Loop Quantum Gravity: Four Recent Advances and a Dozen Frequently Asked Questions

As per organizers' request, my talk at the 11th Marcel Grossmann Conference consisted of two parts. In the first, I illustrated recent advances in loop quantum gravity through examples. In the second, I presented an overall assessment of the status of the program by addressing some frequently asked questions. This account is addressed primarily to researchers outside the loop quantum gravity community.Comment: 21 pages, to appear in the Proceedings of the 11th Marcel Grossmann Conferenc

Implications of a positive cosmological constant for general relativity

Most of the literature on general relativity over the last century assumes that the cosmological constant $\Lambda$ is zero. However, by now independent observations have led to a consensus that the dynamics of the universe is best described by Einstein's equations with a small but positive $\Lambda$. Interestingly, this requires a drastic revision of conceptual frameworks commonly used in general relativity, \emph{no matter how small $\Lambda$ is.} We first explain why, and then summarize the current status of generalizations of these frameworks to include a positive $\Lambda$, focusing on gravitational waves.Comment: A Key Issues Review, Commissioned by Rep. Prog. Phys. 12 pages, 3 figure