Read Euler, read Euler. He is the master of us all.
Pierre Simon de Laplace

For those who have dealt with Engineering, Physics, Mathematics or almost every science, the name of
Euler is not unknown. Born in Basel in 1707, is probably one of the biggest mathematician in the History. If you want to read a
brief summary of his work, you can read the
Eulogy to Mr. Euler, by the Marquis de Condorcet. Despite the 16 pages of the eulogy, Euler work was even bigger, including mechanics, astronomy, optics, acoustics, architecture, ballistics, navigation, cartography, precision instrument manufacture, music and philosophy.
Opera Omnia, is the coursebook of
86 volumes that covers his published works.
But also the quality of his work was incredible for a human being. As a curiosity, he started using the symbols
e for the base of natural logarithms,
i for the imaginary numbers and
f() for the functions. Now, they are used even in the schools worldwide. He had also a good memory and an incredible ability for calculus. He was able to say all prime numbers until 100, their squares, cubes, even to the power of six. When he died, he was working on the Uranus orbit. Those equations, years later, were used to investigate and discover Neptune.
Today, I want to show one of the most amazing mathematic demonstration. It was the year 1735, Euler were only 28, he had studied with Johann Bernoulli. Years ago, the Bernoulli brothers tried to solve the, so called,
Basel problem, the series of the inverse of the squared naturals. Johann Bernoulli had proved the divergence of the harmonic series (the sum of the inverse of the natural numbers). Even the great Leibniz, who discovered the series of the inverse of the triangular numbers in a very elegant and convincing manner, failed solving the Basel problem. It seemed to be a hard problem.
But then, Euler appeared with an amazing solution. It was amazing because the solution were... pi squared over 6!
It was a very simple and at the same time a very astonishing solution. The result was the sixth part of the area of a square with a side equals to the lenght of a circunfenrence of unity radious. What were the connections between pi and the series?
To be continued...Based on:
http://tiopetrus.blogia.com/
http://historias-de-la-ciencia.blocat.com/