Quantum theory is our very best description of the microscopic world of atoms and their constituents. It has given us lasers, computers and nuclear reactors, and even tells us how the sun shines and why the ground beneath our feet is solid. Yet the quantum world defies our sensibilities - it is a place where objects can be in two places at once, influence each other at opposite sides of the cosmos and nothing is as it seems until you measure it. Why is the quantum world so strange? Where does it begin and end? And what does this mean for the bedrock of reality? In attempting to address such frontier questions, physicists have come to realise that the quantum world promises exciting new technologies: the ability to communicate with absolute security, computers more powerful than anything built before and even quantum teleportation. In The Trouble With Reality leading physicists and New Scientist take us on journey through the quantum world, its mind-bending properties and the technologies transforming our world. There is a sting in the tale: is quantum theory truly the ultimate theory of reality?