Lensing as a probe of Gravitation and Cosmology

Gravitational lensing is was the first prediction of General Relativity to be observationally verified. It has been a great probe of various facets of Gravitation and Cosmology since then. In this talk we will discuss how does lensing help as a probe of  Cosmic Censorship, of UV and IR modifications to gravity and of scalar fields in Cosmology. It has been conjectured that `Nature Abhors a Naked Singularity'. to get rid of some  pathologies associated with such spacetimes, but it has not been proved and as such remains an open question. On the observational front gravitational lensing might be a useful tool to discriminate Black Holes and Naked Singularities. We investigate this question by modeling the Galactic Supermassive Object as a compact object that forms as end state of gravitational collapse in some toy calculations and which happen to be Naked Singularities.. Lensing in such spacetimes where relativistic images are present  even in the absence of photon sphere will be discussed and compared to Schwarzschild Black Hole case. We will also discuss the features of  `time delay' between relativistic images for such cases and its role as a discriminator between possible candidate spacetimes. 
Also we will briefly discuss how lensing can act as a probe of UV modifications to gravity (like Loop Quantum Gravity) , of IR modifications motivated by Cosmology (like Rindler Force) and of scalar fields in Nature.