When it comes to quantum science, you may be so overwhelmed by the word "quantum" that you don't even notice if it's followed by "mechanics" or "physics." Many teachers and textbooks treat the two words as synonymous, but technically, quantum physics is the broader term that includes the subfields of quantum mechanics, quantum field theory, quantum optics and quantum electrodynamics. This is similar to classical physics, which encompasses the study of classical mechanics, electricity and magnetism, thermodynamics and relativity.
The "mechanics" in quantum mechanics comes from classical mechanics, which is concerned with the motion of bodies in a frame of reference. In the late 1800s and early 1900s, many physicists reasoned that the laws governing the motion of large objects would also apply to the motion of atoms. They didn't. Gradually, scientists like Niels Bohr began to understand that a new, non-Newtonian mathematics would be needed to describe the motion of atoms and subatomic particles. The term quantum mechanics seemed a good way to build a bridge between new and classical physics [source: University of Winnepeg].
In both cases, the term "quantum" refers to "quanta," or the units of energy and momentum that an atom absorbs and emits. Quantum particles can act as both waves and particles, and they tend to behave erratically. Also, because they are so miniscule, they can be difficult to study. Physicists use the Standard Model of Particle Physics, a quantum theory, to describe all the essential components that make up an atom, and they employ quantum mechanics to study how all those components work together.
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