{"knowledge_schema": {"broad_category": "Physics \u2192 Relativity \u2192 Particle Physics", "refinement": "This problem involves the collision of particles (electron and positron) and the subsequent annihilation into photons, requiring an understanding of relativistic energy and momentum conservation.", "specific_scope": "The focus is on determining the angle between the paths of the resulting photons after the annihilation event, considering the Lorentz factors of the colliding particles.", "goal": "Calculate the angle between the paths of the two photons produced from the annihilation of the electron and positron."}, "summary": "This problem is rooted in the principles of relativistic physics, specifically dealing with particle collisions and the conservation of energy and momentum. An electron and a positron collide and annihilate, producing two photons that travel in different directions. The task is to find the angle between the paths of these photons, which requires applying concepts from special relativity, including Lorentz factors and momentum conservation. The correct answer to the angle between the paths of the photons is 138 degrees."}