## Über irreversible Strahlungsvorgänge [On Irreversible Radiation Processes], Part V

*“These [constants] necessarily retain their meaning for all times and for all civilizations, even extraterrestrial and non-human ones, and can therefore be designated as 'natural units...'" - Planck, in his May 1899 paper, on his new system of units defining the “Planck constant”*

FIRST EDITION, FIRST PRINTING, IN EXTREMELY RARE ORIGINAL WRAPPERS of Planck’s introduction of his universal “Planck” constant.

In the fifth installment of his continuing study of irreversible radiation processes (May 1899), Planck “believed that he had reached the main objectives of his program: a deduction of irreversibility from electrodynamic processes, and a derivation of the universal law of blackbody radiation. As a clear manifestation of his trust in the fundamental character of his theory, he suggested that the constants a and b appearing in the resonator entropy be considered new fundamental constants and recommended natural units of length, time, mass, and temperature built from a, b, c , and the universal gravitation constant.... The following year, he re-designated the constant b by the famous letter h (and in place of a, he introduced k = b/a, the Boltzmann constant)” (Darrigol, *From c-Numbers to q-Numbers*; Gorelik, *First Steps of Quantum Gravity and the Planck Values*).

“Planck’s constant has had profound ramifications in three important areas: our technology, our understanding of reality, and our understanding of life itself. Of the universal constants—the cosmic numbers which define our Universe—the speed of light gets all the publicity (partially because of its starring role in Einstein’s iconic equation E = mc2), but Planck’s constant is every bit as important. Planck’s constant has also enabled the construction of the transistors, integrated circuits, and chips that have revolutionized our lives.

“More fundamentally, the discovery of Planck’s constant advanced the realization that, when we probe the deepest levels of the structure of matter, we are no longer looking at ‘things’ in the conventional meaning of the word... The concepts of location, velocity, and even existence itself blur at the atomic and subatomic level... Reconciling the probabilistic subatomic world with the macroscopic everyday world is one of the great unsolved problems in physics...

“Finally, Planck’s constant tells us how the universe is numerically fine-tuned to permit life to exist... The fundamental nuclear reaction eventually leading to the explosion of a supernova is the fusion of four hydrogen atoms to produce a single atom of helium. In the process, approximately 0.7% of the mass is converted to energy via E=mc2... This 0.7% is known as the efficiency of hydrogen fusion, and our understanding of it is one of the consequences of Planck’s investigations... The 0.7% efficiency of hydrogen fusion is what is sometimes referred to as a ‘Goldilocks number’... [T]he 0.7% efficiency of hydrogen fusion is “just right” to permit the emergence of life as we know it...

“Planck’s quantization of energy was an essential step on the road to the theory of quantum mechanics, which is critical to our understanding of stellar evolution. Science hasn’t filled in all the pieces of the puzzle of how life actually evolved, but quantum mechanics did begin to answer the question of how the pieces got there in the first place...’ (James Stein, *Planck’s Constant: The Number That Rules Technology, Reality, and Life*).

IN: Sitzungsberichte der Königlich Preussischen Akademie der Wissenschaften zu Berlin, XXV, 18 May 1899, pp.440-480. Berlin: Verlag der Königlichen Akademie der Wissenschaften, 1899. Octavo, original wrappers; custom box. A hint of fading and soiling around spine and edges; largely unopened. A FINE COPY, SCARCE IN ORIGINAL WRAPPERS.

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