In algebraic geometry, a Calabi–Yau manifold, also known as a Calabi–Yau space, is a particular type of manifold which has properties, such as Ricci flatness, yielding applications in theoretical physics. Particularly in superstring theory, the extra dimensions of spacetime are sometimes conjectured to take the form of a 6-dimensional Calabi–Yau manifold, which led to the idea of mirror symmetry. Calabi–Yau manifolds are complex manifolds that are generalizations of K3 surfaces in any number of complex dimensions (i.e. any even number of real dimensions). They were originally defined as compact...

Maxwell Zombies (MZ) are a class of thermodynamic paradoxes closely related to the famous 19th-century thought experiment, Maxwell's Demon (MD), which tests the foundations of the second law of thermodynamics. MZs differ from MDs insofar as they are not prone to the same physical shortcomings that ultimately foil the demons. The original Maxwell's demon is an imaginary creature that sorts gas molecules on an individual basis, creating a thermodynamic disequilibrium (either in pressure or temperature), whereby work can be performed on a perpetual basis, thereby subverting the second law. MDs fail...