Evangelista Torricelli

Evangelista Torricelli (October 15, 1608 - October 25, 1647) was an Italian physicist and mathematician.

Torricelli's work in mathematics

Torricelli is also famous for the discovery of an infinitely long solid now called Gabriel's horn, whose surface area is infinite, but whose volume is finite. This was seen as an "incredible" paradox by many at the time (including Torricelli himself, who tried several alternative proofs), and prompted a fierce controversy about the nature of infinity, involving the philosopher Hobbes. It is supposed by some to have led to the idea of a "completed infinity".

Related Topics:
Gabriel's horn - Infinite - Hobbes

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Torricelli was also a pioneer in the area of infinite series. In his De dimensione parabolae of 1644, Toricelli considered a decreasing sequence of

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positive terms a_0, a_1, a_2 cdots and showed the corresponding

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telescoping series (a_0-a_1) + (a_1-a_2) + cdots necessarily converges to a_0-L, where L is the limit of the sequence, and in this way gives a proof of the formula for the sum of a geometric series.

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