Scientific autobiography, p.1
Scientific Autobiography, page 1
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Max Planck
Scientific Autobiography and Other Papers
Max Planck
With a Memorial Address on Max Planck by Max Von Laue
Translated from German by Frank Gaynor
Contents
Introduction - MEMORIAL ADDRESS
A Scientific Autobiography
Phantom Problems in Science
The Meaning and Limits of Exact Science
The Concept of Causality in Physics
Religion and Natural Science
Notes
Titles of essays as they appeared in the German original:
Wissenschaftliche Selbstbiographie (1948)
Scheinprobleme der Wissenschaft (1947)
Sinn und Grenzen der Exakten Wissenschaft (1947)
Religion und Naturwissenschaft (1947)
Der Kausalbegriff in der Physik (1948)
Introduction
MEMORIAL ADDRESS
delivered by Max von Laue
in the Albani Church in Göttingen
on October 7, 1947
My Fellow Mourners:
We stand at the bier of a man who lived to be almost four-score-and-ten. Ninety years are a long life, and these particular ninety years were extraordinarily rich in experiences. Max Planck would remember, even in his old age, the sight of Prussian and Austrian troops marching into his native town of Kiel. The birth and meteoric ascent of the German Empire occurred during his lifetime, and so did its total eclipse and ghastly disaster. These events had a most profound effect on Planck in his person, too. His eldest son, Karl, died in action at Verdun in 1916. In the Second World War, his house went up in flames during an air raid. His library, collected throughout a whole long lifetime, disappeared, no one knows where, and the most terrible blow of all fell when his second son, Erwin, lost his life in the rule of terror in January, 1945. While on a lecture tour, Max Planck, himself, was an eye-witness of the destruction of Kassel, and was buried in an air raid shelter for several hours. In the middle of May, 1945, the Americans sent a car to his estate of Rogätz on the Elbe, then a theatre of war, to take him to Göttingen. Now we are taking him to his final resting-place.
In the field of science, too, Planck’s lifetime was an epoch of deep-reaching changes. The physical science of our days shows an aspect totally different from that of 1875, when Planck began to devote himself to it—and Max Planck is entitled to the lion’s share in the credit for these changes. And what a wondrous story his life was! Just think—A boy of seventeen, just graduated from high school, he decided to take up a science which even its most authoritative representative whom he could consult, described as one of mighty meager prospects. As a student, he chose a certain branch of this science, for which even its neighbor sciences had but little regard—and even within this particular branch a highly specialized field, in which literally nobody at all had any interest whatever. His first scientific papers were not read even by Helmholtz, Kirchhoff and Clausius, the very men who would have found it easiest to appreciate them. Yet, he continued on his way, obeying an inner call, until he came face to face with a problem which many others before him had tried and failed to solve, a problem for which the very path taken by him turned out to have been the best preparation. Thus, he was able to recognize and to formulate, from measurements of radiations, the law which bears and immortalizes his name for all times. He announced it before the Berlin Physical Society on October 19, 1900. To be sure, the theoretical substantiation of it made it necessary for him to reconsider his views and to fall back on methods of the atom theory, which he had been wont to regard with certain doubts, And beyond that, he had to venture a hypothesis, the audacity of which was not clear at first, to its full extent, to anybody, not even to him. But on December 14, 1900, again before the German Physical Society, he was able to present the theoretic deduction of the law of radiation. This was the birthday of the quantum theory. This achievement will perpetuate his name forever.
This is why on this day innumerable scientific bodies have expressed their sympathy and grief over his death, in telegrams, or by sending their representatives here. Thus, we have with us now the President of the Academy of Berlin, and the Rector of the University of Berlin, two bodies with which Max Planck was especially closely affiliated. He taught at the University for more than forty years, and he was a member of the Academy for more than half a century; in fact, most of that time he held the office of one of its four Permanent Secretaries. Likewise, the Academies of Munich and Göttingen are represented here by their Presidents, the University of Göttingen by its Rector, and the School of Engineering of Hannover by its Faculty delegate. Furthermore, wreaths have been placed on the bier in behalf of the State Government of Lower Saxony.
I would like to mention, in particular, some of the many wreaths lying here. One of them was sent by the German Museum in Munich, which is just about to place Max Planck’s bust in its Hall of Fame. Next to the respects paid by the Academy of Munich, this wreath is the last salute from Bavaria, where Planck grew up, and where he would spend his vacation every year, to seek and find pleasure and relaxation.
Another wreath is inscribed: “The German Physical Societies to their Honorary Member.” These Societies remember the fifty-eight years of Planck’s membership, his selfless work in the most diverse administrative posts; for the major part of his membership he was a member of the Board, and also held its chairmanship several times. They remember, in particular, the great many enlightening lectures which he delivered at their scientific meetings, and above all, that address in 1900 when, as mentioned before, he made his first disclosure of his law of radiation and its deduction. A bright ray of his brilliant fame was thus reflected on the German Physical Society, too.
And here is a plainer wreath, without any streamers. It was placed here by me in behalf of all his pupils, among whom I count myself, as a perishable token of our never-ending affection and gratitude.
A Scientific Autobiography
My original decision to devote myself to science was a direct result of the discovery which has never ceased to fill me with enthusiasm since my early youth—the comprehension of the far from obvious fact that the laws of human reasoning coincide with the laws governing the sequences of the impressions we receive from the world about us; that, therefore, pure reasoning can enable man to gain an insight into the mechanism of the latter. In this connection, it is of paramount importance that the outside world is something independent from man, something absolute, and the quest for the laws which apply to this absolute appeared to me as the most sublime scientific pursuit in life.
These views were bolstered and furthered by the excellent instruction which I received, through many years, in the Maximilian-Gymnasium in Munich from my mathematics teacher, Hermann Müller, a middle-aged man with a keen mind and a great sense of humor, a past master at the art of making his pupils visualize and understand the meaning of the laws of physics.
My mind absorbed avidly, like a revelation, the first law I knew to possess absolute, universal validity, independently from all human agency: The principle of the conservation of energy. I shall never forget the graphic story Müller told us, at his raconteur’s best, of the bricklayer lifting with great effort a heavy block of stone to the roof of a house. The work he thus performs does not get lost; it remains stored up, perhaps for many years, undiminished and latent in the block of stone, until one day the block is perhaps loosened and drops on the head of some passerby.
After my graduation from the Maximilian-Gymnasium, I attended the University, first in Munich for three years, then in Berlin for another year. I studied experimental physics and mathematics; there were no professorships or classes in theoretical physics as yet. In Munich, I attended the classes of the physicist Ph. von Jolly, and of the mathematicians Ludwig Seidel and Gustav Bauer. I learned a great deal from these three professors, and I still retain them in reverent memory. But I did not realize until I came to Berlin that in matters concerned with science they had really just a local significance, and it was in Berlin that my scientific horizon widened considerably under the guidance of Hermann von Helmholtz and Gustav Kirchhoff, whose pupils had every opportunity to follow their pioneering activities, known and watched all over the world. I must confess that the lectures of these men netted me no perceptible gain. It was obvious that Helmholtz never prepared his lectures properly. He spoke haltingly, and would interrupt his discourse to look for the necessary data in his small note book; moreover, he repeatedly made mistakes in his calculations at the blackboard, and we had the unmistakable impression that the class bored him at least as much as it did us. Eventually, his classes became more and more deserted, and finally they were attended by only three students; I was one of the three, and my friend, the subsequent astronomer Rudolf Lehmann-Filhés, was another.
Kirchhoff was the very opposite. He would always deliver a carefully prepared lecture, with every phrase well balanced and in its proper place. Not a word too few, not one too many. But it would sound like a memorized text, dry and monotonous. We would admire him, but not what he was saying.
Under such circumstances, my only way to quench my thirst for advanced scientific knowledge was to do my own reading on subjects which interested me; of course, t
Clausius deduced his proof of the Second Law of Thermodynamics from the hypothesis that “heat will not pass spontaneously from a colder to a hotter body.” But this hypothesis must be supplemented by a clarifying explanation. For it is meant to express not only that heat will not pass directly from a colder into a warmer body, but also that it is impossible to transmit, by any means, heat from a colder into a hotter body without there remaining in nature some change to serve as compensation.
In my endeavor to clarify this point as fully as possible, I discovered a way to express this hypothesis in a form which I considered to be simpler and more convenient, namely: “The process of heat conduction cannot be completely reversed by any means.” This expresses the same idea as the wording of Clausius, but without requiring an additional clarifying explanation. A process which in no manner can be completely reversed I called a “natural” one. The term for it in universal use today, is: “Irreversible.”
Yet, it seems impossible to eradicate an error which arises out of an all too narrow interpretation of Clausius’ law, an error against which I have fought untiringly all my life. To this very day, instead of the definition I just mentioned, one often finds irreversibility defined as “An irreversible process is one which cannot take place in the opposite direction.” This formulation is insufficient. For it is quite possible to conceive of a process which cannot take place in the opposite direction but which can in some fashion be completely reversed.
Since the question whether a process is reversible or irreversible depends solely on the nature of the initial state and of the terminal state of the process, but not on the manner in which the process develops, in the case of an irreversible process the terminal state is in a certain sense more important than the initial state—as if, so to speak, Nature “preferred” it to the latter. I saw a measure of this “preference” in Clausius’ entropy; and I found the meaning of the Second Law of Thermodynamics in the principle that in every natural process the sum of the entropies of all bodies involved in the process increases. I worked out these ideas in my doctoral dissertation at the University of Munich, which I completed in 1879.
The effect of my dissertation on the physicists of those days was nil. None of my professors at the University had any understanding for its contents, as I learned for a fact in my conversations with them. They doubtless permitted it to pass as a doctoral dissertation only because they knew me by my other activities in the physical laboratory and in the mathematical seminar. But I found no interest, let alone approval, even among the very physicists who were closely concerned with the topic. Helmholtz probably did not even read my paper at all. Kirchhoff expressly disapproved of its contents, with the comment that the concept of entropy, whose magnitude could be measured by a reversible process only, and therefore was definable, must not be applied to irreversible processes. I did not succeed in reaching Clausius. He did not answer my letters, and I did not find him at home when I tried to see him in person in Bonn. I carried on a correspondence with Carl Neumann, of Leipzig, but it remained totally fruitless.
However, deeply impressed as I was with the importance of my self-imposed task, such experiences could not deter me from continuing my studies of entropy, which I regarded as next to energy the most important property of physical systems. Since its maximum value indicates a state of equilibrium, all the laws of physical and chemical equilibrium follow from a knowledge of entropy. I worked this out in detail during the following years, in a number of different researches. First, in investigations on the changes in physical state, presented in my probationary paper at Munich in 1880, and later in studies on gas mixtures. All my investigations yielded fruitful results. Unfortunately, however, as I was to learn only subsequently, the very same theorems had been obtained before me, in fact partly in an even more universal form, by the great American theoretical physicist Josiah Willard Gibbs, so that in this particular field no recognition was to be mine.
While an instructor in Munich, I waited for years in vain for an appointment to a professorship. Of course, my prospects for getting one were slight, for theoretical physics had not as yet come to be recognized as a special discipline. All the more compellingly grew in me the desire to win, somehow, a reputation in the field of science.
Guided by this desire, I decided to submit a paper for the prize to be awarded in 1887 by the Philosophical Faculty of Göttingen. The subject to be discussed was, “The Nature of Energy.” After I had completed my paper, in the spring of 1885, I was offered the associate professorship in theoretical physics at the University of Kiel. This offer came as a message of deliverance. The moment when I paid my respects to Ministerial Director Althoff in his suite in the Hotel Marienbad, and he informed me of the particulars and conditions of my appointment, was, and will always be, one of the happiest of my life. For even though my life in my parents’ house was as beautiful and contented as any man could wish for, my longing for independence kept growing within me, and I was yearning for a home of my own.
To be sure, I suspected, and by no means without reason, that this smile of good fortune was actually not so much a reward for my scientific accomplishments as a practical result of the circumstance that Gustav Karsten, Professor of Physics in Kiel, happened to be a close friend of my father. Nevertheless, this realization could not mar my supreme happiness, and I was firmly resolved to justify the confidence in me in every way in my power.
I soon moved to Kiel, where I put the finishing touches on my paper, and submitted it in Göttingen. It won second prize. Besides my entry, two other papers had been submitted on the subject, but these two were awarded no prize at all. Obviously, I was wondering why my paper had failed to win first prize, and I found the answer in the text of the detailed decision of the Faculty of Göttingen. The judges set forth a few points of criticism of minor import, and then stated: “Finally, the Faculty must withhold its approval from the remarks in which the author tries to appraise Weber’s Law.” Now, the story behind these remarks was: W. Weber was the Professor of Physics in Göttingen, between whom and Helmholtz there existed at the time a vigorous scientific controversy, in which I had expressly sided with the latter. I think that I make no mistake in considering this circumstance to have been the main reason for the decision of the Faculty of Göttingen to withhold the first prize from me. But while with my attitude I had incurred the displeasure of the scholars of Göttingen, it gained me the benevolent attention of those of Berlin, the results of which I was soon to feel.
No sooner had I finished my paper for Göttingen than I returned to my favorite subject, and wrote a number of monographs, which I published under the collective title, On The Principle of the Increase of Entropy. In these articles I discussed the laws of chemical reactions, of the dissociation of gases, and finally the properties of dilute solutions. With respect to the latter, my theory led to the conclusion that the values of the lowering of the freezing point, observed in many salt solutions, could be explained only by a dissociation of the substances dissolved, and that this finding constituted a thermodynamic foundation for the electrolytic dissociation theory advanced by Svante Arrhenius approximately at the same time. This conclusion, unfortunately, got me into an unpleasant conflict. For Arrhenius challenged, in a rather unfriendly manner, the admissibility of my arguments, pointing out that his theory related to ions, i.e. electrically charged particles. I could reply only that the laws of thermodynamics were valid regardless of whether or not the particles carried a charge.
