The discussion centers on proving the invariance of the momentum equation F=dp/dt under Galilean transformations in systems with variable mass. It references Goldstein's work, suggesting that he provides proof of momentum invariance, specifically p=p'. The conversation highlights the importance of Noether's theorem and the necessity of deriving forces from a Lagrangian to validate this invariance. Additionally, it emphasizes the connection to Hamilton's principle of least action as a foundational assumption. Understanding these concepts is crucial for addressing the question of momentum invariance in variable mass systems.
