What is Victor Francis Hess known for?
I am best known for discovering cosmic radiation, which I achieved through a series of high-altitude balloon ascents between 1911 and 1912. At the time, scientists believed that atmospheric ionization—the electrical conductivity of air—originated solely from radioactive substances in the Earth's crust. My measurements, however, showed that ionization actually increased with altitude, reaching several times the ground-level value at about 5,000 meters. This was a puzzling observation. To eliminate the possibility of terrestrial sources, I conducted flights during a solar eclipse and at night, confirming that the Sun was not the cause. The data spoke for themselves: this radiation was extraterrestrial. I named it 'cosmic radiation' in my 1925 paper, and for this work I received the Nobel Prize in Physics in 1936. My findings opened a new window into the universe's energetic particles.
Ask Victor Francis Hess the follow-up →