A mad physicist claims to have observed the decay of a particle of mass M into two identical particles of mass m, with M . In response to the objections that this violates conservation of energy, he replies that if M was traveling fast enough it could easily have energy greater than 2mc2 and hence could decay into the two particles of mass m. Show that he is wrong. [He has forgotten that both energy and momentum are conserved. You can analyse this problem in terms of these two conservation laws, but it is much simpler to go to the rest frame of M.]