From Immigrant to Inventor

by Michael Pupin

In October, 1899, Rowland delivered his presidential address before the society at whose head he stood. I can see now how happy he looked on that memorable occasion. Inspired by the latest revelations in Electron Physics, he prophesied what new revelations the physicists should expect in the approaching future. After describing physics as “a science above all sciences, which deals with the foundation of the universe, with the constitution of matter from which everything in the universe is made, and with the ether of space by which alone the various portions of matter forming the universe affect each other ...” he stated frankly that the physicists of America “form an aristocracy, not of wealth, not of pedigree, but of intellect and ideals.... Let us cultivate the idea of the dignity of our pursuit so that this feeling may sustain us in the midst of a world which gives its highest praise, not to the investigator in the pure ethereal physics which our society is formed to cultivate, but to the one who uses it for satisfying the physical rather than the intellectual needs of mankind.” He then pleaded that we “recognize the eras when great thoughts have been introduced into our subject and honor the great men who introduced them and proved them correct.” Then, enumerating the great problems of the physical universe, he asked: “What is matter; what is gravitation; what is ether and radiation; what is electricity and magnetism; how are these connected together, and what is their relation to heat?” Now, these are the very questions which Electron Physics has been trying to answer since that time; and this is the idealism which the American physicist has had before him ever since the days of Rowland.

Electromagnetic theory of matter was the first answer to Rowland’s question: What is matter? But how about the answer to his second question: What is gravitation? If matter contains nothing but electrons, if they are really the most fundamental building stones of matter, then electricity as concentrated and stored up in the electrons can exert in addition to the well-known electrical force also a gravitational force. A somewhat novel idea, but ... why not, and why so? Einstein gives the best answer to this.

To Rowland’s question: What is Ether? Electron Physics gave a puzzling answer, but the puzzle has led us into a side path of surpassing beauty. Our famous physicists, Michelson and Morley, are a combination of two names better known in the world of physical science to-day than Castor and Pollux were known when Zeus, descending from the heights of Mount Olympus, sought the companionship of mortal men. The fame of the twins, Michelson and Morley, not, however, of Michelson alone, rests upon an experimental demonstration, the importance of which was not until recently fully appreciated, the demonstration, namely, that there is no ether drift; that is to say, so far as man can tell, there is no relative motion between the earth moving through space and the ether which is supposed to fill all interstellar space. On the other hand, the hypothesis that the ether moves with the moving earth leads to insurmountable difficulties. This was, indeed, a most embarrassing situation! Since Michelson originally, and, later, Michelson and Morley, employed the radiation of light in their attempts to detect the ether drift, it became necessary to re-examine the electromagnetic theory of propagation of light for the case that light, as in the Michelson and Morley experiment, proceeds from a source which together with the observer is moving through space. The famous Professor Lorentz, of Leyden, Holland, whom I have the honor of knowing personally, made the first successful extension of this theory, and explained satisfactorily Michelson and Morley’s result. But the extension was obtained by what was acknowledged to be a clever notion, and not by an unavoidable physical fact. The same extension of the theory was obtained by Einstein, but it was founded upon a broad physical principle which Lorentz’s extension lacked. Lorentz preferred Einstein’s deduction of his extension, called the Lorentz transformation. The physical principle just referred to is now popularly known as the Special Relativity Theory, which Einstein extended later into the General Relativity Theory. Einstein’s theory explains very simply the Michelson-Morley experiment, but how does it answer Rowland’s question: What is Ether? Also very simply by saying that ether is superfluous in our analysis of physical phenomena. Faraday expressed a similar view nearly eighty years ago. That, however, which is essential in this narrative in connection with Einstein’s relativity theory is the great fact that by it a general demonstration is furnished that all forms of electrical energy are a mass which has inertial as well as gravitational activity. In the electromagnetic theory of matter this demonstration plays a most important part. One of the schemes of this theory is so simple and so beautiful, and appeals so strongly even to an imagination not scientifically trained, that I must tell here very briefly some of its most striking features.

All atoms are built up from a single atom, the atom of hydrogen, which consists of a positive electron or proton, the nucleus, and a single negative electron revolving around it like a satellite around the central planet. A heavier atom, say an atom of oxygen, consists of sixteen atoms of hydrogen, the positive nuclei of which form the positive nucleus or central portion of the oxygen atom. Some of the negative electrons are distributed among the positive electrons of the central nucleus, serving to cement them together, and the other negative electrons are revolving like satellites around the central nucleus. The number of these satellites is the atomic number of the atom, and it is this number, and not the atomic weight, which determines the chemical characteristics of the atoms. This is only a mere glance into the structure of Electron Physics, made here for the purpose of pointing out some of the never-dreamt-of possibilities that Electron Physics holds in view. For instance, four atoms of hydrogen combining into an atom of helium give off a certain amount of energy. We say the atoms of hydrogen degrade into the heavier atom of helium and, thereby, a certain amount of energy is liberated. A helium atom weighs less than four atoms of hydrogen, because of the diminished energy per atom of hydrogen, the decrement of the weight being proportional to the decrement of energy. This is demanded by Einstein’s theory, which is really an extension of the theory first proposed by Sir John Joseph Thomson, and it is a remarkable fact that these weight relations satisfy the prophecy of the theory. The amount of energy obtained by the degradation of the lighter into heavier atoms is enormous. But we do not know how to produce the process of this degradation. The question arises: Do not the young stars, the very hot stars, which always consist of gases of small atomic weight, obtain a supply of radiant energy from the degradation of atoms of small into atoms of high atomic weight, and, if this is so, then why shall we not some day learn this great secret from the stars? The language of the stars has many deep secrets to tell; it mystifies me just as much to-day as it did on the pasturelands of my native village fifty years ago.

Many other most startling contemplations may be connected with the new views opened up by Electron Physics, all of them illustrating the beauty, the wealth, and the power of a new science which represents the marriage of two great sciences, physics and chemistry.

Industrial science is very much impressed by new discoveries which, as Rowland expressed it, “deal with the foundation of the universe,” but which in spite of their revolutionary character are easily understood by the practical man. Electron Physics abounds in discoveries of that kind, and it seems that they have rushed upon us like a cloud-burst. Things have been done that formerly seemed impossible. Take, for an illustration, a thing which is so familiar to all, the complete transformation of wireless telegraphy into the new art which is called Radio. A vacuum-tube with a hot filament fills up with negative electrons, which are thrown off by the hot filament. The filament may be said to be radioactive. A current can be established by applying an electromotive force which drives these negative electrons from the space surrounding the hot filament to a positive electrode. Here we have a new type of Crookes’s tube, operated by a small electrical tension, and not by that of a powerful induction-coil, which is necessary when the negative electrode is cold. This current is called the thermionic current, and its value can be varied in any way we please by a second electrical force which acts through a third electrode, called the grid, placed in the path of the thermionic current. This is the so-called audion tube, invented by a Yale graduate, Doctor Lee De Forest. In the hands of the Western Electric Company and of the General Electric Company, this tube has transformed the whole radio art by its amplifying power. My old inventions of electrical tuning and rectification have been raised to unexpected powers by the action of these tubes, and the inventions of my former pupil and research associate, Major E. H. Armstrong, and of others, have given us the broadcasting art, which surpasses the wildest expectations of even the rosiest of optimists of a few years ago. Wherever Electron Physics has entered there have sprung up new crops of the rarest fruit, and it is no wonder that there are to-day so many workers in the newly discovered fertile fields of the electromagnetic theory. Attend any meeting of the American Physical Society and you will be convinced that the research in the university laboratories as well as in the research laboratories of our industries would satisfy even the highest expectations of the men who fifty years ago, under the leadership of Joseph Henry, started the movement in favor of higher scientific research. The university and the industrial laboratories are mindful of Rowland’s admonition: “In choosing subjects for our investigation, let us, if possible, work upon those subjects which will finally give us advanced knowledge of some great subject.” What subject can be greater than eternal truth, and that aim, according to my definition, is idealism in science.

It is very true that our American scientific research activities in physics and chemistry are so alive to-day because they have been greatly stimulated by the wonderful advances, through electron physics, in the electromagnetic theory, and in its very successful applications to technical and industrial problems. But it is also true that the scientific research activities in other branches, like biology, which are not closely connected with the electromagnetic theory and its applications, have also blossomed up with wonderful rapidity during the last twenty-five years. It will be conceded, I think, that all these activities in abstract science are to a very substantial extent due to the rapid rise of the American university and to its splendid influence upon the mentality of our industries. But in this democratic country, covering a vast area, each State has the privilege of regulating in its own way its own educational programme and policy, and each privately endowed university can pursue its own ideals in its own way without worrying very much about any other university. Lack of unity and uniformity was, therefore, always felt, and there was always a strong although often an unconscious desire in the hearts of scientific men to bring about a uniformity in the aims and aspirations of higher scientific research in our universities. The American Association for the Advancement of Science made quite a number of efforts in this direction, but the progress was slow. The great World War forced us to make another big effort in this direction, and this time the effort succeeded beyond all expectations. The following story of this big effort is, I am sure, of national importance, and should be known by every intelligent person in the United States.

Just as the cultivation of science in the United States was first taken up in the technical schools, like the School of Mines of Columbia College, the Massachusetts Institute of Technology, and many others, and not in colleges or universities, so the organization of scientific associations took place first among the engineers, the graduates of the technical schools. The American Society of Civil Engineers, the American Institute of Mining and Metallurgical Engineers, the American Society of Mechanical Engineers, and the American Institute of Electrical Engineers, for instance, were organized some time before most of the present associations in abstract science, that is in mathematics, physics, chemistry, and biology were organized. Even the youngest among the leading engineering societies, that is, the American Institute of Electrical Engineers, was organized in the early eighties, whereas the American Physical Society was organized nearly twenty years later, in 1899.

The organization of these technical societies did not wait for the arrival of the American university. But, nevertheless, when the American university arrived, and with it the research laboratories in the fundamental sciences, it improved the quality of the American engineer, and of the American engineering societies, just as it improved the scientific standards of the American industrial organizations. The National Academy of Sciences deserves here a special consideration. It is an association of workers in abstract science, principally, but, contrary to what I have just said, it is, like the American Philosophical Society, founded by Franklin, older than any of our national engineering societies. Its early birth was due to the conditions created by the Civil War. Joseph Henry, I imagine, suggested to President Lincoln that a mobilization of the scientific resources of the North would improve greatly its military strength, and thus the National Academy of Sciences was chartered by Congress during the Civil War, in 1863, and was approved by President Lincoln. It was a creation of the Civil War, and is in many respects an institution which forms a part of the Federal Government. I shall describe now how the National Academy of Sciences, itself a creation of the Federal Government during the Civil War, gave birth during the World War to another national scientific institution which is the climax of the great scientific movement started fifty years ago. I have watched this movement almost from its very beginning up to the present time; yes, I have been a part of it during its most active period, and I believe that I understand its full meaning.

The four leading engineering societies, mentioned above, were in quite a flourishing condition at the beginning of this century; flourishing not only with regard to the number, but also with regard to the quality of their membership, and their progress was speeding on with remarkable rapidity. For instance, the papers read before the American Institute of Electrical Engineers in 1900, and the discussions which followed them, were immeasurably superior to those read in 1890, when I first became a member of this Institute, because the quality of its membership was also immeasurably superior. The great American industries paid much more respectful attention to these engineering societies than when I first came to Columbia College in 1889. The greatest among the American captains of industry of those days, the late Andrew Carnegie, held them in so high an esteem that he presented a magnificent gift to them which led to the formation of the United Engineering Society. This happened in 1904, and marks one of the great events in the history of American technical science.