1
vote
1answer
54 views

Can I applicate the law of action and reaction on energy?

It is clear that if you push on some object, there is reaction of the same force. But is it the same energy? Thanks a lot.
4
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0answers
230 views

Dirac action and conventions

I have a (possibly) fundamental question, which is driving me crazy. Notation When considering the Dirac action (say reading Peskin's book), one have $\int ...