When two bulk objects are separated by a sufficiently small distance, quantum fluctuations in the electromagnetic field give rise to Casimir forces between them. Two papers explore how these forces are affected by the electrical properties of the materials.
Bell showed that quantum entanglement cannot be modeled with local hidden variables alone. Now, physicists argue that only models based exclusively on nonlocal hidden variables can reproduce all possible quantum correlations.
The Dirac and Klein-Gordon equations provide a full relativistic description for particles with spin ½ and 0, respectively. A calculation now shows how to extend this description to particles, such as nuclei, with spin greater than ½.