Precession for me is one of the most confusing and interesting concepts in physics so far, I've thought about it alot and I still don't have it all figured out. Here's an interesting question: Consider a gyroscope that has the axle in a horizontal position and spinning so that the angular momentum vector is pointing horizontal. The angular momentum is large and the support is taken away so the gyroscope starts to pivot in a horizontal circle - this is a very familiar form of precession. Ok, the precessional angular velocity is constant, as well as the angular velocity of the rotor, correct? Therefore, neglecting friction, the total angular momentum of the system is constant. Now, torque changes angular momentum - If you have a spinning object and you apply torque so that the torque vector is in the same direction as the angular momentum vector, it will spin faster. If the torque is in the other direction, it will spin slower. Also, if you apply a torque continuously, the angular velocity will keep increasing. The torque on the gyroscope that causes the precession is the torque due to gravity. Gravity is always pulling down with a constant force, so the torque is constant and continuous. Therefore, with a continuous torque, the total angular momentum of the system should be changing. However, this can be experimentally disproved. How is this possible?