Even though general relativity has enjoyed profound success throughout the century since its discovery, there are at least two reasons to think that it may have to undergo small, albeit possibly profound, revisions. One reason, essentially uncontroversial, is the open problem of how to unify general relativity with quantum theory, while the second reason, essentially controversial, regards whether certain dynamical anomalies in astronomy and cosmology are best explained in terms of new, otherwise undetected forms of matter, or in terms of a modification of gravitational theory.

We will explore these two themes from a more specific angle. In particular, the conference speakers will address the issue of “spacetime emergence” within certain approaches to quantum gravity in a cosmological setting. If, as is usually taken to be the case, general relativity breaks down as a classical initial singularity is approached, what could this mean for the view of spacetime as emergent in the early universe? Does the thermodynamic arrow of time require treating initial and final singularities differently and thereby impose fundamental constraints on the structure of a future theory of quantum gravity? More generally, what could in principle even be meant by a physical theory without at least some underlying notion of spacetime?

Similarly, if the path is pursued of modifying general relativity (MOND, TeVeS, f(R), torsion, etc.) in order to avoid the new forms of matter and/or energy that the cosmological concordance model posits, what does this mean for the lessons about matter, motion, gravity and spacetime that Einstein taught us? We will also consider recent work that clarifies the space of alternatives to general relativity, in order to assess the viability of proposals to emulate general relativity’s success at length scales where it has passed stringent tests, while differing at cosmological scales.

**June 12 – 14, 2017
Western University**

**London, Ontario**

##### Confirmed Speakers:

Niayesh Afshordi (University of Waterloo, Perimeter Institute for Theoretical Physics)

Tessa Baker (University of Oxford)

Robert Brandenberger (McGill University)

Karen Crowther (University of Geneva)

Henrique Gomes (Perimeter Institute for Theoretical Physics)

Nick Huggett (University of Illinois at Chicago)

Michela Massimi (University of Edinburgh)

Daniele Oriti (Max Planck Institute for Gravitational Physics – Albert Einstein Institute)

Simon Saunders (University of Oxford)

Lee Smolin (Perimeter Institute for Theoretical Physics)

Francesca Vidotto (Institute for Mathematics, Astrophysics and Particle Physics – Radboud University Nijmegen)

##### Conference Videos

*Pictured above: Original artwork by Kaća Bradonjić. Part of the “Projections” series, inspired by Carlo Rovelli, “Space and Time (or not?) in Loop Quantum Gravity”.*