**Part One. Planck's Black-Body Theory, 1894-1906: The Classical Phase**

*I. Planck's Route to the Black-Body Problem*

The Black-Body Problem

Planck and Thermodynamics

Planck and the Kinetic Theory of Gases

Planck and the Continuum and Electromagnetism

*II. Planck's Statistical Heritage: Boltzmann on Irreversibility*

Boltzmann's H-Theorem

The First Interpretation of the *H*-Theorem

Loschmidt's Paradox and the Combinatorial Definition of Entropy

The Conflation of "Molecular" and "Molar"

Molecular Disorder

Epilogue: Molecular Disorder and the Combinatorial Definition after 1896

*III. Planck and the Electromagnetic* H*-Theorem 1897-1899*

Cavity Radiation without Statistics

The Entry of Statistics and Natural Radiation

Planck's "Fundamental Equation"

Entropy and Irreversibility in the Field

*IV. Planck's Distribution Law and Its Derivations, 1900-1901*

Planck's Uniqueness Theorem and the New Distribution Law

Recourse to Combinatorials

Deriving the Distribution Law

The New Status of the Radiation Constants

*V. The Foundations of Planck's Radiation Theory, 1901-1906*

The Continuity of Planck's Theory, 1894-1906

Natural Radiation and Equiprobable States

Energy Elements and Energy Discontinuity

The Quantum of Action and Its Presumptive Source

Planck's Early Readers, 1900-1906

**Part Two. The Emergence of the Quantum Discontinuity, 1905-1912**

*VI. Dismantling Planck's Black-Body Theory: Ehrenfest, Rayleigh, and Jeans*

The Origin of the Rayleigh-Jeans Law, 1900-1905

Ehrenfest's Theory of Quasi-Entropies

The Impotence of Resonators

Complexion Theory and the Rayleigh-Jeans Law

*VII. A New Route to Black-Body Theory: Einstein, 1902-1909*

Einstein on Statistical Thermodynamics, 1902-1903

Fluctuation Phenomena and Black-Body Theory, 1904-1905

Einstein on Planck, 1906-1909

*VIII. Converts to Discontinuity, 1906-1910*

Lorentz's Rome Lecture and Its Aftermath

Planck on Discontinuity, 1908-1910

The Consolidation of Expert Opinion: Wien and Jeans

*IX. Black-Body Theory and the State of the Quantum, 1911-1912*

The Decline of Black-Body Theory

The Emergence of Specific Heats

Quanta and the Structure of Radiation

The Quantum and Atomic Structure

The State of the Quantum

**Part Three. Epilogue**

*X. Planck's New Radiation Theory*

Planck's "Second Theory"

Revising the *Lectures*

Some Uses of the Second Theory

The Fate of the Second Theory

Notes

Bibliography

Afterword: Revisiting Planck

Index