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Geller, Margaret Joan

galaxies universe dimensional survey

(1947–) American astronomer: carried out pioneering work on the structure of the universe.

After gaining a PhD at Princeton and a period of work at the Institute of Astronomy at Cambridge, England, Geller moved to Harvard in 1980 and was appointed professor of astronomy there in 1988, and a member of the Smithsonian Astrophysical Observatory.

Her research focused on the overall distribution and motions of galaxies in a search for the shape of the universe. Before the 1930s astronomers were restricted to a two-dimensional view of the universe. In 1929 discovery of the expansion of the universe opened up the possibility of three-dimensional measurement – by measuring the red-shifts of galaxies thereby estimating their distance from Earth. From the early 1980s Geller was involved in a redshift survey (in three-dimensional space) of some 15 000 galaxies, with a view to mapping all galaxies above a certain brightness, out to 650 million light years, in a sector of the heavens.

It was thought a large-scale survey might provide evidence for the missing homogeneity of galaxies predicted by the Big Bang theory. However, in plotting the distribution of galaxies, neither a uniform spread, nor a random scattering of galaxies was found, but large-scale clusters grouped into enormous structures. The largest (named the ‘Great Wall’) stretches more than 500 million light years, disturbing current cosmological theory.

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