REASON, OF COURSE, is weak, when measured against its never-ending task. Weak, indeed, compared with the follies and passions of mankind, which, we must admit, almost entirely control our human destinies, in great things and small. Yet the works of the understanding outlast the noisy bustling generations and spread light and warmth across the centuries. Consoled by this thought let us turn, in these unquiet days, to the memory of Newton, who three hundred years ago was given to mankind.
To think of him is to think of his work. For such a man can be understood only by thinking of him as a scene on which the struggle for eternal truth took place. Long before Newton there had been virile minds who conceived that it ought to be possible, by purely logical deduction from simple physical hypotheses, to make cogent explanations of phenomena perceptible to the senses. But Newton was the first to succeed in finding a clearly formulated basis from which he could deduce a wide field of phenomena by means of mathematical thinking, logically, quantitatively and in harmony with experience. Indeed, he might well hope that the fundamental basis of his mechanics would come in time to furnish the key to the understanding of all phenomena. So thought his pupils—with more assurance than he himself—and so his successors, up till the end of the eighteenth century. How did this miracle come to birth in his brain? Forgive me, reader, the illogical question. For if by reason we could deal with the problem of the “how,” then there could be no question of a miracle in the proper sense of the word. It is the goal of every activity of the intellect to convert a “miracle” into something which it has grasped. If in this case the miracle permits itself to be converted, our admiration for the mind of Newton becomes only the greater thereby.
Galileo, by ingenious interpretation of the simplest facts of experience, had established the proposition: a body upon which no external force is at work permanently maintains its original velocity (and direction); if it alters its velocity (or the direction of its movement) the change must be referred to an external cause.
To utilize this knowledge quantitatively the conceptions velocity and rate of change of velocity—that is, acceleration in the case of any given motion of a body conceived as dimensionless (material point)—must first be interpreted with mathematical exactness. The task led Newton to invent the basis of differential and integral calculus.
This in itself was a creative achievement of the first order. But for Newton, as a physicist, it was simply the invention of a new kind of conceptual language which he needed in order to formulate the general laws of motion. For a given body he had now to put forward the hypothesis that his precisely formulated acceleration both in magnitude and direction was proportional to the force directed upon it. The coefficient of proportionality which characterizes the body with reference to its power of acceleration completely describes the (dimensionless) body with reference to its mechanical quality; thus was discovered the fundamental conception of mass.
All the foregoing might be described—though in the extremely modest manner of speaking—as an exact formulation of something the essence of which had already been recognized by Galileo. But it by no means succeeded in solving the main problem. In other words, the law of motion yields the movement of a body, only when the direction and magnitude of the force exerted upon it are known for all times. Thus the problem reduced itself to another problem: how to find out the operative forces. To a mind any less bold than Newton’s it must have seemed hopeless, considering the immeasurable multifarity of the effects which the bodies of a universe seem to produce upon each other. Moreover, the bodies whose motions we perceive are by no means dimensionless points—that is to say, perceptible as material points. How was Newton to deal with such chaos?
If we push a cart moving without friction on a horizontal plane it follows that the force we exert upon it is given directly. That is the ideal case from which the law of motion is derived. That we are not here dealing with a dimensionless point appears unessential.
How does it stand then with a falling body in space? A freely falling body behaves almost as simply as the dimensionless point, if one regards its movement as a whole. It is accelerated downwards. The acceleration, according to Galileo, is independent of its nature and its velocity. The earth, of course, must be decisive for the existence of this acceleration. It seemed, then, that the earth by its mere presence exerted a force upon the body. The earth consists of many parts. The idea seemed inevitable that each of these parts affects the falling body and that all these effects are combined. There seems then to be a force which bodies by their very presence exert upon each other through space. These forces seem to be independent of velocities, dependent only upon the relative position and quantitative property of the various bodies exerting them. This quantitative property might be conditioned by its mass, for the mass seems to characterize the body from the mechanical point of view. This strange effect of things at a distance may be called gravitation.
Now to gain precise knowledge of this effect, one has only to find out how strong is the force exerted upon each other by two bodies of given mass from a given distance. As for their direction, it would probably be no other than the line connecting them. Finally then, what remains unknown is only the dependence of this force upon the distance between the two bodies. But this one cannot know a priori. Here, only experience could be of use.
Such experience, however, was available to Newton. The acceleration of the moon was known from its orbit and could be compared with the acceleration of the freely falling body on the surface of the earth. Furthermore, the movements of the planets about the sun had been determined by Kepler with great exactness and comprehended in simple empirical laws. So it was possible to ascertain how the effects of gravitation coming from the earth and those coming from the sun depended on the factor of distance. Newton found that everything was explainable by a force which was inversely proportional to the square of the distance. And with that the goal was reached, the science of celestial mechanics was born, confirmed a thousand times over by Newton himself and those who came after him. But how about the rest of physics? Gravitation and the law of motion could not explain everything. What determined the equilibrium of the parts of a solid body? How was light to be explained, how electrical phenomena? By introducing material points and forces of various kinds acting at a distance, everything seemed in a fair way to be derivable from the law of motion.
That hope has not been fulfilled, and no one any longer believes in the solution of all our problems on this basis. Nevertheless, the thinking of physicists today is conditioned to a high degree by Newton’s fundamental conceptions. It has so far not been possible to substitute for the Newtonian unified conception of the universe a similarly unified comprehensive conception. But what we have gained up till now would have been impossible without Newton’s clear system.
From observation of the stars have chiefly come the intellectual tools indispensable to the development of modern technique. For the abuse of the latter in our time creative intellects like Newton’s are as little responsible as the stars themselves, contemplating which their thoughts took wing. It is necessary to say this, because in our time esteem for intellectual values for their own sake is no longer so lively as it was in the centuries of the intellectual renascence.
IN KEPLER’S LETTERS we find ourselves confronted with a sensitive personality, passionately devoted to the quest for deeper insight into the character of natural processes—a man who reached the exalted goal he set himself in spite of all internal and external difficulties. Kepler’s life was devoted to the solution of a dual problem. The sun and the planets change their apparent position with reference to their background of fixed stars in a complex manner open to immediate observation. In other words, all the observations and records compiled with such care dealt not actually with the movements of the planets in space but with temporal shifts undergone by the direction earth-planet in the course of time.
Once Copernicus had convinced the small group capable of grasping it that in this process the sun must be regarded as being at rest, with the planets, including the earth, revolving about the sun, the first great problem proved to be this: to determine the true motions of the planets, including the earth, as they might be visible to an observer on the nearest fixed star who was equipped with a perfect stereoscopic double-telescope. This was Kepler’s first great problem. The second problem was embodied in this question: What are the mathematical laws under which these motions proceed? It is plain that the solution of the second problem, if at all within reach of the human mind, was predicated on the solution of the first. Before a theory explaining a certain process can be tested, that process must first be known.
Kepler’s solution of the first problem is based on a truly inspired notion that made possible the determination of the true orbit of the earth. To construct that orbit, a second fixed point in planetary space, in addition to the sun, is required. When such a second point is available, it and the sun may both be used as points of reference for angular measurements, and the earth’s true orbit can be determined by the same methods of triangulation that customarily serve in surveying and cartography.
But where was such a second fixed point to be found, since all visible objects, except the sun, themselves execute motions that are not known in detail? This was Kepler’s answer: The apparent motions of the planet Mars are known with great accuracy, including the time of its revolution about the sun (the “Martian year”). It is probable that at the end of each Martian year Mars is at the same spot in (planetary) space. If we limit ourselves for the time being to these points in time, then the planet Mars represents for them a fixed point in planetary space, a point that may be used in triangulation.
Employing this principle, Kepler first of all determined the true motion of the earth in planetary space. Since the earth itself may be used as a point for triangulation at any time, he was also able to determine the true motions of the other planets from his observations.
This is how Kepler gained the basis for formulating the three fundamental laws with which his name will remain associated for all time to come. Today, after the fact, no one can fully appreciate how much ingenuity, how much hard and tireless work was required to discover these laws and ascertain them with such precision.
The reader ought to know this as he learns from the letters under what hardships Kepler accomplished this gigantic work. He refused to be paralyzed or discouraged either by poverty or by the lack of comprehension among those of his contemporaries who had the power to shape his life and work. Yet he was dealing with a subject that offered immediate danger to him who professed the truth. But Kepler was one of the few who are simply incapable of doing anything but stand up openly for their convictions in every field. At the same time he was not one who took undiluted pleasure in personal controversy, as was plainly the case with Galileo, whose inspired barbs delight the informed reader even today. Kepler was a devout Protestant, but he made no secret of the fact that he did not approve of all decisions by the Church. He was, accordingly, regarded as a kind of moderate heretic and treated as such.
This brings me to the inner difficulties Kepler had to overcome—difficulties at which I have already hinted. They are not as readily perceived as the outward difficulties. Kepler’s lifework was possible only once he succeeded in freeing himself to a great extent of the intellectual traditions into which he was born. This meant not merely the religious tradition, based on the authority of the Church, but general concepts on the nature and limitations of action within the universe and the human sphere, as well as notions of the relative importance of thought and experience in science.
He had to rid himself of the animist approach in research, a mode of thought oriented toward ulterior ends. He first had to recognize that even the most lucidly logical mathematical theory was of itself no guarantee of truth, becoming meaningless unless it was checked against the most exacting observations in natural science. But for this philosophical orientation Kepler’s work would not have been possible. He does not speak of it, but the inner struggle is reflected in his letters. Let the reader watch out for remarks concerning astrology. They show that the vanquished inner foe had been rendered harmless, even though he was not yet altogether dead.
Marie Curie in Memoriam
AT A TIME WHEN a towering personality like Mme. Curie has come to the end of her life, let us not merely rest content with recalling what she has given to mankind in the fruits of her work. It is the moral qualities of its leading personalities that are perhaps of even greater significance for a generation and for the course of history than purely intellectual accomplishments. Even these latter are, to a far greater degree than is commonly credited, dependent on the stature of character.
It was my good fortune to be linked with Mme. Curie through twenty years of sublime and unclouded friendship. I came to admire her human grandeur to an ever growing degree. Her strength, her purity of will, her austerity toward herself, her objectivity, her incorruptible judgment—all these were of a kind seldom found joined in a single individual. She felt herself at every moment to be a servant of society and her profound modesty never left any room for complacency. She was oppressed by an abiding sense for the asperities and inequities of society. This is what gave her that severe outward aspect, so easily misinterpreted by those who were not close to her—a curious severity unrelieved by any artistic strain. Once she had recognized a certain way as the right one, she pursued it without compromise and with extreme tenacity.
The greatest scientific deed of her life—proving the existence of radioactive elements and isolating them—owes its accomplishment not merely to bold intuition but to a devotion and tenacity in execution under the most extreme hardships imaginable, such as the history of experimental science has not often witnessed.
If but a small part of Mme. Curie’s strength of character and devotion were alive in Europe’s intellectuals, Europe would face a brighter future.
Max Planck in Memoriam
A MAN TO WHOM it has been given to bless the world with a great creative idea has no need for the praise of posterity. His very achievement has already conferred a higher boon upon him.
Yet it is good—indeed, it is indispensable—that representatives of all who strive for truth and knowledge should be gathered here today from the four corners of the globe. They are here to bear witness that even in these times of ours, when political passion and brute force hang like swords over the anguished and fearful heads of men, the standard of our ideal search for truth is being held aloft undimmed. This ideal, a bond forever uniting scientists of all times and in all places, was embodied with rare completeness in Max Planck.
Even the Greeks had already conceived the atomistic nature of matter and the concept was raised to a high degree of probability by the scientists of the nineteenth century. But it was Planck’s law of radiation that yielded the first exact determination—independent of other assumptions—of the absolute magnitudes of atoms. More than that, he showed convincingly that in addition to the atomistic structure of matter there is a kind of atomistic structure to energy, governed by the universal constant h, which was introduced by Planck.
This discovery became the basis of all twentieth-century research in physics and has almost entirely conditioned its development ever since. Without this discovery it would not have been possible to establish a workable theory of molecules and atoms and the energy processes that govern their transformations. Moreover, it has shattered the whole framework of classical mechanics and electrodynamics and set science a fresh task: that of finding a new conceptual basis for all physics. Despite remarkable partial gains, the problem is still far from a satisfactory solution.
In paying homage to this man the American National Academy of Sciences expresses its hope that free research, for the sake of pure knowledge, may remain unhampered and unimpaired.
Paul Langevin in Memoriam
THE NEWS OF Paul Langevin’s death dealt me a greater blow than most of the events of these fateful years, so fraught with disappointment. Why should this have been the case? Was his not a long life, crowded with fruitful creative work—the life of a man in harmony with himself? Was he not widely revered for his keen insight into intellectual problems, universally beloved for his devotion to every good cause, for his understanding kindness toward all creatures? Is there not a certain satisfaction in the fact that natural limits are set to the life of the individual, so that at its conclusion it may appear as a work of art?
The sorrow brought on by Paul Langevin’s passing has been so particularly poignant because it has given me a feeling of being left utterly alone and desolate. There are so very few in any one generation, in whom clear insight into the nature of things is joined with an intense feeling for the challenge of true humanity and the capacity for militant action. When such a man departs, he leaves a gap that seems unbearable to his survivors.
Langevin was endowed with unusual clarity and agility in scientific thought, together with a sure intuitive vision for the essential points. It was as a result of these qualities that his lectures exerted a crucial influence on more than one generation of French theoretical physicists. But Langevin also knew a great deal about experimental technique and his criticism and constructive suggestions always carried a fruitful effect. His own original researches, moreover, decisively influenced the development of science, mainly in the fields of magnetism and ion theory. Yet the burden of responsibility which he was always ready to assume circumscribed his own research work, so that the fruits of his labors emerge in the publications of other scientists to a greater extent than in his own.
It appears to me as a foregone conclusion that he would have developed the Special Theory of Relativity, had that not been done elsewhere; for he had clearly perceived its essential aspects. Another admirable thing is that he fully appreciated the significance of De Broglie’s ideas—from which Schrödinger subsequently developed the methods of wave mechanics—even before these ideas had become consolidated into a consistent theory. I vividly recall the pleasure and warmth with which he told me about it—and I also remember that I followed his remarks but hesitantly and doubtfully.
All his life Langevin suffered from an awareness of the deficiencies and inequities of our social and economic institutions. Yet he believed firmly in the power of reason and knowledge. So pure in heart was he that he was convinced all men should be ready for complete personal renunciation, once they had seen the light of reason and justice. Reason was his creed—a creed that was to bring not only light but also salvation. His desire to promote the happier life for all men was perhaps even stronger than his craving for pure intellectual enlightenment Thus it was that he devoted much of his time and vital energy to political enlightenment No one who appealed to his social conscience ever went away from him empty-handed. Thus it was too that the very moral grandeur of his personality earned him the bitter enmity of many of the more humdrum intellectuals. He in turn understood them all and in his kindness never harbored resentment against anyone.
I can only give expression to my gratitude for having personally known this man of purity and illumination.
Walther Nernst in Memoriam
WALTHER NERNST, WHO DIED recently, was one of the most characteristic and most interesting scholars with whom I have been closely connected during my life. He did not miss any of the conferences on physics in Berlin, and his brief remarks gave evidence of a truly amazing scientific instinct combined both with a sovereign knowledge of an enormous volume of factual materials, which was always at his command, and with a rare mastery of the experimental methods and tricks in which he excelled. Although sometimes good-naturedly smiling at his childlike vanity and self-complacency, we all had for him not only a sincere admiration, but also a personal affection. So long as his egocentric weakness did not enter the picture, he exhibited an objectivity very rarely found, an infallible sense for the essential, and a genuine passion for knowledge of the deep interrelations of nature. But for such a passion his singularly creative productivity and his important influence on the scientific life of the first third of this century would not have been possible.
He ascended from Arrhenius, Ostwald and Van’t Hoff, as the last of a dynasty which based their investigations on thermodynamics, osmotic pressure and ionic theory. Up to 1905 his work was essentially restricted to that range of ideas. His theoretical equipment was somewhat elementary, but he mastered it with a rare ingenuity. I refer, for instance, to the theory of electromotive powers in solutions of locally variable concentration, the theory of diminution of the solubility by adding a dissolved substance. During this period he invented the witty null-method of determining the dielectric constant of electrically conducting bodies by means of Wheatstone’s Bridge (alternating current, telephone as indicator, compensating capacity in comparison-bridge branches).
This first productive period is largely concerned with improving the methodology and completing the exploration of a field the principles of which had already been known before Nernst. This work led him gradually to a general problem which is characterized by the question: Is it possible to compute from the known energy of the conditions of a system, the useful work which is to be gained by its transition from one state into another? Nernst realized that a theoretical determination of the transition work A from the energy-difference U by means of equations of thermodynamics alone is not possible. There could be inferred from thermodynamics that, at absolute zero, the temperature of the quantities A and U must be equal. But one could not derive A from U for any arbitrary temperatures, even if the energy-values or differences in U were known for all conditions. This computation was not possible until there was introduced, with regard to the reaction of these quantities under low temperatures, an assumption which appeared obvious because of its simplicity. This assumption is simply that A becomes temperature-independent under low temperatures. The introduction of this assumption as a hypothesis (third main principle of the theory of heat) is Nernst’s greatest contribution to theoretical science. Planck found later a solution which is theoretically more satisfactory; namely, the entropy disappears at absolute zero temperature.
From the standpoint of the older ideas on heat, this third main principle required very strange reactions of bodies under low temperatures. To pass upon the correctness of this principle, the methods of calorimetry under low temperatures had to be greatly improved. The calorimetry of high temperatures also owes to Nernst considerable progress. Through all these investigations, as well as through many stimulating suggestions with which his untiring inventive genius supplied experimenters in his field, he promoted the research work of his generation most effectively. The beginnings of the quantum theory were assisted by the important results of those caloric investigations, and this especially before Bohr’s theory of the atom made spectroscopy the most important experimental field. Nernst’s standard work, “Theoretical Chemistry,” offers, not only to the student but also to the scholar, an abundance of stimulating ideas; it is theoretically elementary, but clever, vivid and full of intimations of manifold interrelations. It truly reflects his intellectual characteristics.
Nernst was not a one-sided scholar. His sound common sense engaged successfully in all fields of practical life, and every conversation with him brought something interesting to light. What distinguished him from almost all his fellow-countrymen was his remarkable freedom from prejudices. He was neither a nationalist nor a militarist. He judged things and people almost exclusively by their direct success, not by a social or ethical ideal. This was a consequence of his freedom from prejudices. At the same time he was interested in literature and had such a sense of humor as is very seldom found with men who carry so heavy a load of work. He was an original personality; I have never met any one who resembled him in any essential way.
Paul Ehrenfest in Memoriam
IT HAPPENS SO often nowadays that men of high qualities depart this life of their own free will that we no longer feel such a conclusion to be unusual. Yet the decision to take leave generally stems from an incapacity—or at least an unwillingness—to resign oneself to new and more difficult outward conditions of life. To refuse to live out one’s natural life because of inner conflicts that are felt to be intolerable—that is even today in persons of sound mind a rare occurrence, possible only in the case of the noblest and morally most exalted personalities. It is to such a tragic inner conflict that our friend Paul Ehrenfest has succumbed. Those who knew him well, as was vouchsafed to me, know that this unblemished personality in the main fell victim to a conflict of conscience that in some form or other is spared no university teacher who has passed, say, his fiftieth year.
I came to know him twenty-two years ago. He visited me in Prague, coming straight from Russia where he as a Jew was debarred from teaching at institutions of higher learning. He was looking for a sphere of work in central or western Europe. But we talked little of that, for it was the state of science at the time that took up almost all of our interest. Both of us realized that classical mechanics and the theory of the electric field had failed in the face of the phenomena of heat radiation and molecular processes (the statistical theory of heat), but there seemed to be no feasible way out of this dilemma. The logical gap in Planck’s Theory of Radiation—which we both, nevertheless, greatly admired—was apparent to us. We also discussed the Theory of Relativity, to which he responded with a certain skepticism but with the critical judgment peculiar to him. Within a few hours we were true friends—as though our dreams and aspirations were meant for each other. We remained joined in close friendship until he departed this life.
His stature lay in his unusually well developed faculty to grasp the essence of a theoretical notion, to strip a theory of its mathematical accouterments until the simple basic idea emerged with clarity. This capacity made him a peerless teacher. It was on its account that he was invited to scientific congresses; for he always brought clarity and acuteness into any discussion. He fought against fuzziness and circumlocution, when necessary employing his sharp wit and even downright discourtesy. Some of his utterances could have been interpreted almost as arrogant, yet his tragedy lay precisely in an almost morbid lack of self-confidence. He suffered incessantly from the fact that his critical faculties transcended his constructive capacities. In a manner of speaking, his critical sense robbed him of his love for the offspring of his own mind even before they were born.
Shortly after our first encounter there occurred the great turning-point in Ehrenfest’s outward career. Our revered master, Lorentz, anxious to retire from regular university teaching, had recognized Ehrenfest for the inspired teacher that he was and recommended him as his successor. A marvelous sphere of activity opened up to the still youthful man. He was not merely the best teacher in our profession whom I have ever known; he was also passionately preoccupied with the development and destiny of men, especially his students. To understand others, to gain their friendship and trust, to aid anyone embroiled in outer or inner struggles, to encourage youthful talent—all this was his real element, almost more than immersion in scientific problems. His students and colleagues in Leyden loved and esteemed him. They knew his utter devotion, his nature so wholly attuned to service and help. Should he not have been a happy man?
In truth he felt unhappier than anyone else who was close to me. The reason was that he did not feel equal to the lofty task that confronted him. Of what use was it that everyone held him in esteem? His sense of inadequacy, objectively unjustified, plagued him incessantly, often robbing him of the peace of mind necessary for tranquil research. So greatly did he suffer that he was compelled to seek solace in distraction. His frequent aimless travels, his preoccupation with the radio, and many other features of his restless life stemmed not from a need for composure and harmless hobbies but rather from a curious urge for escape caused by the psychic conflict at which I have hinted.
In the last few years this situation was aggravated by the strangely turbulent development which theoretical physics has recently undergone. To learn and to teach things that one cannot fully accept in one’s heart is always a difficult matter, doubly difficult for a mind of fanatical honesty, a mind to which clarity means everything. Added to this was the increasing difficulty of adaptation to new thoughts which always confronts the man past fifty. I do not know how many readers of these lines will be capable of fully grasping that tragedy. Yet it was this that primarily occasioned his escape from life.
It seems to me that the tendency toward exaggerated self-criticism is associated with experiences in boyhood. Humiliation and mental oppression by ignorant and selfish teachers wreak havoc in the youthful mind that can never be undone and often exert a baleful influence in later life. The intensity of such experiences in Ehrenfest’s case may be judged from the fact that he refused to entrust his dearly beloved children to any school.
His relations with his friends played a far greater role in Ehrenfest’s life than is the case with most men. He was virtually dominated by his sympathies and also by antipathies based on moral judgments. The strongest relationship in his life was that to his wife and fellow worker, an unusually strong and steadfast personality and his intellectual equal. Perhaps her mind was not quite as agile, versatile, and sensitive as his own, but her poise, her independence of others, her steadfastness in the face of all hardships, her integrity in thought, feeling, and action—all these were a blessing to him and he repaid her with a veneration and love such as I have not often witnessed in my life. A fateful partial estrangement from her was a frightful experience for him, one with which his already wounded soul was unable to cope.
We whose lives have been enriched by the power and integrity of his spirit, the kindness and warmth of his rich mind, and not least his irrepressible humor and trenchant wit—we know how much his departure has impoverished us. He will live on in his students and in all whose aspirations were guided by his personality.
A LEADER OF his people, unsupported by any outward authority: a politician whose success rests not upon craft nor the mastery of technical devices, but simply on the convincing power of his personality; a victorious fighter who has always scorned the use of force; a man of wisdom and humility, armed with resolve and inflexible consistency, who has devoted all his strength to the uplifting of his people and the betterment of their lot; a man who has confronted the brutality of Europe with the dignity of the simple human being, and thus at all times risen superior.
Generations to come, it may be, will scarce believe that such a one as this ever in flesh and blood walked upon this earth.
Carl von Ossietzky
ONLY ONE WHO SPENT the years following the First World War in Germany can fully understand how hard a battle it was that a man like Ossietzky had to fight. He knew that the tradition of his countrymen, bent on violence and war, had not lost its power. He knew how difficult, thankless and dangerous a task it was, to preach sanity and justice to his countrymen who had been hardened by a rough fate and the demoralizing influence of a long war. In their blindness they repaid him in hatred, persecution and slow destruction; to heed him and to act accordingly would have meant their salvation and would have been a true relief for the whole world.
It will be to the eternal fame of the Nobel Foundation that it bestowed its high honor on this humble martyr, and that it is resolved to keep alive his memory and the memory of his work. It is also wholesome for mankind today, since the fatal illusion against which he fought has not been removed by the outcome of the last war. The abstention from the solution of human problems by brute force—is the task today as it was then.