The interpretation of observed astrophysical data lies at the heart of modern cosmology and general relativity. Advancements in technology, including sensitive telescopes, high-energy neutrino detectors, and gravitational wave detectors, have revolutionized our ability to observe the universe. Modern astrophysics relies on mathematical properties of the initial conditions for the evolution of Einstein’s equations combined with numerical simulations used to analyze data and improve our understanding of the astrophysical systems. The objective of this research is to study inverse problems in astrophysics, which seek the underlying causes of observed astrophysical phenomena. This involves addressing mathematical questions such as uniqueness and stability for predictive models and developing efficient numerical reconstruction techniques. This research additionally has applications in fields such as medical imaging, while also offering opportunities for graduate student training and interdisciplinary collaborations. This proposal aims to investigate two challenges in cosmology and general relativity. The first project focuses on the recovery of the initial status of the universe from the Cosmic Microwave Background. The project will explore an X-ray tomography approach integrated with the physical model, especially the Einstein’s equations governing the evolution of the universe. Collaborative efforts will concentrate on advancing statistical inference techniques and developin