Fritz Zwicky

Fritz Zwicky was a Swiss-American astronomer and astrophysicist who proposed unseen mass in galaxy clusters, coined “supernova,” and discovered compact galaxies.

Dark matter: Dark matter is matter inferred from gravitational effects but not detected through emitted or absorbed light. Zwicky inferred unseen cluster mass from galaxy motions, an early argument for dark matter.
Virial theorem: The virial theorem relates the average kinetic and potential energies of a stable gravitational system. Zwicky used galaxy-cluster motions and the theorem to estimate cluster mass.
Caltech: The California Institute of Technology is a private research university in Pasadena, California. Zwicky spent most of his scientific career at Caltech, where he conducted his major astronomical work.
Walter Baade: Walter Baade was a German-American astronomer who studied stellar populations, galaxies, and supernovae. Baade and Zwicky jointly introduced the term “supernova” and proposed their connection to neutron stars.
Modified Newtonian dynamics: Modified Newtonian dynamics is a theory that changes Newtonian gravity at very low accelerations to explain galactic motions. It seeks to explain some mass discrepancies without the unseen matter Zwicky inferred.
Supernova: A supernova is a powerful stellar explosion that briefly produces an enormous increase in a star system’s brightness. Zwicky helped establish supernovae as a distinct class of astronomical events and developed their study.
Coma Cluster: The Coma Cluster is a rich galaxy cluster in the constellation Coma Berenices. Its galaxy velocities supplied Zwicky’s evidence for far more mass than visible matter explained.
Mount Wilson Observatory: Mount Wilson Observatory is an astronomical observatory in the San Gabriel Mountains of California. Zwicky used its facilities during the period when he developed his early ideas about supernovae.
Jan Oort: Jan Oort was a Dutch astronomer known for research on the Milky Way and the dynamics of galaxies. Oort independently found mass discrepancies in galaxies, placing Zwicky’s cluster result in a wider context.
Dark energy: Dark energy is the name for the component driving the accelerated expansion of the universe. Unlike Zwicky’s proposed dark matter, dark energy addresses cosmic expansion rather than excess gravitational mass.

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