Léon Foucault Google Doodle

Published by Gerald Ferreira Date: September 17, 2013
Categories: General News

Today September 18, 2013 if you visit your local Google Homepage you will find the Google Doodle celebrating the live and legacy of Léon Foucault. If you look at the logo today you might be slightly confused by it, for me it looked like something do to with the Egyptians or the Mayan’s, yet I am very sure that we do not have to be worried about the earth coming to an end when the Mayan’s Calendar ends as it already did so in 2012.

Léon Foucault

Without reading that the Google Doodle were about Léon Foucault I guessed that it might also have something to do with a pendulum and the magic of gravity and how we can in certain circumstances create things like the pendulum that keeps on moving longer than expected due to perfect balance and the earth’s gravity.

Also before reading more about the Léon Foucault Google Doodle, I tried to figure out what the controls are for, I finally managed to work out that the first one is a clock – representing time, and the second one presumably have something to do with the equator and the movement of the earth around its own axis and that of the sun. I eventually clicked on the find button to learn more about Léon Foucault and why Google have chosen him to be featured as an international Google Doodle.

Who was Léon Foucault?

Léon Foucault was a French physicist born on the 18th of September 1819 and whom have died on the 11th of February 1868. He was born in Paris France and also died there. Léon Foucault was best known for his “Invention of the Léon Foucault Pendulum”, a device demonstrating the effect of Earth’s Rotation on its own axis and also around the sun.

Interestingly he did not invent the Gyroscope but gave it its name after working with the early measurement of light and the speed of light.

Wikipedia entry about Léon Foucault?

In 1850, he did an experiment using the Fizeau–Foucault apparatus to measure the speed of light; it came to be known as the Foucault–Fizeau experiment, and was viewed as "driving the last nail in the coffin" of Newton's corpuscle theory of light when it showed that light travels more slowly through water than through air.

In 1851, he provided the first experimental demonstration of the rotation of the Earth on its axis (see diurnal motion). He achieved this by showing the rotation of the plane of oscillation of a long and heavy pendulum suspended from the roof of the Panthéon in Paris. The experiment caused a sensation in both the learned and popular worlds, and "Foucault pendulums" were suspended in major cities across Europe and America and attracted crowds. In the following year he used (and named) the gyroscope as a conceptually simpler experimental proof. In 1855, he received the Copley Medal of the Royal Society for his 'very remarkable experimental researches'. Earlier in the same year he was made physicien (physicist) at the imperial observatory at Paris.

In September, 1855, he discovered that the force required for the rotation of a copper disc becomes greater when it is made to rotate with its rim between the poles of a magnet, the disc at the same time becoming heated by the eddy current or "Foucault currents" induced in the metal.

Diagram of a variant of Foucault's speed of light experiment where a modern laser is the source of light.

In 1857, Foucault invented the polarizer which bears his name,[ and in the succeeding year devised a method of testing the mirror of a reflecting telescope to determine its shape. The so-called "Foucault knife-edge test" allows the worker to tell if the mirror is perfectly spherical or has non-spherical deviation in its figure. Prior to Foucault's publication of his findings, the testing of reflecting telescope mirrors was a "hit or miss" proposition.

Foucault's knife edge test determines the shape of a mirror by finding the focal lengths of its areas, commonly called zones and measured from the mirror center. The test focuses light point source at the center of curvature and reflected back to a knife edge. The test enables the tester to quantify the conic section of the mirror, thereby allowing the tester to validate the actual shape of the mirror, which is necessary to obtain optimal performance of the optical system. The Foucault test is in use to this date, most notably by amateur and smaller commercial telescope makers as it is inexpensive and uses simple, easily made equipment.

With Charles Wheatstone’s revolving mirror he, in 1862, determined the speed of light to be 298,000 km/s (about 185,000 mi. /s) —10,000 km/s less than that obtained by previous experimenters and only 0.6% off the currently accepted value.

Today scientists might enjoy this Google Doodle about Léon Foucault more than those not involved in science, but I do still enjoy every time Google picks someone like Léon Foucault to be featured in their doodles, I don’t always get the chance to broaden my perspective on things outside of my field of work and the once in a while that Google shares something interesting like the doodle today, I just love to grab the opportunity and learn more about why Google have picked someone to be featured on their homepage!