When Max Planck began studying physics at the University of Munich in 1874 his teacher, Philipp von Jolly, warned him that it was already a mature field with little more to learn. This attitude was widely held through the end of the 19th century. In 1900 Lord Kelvin, the great British physicist, put it clearly: "There is nothing new to be discovered in physics now. All that remains is more and more precise measurement."
In Planck's early career he had no reason to doubt this complacent position. And yet, in the same year that Kelvin made his pronouncement, Planck found himself disproving it. He had been working on the relationship of heat to light, a topic of great interest to the emerging electric companies, and he had proposed an equation that was consistent with classical physical concepts. But he was dismayed to learn of new experimental results that proved him wrong.
With his back against the wall, the 42-year-old Planck quickly thought up an alternative equation that fit the data. But the new equation also had a disruptive effect. Being hard to reconcile with traditional ideas, it turned out to be an initial building block for a completely new view of physics called quantum theory. The resistance to this disruption by conservative members of the physics community may have been what led to Planck's petulant claim that a new scientific truth will not triumph "until its opponents eventually die."
But the triumph of quantum theory did not really depend on this grim prospect. Members of the physics establishment soon began to take quantum theory seriously because it wasn't just a weird idea that had popped into Planck's head. It had become necessary because of a surprising experimental result.
This is how science usually works. When experiments challenge a prevailing idea attention is paid. If the experiments are confirmed the old idea is modified. In fields in which decisive experimentation is relatively easy, such change may happen quickly and is certainly not dependent on the death of its senior practitioners. It is only in fields that don't lend themselves to decisive experimentation that it is hard to definitively challenge a prevailing position. In such fields even death may not be enough, and tenuous positions may survive for generations.
So Plank got it wrong. The development of new scientific truths does not depend on the passing of stubborn conservative opponents. It is, instead, mainly dependent on the continuous enrollment of talented newcomers who are eager to make their mark by changing the existing order. In Planck's case it was, in fact, the arrival of the young Albert Einstein, rather than the demise of his senior opponents, that propelled quantum theory forward. As Douglas Stone showed, in Einstein and the Quantum, it was the 25-year-old patent clerk, a fledgling outsider with nothing to lose, who became the driving force in the development of this theory. As for his elders, Einstein couldn't care less.