Serving the Reich Page 2

  The cases of these three men have much to tell us about the factors behind the dominance of the Nazi state. Such a regime becomes possible not because people are powerless to prevent it, but because they fail to take effective action—indeed, even to perceive the necessity of doing so—until it is too late. It is for this reason that judging Planck, Heisenberg and Debye should not be concerned with whether a person’s historical record can be deemed ‘clean’ enough to honour them with medals, street names and graven images. It is about whether we can adequately understand our own moral strengths and vulnerabilities. As Hans Bernd Gisevius, a civil servant under Hitler and a member of the German Resistance, puts it:

  One of the vital lessons that we must learn from the German disaster is the ease with which a people can be sucked down into the morass of inaction; let them as individuals fall prey to overcleverness, opportunism, or cowardliness and they are irrevocably lost.

  1

  ‘As conservatively as possible’

  Science was done differently a hundred years ago. To appreciate just how differently, you need only compare the traditional group photographs of today’s scientific meetings with that from the 1927 Solvay conference on quantum physics in Brussels.*1 There are no casual clothes here, no students, and most definitely no cheerful grins—only Heisenberg’s nervous, boyish smile comes close. The rigidity of the dress code matches the severity of the gazes, which exude an oppressive expectation that codes of conduct will be observed and hierarchy respected. One feels that Hendrik Lorentz, on Einstein’s right in the front row, is silently reprimanding us for some breach of protocol. It is, needless to say, an all-male assembly, except for Marie Curie, not yet quite sixty but already looking aged by exposure to the radioactivity that would kill her seven years later. There on the far left of the middle row, stiff and uncomfortable, is Peter Debye.

  Much of this appearance simply reflects the times, of course. But some is specifically German, for German-speakers dominate this assembly. Even now German science retains something of this sense of decorum and form; foreign visitors are surprised to find that even close colleagues address one another by title and surname, while grades of seniority are demarcated almost as subtly as they are in Japanese society. And of course the status of personal relationships remains explicitly codified in the du/Sie distinction. For the German-speaking scientists at the Solvay meeting this linguistic etiquette reflected one’s professional standing—despite being friends by any other standard, the young Heisenberg and Wolfgang Pauli were Sie to one another until they both became full professors.

  The delegates at the 1927 Solvay conference in Brussels, officially titled ‘Electrons and photons’. From left to right: top row, A. Piccard, E. Henriot, P. Ehrenfest, E. Herzen, Th. de Donder, E. Schrödinger, J. E. Verschaffelt, W. Pauli, W. Heisenberg, R. H. Fowler, L. Brillouin; middle row, P. Debye, M. Knudsen, W. L. Bragg, H. A. Kramers, P. A. M. Dirac, A. H. Compton, L. de Broglie, M. Born, N. Bohr; front row, I. Langmuir, M. Planck, M. Curie, H. A. Lorentz, A. Einstein, P. Langevin, Ch.-E. Guye, C. T. R. Wilson, O. W. Richardson.

  It is not just unfair but in fact meaningless to evaluate the German physicists’ response to Hitler without taking into account the social and cultural expectations that framed it. What today’s sneakers and sweatshirts are perhaps telling us is that, among other things, academic scientists no longer enjoy quite the same status as they did when Einstein and his peers lined up soberly for posterity’s sake at the Hotel Metropole.

  That respect brought with it duties and responsibilities. German academics came largely from the middle and upper middle classes: they knew their niche in the social hierarchy and that, by occupying it, they were obliged to support the tiers. The education that these men received placed great emphasis on the concept of Bildung, a notion of development that went far beyond the matter of learning facts and skills. It entailed cultivation and maturation of personality—intellectual, social and spiritual—in the course of which the individual learnt to align his outlook with the demands and expectations of society. The German education system stressed the importance of philosophy and literature, bestowing an appreciation for Kultur; the educated elite were expected to be guardians of this national heritage, a role for which they felt in a sense contracted by the state. The Dutch physicist Samuel Goudsmit, who as we shall see had good reason to ponder on the consequences of German scientific culture in the early twentieth century, wrote in 1947 that ‘Prussia . . . could not afford more than a qualified liberty for its own bourgeoisie, and could certainly not afford to breed men of science who might question the divine mission of the State.’

  This form of patriotic devotion was not, however, seen as a political stance, but as something that superseded it. ‘Like the majority of the professoriate’, says historian Alan Beyerchen, ‘German physicists desired strongly to remain aloof from political concerns.’ This does not mean that they spurned politics altogether. Most respectable citizens proclaimed an allegiance to a political party—but they did so as citizens, and generally maintained a clear separation between the political and the professional. It was precisely the complaint often made against Einstein, and even conceded by some of his supporters, that he did not respect this division—that he ‘played politics’ through his advocacy of internationalism. His pacifism, which was part and parcel of that attitude, made him still more suspect, for patriotism and national pride were regarded not as a choice but as a duty. In striking contrast to what one might anticipate from academics today, there was scarcely any support from scientists for the popular left-wing Bolshevik movements in the aftermath of the First World War. On the contrary, the German university faculties were predominantly of a conservative inclination, opposed to the Weimar government and resentful about the war reparations.

  Physics, a young discipline less steeped in tradition than most others, was somewhat more liberal—but again we must not assume that this has quite the same connotation as today. The allegedly apolitical stance of German academics was in fact tailored to suit a particular political position: it was ‘apolitical’ to observe the convention of supporting German militarism and patriotism, and equally so to be antagonistic towards democratic Weimar.

  The reluctant revolutionary

  No one illustrates the traditionalist traits of the fin de siècle German scientist better than Max Planck. According to his biographer John Heilbron, ‘Respect for law, trust in established institutions, observance of duty, and absolute honesty—indeed sometimes an excess of scruples—were hallmarks of Planck’s character.’ These were his great strengths; they are the reasons why we must consider him an honourable man. In the Nazi era they would also become weaknesses, trapping him into stasis and compromise.

  Born in 1858 in Kiel, Holstein, when it was still officially Danish, Planck was a gentle man; as he put it himself, ‘by nature peaceful and disinclined to questionable adventures’. The finest adventure that he could conceive of was one removed from the messy, unpredictable travails of human community: science. ‘The outside world is something independent from man,’ Planck wrote, ‘something absolute, and the quest for the laws which apply to this absolute appeared to me as the most sublime scientific pursuit in life.’ Like many scientists today, Planck seemed to find and welcome in science an abstract order that made few demands on the human soul. His relationships did not lack warmth, to judge by the affection that he inspired, but they were conducted with great reserve and decorum: only with people of his own rank could Planck relax a little and enjoy a cigar.

  But this mild nature did not prevent a certain bellicosity when it came to national pride and sentiment. Accepting the standard view that Germany was engaged in a purely defensive struggle at the outbreak of the First World War, he wrote to his sister in September 1914 to say ‘What a glorious time we are living in. It is a great feeling to be able to call oneself a German.’

  Taken in isolation, such a comment might be seen as evidence that Planck was a nationalistic chauvinist. And i
f one can make that charge of Planck, who his colleagues praised in 1929 for ‘the spotless purity of his conscience’, there would then be hardly a German scientist of that age who could not be similarly labelled. Indeed, one could strengthen the charge in several ways. Planck was one of the many scientists who signed the infamous Professors’ Manifesto, ‘Appeal to the Cultured People of the World’, in October 1914, supporting the German military action and denying the (all too real) German atrocities perpetrated in occupied Belgium. Here Planck joined his name to those of the chemists Fritz Haber, Emil Fischer and Wilhelm Ostwald and the physicists Wilhelm Wien, Philipp Lenard, Walther Nernst and Wilhelm Röntgen, existing or future Nobel laureates all (but not, notably, Einstein). More, Planck supported the moderate right German People’s Party (Deutsche Volkspartei, DVP), in which it was not hard to find currents of anti-Semitism. He was sceptical of the political validity of democracy in the modern sense.

  Max Planck (1858–1947) in 1936.

  But it would be dishonest to select Planck’s character for him in such a manner, for we might equally highlight his progressive, enlightened attitudes. He supported women’s rights to higher education (although not universal suffrage). He refused to sign an appeal drawn up by Wilhelm Wien in 1915 which deplored the influence of British physicists in Germany, accused them of all manner of professional transgressions, and called for scientific relationships with England to be severed. And Planck had the courage to realize his error in putting his name to the Professors’ Manifesto and to recant publicly during the war. It is some kind of testimony that Einstein came to hold Planck in close affection and esteem, and that the part-Jewish physicist Max Born said of him that ‘You can certainly be of a different opinion from Planck’s, but you can only doubt his upright, honourable character if you have none yourself.’ We need to know all this before we see what became of Planck, and then of his name.

  Planck’s characteristics were reflected in his science, which was cautious, conservative and traditional yet displayed open-mindedness and generosity. He readily admitted that he was no genius—indeed, it has been said that he was so often wrong, it was not surprising he was sometimes right. But he made one great discovery, and it brought him a Nobel Prize in 1918.*2 It concerned a question that seems simultaneously exceedingly esoteric and mundane: how radiation is emitted from warm bodies. What it led to was quantum theory.

  So-called ‘black-body radiation’—the electromagnetic radiation (including light) emitted by a warm, perfectly non-reflective object—was a long-standing puzzle. Atomic vibrations in the object make its electrons oscillate—and as the Scottish physicist James Clerk Maxwell had shown in the mid-nineteenth century, an oscillating electrical charge radiates electromagnetic waves. The hotter the atoms, the faster they vibrate, and the higher the frequency (shorter the wavelength) of the emitted radiation.†3

  Towards the end of the nineteenth century, Wien had found by experiment the mathematical relationships between the temperature of a ‘black body’, the amount of energy it radiates, and the wavelength of the most intense radiation. This wavelength gets shorter as the temperature increases, an observation familiar from experience with an electric heater: as it warms up, it first emits long-wavelength, invisible infrared rays (which you can feel as heat), then red light and then yellow. Objects hotter still acquire a bluish glow. In attempting to explain this process of emission from the warm, vibrating atoms of the black body, Planck stumbled on the quantum nature of the physical world.

  Previous efforts to relate atomic vibrations to temperature seemed to lead to the conclusion that the amount of energy radiated should get ever greater the shorter the wavelength of the radiation. In the ultraviolet range (that is, at wavelengths shorter than that of violet light) this quantity was predicted to rise towards infinity, an evident absurdity called the ultraviolet catastrophe. In 1900 Planck found that the equations of black-body radiation would produce more sensible results if one assumed that the energy of the ‘oscillators’ in the black body were divided into packets or ‘quanta’ containing an amount of energy proportional to their frequency. He labelled the constant of proportionality h, which became known as Planck’s constant.

  For Planck this was simply a mathematical trick—as he put it, a ‘fortunate guess’—to make the equations yield a meaningful answer. But Einstein saw it differently. In 1905 he argued not only that one might assume Planck’s energy quanta to be real, but that they applied to light itself: he wrote that the energy in light ‘consists of a finite number of energy quanta localized at points of space that move without dividing, and can be absorbed or generated only as complete units’. These light quanta became known as photons.

  Einstein explained that his proposal might be tested by investigating the photoelectric effect, in which light shining on a metal can eject electrons and thereby elicit a tiny electric current. Philipp Lenard had studied the effect closely, and had puzzled over why, as the light becomes more intense, the electrons don’t get kicked out of the metal with increasing energy, as one might have expected. But in Einstein’s picture, in which the light is composed of photons whose energy is governed by Planck’s law, making the light more intense doesn’t alter the photons’ individual energy; it merely supplies them in greater numbers. This, in turn, increases the number of ejected electrons but not their energies. Only by using light of a shorter wavelength, meaning that the photons have more energy, could the energy of the ejected electrons be increased. Einstein’s theory led to predictions that were experimentally confirmed a decade later by the American Robert Millikan. This work on the photoelectric effect was cited as the primary motivation for awarding Einstein the Nobel Prize in Physics in 1921.

  It is hard to overestimate the disruption that Einstein’s ‘quantum light’ paper caused. No one had previously questioned the view that light was a smooth wave, and it is often forgotten now how challenging the notion of ‘granular light’ was. Even after most physicists were willing to accept a quantum picture of the energies of atoms and their constituent particles, invoking it for light was deemed a step too far, and—despite Millikan’s work—it was resisted for two decades.

  Planck himself was initially too disturbed by this dislocation in the traditional view of light to accept the quantum hypothesis that he’d unwittingly unleashed. He advised that his constant h, the finite measure of how fine-grained the world was, be introduced into theory ‘as conservatively as possible’. Planck came only gradually and reluctantly to recognize that the quantum hypothesis was the best way to understand the world of ‘electrons and photons’ that he and his peers debated in Brussels in 1927. And yet his broader question—how much of quantum theory is a mathematical formalism and how much reflects physical reality—remained contentious, and is no less so today.

  Planck was more receptive to Einstein’s second revelation in 1905: the theory of special relativity. Here Einstein proposed that time and space are not uniform everywhere but can be distorted by relative motion. For an object moving relative to another at rest, space is compressed in the direction of motion while time slows down. This mutable notion of what became known as space—time compromised the old view of mechanics based on Isaac Newton’s laws of motion, in which the physical world was regarded as a system of bodies interacting with one another on a fixed, eternal grid of time and space. Einstein’s discovery was extremely disorientating; literally, it deprived physics of its bearings. Out of the theory of special relativity came a succession of revolutionary concepts: that no object can travel faster than light, that an object’s mass increases as it speeds up, that energy and mass are related via the iconic equation E = mc2.*4 The startling consequences of special relativity are barely apparent, however, until the velocities of objects approach the speed of light—about 300,000 kilometres per second. Scientists could not yet knowingly induce such awesome speeds artificially. That was soon to change.

  Planck was an enthusiastic advocate of special relativity, but he was much more wary o
f Einstein’s extension of these ideas in 1912 in the theory of general relativity. By apparently dispensing with the force of gravity, reducing it to a distortion of space—time itself, Einstein seemed to Planck to be departing too far from convention and entering into pure speculation. This initial resistance by one of the most eminent German scientists of the age was a source of immense frustration for Einstein. There was rather less hesitancy outside Germany, albeit perhaps for complex reasons. The English astronomer Arthur Eddington was almost zealous in his determination to validate the theory: a pacifist Quaker, he saw this as a way of welcoming German science back into the international fold after the rupture of the war. Eddington has been accused of being selective with the data taken during two expeditions in 1919 to Brazil and Africa to view the solar eclipse and search for bending of starlight round the sun, which general relativity predicted. Whether they were secure or not, Eddington’s findings, published the following year, were taken as confirmation of Einstein’s genius, and they made him an international celebrity.

  Rebuilding German science

  The names of scientists working in the German-speaking nations in the early twentieth century—Planck, Einstein, Heisenberg, Schrödinger—are so intimately tied to the revolutions taking place in theoretical physics that it is easy to overlook how precarious German science was at the time. The First World War brought not only a crippling financial burden which eventually ballooned into the hyperinflation and economic stagnation of the Weimar Republic, but also a sense of national shame and isolation. Everyone in Germany felt this affliction; the scientists, accustomed to pre-war supremacy, experienced it especially keenly. The theoretical discoveries of Planck and Einstein at the start of the century had followed on the heels of an unmatched mastery of experimental physics. In 1895 Wilhelm Röntgen at Würzburg had amazed and enchanted the world by discovering X-rays, a form of electromagnetic radiation with very short wavelengths. His work built on the pioneering studies of Philipp Lenard at Heidelberg on ‘cathode rays’, which were revealed in 1897 to be not rays at all but streams of subatomic, electrically charged particles subsequently called electrons, fundamental constituents of atoms.