{"knowledge_schema": {"broad_category": "Physics \u2192 Particle Physics \u2192 High-Energy Interactions", "refinement": "This problem involves the interaction of high-energy gamma rays with low-energy photons from the Cosmic Microwave Background (CMB) to produce particle-antiparticle pairs.", "specific_scope": "The focus is on calculating the threshold energy of gamma rays required for the production of a muon-antimuon pair through the interaction with CMB photons, considering the rest mass energy of the muons and the energy of the CMB photons.", "goal": "Determine the minimum energy of gamma rays that leads to significant interactions with CMB photons, resulting in muon-antimuon pair production."}, "summary": "This problem examines the interaction between high-energy gamma rays and low-energy photons from the Cosmic Microwave Background (CMB), specifically focusing on the production of muon-antimuon pairs. To find the threshold energy of gamma rays that would lead to this process, we consider the rest mass energy of the muons and the average energy of CMB photons. The goal is to calculate the energy at which gamma rays would have their lifetimes limited by this interaction, leading to the conclusion that the required energy is approximately 1.1 \u00d7 10^7 GeV."}