Geometric Algebra and symmetry in crystallography and physics	

Eckhard Hitzer	-- International Christian University	

From viewpoints of crystallography and of elementary particles, we explore symmetries of multivectors in the geometric (Minkowski) algebra Cl(3,1) that can be used to describe space-time.
Dr. Carsten	Dr. Carsten Held	Euro-Schulen Erfurt, Germany	A Presupposition of Bell’s Theorem	The most prominent version of Bell’s theorem consists of the Bell-CHSH inequality and a quantum-mechanical example violating it. The inequality is shown to rest on the non-trivial presupposition that the values of elementary spin quantities are scalars, not, e.g., vectors. In the version considered, the theorem’s argument succeeds for scalars and fails for vectors. However, the reference to vector values can be motivated from the physics of spin. Hence, recognizing the presupposition suggests a critical reassessment of the theorem.