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Incoming links: David B. Hall
Bruno Rossi Created 2026-10-24 Updated 2026-11-05
Bruno Rossi used penetrating cosmic-ray particles to test relativistic particle lifetimes. His experiment with David B. Hall compared particles selected by momentum and examined how many survived propagation through the atmosphere.
The decay probability depends on the proper time elapsed along the particle's path. Faster particles can travel farther in the laboratory because their rest-frame clock accumulates less proper time over a given laboratory interval. The measured momentum dependence connected an observed particle population to time dilation.[ref]
Variation of the Rate of Decay of Mesotrons with Momentum by Bruno Rossi and David B. Hall. 1941 experiment: momentum selection, atmospheric survival and decay interpretation
Rossi also coauthored the early rocket detection of extrasolar X-rays, extending astronomical measurement beyond wavelengths accessible through the atmosphere.[ref]
Portrait of Bruno Rossi
. Massachusetts Institute of Technology. CC BY-SA 3.0, via Wikimedia Commons. Source.
Variation of the Rate of Decay of Mesotrons with Momentum by Bruno Rossi and David B. Hall Created 2026-10-20 Updated 2026-11-05
Bruno Rossi and David B. Hall, Physical Review 59, 223–228 (1941). The primary experiment compared more and less penetrating cosmic-ray particle populations and found momentum-dependent decay rates compatible with relativistic moving-clock rates.