Theaetetos (mathematician)

Theaetetus ( Greek Θεαίτητος Theaitetos , Latin Theaetetus , German and Theaetetus or Theaetetus * to 415 BC.. , † .. 369 BC ) was a Greek mathematician of antiquity.

Theaetetus came from Athens. He was a pupil of Plato in philosophy and of Theodorus of Cyrene in mathematics . Plato named one of his later dialogues, the Theaetetus , after the mathematician who appeared there as a dialogue partner of Socrates . With his namesake, the philosopher and mathematician Socrates the Younger , he was associated as a practicing companion in sporting and military exercises, as Plato communicates in his dialogue with Sophistes .

Theaetetus proved the irrationality of all square roots of non-square integers. In the further he classified the irrational numbers . He also proved that there are exactly five regular bodies. These five solids are also known as the Platonic solids . Finally, Theaetetos established a connection between the irrational and the Platonic solids. His work has entered the elements of the Euclid of Alexandreia (Euclid) , namely in Books X and XIII.

Theaetetus probably had a strong influence on Plato's relationship to mathematics.

The Theaetetus crater on the moon was named after the ancient mathematician.

literature

• Michel Narcy: Théétète d'Athènes. In: Richard Goulet (ed.): Dictionnaire des philosophes antiques. Volume 6, CNRS Éditions, Paris 2016, ISBN 978-2-271-08989-2 , pp. 844-846
• Eva Sachs : De Theaeteto mathematico . Berlin 1914 (basic)
• Eva Sachs: The five platonic solids. On the history of mathematics in the theory of elements by Plato and the Pythagoreans (= Philological Studies, Vol. 24), Berlin 1917.
• Kurt von Fritz : Platon, Theaetet and ancient mathematics . With a supplement to the reprint, Darmstadt 1969 (first in Philologus 87, 1932, pp. 40–62, 136–178)
• Siegfried Heller: Theaetets importance as a mathematician. In: Sudhoffs Archiv 51, 1967, pp. 55-78.

Web links

• Literature by and about Theaetetos in the catalog of the German National Library