Fritz Zwicky was a prolific scientist and made important contributions in many areas of astronomy.
Ionic crystals and electrolytes His first scientific contributions pertained to
ionic crystals and
electrolytes.
Supernovae and neutron stars Together with colleague
Walter Baade, Zwicky pioneered and promoted the use of the first
Schmidt telescopes used in a mountain-top observatory in 1935. In 1934 he and Baade coined the term "
supernova" and hypothesized that supernovae were the transition of normal stars into
neutron stars, as well as the origin of
cosmic rays. a record which stood until 2009 when passed by
Tom Boles. Zwicky did his laborious work, comparing photographic plates with the human eye, which is far more challenging and difficult than Boles accomplished using modern technology for his record.
Gravitational lenses In 1937, Zwicky posited that galaxies could act as
gravitational lenses by the previously discovered Einstein effect. It was not until 1979 that this effect was confirmed by observation of the so-called
"Twin Quasar" Q0957+561.
Dark matter Accounts of the history of the cosmological concept of
dark matter typically start with Zwicky's work on galaxy clusters. Using the number of observed galaxies, crude approximations for the size of the cluster, and the average mass of a galaxy, the virial theorems' balance of average kinetic and potential energy predicted a velocity dispersion much lower than the observed value. Zwicky concluded that If this would be confirmed, we would get the surprising result that dark matter is present in much greater amount than luminous matter. Zwicky immediately pointed out that the correlation between the calculated distances of galaxies and their redshifts had a discrepancy too large to fit in the distance's
error margins. He proposed that the reddening effect was not due to motions of the galaxy, but to an unknown phenomenon that caused photons to lose energy as they traveled through space. He considered the most likely candidate process to be a drag effect in which photons transfer momentum to surrounding masses through gravitational interactions; and proposed that an attempt be made to put this effect on a sound theoretical footing with general relativity. He also considered and rejected explanations involving interactions with free electrons, or the expansion of space. Zwicky was skeptical of the expansion of space in 1929, because the rates measured at that time seemed too large. It was not until 1956 that
Walter Baade corrected the distance scale based on
Cepheid variable stars, and ushered in the first accurate measures of the expansion rate. Cosmological redshift is now conventionally understood to be a consequence of the
expansion of space; a feature of
Big Bang cosmology.
Catalog of Galaxies and Clusters Zwicky devoted considerable time to the search for galaxies and the production of catalogs. From 1961 to 1968 he and his colleagues published a comprehensive six volume
Catalogue of galaxies and of clusters of galaxies. They were all published in Pasadena, by the California Institute of Technology. • • • • • • Galaxies in the original catalog are called
Zwicky galaxies, and the catalog is still maintained and updated today. Zwicky with his wife Margaritha also produced an important catalog of compact galaxies, sometimes called simply
The Red Book. :
Morphological analysis Zwicky developed a generalised form of
morphological analysis, which is a method for systematically structuring and investigating the total set of relationships contained in multi-dimensional, usually non-quantifiable, problem complexes. He wrote books on the subject in 1957 and 1969, and claimed that he made many of his discoveries using this method.
Original thinker Zwicky was an original thinker, and his contemporaries frequently had no way of knowing which of his ideas would work out and which would not. In a retrospective look at Zwicky's life and work, Stephen Maurer said: When researchers talk about neutron stars, dark matter, and gravitational lenses, they all start the same way: "Zwicky noticed this problem in the 1930s. Back then, nobody listened..." He is celebrated for the discovery of neutron stars. He also proposed a concept he called
nuclear goblins, which he described as "a body of nuclear density ... only stable under sufficient external pressure within a massive and dense star". He considered that these goblins could move within a star, and explode violently as they reach less dense regions towards the star's surface, and serve to explain eruptive phenomena, such as flare stars. This idea has never caught on. An anecdote often told of Zwicky concerns an informal experiment to see if he could reduce problems with
turbulence hindering an observation session one night at
Mount Wilson Observatory. He told his assistant to fire a gun out through the telescope slit, in the hope it would help smooth out the turbulence. No effect was noticed, but the event shows the kind of lateral thinking for which Zwicky was famous. In a talk to a Caltech PhD student
Frank Malina, who experienced some difficulties working on a dissertation regarding characteristics of oxygen-gasoline
rocket engine, Fritz Zwicky claimed the engineer "must realize that a rocket could not operate in space as it required the atmosphere to push against to provide thrust". Zwicky later admitted that he had been mistaken. He was also very proud of his work in producing the first artificial
meteors. He placed explosive charges in the nose cone of a
V2 rocket, to be detonated at high altitude and fire high velocity pellets of metal through the atmosphere. The first attempts appeared to be failures, and Zwicky sought to try again with the
Aerobee rocket. His requests were denied, until the Soviet Union launched
Sputnik 1. Twelve days later, on October 16, 1957, Zwicky launched his experiment on the Aerobee, and successfully fired pellets visible from the
Mount Palomar observatory. It is thought that one of these pellets may have escaped the gravitational pull of the Earth and become the first object launched into a solar orbit. he spoke of changing planets, or relocating them within the
Solar System. In the 1960s he even considered how the whole Solar System might be moved like a giant spaceship to travel to other stars. He considered this might be achieved by firing pellets into the Sun to produce asymmetrical fusion explosions, and by this means he thought that the star
Alpha Centauri might be reached within 2500 years. == Humanitarian ==