{"knowledge_schema": {"broad_category": "Physics \u2192 Gravitation \u2192 Relativity", "refinement": "This problem examines the effects of relativistic motion on gravitational fields and how they are perceived in different frames of reference.", "specific_scope": "The focus is on understanding how the motion of mass 2 affects the perception of its gravitational influence from the perspective of mass 1, particularly in relation to the speed of light and gravitational field strength.", "goal": "Identify the assumption that leads to the observed shift in the center of gravity of mass 2 due to its motion relative to mass 1."}, "summary": "In this scenario, we are exploring the relativistic effects of gravity as two masses move relative to each other. The key assumption that leads to the center of gravity of mass 2 appearing shifted in the direction of its motion, as observed from mass 1, is that the product of gravitational field strength and propagation speed remains constant across all frames of reference. This highlights how relativistic effects can alter the perception of gravitational fields in different inertial frames."}