The crooked road to effective stress

摘要: Two Lagrangian functions are said to be variationally equivalent if they differ by a null (a whose associated Euler-Lagrange equations identically satisfied). Kibble [1] noted in his seminal paper of 1961 that Lagrangians lead inequivalent gauge field theories, after which this important observation was actively ignored. There is an understandable reason for situation; distinguished only their distinct natural Neumann data, while elementary particle physics rarely ever considers problems with imposed data. On the other hand, data demand inclusion appropriate order made natural. It thus clear theories must make due allowances gauge-theoretic inequivalence Lagrangians. A specific case point theory materials defects subjected tractions on boundaries.