Talks

In my talk, I will argue that symmetry strongly changes the behaviour of massive gravity relative to its massless sibling.   After reviewing the formulation of dRGT theory of ghost-free massive gravity, I will examine the minimal model and next-to-minimal model in spherical symmetry. Although the latter has been argued to have a good Vainshtein mechanism in spherical symmetry, I will derive a restriction on non-relativistic matter that is at odds with a reasonable phenomenology. Moreover, the theory cannot reproduce the same behaviour as GR for a scalar field collapse in the small mass limit without encountering a singularity at some point in the evolution.   Since symmetry is the epitome of non-genericity, the resolution may well be that we should forgo symmetry and focus on more generic behaviour in massive gravity to study the screening mechanism. This talk is based on https://arxiv.org/pdf/2409.18802

I will discuss two fundamental systems in moist geophysical fluid dynamics: (1) The moist shallow water equations, giving rise to a theory of the MJO, and (2) A idealised system of moist convection, the 'Rainy-Benard Model'.

The tropical climate varies in a wide range of spatial and temporal scales. The tropical climate variability is more complex than the climate of the mid-latitudes because of the important role played by latent heat of condensation. The land-sea contrast theory that was proposed more than 300 years ago has been shown to be inadequate. A new paradigm based on the moist static energy budget has gained currency. I will discuss how this new paradigm provides new insight into the variability of the monsoon and the role land and oceans play in the evolution of tropical climate variability