Quantum mechanics is the most revolutionary scientific theory to appear in the past 150 years. In the atomic domain, it superseded laws first set out by Isaac Newton a quarter of a millennium earlier and has since had an unbroken string of successes. Today, it continues to give an utterly reliable account of the behavior of the subatomic world, yet there are nagging doubts that there is something rotten at its core.

In his lively new book, “Quantum,” the science writer Manjit Kumar cites a poll about the interpretation of quantum mechanics, taken among physicists at a conference in 1999. Of the 90 respondents, only four said they accepted the standard interpretation taught in every undergraduate physics course in the world. Thirty favored a modern interpretation, laid out in 1957 by the Princeton theoretician Hugh Everett III, while 50 ticked the box labeled “none of the above or undecided.” Almost a century after a few physicists first set out the basic theory, quantum mechanics is still a work in progress.

It was the German theoretician Max Planck who first presented the idea that energy is fundamentally granular. In a lecture given in the closing weeks of 1900, he described his bizarre proto-theory that when light and matter interact, energy cannot be transferred in arbitrary amounts, as would be expected on the basis of Newton’s account. Rather, Planck suggested, energy transfers take place only in discrete chunks, which he called “quanta.” A deeply conservative thinker, he was never comfortable with this notion, which he saw as a “purely formal assumption,” and was unconvinced when the young Albert Einstein suggested — in what he considered to be his only revolutionary contribution to science — that it was possible to think of light in terms of particles, later called photons. Planck died, almost 50 years later, unwilling to believe the picture of light that he himself had introduced. This is a classic example of the adage that physics progresses through a succession of funerals — of the pioneers who could not live with the consequences of their most radical work.

In resisting the photon concept, Planck was in good company. Another influential skeptic was the Danish physicist Niels Bohr, a remarkably profound thinker and inveterate mumbler who continually struggled to find coherent expressions of his ideas. (“You should never express more clearly than you can think,” he would whisper to often-baffled colleagues.) Bohr at first refused to believe in the reality of photons, even after the American experimenter Arthur Compton first found compelling evidence for them in 1922. For a short time, Einstein was in the vanguard of quantum theory, while Bohr lagged ­behind.