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Jean Foucault and his pendulum


Jean Foucault pendulum

.. There is something, however, in that the pendulum,
That makes me stare
On it carefully.
Edgar Allan Poe

I will not hide that I was honored to have the opportunity to attend and speak at this important event, although held it was held in our own KPI, but without exaggeration, it is necessary to talk about an event of national importance. I am referring to the opening of 24 February 2011, I repeat, in Ukraine, this Foucault pendulum.

To begin with, it was thanks to this pendulum the name of prominent French experimental physicist is known, one might say, to every educated person. But the pendulum, which glorified the Parisian professor, a member of the Paris Academy of Sciences Jean Bernard Foucault is not the main thing this world-renowned scientist had done in science. I recall that the study Foucault more concerned not mechanics, but optics and electricity. For example, in optics, he is one of the first to measure the speed of light and the first to prove that the value of it in the air and in the water is different, that was important for the understanding of the wave nature of light. If you look at the electricity, even engineering students, I'm sure, are well-known with so-called induction eddy currents, which cause parasitic heating. This effect impairs large number of devices and with which therefore must be fought. Foucault worked also with improving the instruments. His improved gyroscope has become widely used in navigation and geodesy. And all this belongs to the same researcher, whose name was given to several well-known physical phenomena. No wonder the Russian Academy of Sciences elected Jean Bernard Foucault its foreign member!

I think this should definitely be reminded, but today I am not writing to honor the name of the famous Foucault, but on a quite another occasion - the opening and running in KPI of simple device that consists of two elements: a sufficiently heavy object, usually a metal ball and a relatively light rope or chain on which the ball is hanging. All together, it is a ball on the suspension, as we all know, is called the pendulum, precise mathematical pendulum, which can carry out periodic restricted movement, which is called an oscillating movement, or simply vibrations. And at school and at university the same pendulum is one of the main instruments for the study of Newton's laws and demonstrations of Earth's gravity, as well as measurements of various physical quantities, such as: frequency of oscillation periods, depending on the length of the suspension and the ball weight and the like. Interestingly, all these properties of pendulums were well known and used long before Foucault's own research.

But again, this is not important in Foucault pendulum, in question. The main thing is that for the first time Foucault realized - is that the plane of oscillation of the pendulum is maintained during its movement. So, if fluctuations occur in the reference system, which itself is fixed, then the motion of any object, move in it, can be traced and measured. Thus, if, say, Earth moving, it will change its position in space relative to said plane of oscillation.

This is very simple, at first glance, but actually a brilliant idea not visited, figuratively speaking, any of Foucault’s predecessors. From there it is immediately followed that with a sufficiently long length of the suspension and possible greater weight of the ball when the period of oscillation becomes large enough, we can clearly observe the rotational motion of the Earth in real time, because the pendulum is not rigidly fixed relative to the Earth.

I appeal primarily to young people, they are not surprised, because the words of the rotational motion of the Earth, most likely, are seemed to them almost trivial. To young and middle generation the idea of the spherical shape of the Earth is known not from their parents or teachers, but thanks in particular television, which often exhibit of photography and filming from space. Therefore it seems about such trivial things it is needless to say - anyone declares that on such a long time and knows well. However, I urge, do not be so arrogant as fashionable and popular now various opinion polls reveal a few sad things. Thus, according to one of them, recently occurred in different regions of Russia, including Moscow and St. Petersburg, only 17% of respondents correctly answered the question about the reasons for the change of seasons. I do not think that our data would have been much better.

Therefore, let us remember what preceded the appearance of Foucault's pendulum and what is its role, which is so strongly impressed people. The fact is that people are always interested in the universe. I tell people in common, but it's not quite true, because in fact about such profound things only some individuals think, who have the ability to understand something in general sense. There are those who want to understand the true nature of things, always present in the mass of people. And the answer to the question of how to organize the world as a whole, was founded by Greek philosopher Ptolemy, who proposed a model that has become a recognized and called geocentric or Ptolomy’s systems in the world. Based on visual observations, it states that the center of the universe is a fixed Earth.The Sun and other celestial bodies move in circular orbits, while stars form an immobile spherical sky.

Strangely enough, but such ideas existed for almost fifteen hundred years. More precisely, the 1400 years all people of the earth were happy with the teaching that the Earth is the central object of the world order, and no one, or almost no one doubt it. Moreover, the Ptolemaic system was canonized by the church and for many years it has become a fundamental part of Christian doctrine.

But some cranks who did not believe the generally accepted statement still remained. Or rather, not so much not believe how they wanted to make sure that the geocentric system works. Moreover, that means of observing were continuously improved.

Revolution in consciousness was made by Polish astronomer Nicolaus Copernicus, who, under the pressure of irrefutable observational facts, not consistent with the calculations based on Ptolomy system of the motion of the planets and the sun actually was forced to drop the geocentric universe, where the main postulate was the center position and the immobility of the earth, and the complexity of the movements of the planets and the sun was due to the will of the Creator, or God. Rejection of the geocentric system entailed rejection of the idea of man as central in the literal and figurative sense divine element of the structure of the world, which were the main provisions of the sacred book - the Bible. Copernicus placed the Sun in the center, assuming that all the planets, including Earth, revolve around him. This puts into circulation idea of the heliocentric system of the world, which radically contradicts the biblical canons, breaks them. That is why the Copernican treatise "On the Revolutions of the Celestial Bodies", promulgated in 1543, the churche strictly prohibited, and the prohibition lasted for about three centuries, until 1828. What Copernicus made, could not be named other than the scientific feat. I should add that the dissemination of ideas of Copernicus met great resistance on the part of church leaders and the church as a whole. Proponents of this doctrine Giordano Bruno was burned at the stake, and his own writings about the infinity of space in the universe also burned. And Galileo Galilei, not to be punished by the Inquisition, as we know, abandoned some of his beliefs about the motion of the Earth, but before his death, said the well-known words: "And yet it moves!" concerning the Earth.

It should also be understood that all these dramatic events did not prove and they could not prove to the general public the Earth's rotation, as itself the rotation of the planets around the sun still does not imply their own rotation. Therefore, when Foucault understood how and why you can use an ordinary pendulum, at the same time he also realized the risk, and after the demonstration of the experiment to Emperor of France, who liked it, he decided to appeal to the Pope for the special permission. Last, oddly enough, was given with the blessing, because, as stated by Pope letter, the demonstration not only does not negate God, but rather shows its power. And exactly 160 years ago in the Paris Pantheon it was made the first demonstration that the rotational motion is indeed the case and takes around an axis corresponding to the direction of real suspension or vertically at the point of the Earth, where the suspension is. Parisian newspapers wrote that people, gathered at the first demonstration, were not so excited by what he saw how shocked with it, and almost unknown to anyone but the professional community, the name of Foucault rather quickly gained worldwide fame and now its not even know the students as their parents or school teachers attended one or another Foucault pendulum. Pendulums with high suspensions became fashionable and as a special gimmick that, nevertheless, to a certain extent continues to this day, began to build a lot of countries, but the number of the famous Foucault pendulums is not more than half a dozen. For example, in the USSR it was built in the former Leningrad, St. Isaac's Cathedral, and was opened exactly 80 years ago, in March 1931. It is interesting that while there was an anti-religious State Museum, and the launch of the pendulum in the newspaper "Pravda" was named the triumph of science over religion, which, of course, is unfortunately not true.

Returning to the actual Foucault pendulum, adding that it allows to measure the latitude of its geographical location, and what is known less, the phenomenon of non-inertial coordinate reference systems, inertial force as a kind of origin, for the first time calculated the French physicist and engineer, also a member of the French Academy of Sciences Gustave Coriolis and 150 years bears his name. It defines how the object should move when his motion is described in the non-inertial system, but other parts of that power beyond that of my posts.

Thus, the construction of a Foucault pendulum is, in my opinion, an outstanding event, and the place of its construction and regular demonstrations are, to be exact - have become an important center of education. And the fact that for such a place in Kiev is is selected scientific and technical library KPI also is correct and deeply symbolic.

Finally. About five, maybe six years ago, one of the most influential newspapers in the world «New York Times» conducted a survey of several thousand physicists of many countries on the most important and beautiful physical experiments in the history of mankind. So, the Foucault pendulum took among the first ten honorable 5th place. This clearly indicates that the Foucault pendulum did and is doing its job - irrefutably proves to everyone who wants to see this, that the Earth really rotates continuously.

I would like to wish all of us that Foucault pendulum Kiev Polytechnic met our common hopes, and always without any obstacles harmoniously swings, carrying people real knowledge.

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