Gaston Maurice Julia: Quick Facts

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Facts

Born	February 3, 1893 • Sidi Bel Abbès • Algeria
Died	March 19, 1978 (aged 85) • Paris • France
Subjects Of Study	Julia set • fractal • iteration • polynomial function

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Julia setFrench mathematician Gaston Julia studied the set that bears his name in the early years of the 20th century. In general terms, a Julia set is the boundary between points in the complex number plane or the Riemann sphere (the complex number plane plus the point at infinity) that diverge to infinity and those that remain finite under repeated iteration of some mapping (function). The most famous example is the Mandelbrot set.

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$Mandelbrot setDuring the late 20th century, Polish mathematician Benoit Mandelbrot helped popularize the fractal that bears his name. The fundamental set contains all complex numbers C such that the iterative equation Zn + 1 = Zn2 + C stays finite for all n starting with Z0 = 0. As shown here, the set of points that remain finite through all iterations is white, with darker colours showing how quickly other values diverge to infinity. The fractal edge between points that remain finite and those that diverge to infinity is extremely complicated, with self-repeating features that can be seen at all scales.$

Benoit Mandelbrot

Polish-born French American mathematician

$Sierpiński gasketPolish mathematician Wacław Sierpiński described the fractal that bears his name in 1915, although the design as an art motif dates at least to 13th-century Italy. Begin with a solid equilateral triangle, and remove the triangle formed by connecting the midpoints of each side. The midpoints of the sides of the resulting three internal triangles are connected to form three new triangles that are then removed to form nine smaller internal triangles. The process of cutting away triangular pieces continues indefinitely, producing a region with a Hausdorf dimension of a bit more than 1.5 (indicating that it is more than a one-dimensional figure but less than a two-dimensional figure).$