zeph’s pop culture quiz #45

What is the large mechanical contraption in the picture everybody is staring at? In which movie does it appear and what does it do within the plot of that movie?
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UPDATE and solution (09 October 2012):

Once again Alexander Rabitsch ↵has done it: The machine is a Bush Differential Analyzer. About one hour into ‘↵Earth vs. The Flying Saucers‘ (Sears 1956) it helps to decrypt a message from the aliens. The machine seen in the movie belonged to the ↑UCLA and was installed there in 1947. The machine was the child of ↑Vannevar Bush (1890-1974) who had begun to work on this kind of analogue special purpose computers during the late 1920s.
    ‘My main effort was on the differential analyzer, which could mechanically solve differential equations.’ (Bush 1970: 161) Accordingly in 1927 Bush at ↑MIT starts to construct a practical version of the Differential Analyzer as invented by ↑James Thomson (1822-1892), elder brother of mathematical physicist and engineer ↑William Thomson, 1st Baron Kelvin (1824-1907). Once finished, in 1930, this analogue computer proofs to work flawlessly and is able to solve differential equations comprising up to 18 independent variables. (Puchta 1996)
    A young doctoral student at the MIT is involved in the project—↑Claude Elwood Shannon (1916-2001). For his thesis he takes ‘the application of the techniques of classical Boolean algebra of classes to the study of switching systems in electrical engineering,’ (Wiener 1965 [1948]: 13) and thus creates digital circuit design theory.
    ‘We actually built three successive analyzers. The first one was just a breadboard machine. That is, it was made out of pieces of steel and anything else that was handy, […]‘ (Bush 1970: 182)—improvisation, and, much more important, rededication again.
    During the 1930s Bush Analyzers are built in Great Britain, at Manchester, Cambridge, Belfast, and Farnborough, and in Oslo, Norway. During the early 1940s more incarnations follow in the United States, e.g. at Wright-Patterson Air Force Base and in the basement of the Moore School of Electrical Engineering at the University of Pennsylvania.
 

In 1941 an advanced version is constructed at MIT, called the ‘Rockefeller Differential Analyzer’ (RDA), because the Rockefeller Foundation largely has funded this apparatus of Babbageian dimensions, weighing 100 tons, comprising ‘2,000 electronic tubes, 200 miles of wire, 150 motors, and several thousand relays.’ (Wildes & Lindgren 1985: 92) Its predecessors are hard to set up for solving a particular problem, because the procedure requires e.g. manual reconnection of shafts. The RDA in contrast reads its instructions from three punched tapes.
    With Vannevar Bush’s Differential Analyzer the story of the analogue computer, which started with the ↵Antikythera Mechanism, has come full circle and reaches its full bloom.

Nearby Hollywood also discovered the oversized computer [at UCLA], measuring some 31 feet long by 9 feet wide. In the era before “Star Wars” [Lucas 1977] and “Close Encounters” [Spielberg 1977] the differential analyzer was the latest in way-out gadgetry, and it performed skillfully in such science fiction epics of the mid-’50s as “When Worlds Collide” [Maté 1951] and “Earth vs. The Flying Saucers.” (Anonymous 1978)