the Leaning Tower of Pisa
by Lane Cooper, Copyright 1935, Cornell University Press. Reissued 1972, Kennikat Press
A logical argument that Galileo never experimented at the Tower
and that Aristotle never suggested the rate of fall in a gravitational field is proportional to an object's weight.
Sometimes available at www.amazon.com
MONUMENTAL DOUBT: Historians have long doubted Galileo's famous `leaning tower of Pisa' experiment.
Galileo's Experiments at the Tower
A high-tech experiment confirms Galileo's Experiment
Galileo's Experiment at the Leaning Tower of Pisa
has been vindicated anew. Italian scientists at the
University of Pisa (appropriately enough) have verified
the universality of the free fall acceleration, g, at
the Earth's surface to an accuracy of a few parts in
10^(-10). (S. Carusotto et al., 21 Sept. 1992 issue of
Physical Review Letters).
They did so by measuring the angular acceleration of a falling disk in vacuum. The falling disk, with mirrors at its rim, acted as a sort of Michelson interferometer.
Galileo Galilei was unjustly condemned by the Roman Catholic Church for promoting a Copernican cosmology, says Pope John Paul II. The Pontiff issued the reassessment of this famous 1633 case after a special Vatican commission finished its investigation of the matter. Mr. Galileo was unavailable for comment.
(Sky & Telescope, Jan. 1993.)
The Tale of Galileo and the Tower of Pisa
The story goes that in order to demonstrate to Aristotlean scholars that two balls of different weights fall at the same rate, Galileo dropped a cannon ball and wooden ball from the top of the Tower of Pisa.
This story is apocryphal. While some of his earlier predecessors actually performed this experiment, Galileo did not. However, when Galileo was an old man, one of his students did perform the demonstration to an audience of Aristotlean scholars and found in fact a slight difference in the time the two balls struck the ground. This came as no surprise to Galileo who had already explained the effects of viscosity (wind friction) years before. However the Aristotlean scholars, completely ignorant of the (then new) scientific method, walked away from this demonstration convinced that their old master had been thereby proven correct. Talk about "accommodation"!
by: Joe Milana : milana@quark.umd.edu
Galileo: The Early Years
Galileo Galilei was born near Pisa in 1564 -- the same year in which Shakespeare was born and the year in which Michelangelo and Calvin died.After studying at the University of Pisa, he was appointed to the chair of mathematics -- but as this picture of Pisa reminds us, it was a Pisa, of course, that the famous leaning tower might well have suggested Galileo's most famous experiment. The computer animation linked to this picture, llustrates what Galileo's demonstration would have shown.
First of all the theory which virtually everyone
accepted at the time was the traditional theory
of Aristotle, who believed that heavier objects
fall more quickly than lighter ones.Consider, for example, two objects -- one twice as heavy as the other. Imagine Aristotle at the top of the leaning tower of Pisa, dropping off two cannonballs, one twice as heavy as the other. According to Aristotle, it should fall twice as fast. If it were four times heavier, it should fall four times faster. But in fact, what the leaning tower of Pisa type of experiment demonstrates, when actually performed, is that Aristotle was wrong, that no matter what the difference in weight, two heavy objects will fall simultaneously at virtually the same speed.
Recently it has been fashionable to question
whether or not Galileo ever dropped anything off the campanile -- or leaning tower -- of the Duomo in Pisa. If he did so, it certainly could not have been an "experiment" in the modern sense of the word -- can you imagine running up and down the leaning tower of Pisa -- trying to drop objects of different weights simultaneously, from the edge of the tower, at the
very same time, which is not easy to do, and then observe how quickly
they fall, especially when the time elapsed would only have been a
matter of seconds -- and nothing like the stop watch or any other
convenient device -- had been invented yet?Actually, whether or not Galileo ever performed his famous experiment on the leaning tower hardly seems to matter -- a similar experiment- demonstration had already been published by Benedetti Giambattista in 1553, and the test had also been made and published by the Flemish engineer Simon Stevin in 1586. As for Galileo's interest in disproving Aristotle's Theory about falling objects, years later he said that he had first thought about this during a hailstorm, when he notice that both large and small hailstones hit the ground at the same time.
If Aristotle were right, this could only happen if the larger
stones dropped from a higher point in the clouds -- but at
virtually the same time -- or that the lighter ones started
falling earlier than the heavier ones -- neither of which
seemed very probable to Galileo. Instead, the simplest
explanation was simply that heavy or light, all hailstones
fell simultaneously with the same speed.
On January 8, 1642, astronomer Galileo Galilei died in Arcetri, Italy.
Galileo (1564 -- 1642). Lithograph from a work published by Wm. Wise & Co
New York
by the Roycrofters in 1916.
Galileo was an astronomer and mathematician, born in Pisa, Italy. He entered Pisa University as a medical student in 1581, and became professor of mathematics at Padua (1592--1610), where he improved the refracting telescope (1610), and was the first to use it for astronomy.
His bold advocacy of the Copernican theory brought severe ecclesiastical censure. He was forced to retract before the Inquisition, and was sentenced to indefinite imprisonment - though the sentence was commuted by the pope, at the request of the Duke of Tuscany. Under house arrest in Florence, he continued his research, though by 1637 he had become totally blind.
Among his other discoveries were the law of uniformly accelerated motion towards the Earth, the parabolic path of projectiles, and the law that all bodies have weight.
His work was finally removed from the Inquisiton's banned book list in 1954. The validity of his scientific work was formally recognized by the Roman Catholic Church in 1993.
Galileo Galilei Links:
Catholic Encyclopedia Galileo Galilei Biography
Galileo Biography - BBC News
Galileo and the Inquisition
Galileo and the Inquisition by Jose Wudka
Galileo Term Papers
The Galileo Project - Rice University
Galileo Galilei Biography from About.com6/01/96
Galileo Biography by Crystalinks
URL's related to Galileo's Pisa Experiment
Galileo and the Leaning Tower of Pisa by Jim Loy
Return to Leaning Tower of Pisa Page
Personal e-mail to: gary@endex.com