We review recent progress in massive gravity. We start by showing how different theories of
massive gravity emerge from a higher-dimensional theory of general relativity, leading to the …

Quantum mechanics is an extremely successful theory that agrees with every experimental
test. However, the principle of linear superposition, a central tenet of the theory, apparently …

The metric-affine variational principle is applied to generate teleparallel and symmetric
teleparallel theories of gravity. From the latter we discover an exceptional class which is …

In Einstein's gravitational theory, the spacetime is Riemannian, that is, it has vanishing
torsion and vanishing nonmetricity (covariant derivative of the metric). In the gauging of the …

Geometric Algebra has advanced rapidly in the last ten years, becoming an important topic
in the physics and engineering communities. As leading experts in the field the authors have …

Understanding the reason for the observed accelerated expansion of the Universe
represents one of the fundamental open questions in physics. In cosmology, a classification …

We introduce a technique for restoring general coordinate invariance into theories where it
is explicitly broken. This is the analog for gravity of the Callan–Coleman–Wess–Zumino …

Planar metamaterials that exhibit a zero index of refraction have been realized
experimentally by several research groups. Their existence stimulated the present …

The unifying theme of this book is the interplay among noncommutative geometry, physics,
and number theory. The two main objects of investigation are spaces where both the …

This paper points out the importance of the assumption of locality of physical interactions,
and the concomitant necessity of propagation of an entity (in this case, off-shell quanta …