Raj works on planetary-scale geophysical problems using new techniques that reconcile and fit concurrently a wide variety of seismological observations. His doctoral work has resulted in the next-generation three-dimensional images of the Earth’s interior, similar to a CT-scan for the human body. Recent progress includes evaluating the extent of radial anisotropy with implications for large-scale mantle flow, detecting seismological signatures of chemical heterogeneity from scaling relationships between the elastic parameters and density, as well as radial models that represent accurately the Earth’s spherically averaged properties. He works with several collaborators to infer the modeled properties in terms of the dynamics and evolution of the Earth's interior.