Over hundreds of years the conservation of energy and momentum in a closed System was proven. 100 years ago, Emmy Noether showed that these fundamental laws arise from the following facts and vice versa: - Homogenity in time (i.e. physical laws will be the same independent of the time where physics take place) leads to energy conservation - Homogenity in space leads to momentum conservation

Now I have heard that quantum field theory in curved spacetime does not contain energy and momentum conservation (Why?). Also in the theory of Phonons I have seen that there are existing single interactions with no momentum or energy conservation.

But almost every physical Research states that energy and momentum is conserved; even in single quantum mechanical interactions like electron + positron -> photon.

Can it be that there might be interactions on Quantum Level where energy and momentum is not conserved?


1 Answer 1


The violation of conservation and momentum in quantum field theory is only local; globally, these quantities are still conserved.

  • $\begingroup$ A quantum interaction is local, right? Do you mean if the theory has some non-conserving interactions then there must occur the gain-interaction with the same probability as the loss-interaction, right? Are there such theories which state local nonconservations? $\endgroup$
    – kryomaxim
    Feb 5, 2015 at 17:16
  • $\begingroup$ Individual interactions are local. Conservation of energy and momentum must still occur globally; that is the correspondence principle. $\endgroup$
    – Paul
    Feb 5, 2015 at 17:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.