THE ORIGINS OF THE QUANTUM THEORY W（量子理论的起源）.pdf

THE ORIGINS OF THE QUANTUM THEORY by CATHRYN CARSON HAT IS A QUANTUM THEORY? We have been asking that question for a long time, ever Wsince Max Planck introduced the element of dis- continuity we call the quantum a century ago. Since then, the chunkiness of Nature (or at least of our theories about it) has been built into our basic conception of the world. It has prompted a fundamental rethinking of physical theory. At the same time it has helped make sense of a whole range of pe- culiar behaviors manifested principally at microscopic levels. From its beginning, the new regime was symbolized by Planck’s constant h, introduced in his famous paper of 1900. Measuring the world’s departure from smooth, continuous behavior, h proved to be a very small number, but different from zero. Wherever it appeared, strange phenomena came with it. What it really meant was of course mysterious. While the quantum era was inaugurated in 1900, a quantum theory would take much longer to jell. Intro- ducing discontinuity was a tentative step, and only a first one. And even thereafter, the recasting of physical theory was hesitant and slow. Physicists pondered for years what a quantum theory might be. Wondering how to inte- grate it with the powerful apparatus of nineteenth-century physics, they also asked what relation it bore to existing, “classical” theories. For some the answers crystallized with quantum mechanics, the result of a quarter- century’s labor. Others held out f