‎"KIRCHHOFF, G. (GUSTAV ROBERT).- THE KEY TO THE NEW WORLD OF QUANTA - INTRODUCING ""BLACK-BODY RADIATION""‎
‎Über das Verhältnis zwischen dem Emissionsvermögen und dem Absorptionsvermögen der Körper für Wärme und Licht. (On the relation between the radiating and the absorbing powers of different bodies for light and heat). (+) Über die Frauenhofer'schen Lin...‎

‎Leipzig, Johann Ambrosius Barth, 1860. Contemp. hcalf, raised bands, gilt spine. A few scratches to spine. In ""Annalen der Physik und Chemie. Hrsg. von J.C. Poggendorff"", Bd. 109. X,660 pp. and 4 folded engraved plates. Kirchhoff's papers: pp. 275-301 and pp. 148-150. Internally clean and fine. Small stamps to verso of titlepage and plates.‎

Reference : 43085

‎First printing of a milestone paper by ""The Grandfather of Quantum Theory"" in which he formulates the law named after him, ""KIRCHHOFF'S LAW"", which was the ""key to the whole thermodynamics of radiation. In the hands of Planck, Kirchhoff's successor to the Berlin chair, it proved to be the key to the new world of the quanta, well beyond Kirchhoff's conceptual horizon.""(DSB, VII, p.382).""Kirchhoff's Law of Thermal Emission was formulated in 1859 (Über das Verhältnis....) - the paper offered. It is at the same time the simplest and least understood law in physics. Kirchhoff's law states that given thermal equilibrium with an enclosure, the radiation inside will be always black, or normal, in a manner which is independent of the nature of the walls, or the objects they contain. This is known as the concept of universality. That is, that radiation within an enclosure can always be described by a universal function dependent only ontemperature and frequency. This universal function was first given us by Max Planck, in 1900. Kirchhoff's law STANDS AT THE HEARTH OF ALL MODERN ASTROPHYSICS. It is the basis for setting the temperature of the stars, for the gaseous model of the Sun, and for believing that we now know the temperature of the entire universe.""(Pierre-Marie Robitaille)..The research background for the paper was his unexpected observation that if the intensity of the solar spectrum increased above a certain limit, the dark D lines were made much darker by the interposition of the sodium flame. he instantly felt, that he had got hold of ""something fundamental"". These observations are described in the second paper offered here ""Über die Frauenhofer'schen Linien..."" which was published first in 1859 in Monatsschrift der Berliner Academie.The volume contains many other importent papers in physics and chemistry, by C.F. Schönbein, Zöllner, H. Fizeau, Eisenlohr, W. Heine, Knoblauch, K.G. Neumann, W. Siemens etc.‎