is covered through the prism of prisms.