 
    
      
        | 
        Architecture and Mathematics: Soap Bubbles and
        Soap Films |  
       
     
    Michele Emmer, Professor of Mathematics Università di Roma "La Sapienza,"
    Rome  
    and Università "Ca' Foscari," Venice
    I hope that none of you are yet tired of playing
    with bubbles, because, as I hope we shall see, there is more
    in a common bubble than those who have only played with them
    generally imagine. Charles V. Boys
     When
    Joseph Plateau published his treatise on soap bubbles and film
    in 1873, soap bubbles already had their own place in literature
    and art. Plateau's problem consists in taking a generic curve
    in three-space and finding a surface with the least possible
    area bounded by that curve. The empirical solution may be obtained
    by dipping a tridimensional model of the curve into soapy water,
    resulting in a form called a minimal surface. When a soap
    bubble is blown, the soapy surface stretches; when blowing ceases,
    the film tends toward equilibrium. The sphere presents the least
    exterior surface area of all surfaces containing the same volume
    of air. 
    The isoperimetric property refers to the fact that
    the circumference encloses the largest surface area. It is reasonable
    to suppose that people of ancient times in charge of founding
    a town were aware of the isoperimetric property, at least empirically:
    A town wall of the least possible length containing the largest
    area had to be circular. The circular plan is more prevalent
    in some periods of history than in others. C.N. Ledoux presented
    a circular plan for a town, the form as "pure as the one
    the Sun describes in its movement." 
    Like the circle, the sphere also appears in architecture.
    Ledoux planned a spherical house. His contemporary, Boullée,
    used the sphere in the cenotaph of Newton. The hemispherical
    igloos of the Eskimos solve the problem of a structure based
    on a plane with the greatest possible volume for the same external
    surface. 
    Frei Otto used soap film models to design his tensile-structures.
    He developed a technique to obtain a precise photogrammetric
    evaluation of soap film models and another method to simulate
    peaks in a membrane of soap films. Otto's Institute of Architecture,
    Stuttgart, was built along the lines of such a model. 
    H.A. Schwarz solved Plateau's problem for a non-plane boundary
    by developing the periodic minimal surface. Infinite periodic
    minimal surfaces, combinations of saddle polygons or surfaces,
    are more stable. Such a surface has been adapted as a play sculpture
    in the Brooklyn Museum, where children can actually enter into
    the labyrinthic structure of periodic minimal surfaces. 
    
      
        
         The correct citation for
        this paper is: Michele
        Emmer, "Architecture and Mathematics: Soap Bubbles and Soap
        Films", pp. 53-65 in Nexus: Architecture and Mathematics,
        ed. Kim Williams, Fucecchio (Florence): Edizioni dell'Erba, 1996.
        http://www.nexusjournal.com/conferences/N1996-Emmer.html | 
       
     
    
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