Quantum_ Einstein, Bohr and the Great Debate About the Nature of Reality - Manjit Kumar [19]
Two months later, in the middle of May, Einstein wrote to his friend Conrad Habicht promising to send four papers he hoped to see published before the year's end. The first was the quantum paper. The second was his PhD dissertation in which he set out a new way to determine the sizes of atoms. The third offered an explanation of Brownian motion, the erratic dance of tiny particles, like grains of pollen, suspended in liquid. 'The fourth paper,' Einstein admitted, 'is only a rough draft at this point and is an electrodynamics of moving bodies which employs a modification of the theory of space and time.'6 It is an extraordinary list. In the annals of science only one other scientist and one other year bears comparison with Einstein and his achievements in 1905: Isaac Newton in 1666, when the 23-year-old Englishman laid the foundations of calculus and the theory of gravity, and outlined his theory of light.
Einstein would become synonymous with the theory first sketched out in his fourth paper: relativity. Although it would change humanity's very understanding of the nature of space and time, it was the extension of Planck's quantum concept to light and radiation that he described as 'very revolutionary', not relativity.7 Einstein regarded relativity as simply a 'modification' of ideas already developed and established by Newton and others, whereas his concept of light-quanta was something totally new, entirely his own, and represented the greatest break with the physics of the past. Even for an amateur physicist it was sacrilegious.
For more than half a century it had been universally accepted that light was a wave phenomenon. In 'On a Heuristic Point of View Concerning the Production and Transformation of Light', Einstein put forward the idea that light was not made up of waves, but particle-like quanta. In his resolution of the blackbody problem Planck had reluctantly introduced the idea that energy was absorbed or emitted as quanta, in discrete lumps. However, he, like everyone else, believed that electromagnetic radiation itself was a continuous wave phenomenon, whatever the mechanism of how it exchanged energy when it interacted with matter. Einstein's revolutionary 'point of view' was that light, indeed all electromagnetic radiation, was not wavelike at all but chopped up into little bits, light-quanta. For the next twenty years, virtually no one but he believed in his quantum of light.
From the beginning Einstein knew it would be an uphill struggle. He signalled as much by including 'On a Heuristic Point of View' in the title of his paper. 'Heuristic', as defined by The Shorter Oxford English Dictionary, means 'serving to find out'. What he was offering physicists was a way to explain the unexplained when it came to light, not a fully worked-out theory derived from first principles. His paper was a signpost towards such a theory, but even that proved too much for those unprepared to travel to a destination in the opposite direction to the long-established wave theory of light.
Received by the Annalen der Physik between 18 March and 30 June, Einstein's four papers would transform physics in the years ahead. Remarkably, he also found the time and energy to write 21 book reviews for the journal during the course of the year. Almost as an afterthought, since he did not tell Habicht about it, he wrote a fifth paper. It contained the one equation that almost everyone would come to know, E=mc2. 'A storm broke loose in my mind', was how he described the surge of creativity that consumed him as he produced his breathtaking succession of papers during that glorious Bern spring and summer of 1905.8
Max Planck, the adviser on theoretical physics for the Annalen der Physik,