# Image Sources

Cover for "A Nearly 350-Year-Old Burden of Proof," 17 October 2026.

The current version adds a blue "QTT Declared Equation" label and highlights the fourth, fifth and sixth equation terms in blue. The historical composition and references remain the same.

AI-assisted editorial collage based on the archival references below. The portraits and title page have been restyled for the composition; this is not an unaltered archival reproduction. The question marks represent the essay's argument, not quotations or endorsements by the pictured scientists.

- Isaac Newton: woodcut after Godfrey Kneller's portrait, reproduced as the frontispiece to Ernst Mach's *The Science of Mechanics*, supplementary volume, 1915. [Wikimedia Commons reference](https://commons.wikimedia.org/wiki/File:Isaac_Newton_woodcut,_frontispiece_to_Mach.jpg).
- *Philosophiae Naturalis Principia Mathematica*: title page of the 1687 first edition. [Wikimedia Commons reference](https://commons.wikimedia.org/wiki/File:Newton%27s_Principia_title_page.png).
- Albert Einstein: portrait by Ferdinand Schmutzer, 1921. [Wikimedia Commons reference](https://commons.wikimedia.org/wiki/File:Einstein1921_by_F_Schmutzer_2.jpg).
- Werner Heisenberg: detail from the 1927 Solvay Conference photograph, Institut International de Physique Solvay. [Wikimedia Commons reference](https://commons.wikimedia.org/wiki/File:Werner_Heisenberg_at_1927_Solvay_Conference.JPG).
- Erwin Schrodinger: Nobel Foundation portrait, 1933. [Wikimedia Commons reference](https://commons.wikimedia.org/wiki/File:Erwin_Schr%C3%B6dinger_(1933).jpg).

The reference files are identified as public domain on their linked Wikimedia Commons pages. The cover's equation and test references are QTT content, not material from those historical sources.