“God does not play dice.”
Or does he/she?
Based on what we see and experience everyday, the natural laws of the universe appear to work like clockwork where objects follow clearly defined rules. For example, with respect to a car moving down the street, a baseball thrown by a pitcher, a bullet shot from a gun, etc., we can determine with absolute certainty for any point in time both where the object is and how fast it is moving.
Surprisingly, that is not how the universe works at the quantum level – at the level of atoms and subatomic particles the idea that objects can be located exactly breaks down. Subatomic particles exist in a fuzzy range of probability. This concept is known as Heisenberg’s Uncertainty Principle and it states that if an object’s position x is defined precisely then the momentum of the object will be incapable of being determined and vice versa. One cannot simultaneously find both the position and momentum of a subatomic object with accuracy. A consequence of the Uncertainty Principle is that subatomic particles exist in a “probability distribution” – meaning that subatomic particles are in a range of probable space traveling at a range of possible velocities. Upon measuring, for example, the location of a particle, its probability distribution relating to its location collapses and its location is known. But, its velocity is not known and cannot be known with accuracy at that point.
Any attempt to measure one will unavoidably disturb the other. This isn’t a matter of simply needing more precise instruments; it is an immutable property of the universe and a foundation of quantum mechanics.