On Friday evening, November 8, 1895, 50-year-old German physicist Wilhelm Conrad Röntgen (1845–1923) at the University of Würzburg made one of the most momentous discoveries in human history.
Published on December 28, 1895, in Sitzungsberichte der Würzburger Physik.-Med. Gesellschaft titled “Ueber eine neue Art von Strahlen” (“On a New Kind of Rays”), Röntgen announced the discovery of X-Rays (X-Strahlen).
The Würzburg Laboratory Discovery¶
Röntgen was investigating cathode rays inside a Hittorf-Crookes vacuum discharge tube covered with heavy black cardboard in a darkened room:
- Fluorescent Screen Glow: A barium platinocyanide screen placed nine feet away glowed brightly with green fluorescence despite the black cardboard shield!
- Penetrating Radiation: Röntgen placed cardboard, wood, aluminum plates, and human flesh in the beam path—the rays passed straight through, casting shadows of dense bones!
- First Human X-Ray Photograph: On December 22, 1895, Röntgen took the world’s first X-ray image of his wife Anna Bertha’s hand, revealing her skeleton and wedding ring.
The First Nobel Prize in Physics (1901)¶
Röntgen was awarded the inaugural 1901 Nobel Prize in Physics.
In 1912, Max von Laue proved that X-rays are high-frequency electromagnetic photons ($\lambda \sim 0.01 - 10\,\text{nm}$) that undergo X-ray Diffraction off atomic crystal lattices ($2d \sin\theta = n\lambda$), opening modern structural quantum crystallography.
Key Takeaways¶
- Year: 1895
- Key Figure: Wilhelm Conrad Röntgen (German Physicist)
- Core Discovery: Discovered X-Rays (X-Strahlen), revolutionizing medical diagnostics and subatomic physics.
- Inaugural Nobel Laureate: Awarded the first Nobel Prize in Physics in 1901.
- Quantum Relevance: High-frequency quantum photon radiation ($\lambda \sim 1\,\text{Å}$) used in X-ray Crystallography.