The work published by Einstein, Podolsky and Rosen (EPR) in 1935 is a classic in modern physics. It discusses, for the first time, the central feature of the quantum theory: entanglement. In general, systems are intertwined with each other in nature; that is, they have only one common, non-divisible state.

Quantum entanglement is a physical phenomenon that occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot be described independently - instead, a quantum state may be given for the system as a whole. Measurements of physical properties

Finally, addressing the formidable difficulties posed for tensed accounts of time by the Special Theory of Relativity, he suggests that a modified version of the theory, compatible with the account of time in this book, is to be preferred to the standard version.

"In a complete theory there is an element corresponding to each element of reality. A sufficient condition for the reality of a physical quantity is the possibility of predicting it with certainty, without disturbing the system. In quantum mechanics in the case of two physical quantities described by non-commuting operators,

Utterly beautiful. Profoundly disconcerting. Quantum theory is quite simply the most successful account of the physical universe ever devised. Its concepts underpin much of the twenty-first century technology that we now take for granted. But at the same time it has completely undermined our ability to make sense of the