# Conservation of Energy and CP violation

In classical mechanics there is Noether's theorem: If a system has a certain symmetry there is a related conserved quantity. Energy conservation is a result of a system being time invariant. This is what I have learned in my classical physics and also quantum mechanics courses.

In Electroweak theory there is $CP$ violation which also means that time reversal $T$ is violated as $CPT = I$. Does this mean that energy conservation is violated in electroweak theory? If this would be true and since electroweak theory holds above the Planck (length) scale is it possible to create energy in a closed system?

• electroweak theory holds above the Planck (length) scale. The relevant energy scale for the electroweak interaction is the ~1 TeV electroweak scale, not the Planck scale. – Ben Crowell Aug 15 '13 at 13:43

No. Conservation of energy is generated by the continuous time translation symmetry $t \rightarrow t + \epsilon$. This is a differenty symmetry than the discrete time reversal symmetry $t \rightarrow -t$. Violating the latter symmetry does not mean that you violate the former symmetry.