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Theaetetus (mathematician)

 

 
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Theaetetus (mathematician)
 
 
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Theaetetus (ca. 417 B.C. – 369 B.C.) of Athens, son of Euphronius, of the Athenian deme
Deme

In Ancient Greece, a deme was a subdivision of Attica, the region of Greece surrounding Classical Athens. Demes as simple subdivisions of land in the countryside seem to have existed in the 6th century BC and earlier, but did not acquire particular significance until the reforms of Cleisthenes in 508 BC....
 Sunium, was a classical Greek
Greece

Greece , officially the Hellenic Republic , is a country in southeastern Europe, situated on the southern end of the Balkans. It has borders with Albania, Bulgaria and the former Yugoslav Republic of Macedonia to the north, and Turkey to the east....
 mathematician. His principal contributions were on irrational
Irrational number

In mathematics, an irrational number is any real number that is not a rational number ? that is, it is a number which cannot be expressed as a fraction m/n, where m and n are integers, with n non-zero....
 lengths, which was included in Book X of Euclid's Elements
Euclid's Elements

Euclid's Elements is a mathematics and geometry treatise consisting of 13 books written by the Greek mathematics Euclid in Alexandria circa 300 BC....
, and proving that there are precisely five regular convex polyhedra
Platonic solid

In geometry, a Platonic solid is a convex set polyhedron that is regular polyhedron, in the sense of a regular polygon. Specifically, the faces of a Platonic solid are congruence regular polygons, with the same number of faces meeting at each vertex....
.

Theaetetus, like Plato, was a student of the Greek mathematician Theodorus of Cyrene
Theodorus of Cyrene

Theodorus of Cyrene was a Ancient Greece mathematician of the 5th century BC who was admired by Plato . Little is known about him; however, Plato attributes to him the first mathematical proof of the irrational number of the square roots of square root of 3, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15 and 17....
. Cyrene was a prosperous Greek colony on the coast of North Africa, in what is now Libya, on the eastern end of the gulf of Sidra.






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Theaetetus (ca. 417 B.C. – 369 B.C.) of Athens, son of Euphronius, of the Athenian deme
Deme

In Ancient Greece, a deme was a subdivision of Attica, the region of Greece surrounding Classical Athens. Demes as simple subdivisions of land in the countryside seem to have existed in the 6th century BC and earlier, but did not acquire particular significance until the reforms of Cleisthenes in 508 BC....
 Sunium, was a classical Greek
Greece

Greece , officially the Hellenic Republic , is a country in southeastern Europe, situated on the southern end of the Balkans. It has borders with Albania, Bulgaria and the former Yugoslav Republic of Macedonia to the north, and Turkey to the east....
 mathematician. His principal contributions were on irrational
Irrational number

In mathematics, an irrational number is any real number that is not a rational number ? that is, it is a number which cannot be expressed as a fraction m/n, where m and n are integers, with n non-zero....
 lengths, which was included in Book X of Euclid's Elements
Euclid's Elements

Euclid's Elements is a mathematics and geometry treatise consisting of 13 books written by the Greek mathematics Euclid in Alexandria circa 300 BC....
, and proving that there are precisely five regular convex polyhedra
Platonic solid

In geometry, a Platonic solid is a convex set polyhedron that is regular polyhedron, in the sense of a regular polygon. Specifically, the faces of a Platonic solid are congruence regular polygons, with the same number of faces meeting at each vertex....
.

Theaetetus, like Plato, was a student of the Greek mathematician Theodorus of Cyrene
Theodorus of Cyrene

Theodorus of Cyrene was a Ancient Greece mathematician of the 5th century BC who was admired by Plato . Little is known about him; however, Plato attributes to him the first mathematical proof of the irrational number of the square roots of square root of 3, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15 and 17....
. Cyrene was a prosperous Greek colony on the coast of North Africa, in what is now Libya, on the eastern end of the gulf of Sidra. Theodorus had explored the theory of incommensurable quantities, and Theaetetus continued those studies with great enthusiasm; specifically, he classified various forms of irrational numbers according to the way they are expressed as square roots. This theory is presented in great detail in Book X of Euclid's Elements.

Theaetetus was one of the few Greek mathematicians who were actually natives of Athens. Most Greek mathematicians of antiquity came from the numerous Greek cities scattered around the Ionian coast, the Black Sea and the whole Mediterranean basin. Likewise, most Greek scientists came from the scattered Greek cities and not from Athens. Athens, and later Alexandria were centers of attraction because of the philosophical schools of Plato (the Academy) and Aristotle (the Lyceum), and the renowned Museum and Great Library. The Academy of Plato operated in Athens for almost 600 years, and served as educational center even for some of the early fathers of the Christian church.

He evidently resembled Socrates
Socrates

Socrates was a Classical Greece Philosophy. Credited as one of the founders of Western philosophy, he is an enigmatic figure known only through the classical accounts of his students....
 in the snubness of his nose and bulging of his eyes. This and most of what we know of him comes from Plato
Plato

Plato , was a Classical Greece Greeks philosopher, mathematician, writer of philosophical dialogues, and founder of the Platonic Academy in Ancient Athens, the first institution of higher learning in the western world....
, who named a dialogue after him, the Theaetetus
Theaetetus (dialogue)

The The?tetus is one of Plato's Dialogues of Plato concerning the epistemology. The framing of the dialogue begins when Euclid of Megara tells his friend Terpsion that he had written a book many years ago based on what Socrates had told him of a conversation he'd had with Theaetetus when [Theaetetus] was quite a young man....
. He apparently died from wounds and dysentery
Dysentery

Dysentery is a disorder of the digestive system that results in severe diarrhea containing mucus and/or blood in the feces. If untreated, Dysentery can be fatal....
 on his way home after fighting in an Athenian battle at Corinth
Corinth

Corinth, or Korinth Corinth is now the capital of the Prefectures of Greece of Corinthia. The city is surrounded by the coastal townlets of Lechaio, Isthmia, Kechries, and the inland townlets of Examilia and the archaeological site....
, now widely presumed to have occurred in 369 BC.

The crater Theaetetus
Theaetetus (crater)

Theaetetus is a moon impact crater that is located to the southeast of the crater Cassini near the eastern edge of Mare Imbrium. It lies just to the west of the Montes Caucasus range, which forms the eastern shore of the Lunar mare....
 on the Moon
Moon

The Moon is Earth's only natural satellite and the List of natural satellites by diameter satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is km, about thirty times the diameter of the Earth....
 is named after him.

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