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 …

Recent cosmological observations suggest the existence of a positive cosmological constant
Λ with the magnitude Λ (Gℏ/c3)≈ 10− 123. This review discusses several aspects of the …

Horizon-scale images of black holes (BHs) and their shadows have opened an
unprecedented window onto tests of gravity and fundamental physics in the strong-field …

The Early Universe has become the standard reference on forefront topics in cosmology,
particularly to the early history of the Universe. Subjects covered include primordial …

Twenty-five years ago, Michael Green, John Schwarz, and Edward Witten wrote two
volumes on string theory. Published during a period of rapid progress in this subject, these …

Quantum gravity poses the problem of merging quantum mechanics and general relativity,
the two great conceptual revolutions in the physics of the twentieth century. The loop and …

We study candidate vacuum configurations in ten-dimensional O (32) and E 8× E 8
supergravity and superstring theory that have unbroken N= 1 supersymmetry in four …

We provide an overview of the string landscape and the Swampland program. Our review of
the string landscape covers the worldsheet and spacetime perspectives, including vacua …

It is shown how conformal invariance relates many numerically accessible properties of the
transfer matrix of a critical system in a finite-width infinitely long strip to bulk universal …

We propose new mechanisms for understanding neutrino masses in superstring models that
contain E 6-singlet zero-mass fields after compactification. We show that the low-energy …