Time, Quantum and Information

Springer-Verlag Berlin Heidelberg GmbH

CARL FRIEDRICH VON WEIZSĂCKER © Ingrid von Kruse

Lutz Castell Otfried Ischebeck (Eds.)

Time, Quantum and Information

Springer

Lutz Castell Max-Planck-Institut fur Physik

Fohringer Ring 6

80805 Munchen, Germany

Otfried Ischebeck ZAE Bayern

Walter-Meissner-Strasse 6

85748 Garching, Germany

Library of Congress Cataloging-in -Publication Data.

Time, quantuffi and information : dedicated to C.F. von Weizsăcker in commemoration of

his 90th birthday 1 Lutz Castell, Otfried Ischebeck (eds.). p.cm.

Includes bibliographical references.

1. Nuclear physics. 2. Astrophysics. 3. Space and time. 4. Quantum theory. l. Weizsacker, Carl Friedrich, Freiherr von, '9'2- II. Castell, Lutz. III. Ischebeck, Otfried.

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Preface

This publication centers on the extraordinary ideas in and concepts of physics of CarI Friedrich von Weizsăcker. At the time of his 90th birthday on June 28, 2002, it seems the right moment to try such a survey. The themes of two Festschrifts for CarI Friedrich von Weizsăcker on the occasion of his 60th and 70th birthdays (E. Scheibe and G. Suessmann (eds.): Einheit und Vielheit, and K. Meyer-Abich (ed.): Physik, Philosophie und Politik) were his unique capability to encompass physics, philosophy and politics. He may be more known publicly today for his efforts for containment of the Cold War nuclear threat, for the abolition of war as an instrument of international politics, for the social responsibility of scientists, and for the Conciliar Process of the Churches for Justice, Peace and the Integrity of Creation. But physics has been his primary professional vocation and has always remained in the center of his thought and life.

But even in light of the physics focus of this book, it would not do justice to CarI Friedrich von Weizsăcker to re strict his achievements in physics to efforts only accessible to professionals. The contributions in Part 1 show how his very concentration on physics has led him to take an active part in problems of politics, social change, philosophy and religion.

From his doctorate in 1933 under Werner Heisenberg to the 1950s, CarI Friedrich von Weizsăcker built a successful career as a theoretical physicist in both nuclear physics and astrophysics. The theory of nuclear structure and forces, energy produc­tion in stars, the formation of planetary systems from a dust cloud, and the structure of turbulence are the fields where his contributions are stiH felt today. Part II reports on these achievements and their impact on modem science.

CarI Friedrich von Weizsăcker is one of the rare persons who can creatively link philosophy and natural sciences. Backed with this gift and with his success in the physics of atomic nuclei and stars, he set out, beginning in the mid-fifties, to reconstruct quantum theory as the center of modem natural philosophy. Parts III to V of the book contain contributions to this program. The way into this program is indicated by the concept of time, which is essentially linked to the concept of experience, the factual nature of the past and the indeterminacy of the future. The indeterminacy of the future leads to the central theory of modem physics: quantum

"1 Preface

theory, been understood as a theory which expresses the essential conditions for experience of the physical world. Its predictions provide information on the outcome of measurements in the form of probabilities. Weizsăcker called the elementary unit of information in quantum theory an ur. As an alI encompassing theory of physics, quantum theory should contain the possible fundamental forms of matter, elementary particles, and their interaction. It should thus permit the construction of particles and interactions from quantized bits of information. This hypothesis is called the ur-hypothesis, which was developed during the 1970s at the Max Planck Institut zur Eiforschung der Lebensbedingungen der wissenschaftlich-technischen Welt in Starnberg. It is on this path that CarI Friedrich von Weizsăcker would expect to achieve scientific honesty, eventual scientific discovery and, finally, scientific truth.

CarI Friedrich von Weizsăcker's work in nuclear physics and astrophysics can be considered as the first round on a "circular path", whose following round was marked by two parallel tracks: the scientific program for reconstruction of quantum theory, and his engagement in politics and society. Philosophy provides the common ground of these two tracks: the inquiry into one's own comprehension and understanding, and the moral issue of the engagement of the individual in the society. The person to whom he felt closest on this path has been Niels Bohr.

The driving force in his political engagement has been his involvement with the problems of nuclear power and weapons: under a dictatorship during World War II, as a threat for human existence during the following decades, but also as a source of energy for society. On the scientific track, his starting point is the all-encompassing relevance of quantum theory within science, which is a foundation for our belief in the unity of nature. But the unity of nature includes the history of humankind which, in turn, includes the development of science. So, the two parallel tracks converge again in the search for peace of humanity with nature, and for peace among humankind.

The editors are grateful to CarI Friedrich von Weizsăcker's friends, co-workers and fellow scientists for their contributions in particular for writing texts which can be read by both professional physicists as well as by interested non-physicists. Yet we are aware that a printed book cannot fully present what is to us the most impressive side of CarI Friedrich von Weizsăcker: his ability to listen to others, his power of critic al reasoning and the presence of his enormous knowledge in a discussion. He enjoys these capacities up to his present age of ninety.

The editors wish to thank Christoph Castell, Roger Hilton and Michael Rawn for correcting the English expres sion of translations from German. Christian Oberdorf has cared for the technical work with the edition. We thank the Max Planck Institute for Physics (Werner Heisenberg Insitute), Munich and the Human Science Center of the Ludwig Maximilian University of Munich for financial support. We thank Jam Behrmann for discussions, and last, but certainly not least, Professor Wolf Beiglback and the staff of Springer Verlag for their support of this publication.

Munich, May 2003 Lutz Castell Otfried Ischebeck

Contents

Letters to Cari Friedrich von Weizsacker on the Occasion of His 90th Birthday

Part 1 Cari Friedrich von Weizsacker and His Role

in the Physics of the 20th Century

Cari Friedrich von Weizsacker and The Kaiser Wilhelm/Max Planck Society Reimar Lilst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 17

The Role of the Physicist in the Nuclear Age Edward Teller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 25

"The Atomic Bomb Reveals the Political Responsibility of Science" Gotz Neuneck ....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 27 1 The Problem of Morality of Science in the Service

of Nuclear Weapons Development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 27 2 The Uranium Project 1939-1945 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 29 3 First Attempts to Find a Politica1 Framework

to Nuclear Weapons Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 40 4 Coping with the Nuclear Threat During the Cold War ................. 47 5 Paths Through PeriI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 53 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 55

On the Unfathomableness of Consciousness by Consciousness Klaus Gottstein . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 59

VIII Contents

Part II Cari Friedrich von Weizsăcker's Contributions to Nuclear and Astrophysics

and Their Impact on the Development of Physics

Introduction: From the Atomic Nucleus to Cosmic Vortex Systems Helmut Rechenberg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 75 1 First Research on Re1ativistic Quantum Prob1ems (1931-1934) ......... 75 2 The Theory of Nuclear Structure (1934-1937) ....................... 76 3 Pioneering the Theory of Nuclear Fusion in Stars (1936--1938). . . .. . . ... 77 4 Nuclear Fission Energy, Turbuience and the Structure

of Stellar Systems (1939-1954) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 78 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 80

The Origins of Nuclear Physics and Cari Friedrich von Weizsăcker's Semi-Empirical Mass Formula Karl v. Meyenn ................................................... 83 1 Theoretica1 Physics at the Beginning ofthe 30's . . . . .. . . . . ... . . . . . . . .. 83 2 The Penetration of Quantum Theory into Nuclear Physics . . . . . . . . . . . . .. 85 3 Gamow's Liquid Drop Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 87 4 The Neutron and Heisenberg's First Theory of the Nucleus . . . . . . . . . . . .. 88 5 Nuclear Physics During the Solvay Conference of 1933. . . . . . . . . . . . . . .. 91 6 The Discovery of the "American Forces" . . . . . . . . . . . . . . . . . . . . . . . . . . .. 92 7 CarI Friedrich von Weizsacker's Work in Physics During His Study

in Leipzig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 93 8 A Winter Sojourn in Copenhagen 1933/34:

The Discovery of the Weizsacker-Williams Method . . . . . . . . . . . . . . . . . .. 95 9 The Origin of the Semi-Empirical Mass Formula ..................... 97 10 As Debye's Assistant at the Kaiser Wilhelm Institute in Berlin. . . . . . . . .. 102 11 The Liquid Drop Model and Nuclear Fission . . . . . . . . . . . . . . . . . . . . . . . .. 103 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 105

Thermonuclear Processes in Stars and Stellar Neutrinos Georg Wolschin . .................................................. 115 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 115 2 Energy Evolution in Stars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 119 3 Hydrogen Burning ............................................... 123 4 Stellar Neutrinos ................................................ 127 5 Perspectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 132 References ......................................................... 133

Comets: Fascinating Cosmic Objects Reimar Liist . ..................................................... 135 1 The Nature of Comets ............................................ 135 2 The Orbits of Comets and Their Origin. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 137 3 The Physical and Chemical Properties of Comets . . . . . . . . . . . . . . . . . . . .. 138 4 Artificial Cometary Tails - Experiments in Space ..................... 138

Contents IX

5 The Preparation of the Space Missions to Halley's Cornet and the Spacecrafts .............................. 140

6 The Giotto Mission .............................................. 141

The Spectrum of Thrbulence Siegfried Grossmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 145 l Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 145 2 Historical Remarks .............................................. 145 3 Turbulent Diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 146 4 Scaling Law of Turbulence ........................................ 147 5 Mean Field Theory of Turbulence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 149 6 Temperature Structure Function .................................... 152 7 Outlook ........................................................ 154 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 156

From Dust Disks to Planetary Systems Thomas Henning .................................................. 159 1 The Scheme - From Fiction to Reality .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 159 2 Protoplanetary Disks - The First Steps .............................. 162 3 Detection of Planets and Planetary Systems .......................... 164 4 Interactions - Numerical Simulations ............................... 166 5 Tools for the Future .............................................. 167 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 169

Part III The Unity of Nature and the Nature of Time

Science and Its Relation to Nature in C.F. von Weizsacker's Natural Philosophy Klaus Michael Meyer-Abich ......................................... 173 1 The Meaning of Knowledge, Time, and History

in the Philosophy of Nature ....................................... 173 2 The Crisis of the Atomic Bomb in the Natural History of Mind ......... 176 3 Understanding Explanation - Weizsăcker's Titanic Project,

and Some Suggestions About It .................................... 180 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 184

C.F. von Weizsacker's Philosophy of Science and the Nature of Time Michael Drieschner ............................................... 187 1 Philosophy of Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 188 2 Statistical Thermodynamics ....................................... 191 3 Probability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 194 4 Quantum Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 197

X Contents

What Is Missing? -The Fundamental Role of Time in C.F. von Weizsacker's Conception of Physics and Some Insights from Modern Neuroscience Eva Ruhnau . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 1 Time and Experience ........................................... o. 203 2 SubjectjObject Separation and Observation in Physics ............... o. 205 3 The Now as Transition Point Between Past and Future ............... o. 207 4 Temporal Logistics of the Brain 1 o................................. 209 5 Separation and Integration in the Brain ............................ o. 210 6 Object Formation in the Brain o •••••••••••••••••••••••••••••••••• o. 212 7 Temporal Logistics of the Brain II ................................ o. 213 8 Experience and Time ........................................... o. 214 References o •••••••••••••••••••••••••••••••••••••••••••••••••••••• o. 216

Irreversibility via Semichaos Georg Suessmann ................................................. 219 1 Stochastic Entropy ............................................. o. 219 2 Objections .................................................... o. 220 3 Molecular Semichaos o........................................... 221 4 The Model o.................................................... 223 5 The Equations of Motion o........................................ 223 6 Distribution of Discs in the Case of a Single Rhombus ............... o. 225 7 Distribution of Rhomboid-Disc Pairs o •••••••••••••••••••••••••••••• 226 8 The Time Asymmetric Diffusion Equation ......................... o. 227 9 The Transition to the Continuum ................................. o. 228 10 The H-Theorem .. o •• o. o •• o. o •••••••••• o •••••••••••• o •••••••••• o. 229 Il The Correlations o............................................... 230 12 Heredity o •••••••••••••••••••••••••••••••••••••••••••••••••••••• 231 13 Appendix: Boundary Conditions ................................. o. 232

Remarks on Fractional Time Rudolf Hilfer ..................................................... 235 1 Introduction .................................................. o. 235 2 Requirements for Time Evolution Operators o........................ 236 3 Consequences from the Requirements ............................. o. 238 4 Philosophical Remarks ......................................... o. 240 References o •••••••••••••••••••••••••••••••••••••••••••••••••••••• o. 241

The Dynamics of Modelling Gerard G. Emch o ••••••••••••••••••••••••••••••••••••••••••••••••• 243 1 Introduction .................................................. o. 243 2 Some Models from Thermophysics ............................... o. 244 3 A Longer View ................................................ o. 254 References ....................................................... o. 257

Contents XI

Part IV The Structure of Quantum Theory and Its Interpretation

An Introduction to Cari Friedrich von Weizsăcker's Program for a Reconstruction of Quantum Theory Thomas Gărnitz and Otfried Ischebeck o ••••••••••••••••••••••••••••••• 263 1 The Motivation for a Reconstruction of Quantum Theory

and the Elements of the Program ................................. o. 263 2 Quantum Theory and Philosophy ................................. o. 265 3 Time, Probability and Quantization ............................... o. 268 4 Postulates for the Basic Structure of Quantum Theory ............... o. 269 5 The Vr-Hypothesis o ••••••••••••••••••••••••••••••••••••••••••••• 275 6 On the Interpretation of Quantum Theory .......................... o. 276 References ....................................................... o. 279

Interpreting Quantum Mechanics - in the Light of Quantum Logic Peter Mittelstaedt ................................................. 281 1 Classical and Quantum Physics - Their Respective Roles o............. 281 2 Reduction of Ontological Hypotheses ............................. o. 282 3 The Quantum Logic Approach - An a priori Justification? ........... o. 284 References ....................................................... o. 290

On the Interpretation of Quantum Theory -from Copenhagen to the Present Day Claus Kiefer o •••••••••••••••••••••••••••••••••••••••••••••••••••• 291 1 Copenhagen Interpretations and Altematives ....................... o. 291 2 The Emergence of Classical Properties in Quantum Theory ........... o. 294 3 Quantum Gravity .............................................. o. 297 4 Conclusion ................................................... o. 298 References ....................................................... o. 299

Epistemic and Ontic Quantum Realities Ha raId Atmanspacher and Hans Primas ............................... 301 1 Introduction .................................................. o. 301 2 Distinguishing Epistemic and Ontic Perspectives o.................... 304 3 Epistemic Descriptions of Quantum Systems ....................... o. 306 4 Ontic Descriptions of Quantum Systems o........................... 311 5 Relations Between Epistemic and Ontic Descriptions ................ o. 315 6 Conclusions .................................................. o. 319 References ....................................................... o. 319

Information and Fundamental Elements of the Structure of Quantum Theory Caslav Brukner and Anton Zeilinger .................................. 323 1 Introduction .................................................. o. 323 2 Finiteness of Information, Vr, Elementary System o................... 325

XII Contents

3 Mutually Complememary Propositions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 327 4 Measure ofInformation in a Probabilistic Experiment ... . . . . . . . . . . . . .. 330 5 The Catalog of Knowledge of a Quantum System . . . . . . . . . . . . . . . . . . . .. 333 6 Total Information Content of a Quantum System. . . . . . . . . . . . . . . . . . . . .. 334 7 Malus' Law in Quantum Physics ................................... 337 8 Entanglement -

More Information in Joint Properties than in Individuals ............... 342 9 Time Evolution of the Catalog of Knowledge ........................ 345 10 Measurement - the Update ofInformation . . . . . . . . . . . . . . . . . . . . . . . . . .. 349 11 Conclusions.................................................... 351 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 353

Multiple Quantization in Fock Space Dirk Graudenz ................................................... 355 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 355 2 Setting the Stage: Quantization of a Free Scalar Field. . . . . . . . . . . . . . . . .. 356 3 A Framework for Multiple Quantization . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 359 4 Summary and Open Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 360 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 360

PartV The Ur-Hypothesis and Its Implications for Particle Physics and Cosmology

The Ur-Hypothesis Lutz Castell ...................................................... 363 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 365

The Momentum Eigenstates and the Lorentz-Invariant State Lutz Castell ...................................................... 367 References ......................................................... 371

C.F. von Weizsacker's Reconstruction of Physics: Yesterday, Today, Tomorrow Ho/ger Lyre ...................................................... 373 1 The Origin: The Philosophy of Physics. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 373 2 Yesterday: Urs, Spinors and Spacetime .............................. 374 3 Today: Tetrads, Gravity and Gauges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 377 4 Tomorrow: Qubits, Holographic Principle

and the Ontology of Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 379 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 382

The Operational Structure of Spacetime Heinrich Saller ................................................... 385 1 Ontic or Praxic Spacetime ........................................ 385 2 Operations and Symmetries .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 386

Contents XIII

3 How Simple Can Be Simple? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 388 4 The Binary Alternative, Spin and Space . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 390 5 The External-Internal Dichotomy .................................. 392

Ur Theory and Space-Time Structure David Ritz Finkelstein . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397 1 The Dr ......................................................... 397 2 The Quantum Dniverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 398 3 Quantum Logic ................................................. 399 4 Non-associative Logic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 400 5 Summation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 405 6 Acknowledgements .............................................. 406 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 406

Weizsăcker's Ur Theory - A Cosmological Point of View Thomas Garnitz .................................................. 409 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 409 2 The Way to a Connection Between Dr Theory and Cosmology . . . . . . . . .. 411 3 The lntroduction of Space ......................................... 412 4 An Effective Energy-Momentum Tensor ............................ 415 5 An Estimation for the Entropy of Partic1es . . . . . . . . . . . . . . . . . . . . . . . . . .. 416 6 Dr Number and Bekenstein-Hawking-Entropy for Partic1es . . . . . . . . . . .. 417 7 Conclusions .................................................... 418 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 418

Ur Theory and Cosmological Phase Transition larg D. Becker and Lutz Castell ...................................... 421 1 Do Large Numbers Have a Meaning? ............................... 421 2 From Dr Space to Minkowski Space ................................ 421 3 Photon Condensation in an Einstein Dniverse . . . . . . . . . . . . . . . . . . . . . . .. 423 4 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 425 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 425

Phase Transitions in an Expanding Universe: Paul Roman's Models and Some Remarks on Entropy larg D. Becker ................................................... 427 1 Photon Condensation in an Expanding Dniverse . . . . . . . . . . . . . . . . . . . . .. 427 2 Bubble Formation and Entropy .................................... 428 3 Linking Dr Cosmology to More Conventional Approaches ..... . . . . . . .. 428 4 Conc1usions and Some Remarks on Entropy ......................... 429 References ......................................................... 430

Appendix ....................................................... 433 C. F. von Weizsăcker: Biographical Data and Selected Bibliography in Physics . . . . . . . . . . . . . . . . . .. 433 The Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 449

Letters to Cari Friedrich von Weizsacker on the Occasion of His 90th Birthday

Cornell U niversity Newman Laboratory for Elementary-Particle Physics

Newman Laboratory

Ithaca, NY 14853-5001

(G07) 255-4397

Deal' Cari Friedrich:

27.5.02

Letters 3

Telex: WUI 6713054 Tele!ax: 607-254-4552

hab 11 ',<]corndl.edu

I am happy t.o collgrat.ulate you on yom 90th birthday. Our lives in astrophysics have flown much in parallel: You discovered that the proton-prot.on fusion must be the first nuclear rcaetion in a st.ar; thcn Crit.chficld and 1 worked it out. quantitativdy. A few months later \Ve independently found t.he carbon-nitrogen cyele which is generally accepted as t.he great.cst somee of stellar encrgy.

A few ycars ago: in Copcnhagen and in Ithaca, wc had intcnsh'c talks on arms control and disarmamcnt, and found t.o OUl' mutual pleasure that here also om idcas are running very much in parallel. If they onll' could bc flllfilled i

I am wishing you IUanl' happy ycars of fmther life and thought.

Yours sillrerely,

Hans A. I3ct.he

HAB/dsh

HOOVER INSTITUTION On War Revolution and Peace Stanford, California 94305-6010

FAX: 650-723-1687

Dr. Edward Teller Senior Research Fellow

Letters 5

Den 4. Mărz 2002

Professor Dr. CarI Friedrich von Weizsăcker Max-Planck-Institut fiir Physik (Werner Heisenberg-Institut)

Lieber CarI Friedrich,

Von diesem Briefe getrennt, werde ich ein Paar Zeilen schicken iiber die Fragen die in den letzten 70 ]ahren nichts an ihrer Drohnung verloren haben. Ich hoffe sehr dass ich iiber die Beitrăge deinem 90. Geburtstag hăren kann.

Die Probleme unserer ]ugend blieben im ganzen ungelăst, aber die zweite Hălfte des 20. ]ahrhundert war sicherlich besser als die erste Hălfte. Es tut mir leid dass wir unsere jugendliche Gesprăche nicht wieder von ihren verwirrten Mitte mit emeute Hoffnung neu anfangen kănnen.

Wenn ich Deine religiăse Glauben teilen kănnte, Wiirde ich mir Wiinschen dass Du mich einmal in Purgatorium von einem hăheren Himmel besuchen Wiirdest.

Inzwischen, mit besten Wiinschen zu Deinem 90. Geburtstag.

Dein

Edward Teller

Dear Cari Friedrich,

apart from this letter, 1 shall send a few lines addressing those questions that have not lost any of their menacing character during the past 70 years. 1 hope very much that 1 can hear the contributions to your 90th birthday.

6 Letters

The problems of uur yuuth remain largely unsolved, but the secund half of the 20th century was certainly better than the first half. l feeI sorry that we cannot once more take up our youthful discussions from their bewildering middle and engender new hope.

lf l could share your religious belief, l would wish that you will one day come from a higher heaven and visit me in purgatory.

Meanwhile, with best wishes on your 90th birthday,

Your

Edward Teller

Letters 7

J Urgen Habennas

Lieber, verehrter Herr von Weizsiicker,

gestatten Sie mir, den glucklichen Umstand Ihres 90. Geburtstages, den Sie bei voller

intellektueller Priisenz erleben durfen, zu nutzen, um aus einem Abstand von zwei bis

drei Jahrzehnten auf unsere gemeinsame Zeit am Starnberger Institut zuruckzublicken

und zu erkliiren, wofur ich Ihnen dankbar bin.

Damals hat Ihre Einladung, das Institut gemeinsam zu leiten, nicht nur mich uber­

rascht. Daraus haben sich fur den einen oder anderen von uns auch Problemen erge­

ben, die schwer 16sbar waren. Aber die pers6nliche Beziehung zu Ihnen, dem stets

wohlwollenden, integren und in seiner hellen analytischen Kraft uberlegenen Geist, ist

immer intakt geblieben. Das verdanke ich Ihrer wahrhaft platonischen Fiihigkeit, die

Probleme von der Erdenschwere der schnell beiseite geschobenen organisatorischen

Aspekte zu befreien und auf die H6he intellektuell spannender Themen zu heben. Sie

haben von Ihrer einzigartigen Gabe, aus dem Stand uber beliebig komplexe Sachver­

halte in vollkommener Klarheit zu sprechen, einen zivilen Gebrauch gemacht. Deshalb

konnte sich unsere Zusammenarbeit in dem schwebenden Medium einer allenfalls un­

terbrochenen, jederzeit wieder aufzunehmenden Konversation uber die wahrlich inte­

ressierenden Dinge vollziehen.

8 Letters

2

Auch in meiner Bibliothek steht natLirlich die lange Reihe der gel ben Weizsacker-

Leinenbande aus dem Hanser-Verlag. Vermutlich wissen Sie nicht, lieber Herr von

Weizsacker, wie viei und vor allem was ich von Ihnen gelernt habe. Sie wurden sich

wundern, wenn Sie einen Blick in den ersten dieser Bande aus dem Jahre 1971 wer-

fen wurden. In dem zweiten Teil dieses besonders zerlesenen Buches, das mit "Die

Einheit der bisherigen Physik" beginnt und mit dem Abschnitt uber Quantentheorie

und einem "Entwurf der Einheit der Physik" schlief?,t, sind fast alle Seiten mit den An-

streichungen eines ganz inkompetenten, aber offensichtlich lernbegierigen und enga-

gierten Lesers ubersat.

In einem der spateren Bande finde ich ne ben der Widmung einen Zettel mit dem unge-

duldigen Hinweis auf drei Stellen: S. 116-121, S. 132-33; S. 474-5. Das war es,

woruber Sie mit mir sprechen wollten - Ihre christliche Uberzeugung, dass man die

Moral der Gerechtigkeit nicht verselbstandigen durfe: "Ietzter Grund der Măglichkeit

menschlichen Zusammenlebens ist die Liebe und nicht die Moral".

Ich wunsche Ihnen, dass Sie bei guter Gesundheit bleiben und die Anstrengung der

zahlreichen verdienten Feiern zu Ihrem Ehrentage nicht nur uberstehen, sondern ge-

nief?,en, und bin

mit herzlich Gruf?,en

Dear, honored Mr. v. Weizsăcker,

please permit me to take the opportunity presented by the happy circumstance of your 90th

birthday, which you are able to celebrate with full intellectual presence, to look back two Of

three decades at our time together at the Institute in Starnberg and explain my gratitude to you.

Letters 9

Back then, your invitation to jointly direct the Institute was a surprise not only to myself. From this, problems arose which, for one or the other of us, were difficult to solve. But my personal relation to you, the ever benevoler, upright and superior spirit stemning from dear analytical capability, has always remained intact. I owe this to your truly Platonic capacity to liberate prob\ems from the earthly weight of organizational mundanities and lift them to intellectually exciting heights. You put at the service of the public your unique gift for impromptu speaking with complete darity on complex subjects. Therefore our cooperation could manifest itself in the intangible medium of a conversation on truly interesting things, interruptions of years not preventing resumption at any moment.

On my bookshelf too, there are, of course, the yellow linen volumes of Weizsăcker published by Hanser Verlag. Perhaps you are not aware, dear Mr. von Weizsăcker, how much and, above ali, what I have leamt from you. You would be astonished if you were to take a look at the tirst ofthese volumes from 1971. In the second part of this particularly well wom book, which starts with "The unity of the hitherto existing physics" and ends with the section on quantum theory and an "Essay on the unity of physics", almost ali pages are strewn with underlinings by a totally incompetent but apparently curious and enthusiastic reader.

In one of the later volumes, I tind next to the dedication a slip of paper with an anxious reference to three passages, pp. 116-121, pp. 132-133, and pp. 474-5, conceming something you wanted to discuss with me-your Christian conviction that the morality of justice should not be held up in isolation: "the ultimate basis of the possibility for humans to live together is love not morality."

1 wish you continuing good health and trust that you will not merely bear the numerous festivities which you have merited on the occasion of your day of honor, but that you will genuinely enjoy them, and I remain

with cordial greetings

Yours Jiirgen Habermas

Letters Il

Ruth Grosse

Juli 2002

Lieber Herr v. Weizsăeker,

ieh habe Ihnen hier einen Traum aufgesehrieben, den ieh - angeregt dureh die diversen Feiern zu Ihrem 90. Geburtstag - kilrzlieh hatte, und der in ganz unbefangener Weise das widerspiegelt, was fUr mieh wiehtig war in den zwei Jahrzehnten der Zusammenarbeit mit Ihnen und den Wissensehaftlern im damaligen Institut.

"Eine Gruppe von Mensehen, darunter ieh, maehte eine Wanderung unter Ihrer Filhrung. Wir durchquerten eine sehr fremdartige, wilde, immer wieder atemberaubend schone Landschaft: Eisgraue, abweisende, bizarre Berggipfel im Hintergrund, Gerollhalden mit seltsamen, kostbaren Steinen, ausgetrocknete Flussbetten, gelbe, dilnenartige Sandflăchen. Das Gehen in weglosem Gelănde war sehr milhsam, zumal der Boden nicht sicher war; stellenweise war es sumpfig, dann wieder taten sich Triebsandlocher auf, oder tiefe Wasserlăufe versperrten den Weg. Aber Sie waren unermildbar und guter Dinge. Sie liefen voraus, um den Weiterweg zu erkunden, Sie kamen zurilck gerannt, um uns Instruktionen zu geben und zu ermuntern. Unsere Klagen, wenn z.B. einer bis zur Brust im Morast steckte, ein anderer von einem reissenden Bach mitgerissen wurde, ein dritter sich den Fuss verstaucht hatte, berilhrten Sie nicht weiter. ,Kilmmert Euch um Euch selbst, ich habe keine Zeit fUr diese Dinge' riefen Sie und eilten wieder voraus. Sie hatten eine Kindertrăgerhose an mit zu kurzen, weiten, flatternden Hosenbeinen, Ihre Stirne war extrem hoch, zu hoch, die Haut gelblich mit vielen Sommersprossen, die Augen waren immer geschlossen. Sie schienen aber alles durch die Augenlieder hindurch zu erkennen, jedenfalls orientierten Sie sich in dem unwegsamen Gelănde mit traumwandlerischer Sicherheit und vermieden mit grossem Geschick alle Hindernisse, die uns anderen so zu schaffen machten.

Weit oben am Berg verlief eine Strasse, auf der andere Menschen anscheinend milhelos wanderten, in derselben Richtung wie wir. ,,,Varum gehen Wii' nicht auf der Strasse, da kămen wir besser voran', fragten wir, ,man milsste nur 200 Meter hinaufsteigen und schon wăren wir auf einer sieheren, ebenen Strasse?' Aber einige unter uns sagten, so eine Strasse sei reizlos, die Wildnis fernab der Zivilisation sei viei aufregender und interessanter. Aiso blieben wir unten und sehlugen uns weiter dureh. Unser Filhrer, Sie selbst, war inzwisehen nicht mehr bei uns.

12 Letters

Aufunserer Wanderung kamen wir an mehreren Burgen und Sch16ssern vorbei, die alle von Ihren "Verbilndeten" oder "Anhangern" bewohnt waren. Alles sch6ne, schweigsame Menschen, engelahnliche Gestalten mit hellem Teint, aquamarineblauen Augen und langen, schwarzen Augenwimpern. Sie ilbernahmen in Ihrer Abwesenheit die Filhrung der Gruppe und brachten uns in verwunschenes Wilstenland, in vom Sand verwehte frilhzeitliche Stadte, mit halb verfallenen machtigen Kirchen und prachtigen, maroden Stadtpalasten. Wir sahen, dass keine Bleibe war in diesem herrlichen, verlassenen Geisterland. Wir sehnten uns nach zu Hause."

Die heutige Traumwissenschaft spricht dem Traum lediglich eine Funktion der Verarbeitung von "Tagesresten" zu. Anscheinend aber k6nnen es auch "Lebensreste" sein.

July 2002

Dear Mr. v. Weizsăcker,

1 have written down a dream, which I had recently - inspired by the various festivities on the occasion of your 90th birthday. Put simply, it reflects what has been important for me in the two decades of collaboration with you and with the scientists in the former Institute in Stamberg.

"A group of persons, among them myself, made ajoumey under your leadership. We pas sed through a breathtakingly beautifulland: forbidden peaks, gray with ice, in the far, boulders with rare, precious stones, dried creeks, yellow dune shaped stretches of sand. Making progress in this terrain was very cumbersome, especially as the ground was not safe; at places it had been swampy, then there were shifting sands, and deep waters that barred the way. But you suffered no fatigue and were of good spirits. You went ahead in arder to find out the further path, you carne running back to give us instructions and to encourage us. Our complaints, for example when one of us was stuck in the swamp up to his chest, when another had been torn away by a torrent, when a third had sprained his foot, did not distract you. "Care for yourselves, 1 don't have time for these things" you called and you hurried ahead. You ware a pair of children's trousers with braces and short fluttering trouser-legs, your voice was extremely high, too high, the skin yellowish with freckles, your eyes were always shut. You appeared to recognize everything through your eye lids; in any case you moved in this pathless terrain with sleep-wa1king security and you avoided with great aptitude aII obstacJes that caused us so many troubles.

Far up on the mountain, there was a road on which other people apparently walked without difficuIties in the same direction as we. "Why don't we go on this road, we could advance more easily there", we asked, "we need only cJimb two hundred meters and we would be on a safe and even road?" But some of us said, such a road has no charm, the wildemess far from

Letters 13

civilization is much more exciting and interesting. So we stayed below and continued to battle our way. Our guide, yourself, had meanwhile vanished from our midst.

On our joumey, we pas sed several castles and palaces, which were aH occupied by your "allies" or "adherents", AH of them beautiful, si1ent persons, of angelic appearance, with light complexion, deep blue eyes and long black eye-Iashes. In your absence they took over the lead of the group and brought us into an enchanted desert country, to ancient cities covered with the sand, with ruined churches and splendid but derelict municipal palaces. We saw that there was no possibility to stay in this marvelous, deserted land of spirits. We longed to come home."

The modem science of dreams attributes to the dream only the function of digesting the "day's remnants". Apparently, these can also be "life's remnants".

Ruth Grosse