Hi all, Question for which .I feel silly asking - but since I'm still learning: A particle state in QFT is considered to be an asymptotic state with a well defined energy. Now, if I take an ensemble of particles after a very large number of interactions (say, e.g., a macroscopic object like a person's body, and perhaps since the birth of the universe), can one say that the ensemble has a bounded energy? It would seem that the energy would have to be bounded at any time, even in an interacting picture (otherwise there would be no bound on spacetime curvature, etc., and yes, I realize I'm mixing in general relativity here). I think I'm basically asking about the spectrum of the Hamiltonian for the system - but since I'm still struggling to get through several texts, I'm unsure. Also, given the above, there would be a maximum energy that a body could emit over a given time, correct? (If the above is correct) Thanks!