2. Equations of motion respect relativity if the action is relativistically invariant. Sup pose t...
2. Equations of motion respect relativity if the action is relativistically invariant. Sup pose that the action can be written as S-JdtL and L-J aC, where L is the Lagrangian density. In tis exercise, you will verify that S is a Lorentz scalar if C is a Lorentz scalar. To do this, you want to verify that d'rd d2d is nvari- ant under Lorentz transformations. To do that, recall from your calculus class how, under changes of variables, the integration measure picks up a factor of the Jacobian determinant. Verify that the Jacobian determinant forA is equal to 1 for a boost along the x-axis and also for a rotation around the axis. Show that Ar,A = η implies that detA = ±1, and that transformations that are continuously connected to the identity must have det 1.
2. Equations of motion respect relativity if the action is relativistically invariant. Sup pose that the action can be written as S-JdtL and L-J aC, where L is the Lagrangian density. In tis exercise, you will verify that S is a Lorentz scalar if C is a Lorentz scalar. To do this, you want to verify that d'rd d2d is nvari- ant under Lorentz transformations. To do that, recall from your calculus class how, under changes of variables, the integration measure picks up a factor of the Jacobian determinant. Verify that the Jacobian determinant forA is equal to 1 for a boost along the x-axis and also for a rotation around the axis. Show that Ar,A = η implies that detA = ±1, and that transformations that are continuously connected to the identity must have det 1.