The exploration of the universe has recently entered a new era thanks to the multi-
messenger paradigm, characterized by a continuous increase in the quantity and quality of …

Motivated by ideas about quantum gravity, a tremendous amount of effort over the past
decade has gone into testing Lorentz invariance in various regimes. This review …

I review the current status of phenomenological programs inspired by quantum-spacetime
research. I stress in particular the significance of results establishing that certain data …

The causal set theory (CST) approach to quantum gravity postulates that at the most
fundamental level, spacetime is discrete, with the spacetime continuum replaced by locally …

We present an updated review of Lorentz invariance tests in effective field theories (EFTs) in
the matter as well as in the gravity sector. After a general discussion of the role of Lorentz …

In this Letter, we consider the possibility of reconciling metric theories of gravitation with a
violation of the conservation of energy-momentum. Under some circumstances, this can be …

As we navigate through life we instinctively model time as having a flowing present that
divides a fixed past from open future. This model develops in childhood and is deeply …

We consider here the possibility of quantum gravity induced violation of Lorentz symmetry
(LV). Even if suppressed by the inverse Planck mass such LV can be tested by current …

I review Lorentzian causality theory paying particular attention to the optimality and
generality of the presented results. I include complete proofs of some foundational results …

Trying to combine standard quantum field theories with gravity leads to a breakdown of the
usual structure of space time at around the Planck length, 1.6× 10-35 m, with possible …