Karl Schwarzschild

Statistical Mechanics with Paul Ehrenfest

18. January 2020 Harald Sack

On January 18, 1881, Austrian and Dutch theoretical physicist Paul Ehrenfest was born. Ehrenfest made major contributions to the field of statistical mechanics and its relations with quantum mechanics, including the theory of phase transition and the Ehrenfest theorem. “Einstein, my upset stomach hates your theory — it almost hates you yourself ! How am I to provide for my students ? What am I to answer to the philosophers ?” –…

mathematics

George David Birkhoff and the Ergodic Theorem

21. March 2017 Harald Sack

On March 21, 1884, American mathematician George David Birkhoff was born. Birkhoff is best known for what is now called the ergodic theorem. Birkhoff was one of the most important leaders in American mathematics in his generation, and during his time he was considered by many to be the preeminent American mathematician. George David Birkhoff was born in Overisel Township, Michigan, the son of David Birkhoff, a medical doctor, and Jane Gertrude…

astronomy

Ejnar Hertzsprung and the Hertzsprung-Russell Diagram

8. October 2016 Tabea Tietz

On October 8, 1873, Danish chemist and astronomer Ejnar Hertzsprung was born. Together with Henry Norris Russell, Hertzsprung developed the Hertzsprung–Russell diagram, a scatter graph of stars showing the relationship between the stars‘ absolute magnitudes or luminosities versus their spectral classifications or effective temperatures, which has become fundamental to the study of stellar evolution. Ejnar Hertzsprung – Early Years Ejnar Hertzsprung was probably not formally educated, but studied in technological colleges in Denmark…

physics