Quantum mechanics

Context (archaeology)

Gauss–Bonnet gravity

Theoretical physics

Cosmology

Gravitation

Biology

Einstein

Classical mechanics

Numerical relativity

Introduction to the mathematics of general relativity

Geology

Paleontology

Higher-dimensional Einstein gravity

Physics

Gauss–Bonnet theorem

Gauss

Term (time)

Classical and Quantum Gravity

We review the topic of 4D Einstein-Gauss-Bonnet gravity, which has been the subject of considerable interest over the past two years. Our review begins with a general introduction to Lovelock's theorem, and the subject of Gauss-Bonnet terms in the action for gravity. These areas are of fundamental importance for understanding modified theories of gravity, and inform our subsequent discussion of recent attempts to include the effects of a Gauss-Bonnet term in four space-time dimensions by re-scaling the appropriate coupling parameter. We discuss the mathematical complexities involved in implementing this idea, and review recent attempts at constructing well-defined, self-consistent theories that enact it. We then move on to consider the gravitational physics that results from these theories, in the context of black holes, cosmology, and weak-field gravity. We show that 4D Einstein-Gauss-Bonnet gravity exhibits a number of interesting phenomena in each of these areas.

The 4D Einstein–Gauss–Bonnet theory of gravity: a review