- #1
albedo
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Please refer to p. 99 and 100 of Rovelli’s Quantum Gravity book (here).
I wonder what is the signification of the “naturalness” of the definition of ##\theta_0=p_idq^i##? If I take ##\theta_0'=q^idp_i## inverting the roles of the canonical variables and have the symplectic 2-forms of the Darboux’s theorem changing sign, ##\omega_0=d\theta_0=-d\theta_0'=-\omega_0'##, I would get ##(d\theta'_0)(X_0)=dH_0## the opposite of eq. 3.7. Or maybe I am not allowed to invert the roles of the variables because I need to work in the cotangent space and the only "natural" 1-form ##\theta_0## must be ##p_idq^i## where first you have the covector ##p_i##? What is the signification of this inversion of sign of the ##dH_0##? Could this be related to the assumption that the energy of a system is in reality the difference with an energy taken as zero? I would like to understand better the symplectic formulation of mechanics as it looks crucial when you go from the classical to the general-relativistic Hamiltonian formulation.
Thank you in advance!
I wonder what is the signification of the “naturalness” of the definition of ##\theta_0=p_idq^i##? If I take ##\theta_0'=q^idp_i## inverting the roles of the canonical variables and have the symplectic 2-forms of the Darboux’s theorem changing sign, ##\omega_0=d\theta_0=-d\theta_0'=-\omega_0'##, I would get ##(d\theta'_0)(X_0)=dH_0## the opposite of eq. 3.7. Or maybe I am not allowed to invert the roles of the variables because I need to work in the cotangent space and the only "natural" 1-form ##\theta_0## must be ##p_idq^i## where first you have the covector ##p_i##? What is the signification of this inversion of sign of the ##dH_0##? Could this be related to the assumption that the energy of a system is in reality the difference with an energy taken as zero? I would like to understand better the symplectic formulation of mechanics as it looks crucial when you go from the classical to the general-relativistic Hamiltonian formulation.
Thank you in advance!