In the 20th century, physicists discovered a super strange feature of tiny particles.One of these was that we can never actually know both the mass and the velocity of a particle accurately.This stated that the more accurately we know one of these, the less accurately we'll know the other.In other words, unlike in Newtonian physics where we could predict the next position of a body by just knowing it's initial velocity we can't accurately predict anything in Quantum mechanics. Very Strange