How Analogy Drives Physics
Many new ideas in theoretical physics come from analogies to older ideas in physics. For instance, the abstract notion of “isospin” (or isotopic spin) originated in the prior concept of “spin” (quantized angular momentum); likewise, the concept of “phonon” (quantum of sound, or quantized collective excitation of a crystal) was based on the prior concept of “photon” (quantum of light, or quantized element of the electromagnetic field). But these two examples, far from being exceptions, in fact represent the bread and butter of inventive thinking in physics. In a nutshell, intraphysics analogy-making -- borrowing by analogy with something already known in another area of physics -- is central to the progress of physics. The aim of this talk is to reveal the pervasiveness -- indeed, the indispensability -- of this kind of semi-irrational, wholly intuitive type of thinking (as opposed to more deductive mathematical inference) in the mental activity known as “doing physics”. Speculations as to why wild analogical leaps are so crucial to the act of discovery in physics (as opposed to other disciplines) will be offered.