Galilean invariance

Galilean invariance is a principle in physics stating that the laws governing motion are the same regardless of a uniform, constant motion—meaning no experiment can tell the difference between being at rest or moving at a steady speed in a straight line. For example, inside a smoothly moving train, you wouldn't notice if it's moving at a constant speed; the physics remains the same as if it were stationary. This concept emphasizes that the fundamental laws of mechanics do not depend on your constant-velocity frame of reference, ensuring consistent descriptions of motion across different inertial frames.