Fritz Zwicky: Morphological astronomy
In 1957 Fritz Zwicky published Morphological astronomy (Springer-Verlag). Below we give a version of the Foreword of this book:
Man has a great tendency to get lost or to hide, as the case may be, in a jungle of details and in unnecessary complications. Why do anything simply if you can do it complicated? And still, life itself presents a sufficient number of problems to keep us busy. There would seem to be no need to create additional difficulties, just for the fun of it, especially if these self-made difficulties become practically insuperable and if in the end they cause much unhappiness.
The morphological mode of thought and of action was conceived to break the vicious hold which the parasitic wild growth of complications exerts on life in all of its phases. Morphological thought and action are likely to be of value in all human activities, once such thought and action have been clearly delineated and fully developed, and once they have been practised by a sufficiently large number of people.
Since the morphological method is of the greatest universality, the choice of the field to which one applies it first is not particularly critical. The author intends to write two or three books on the morphology of several large scale problems, which are both of a technical and of a general social nature. The present book is concerned in particular with some implications of morphological thinking in astronomy. We shall above all emphasize the basic character of the morphological approach, and we shall demonstrate its constructive power in a number of specific cases.
The morphological method always attempts to attain the most general perspective. It seeks to furnish the tools for total research in which no prejudices have any place, in which no stone is left unturned and all selectivities are avoided. The morphological method endeavours especially to visualize all the possible solutions of any given problem and to point the way towards the general performance evaluation of these solutions.
In this book we shall describe the intrinsic character and the formalism of the morphological method. We shall also discuss some practical applications of this method. It will, of course, not be possible to carry through the morphological analysis in all fields of astronomy. Detailed applications, however, will be presented in some special fields. Morphological considerations have so far been applied intensively to three problems in astronomy. These problems concern themselves first, with the large scale distribution of matter in the universe, second, with the quest for all possible types of stars and, third, with the large scale planning of future research which will involve not only the observation of but also the experimentation with some of the celestial bodies. Some preliminary work has also been started on the morphology of all possible disturbances in the earth's atmosphere and the question of how far these disturbances can be analysed by optical means, for instance through the observation of the scintillation of stars. Most of the material used had to be drawn from the author's own researches. For this he begs to be excused on the grounds that no other investigator has as yet constructively applied the morphological method.
In the course of my work I came to the conclusion that what is most lacking in astronomy is a sufficient record of the actual contents of the universe and of the nature of the physical laws which govern these contents. The first major need therefore seemed to be to put the morphological method in the service of an all embracing search for new types of objects and new physical laws. The lack of a sufficiently complete record of what actually exists in our universe has led to some very unsatisfactory aspects of present day astronomy. On the one hand there are those youthful and enthusiastic, but totally irresponsible cosmologists and theoretical physicists who build imaginary universes which are neither of any scientific nor of any artistic value. These men simply lack the proper appreciation of the scarcity of definitely known facts and the realisation that without such facts all speculation remains largely futile. It is clear that even the richest imagination falls far short of the surprises which nature has in store for us. On the other hand there are far too many observers, especially some of those who have the use of the largest telescopes, whose knowledge of the fundamentals of physics is meagre. Much of the work of these observers has degenerated into an enterprise of taking beautiful pictures and storing them away by the car load. Interpretations which are being made are all too often autistic rather than scientific in character and actually few unambiguous clues have been produced by these observers during the past two decades which could be used for the construction of sound cosmological theories.
Both groups of men just mentioned might profit if they became acquainted with the morphological method. This book hopes to serve as a first introduction. In illustrating the morphological method a number of new results will be achieved almost automatically. These results, I think, will be of considerable interest to astronomers. In any event, this book will fall short of what I intended it to be if it does not stimulate other scientists, technical men and philosophers to achieve greater independence and versatility of thought and a future of altogether happy research.
As to the technical and methodological subjects which are treated, it should be noted that the present book was written at the suggestion of some friends who had heard my Halley Lecture at Oxford on May 12, 1948: The book actually represents an expansion of this Lecture. During the preparation of the manuscript it became apparent that an additional book will have to be written eventually to cover all of the subjects which were touched upon in the Halley Lecture.
The present volume starts with a general description of the morphological method. Concerning the actual astronomical subjects, it deals almost exclusively with the contents of extragalactic space, that is, with the galaxies, clusters of galaxies and with intergalactic matter, the observable existence of which I was able to prove in the course of writing this book. Much space is devoted to those results on the large scale distribution of matter which I obtained during the past four years. Many of these results are presented here for the first time; some are definite while others are only indicative and need further checking. It is, in my mind, essential that a new method of research should attempt to demonstrate its value through the discovery of as many new facts and relations as possible. This is necessary in order to persuade other thinkers, experimenters and observers to familiarise themselves with the principles of the morphological method and to apply them. Naturally there are many who at the start doubt the power of the method. In order to convince these sceptics those who know how to use the method must constructively prove in action that with its help results can be achieved which with less systematic research would not have been achieved at all, or which would have required much greater expenditure in time and effort. Specifically I set myself the goal of gaining as rapidly as possible new and badly needed knowledge on the large scale distribution of matter in the universe and to explore in particular the contents of the supposedly empty intergalactic spaces. I also endeavoured to prepare the grounds for a decisive analysis of the various issues related to the time scale of the universe and to the problem of whether or not the universe as a whole is expanding. I feel that the morphological method has enabled me to achieve the desired results, some of which are as follows.
- The large scale distribution of galaxies in extended regions in high northern galactic latitudes as it is observable from the earth is very non-uniform both in width and in depth. This, especially for the brighter nebulae, is partly due to their great tendency toward clustering. For faint distant galaxies the great irregularities which are observed in their distribution are mostly due to the absorption of light by intergalactic dust, whose existence thus first revealed itself.
- Clustering among galaxies is far more pronounced than was previously thought.
- The luminosity function of galaxies does not possess a maximum as has been maintained by other observers.
- Numerous faintly luminous bridges, filaments, clouds and other extended formations of stars were discovered which interconnect very widely separated galaxies. These have proved of intense interest to cosmological theory and they have provided the first decisive evidence for the existence of vast amounts of tenuous luminous intergalactic matter (stars) whose total mass in a given large volume of space may be comparable with, or even greater than, the total mass of the galaxies proper which are located in the same volume.
In connection with the luminous intergalactic streamers some properties of the redshift of light from distant galaxies have been found which indicate that this redshift may not be a function only of the distance but that possibly another parameter is involved.
- A powerful method of dimensionless morphology has been developed which has led to a novel type of analysis of the observations and which bids fair to provide us with the means of a decision for or against the concept of an expanding universe.
- There are strong indications that the idea of the existence of only two basic types of stellar populations (now called I and II) which has recently been promoted is much too naive and that there exist several types of populations which are quite different from I and II. In this connection a method of composite photography has been developed which has proved a powerful tool in the exploration of the characteristic material populations which compose the distant galaxies. This method has brought to light some rather unexpected relations between the character of the stellar populations and the structural features of galaxies.
- Means have been devised in principle for the determination of the distances of extragalactic nebulae which arc essentially free from the objections which must be raised against the presently used methods. The contents of the universe in spaces beyond our own galaxy were speculated upon by many astronomers and philosophers before the twentieth century. Sir William Huggins in 1864, equipped with a spectrograph, made the decisive observation that some of the so-called nebulae are masses of luminous gases. From their location in the sky it was subsequently correctly inferred that these nebulae are associated with the Milky Way system. The nature of the very much more numerous small nebulous objects, many of which show spiral structure and which are found everywhere except in the Milky Way, remained uncertain until about three decades ago. The final solution came through the efforts of many men. Some of the notable and vital steps were H Shapley's determination of the distances, sizes and luminosities of the globular clusters, as well as the parallax determinations of the great nebula in Andromeda and other systems by K Lundmark and H D Curtis. From the data on the novae in spiral nebulae Lundmark in 1919 deduced a distance of 200000 parsecs for the Andromeda nebula, which is essentially the value which was later confirmed by E P Hubble. This value has been used until recently. From 1910 to 1925 V M Slipher carried through his most fundamental program on the radial velocities of galaxies which he found to lie in the range from -300 km/sec to +2000 km/sec. A first unsatisfactory attempt was made by Lundmark to relate the apparent radial velocities of galaxies to their distances. This suggestion proved its value later when Hubble, on the basis of improved data, was able to establish the relation between apparent velocity and the distance which Lundmark had suggested. The data which Hubble used were, of course, obtained with the help of the 100-inch reflector which was installed at the Mount Wilson Observatory in 1918. The researches in the period from 1925 to 1945 were concerned mostly with the more detailed investigation of the structure and the material contents of galaxies supplemented by observations on the distribution of galaxies in space, in luminosity and in type. It is with these investigations that I am particulary concerned. My own results in some instances confirm the views of my predecessors and in some respects extend them. There are, however, a number of cases where the pioneers guessed wrong. These cases will be discussed.
In conclusion we must emphasize that morphological astronomy concerns itself with the character and the interrelations of all phases of astronomical research, as well as with the relations of astronomy to all other fields of human endeavour. If we assume our goal to be the continued and unimpeded accumulation of astronomical knowledge, we must not fail to explore all of the influences which either further or hinder our efforts . The rise of observational astronomy in Poland, Denmark, Germany, Italy, England, France and Russia and its subsequent decline into mediocrity and decay in all of these countries must be closely studied. My native country of Switzerland, in spite of the glorious achievements in theoretical astronomy by Euler, Ritz and others has never even had a start in observational astronomy. All of these facts seem to have their origin in certain human weaknesses which now appear to be in action in the United States of America also. False notions of scholarship and gentlemanliness must therefore not prevent us from pointing out the salient facts and to insist in particular that history is made by individual men and by groups of men. Morphological astronomy is therefore vitally concerned with the study of the influences, good or bad, which individuals exert on the future of astronomy and it holds that all of these influences must be clearly pinpointed if we wish to forestall future disasters.
Since the writer is the originator of the morphological method, the present book is largely a one man affair. This does not mean, of course, that I have not had technical help on details and encouragement in general from my friends, past and present. There are, however, too many of them to be all mentioned here individually. My thanks must therefore go to them collectively and anonymously.