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Why lagrangian is negative number?
In the special relativistic action for a massive point particle, $$\int_{t_i}^{t_f}\mathcal {L}dt,$$ where the Lagrangian $$\mathcal {L}=-E_o\gamma^{-1}$$ is a negative number then the action is a negative or positive number?
(in my research it was negative, the result was correct but minus sign make me to ask this question)