Fritz Zwicky was born on February 14, 1898, in Varna, Bulgaria. The son of a prosperous Swiss merchant, in 1904, he was sent to boarding school in his father’s ancestral canton, Glarus, Switzerland. In 1914, he enrolled in the Swiss Federal Institute of Technology in Zürich, receiving a Doctorate in Physics in 1922. In 1925, Zwicky emigrated to the United States to work at the California Institute of Technology (Caltech) in Pasadena, California. He remained at Caltech for the rest of his career but never renounced his Swiss citizenship.

Upon first arriving at Caltech, Zwicky made important contributions to the physics of solid state, gaseous ionization, and thermodynamics but soon became more interested in astrophysics. In 1933, he calculated that certain galaxies contained hundreds times more mass than was visible. Although ridiculed by the scientific community at the time, in the late 1990’s, scientists began to accept Zwicky’s theories as the first proof of what is called “dark matter.” Scientists now believe that much of the universe is comprised of this mysterious force.

In 1934, in collaboration with Dr. Walter Baade, Zwicky proposed that were then known as “bright novae” (now called supernovas) were a class of stellar explosion completely dissimilar from ordinary novas that occur much less often than novas, perhaps only two or three times every 1,000 years in the Milky Way Galaxy. Their article, “Supernovae and Cosmic Rays” was an important milestone in the history of physics and astronomy, and included Zwicky’s formulation of supernovae, cosmic rays and neutron stars. He correctly deduced that supernovae were the transitional form some stars took before becoming neutron stars, and that many cosmic rays originated in supernovae. His concept of neutron stars was so advanced it was not fully accepted until technological advances of the 1960’s proved his hypotheses, thirty years after he proposed them.

In 1935, Baade and Zwicky successfully lobbied for acquiring and installing the first Schmidt telescope to be used in a mountaintop observatory, at Mount Palomar in San Diego County, California. From 1937 to 1941, Zwicky used the Mount Palomar and Mount Wilson observatories to conduct an extensive search of neighboring galaxies for supernovas, discovering eighteen of them, six more than all the supernovas previously in the history of astronomy.

Fritz Zwicky was also known for his work on jet propulsion, cosmic rays, crystals, and slow electrons and ions in gases. As director of research of the Aerojet Engineering Corporation in Azusa, California from 1943 to 1946, and technical adviser thereafter, he developed some of the earliest jet engines, including JATO (jet assisted take-off) units used to launch heavy-laden aircraft from short runways. For this work, Zwicky is sometimes referred to as the “father of the modern jet engine.”

Although famous for his difficult personality and quirky sense of humor, Zwicky played a major role in several charities, including the reconstitution of scientific libraries destroyed throughout Europe during World War II, and in relief efforts for war orphans. Later Zwicky was vice president of the International Academy of Astronautics. In recognition of his lifetime of achievement, Fritz Zwicky was presented with the Gold Medal of the Royal Astronomical Society in 1972.

Dr. Fritz Zwicky died in Pasadena, California on February 8, 1974. He was buried in Switzerland in his ancestral canton of Glarus. The Zwicky Museum in Glarus, displays many of his papers and scientific work. Asteroid 1803 Zwicky, the Moon’s Zwicky Crater, and galaxy I Zwicky 18 are all named in his honour.