A rank 4 tensor example in physics is the Riemann curvature tensor (Rijkl), which is significant in general relativity. Another example is the third-order nonlinear susceptibility tensor, often encountered in materials science. The discussion highlights the challenge of encountering rank 4 tensors in academic settings, especially when prior coursework has only covered up to rank 3 tensors. Understanding these tensors is crucial for advanced studies in physics. Overall, rank 4 tensors play an important role in both theoretical and applied physics contexts.