An ideal, incompressible fluid flows steadily through a horizontal, cylindrical pipe. At Point 1, the pipe has a diameter \(D\) and the fluid flows with a speed \(v_1\). At Point 2, the pipe narrows to a diameter of \(\dfrac{1}{2}D\) and the fluid flows with a speed \(v_2\). What is the ratio of the fluid speed at Point 2 to the fluid speed at Point 1, \(\dfrac{v_2}{v_1}\)?