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In 1824 Arago experimented with suspending a magnetized needle above a copper disk, and noticed that when the copper moved, the needle moved. This was the basis for Faraday’s 1831 discovery of electromagnetic induction. The following year, in 1825, Arago was awarded the Royal Society Copley Medal, and his experimentation continued, this time taking him into the realm of compressing gases. His early work, along with that of Faraday and others, contributed to the foundation of work that continued until 1906, which identified the critical temperature that would liquefy each of the permanent gases.

And so, too, the age of the galaxy doubled, to approximately 10 billion years old. This had an impact back home in the Milky Way. Baade suggested that data about Andromeda’s spiral nature could be applied to our own galaxy. 5-meter reflector telescope in Argentina. 33 Another of Baade’s major discoveries involved another type of variable star—the eruptive variable. This kind of star has an unpredictable outburst—or, more rarely, a decrease—in its luminosity. A nova is an eruptive variable.

Anderson, Carl David (1905–1991) American Physicist Carl David Anderson began his studies in science in 1923 at the California Institute of Technology as an electrical engineering student. But he soon discovered physics and changed disciplines, and eventually changed the world with a scientific discovery that has been called one of the most momentous of the century. Born in New York City on September 3, 1905, Anderson was the only child of Carl David Anderson and Emma Adolfinja Ajaxson, Swedish immigrants.