Scientific Highlights in Memory of Léon Van Hove

The following sections are included:

• PREFACE

• CONTENTS

The following sections are included:

• Introduction

• Hierarchical Modular Systems

• Structure Analysis: the Procrustes Algorithm

• Examples

• Acknowledgement

• References

I first met Léon van Hove on fall 1949, as we both were visitors for a year at the Institute for Advanced Study, Princeton. We became very close friends.

In this talk, I would like first to recall our year in Princeton, portray Léon as he appeared to me at this time of our youth, and tell about the collaboration that he started with Georges Placzek on neutron physics, a collaboration which lasted some five years and proved unusually fruitful.

Then, I will account for his contributions in the field. It culminated with the establishment of the formalism of the so-called pair-distribution function in space and time, which is now of current use in this field of physics.

Finally, I will conclude in recalling the impact of his achievements of this period on the community of physicists, and more specifically, through personnel contacts, on our community in France.

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The search for simplicity at a fundamental level was stimulated by the universality of NB behavior and its subsequent interpretation in terms of clans. A continuous dialog between theory and experiment was at the origin of its success. Recent experimental findings show that the regularity is valid in e⁺e^- annihilation at LEP energy at a more fundamental level than previously expected. Perspectives opened by Léon Van Hove's work in the field are discussed and related to the new discovery.

At the Colloquium in honor of Léon Van Hove it was very moving to speak of him and to hear all what was said of this great physicist, who died one year before, by his friend and his wife. This is an expanded version of the given lecture. It starts from the exposition of a paper that Léon Van Hove wrote nearly forty years ago. This paper was extremely original and important; it is still often quoted.

Léon van Hove was not only a distinguished theoretical physicist; he was also, as Director General of CERN, an experienced science administrator. Aware of the need for the scientist to become involved in science policy issues, he remained informed about political trends and made a major contribution to public information concerning the national and international significance of fundamental research. With this in mind, we draw attention to the changing relations between science and society and the impact of these changes on European cooperation in the field of research. There is a basic contradiction between science, which is by nature universal, and the national interest of individual scientists. European integration may help to overcome this contradiction.

I shall try to describe what can be considered as one of the great scientific adventures of our times, namely the project to develop high intensity beams of antiprotons, so that one could make particle-antiparticle collisions in a hadron storage ring. As is well known, this led to the long awaited discovery of the massive intermediate bosons, W⁺, W^- and Z⁰. It is appropriate to delve into this adventure on this occasion, because Leon Van Hove played the rôle of a courageous leader and inspirer throughout; courageous in particular because he well knew the risks involved in the enterprise.

The following sections are included:

• Introduction

• Symmetries in Classical and Quantum Field Theory

• String Theory as 2D-Gravity

• Fundamental constants in QST

• Field-Theoretic Symmetries in String Theory

• Stringy Symmetries

• Conclusion

• References

The following sections are included:

• Introduction

• Principles of electron holography

• Image Resolution

• Complications

• Improvements in Image Reconstruction

• Acknowledgements

• References

The following sections are included:

• Acknowledgements

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The following sections are included:

• Foreword

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• LIST OF PUBLICATIONS OF SCIENTIFIC SEMINARS AND MEETINGS ORGANIZED BY THE ISTITUTO ITALIANO PER GLI STUDI FILOSOFICI