Here are five key ideas of quantum mechanics—all believed to be fundamental aspects of the way nature operates, all foreign to classical physics. They are discussed in the next five Essays .
(1) Granularity. Much of nature in the small is granular—its physical variables as well as its material pieces. (See Essay Q2)
(2) Probability. The fundamental laws of quantum mechanics are laws of probability, not laws of certainty. (See Essay Q3)
(3) Annihilation and Creation. Any particle may be annihilated or created; stable matter is a happy chance. (See Essay Q4)
(4) Waves and Particles. Units of matter and units of radiant energy both share wave properties and particle properties. (See Essay Q5)
(5) The Uncertainty Principle. Apart from limitations on human ingenuity, nature imposes fundamental limitations on the precision with which some physical quantities can be measured. (See Essay Q6)