Galileo's Leaning Tower of Pisa Experiment

9 Key excerpts on "Galileo's Leaning Tower of Pisa Experiment"

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  Surprising Quantum Bounces

  • Valery Nesvizhevsky, Alexei Voronin(Authors)
  • 2015(Publication Date)
  • ICP

    (Publisher)

  3 describes Galileo’s experiments in Pisa exploring classical free fall. According to this legend, Galileo Galilei performed a spectacular demonstration that objects with different mass fall down identically from the top of the Leaning Tower of Pisa (“Torre pendente di Pisa”) when dropped simultaneously. The qualitative statement that gravity accelerates all objects in an universal manner, independently of their mass and composition, contradicted both the traditional doctrine, common beliefs and everyday experience.

  What is the actual reason for this striking contradiction between seemingly so similar observations of falling objects performed by different people?

  In contrast to naively observing the falling and gliding leaves in the forest on a windy or calm day, or heavy stones falling from the top of a rock in the mountains and breaking up on its foothills, Galileo Galilei succeeded to step beyond the seemingly simple reality and to distinguish false effects (like, for instance, the effect of air resistance) and the principal phenomenon of unrestricted free fall in order to arrive at his nontrivial and revolutionary conclusion.

  Some people call Galileo Galilei “the father of science”. We are not going to contribute to the disputable field of priorities in science. What is clear, however, is that he successfully put the exploration of nature on a ground of solid scientific proofs , based on the concept of physical experiment . This concept is crucial for modern scientific knowledge, and we are going to devote particular attention to its important features, as well as the world of challenging physical experiments.

  In particular, the difficult art of eliminating, suppressing or at least accounting for false effects is the essence of any exploration of nature, and a key feature of a properly designed physical experiment. One unrecognized false effect would spoil thousands of correct measurements and would lead to unreliable conclusions concerning the whole study. Even if it is as simple as observations of freely falling objects.

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  Galileo

  And the Science Deniers

  • Mario Livio(Author)
  • 2020(Publication Date)
  • Simon & Schuster

    (Publisher)

  HAPTER 3 A Leaning Tower and Inclined Planes

  Galileo’s first appointment as a professor and chair of mathematics at Pisa lasted only from 1589 till 1592, yet one particular story associated with that period has generated an iconic image of Galileo. It is a picture of him dressed in his imposing academic gown, dropping balls of different weights from the top of the leaning tower of Pisa.

  The original tale comes from Viviani, who in 1657 put together what he described as his recollections from a conversation he had with Galileo in the latter’s final years:

  A great many conclusions of Aristotle himself on the subject of motion were shown by him [Galileo] to be false which up to that time had been held as most clear and indubitable, as (among others) that speeds of unequal weights of the same material moving through the same medium did not at all preserve the ratio of their heaviness assigned to them by Aristotle, but rather, these all moved with equal speeds, he [Galileo] showing this by repeated experiments made from the height of the leaning tower of Pisa in the presence of other professors and all the students.

  In other words, contrary to the view held by all Aristotelians that the heavier the ball, the faster it would fall, Viviani claimed that by dropping balls from the Leaning Tower (sometime between 1589 and 1592), Galileo had demonstrated that two balls of the same material but of different weights hit the ground simultaneously.

  As if this story wasn’t dramatic enough, later biographers and historians just kept adding more details that weren’t included in Viviani’s original account or in any other contemporary sources. For example, British astronomer and popularizer of science Richard Arman Gregory wrote in 1917 that members of the University of Pisa assembled at the foot of the Leaning Tower “one morning in the year 1591,” even though Viviani never mentioned the precise year or the time of day. Gregory also added that one ball was “weighing a hundred times more than the other”—again a detail not given by Viviani. Author Francis Jameson Rowbotham, who wrote about the lives of great scientists, great musicians, great authors, and great artists, added in his 1918 vivid description that Galileo “invited the whole University to witness the experiment.”

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  Getting Science Wrong

  Why the Philosophy of Science Matters

  • Paul Dicken(Author)
  • 2018(Publication Date)
  • Bloomsbury Academic

    (Publisher)

  We don’t need to drop cannonballs from the top of a tower, because we can go into outer space and drop all variety of heavy bodies to our heart’s content. On the surface of the moon, where the effects of air resistance are negligible, different bodies of different mass will indeed fall at the same rate of motion, and we can see hammers and feathers falling—very slowly—in perfect accord. As we saw in the previous chapter, there will techni-cally always be ways in which to preserve a theory in the face of recalcitrant evidence, but eventually, even the most committed of Aristotelians will have to concede defeat. But what all this does show is that the outcome of a scientific experiment can often involve a complex series of negotiations. It is an attempt to find the theory that best explains the experimental data, and which also fits into everything else that we believe. In many cases, it is as much a matter of showing the plausibility of a particular interpretation as it is of demonstrating a new and unexpected result. Thus when Vincenzo Viviani wrote his story about Galileo and the Leaning Tower of Pisa, he was not simply misremembering an event that never happened or trying to spice up his biography with exciting anecdotes. It was rather a sustained attempt to generate support for the new scientific world view, a deliberate strategy for making the Galilean interpretation more plausible. And it worked. That is why the story continues to have resonance in the modern day, despite all of its glaring historical inaccuracies. Sometimes we make progress in science by conducting careful experimentation—but sometimes it can be just as important simply to tell everyone a damn good story. This emphasis upon telling a good story also helps us to under-stand the larger context in which this whole incident took place.

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  Galileo and the Scientific Revolution

  • Laura Fermi, Gilberto Bernardini(Authors)
  • 2013(Publication Date)
  • Dover Publications

    (Publisher)

  To Galileo the belief in the existence of natural laws so generally valid and reproducible that they rule the universe was equivalent to a faith, based on the conviction that the proper interpretation of natural phenomena cannot contradict the laws of human reason. He expressed this beautifully in the already quoted passage of the letter to Cristina which starts: “Nature . . . is inexorable and immutable.”

  “THIS VAST AND MOST EXCELLENT SCIENCE”

  It is certain, in our opinion, that Galileo performed a large number of experiments, and we probably do not know them all. A few, such as his first with pendulums or that of weights dropped from the Leaning Tower of Pisa, were related by his pupils and became confused in legend. Often Galileo himself described them only sketchily, insisting on their meaning without indicating the limits of errors and therefore their accuracy. Here and there his extreme ingenuity in conceiving experiments flared up, as, for instance, when he tried to measure the velocity of light in order to ascertain whether its propagation is instantaneous. He set up the experiment in this manner: Two men stood at a distance from each other, each holding a light that he could cover and uncover. One of the men uncovered his light, and as soon as the other saw it he uncovered his . Thus the two were sending signals to one another. The distance between the two men was then increased to see whether this increase caused any delay between the signals. A delay, Galileo said, would prove that the propagation of light is not instantaneous. The experiment failed, of course, and he concluded correctly: “In fact I have tried the experiment only at a short distance, less than a mile, from which I have not been able to determine with certainty whether the appearance of the opposite light was instantaneous or not; but if not instantaneous it is extraordinarily rapid.”

  The experiment failed because men’s reactions (here the uncovering of the lamp) take much longer than it takes light to travel the distance of a mile (about eighteen millionths of a second).

  About fifty years later, in 1675, the Danish astronomer Ole Roemer (1644-1710) had the genial idea of using astronomical rather than terrestrial distances. His “lamp” was one of Jupiter’s satellites, “covered” or “uncovered” by its own eclipses; and the distance traveled by light was that of the earth’s orbit.

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  Half-Hours with Great Scientists

  The Story of Physics

  • Charles G. Fraser(Author)
  • 2019(Publication Date)
  • University of Toronto Press

    (Publisher)

  With the zeal of a missionary for proclaiming the truth, he would oppose that authority with all the power of his bril-liant logic and rhetoric. He also made hilarious use of satire and ridicule The School of Galileo 99 in thrusting his arguments down his opponents' throats. This habit, of course, was hardly apt to make the opponents love him more. Tradition says that to demonstrate his contention in this instance, Galileo carried two iron blocks of different weights to the top of the Leaning Tower of Pisa, his native city, and dropped them at the same moment (fig. 87), while observed by a group of peripatetics on the ground below (and a little to one side). The reverberations of those two blocks crashing to earth together have not died down yet, and may they never fade away, for Galileo thereby broke the Aristotelian shackles and helped to secure for his successors a freedom of speech and thought which we should appreciate and use, and, if necessary, defend with our lives. When the peripatetics saw the result of the experiment, they said, It is impossible, for Aristotle says the heavier one wins. You and I can hardly credit such slavish adherence to dogma; but it is surprising to find how many unthinking persons in our own day still hold Aristotle's opinion on this point. The peripatetics resented what they considered Galileo's attack on their faith and they wreaked on him humiliation and an-guish. Sir Oliver Lodge's Pioneers of Science describes Galileo's examination under men-ace of torture when, by denying that the earth moves, he escaped death but not imprisonment. Since he knew that the In-quisition had burned Bruno at the stake, his legendary remark, Eppur si muovi (It moves just the same), is doubtless apocryphal, for it would have meant certain death, but just as likely, it. ; ;ents what he thought. Galileo's exposure of the false doctrine about falling bodies is typical of much of his work; for his best eulogium is a re-cital of the fallacies he corrected.

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  Galileo

  Pioneer Scientist

  • Stillman Drake(Author)
  • 2017(Publication Date)
  • University of Toronto Press

    (Publisher)

  Analysis shows that Galileo was accurate within 107 Galileo: Pioneer Scientist Figure 1. f. 107v. The square numbers in left margin confirmed the law of fall to hold also for descent on an inclined plane. The other entries had been made before the timing device sketched at the end was constructed. The Laws of Pendulum and Fall / 11 1/64 second for all strings except the lowest. Later he adjusted that string by about 20 punti (say 2 cm) and marked also a-I-or a -sign after four other original measures that seemed to Galileo a bit short or a bit long when he made subsequent reruns (these then sounding to him early, or late). The purpose of this work had been to find, if possible, a rule for the increase of speed during natural straight descent of a heavy body. The Aristotelian word 'natural' was used for motions that took place spontaneously upon simple release, to distinguish those from 'forced' or Violent 7 motions. Galileo found that during equal successive time intervals from rest, his measured speeds went up as do the odd numbers 1, 3, 5, 7, ... l This simple and exact rule doubtless surprised Galileo as much as it delighted him, for only a year before he had remarked in a letter that when put to a test with material objects, rules deduced by mathemati-cians simply did not agree with observation. Material impedi-ments, as Galileo called friction, air resistance, absence of perfect smoothness and hardness, or the like, played a very important part in his physics at every stage from 1590 on, if not even earlier. Having found a simple arithmetical law for a natural motion, Galileo thought next of measuring short intervals of time instead of merely equalizing them. Near the bottom of f. 107v he drew a diagram of the device that he used from then on for measuring the times of motions.

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  Science Teaching

  The Contribution of History and Philosophy of Science, 20th Anniversary Revised and Expanded Edition

  • Michael R. Matthews(Author)
  • 2014(Publication Date)
  • Routledge

    (Publisher)

  The study and manipulation of the pendulum led to many things: an accurate method of timekeeping, hence, leading to solving the longitude problem; discovering the conservation and collision laws; and ascertaining the value of the acceleration due to gravity g, showing the variation of g from equatorial to polar regions and, hence, determining the oblate shape of the earth. It provided the crucial evidence for Newton’s synthesis of terrestrial and celestial mechanics, showing that fundamental laws are universal in the Chapter 6 solar system; a dynamical proof for the rotation of the earth on its axis; the equivalence of inertial and gravitational mass; an accurate measurement of the density and, hence, mass of the earth; and much more. Pendulum motion was central to the argument between Aristotelians and Galileo over the role of experience in settling conflicting claims about the world, and it figured in Newton’s major metaphysical dispute with the Cartesians, namely the dispute concerning the existence of the ether (Westfall 1980, p. 376). Domenico Bertoloni Meli observed that: Starting with Galileo, the pendulum was taking a prominent place in the study of motion and mechanics, both as a time-measuring device and as a tool for studying motion, force, gravity, and collision. (Meli 2006, p. 206) With good reason, the historian Bertrand Hall attested: In the history of physics the pendulum plays a role of singular importance. From the early years of the seventeenth century, when Galileo announced his formulation of the laws governing pendular motion, to the early years of this century, when it was displaced by devices of superior accuracy, the pendulum was either an object of study or a means to study questions in astronomy, gravitation and mechanics. (Hall 1978, p.4 41) The importance of the pendulum in science and philosophy was exceeded only by its importance to commerce, navigation, exploration and Western expansion.

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  Theoretical Concepts in Physics

  An Alternative View of Theoretical Reasoning in Physics

  • Malcolm S. Longair(Author)
  • 2020(Publication Date)
  • Cambridge University Press

    (Publisher)

  With indomitable spirit, Galileo set about writing his greatest work, Discourses and Mathematical Demonstrations on Two New Sciences Pertaining to Mechanics and to Local Motion, normally known simply as Two New Sciences, published in 1638. In this treatise, he brought together the understanding of the physical world which he had gained over a lifetime. The fundamental insights concern the second new science – the analysis of motion. 3.6 Galilean Relativity The ideas expounded in Two New Sciences had been in Galileo’s mind since 1608. One of them is what is now called Galilean relativity. Relativity is often thought of as something which was invented by Einstein in 1905, but that does not do justice to Galileo’s great achievement. Suppose an experiment is carried out on the shore and then on a ship moving at a constant speed relative to the shore. If the effect of air resistance is neglected, is there any difference in the outcome of any experiment? Galileo answers firmly, ‘No, there is not.’ The relativity of motion is illustrated by dropping an object from the top of a ship’s mast (Fig. 3.8). If the ship is stationary, the object falls vertically downwards. Now suppose the ship is moving. If the object is dropped from the top of the mast, it again falls vertically downwards according to the observer on the ship. However, a stationary observer on the shore notes that, relative to the shore, the path is curved (Fig. 3.8(c)). The reason is that the ship moves at some speed v and so, relative to the shore, the object has two separate Fig. 3.8 (a) Dropping an object from the top of a mast in a ship, stationary in the frame of reference S. (b) Dropping an object from the top of a mast in a moving ship, viewed in the frame of reference S  of the ship. (c) Dropping an object from the top of a mast in a moving ship, as observed from the frame of reference S. The ship moves during the time the object falls. 44 Galileo and the Nature of the Physical Sciences Fig.

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  Geotechnics and Heritage

  Case Histories

  • Emilio Bilotta, Alessandro Flora, Stefania Lirer, Carlo Viggiani(Authors)
  • 2013(Publication Date)
  • CRC Press

    (Publisher)

  Geotechnics and Heritage – Bilotta, Flora, Lirer & Viggiani (eds) © 2013 Taylor & Francis Group, London, ISBN 978-1-138-00054-4 207 The Leaning Tower of Pisa J.B. Burland Imperial College of London, London, UK M. Jamiolkowski Technical Univesity of Torino, Torino, Italy N. Squeglia University of Pisa, Pisa, Italy C. Viggiani University of Napoli Federico II, Napoli, Italy ABSTRACT: The Leaning Tower of Pisa is one of the world’s best known and most treasured monu-ments. It was erected in the Middle Ages, at the time of maximum power of Pisa. The Tower is founded on highly compressible soils and started leaning from commencement of its construction. In the 1990s the overhang had reached the value of 4.7 m and was increasing at a rate of 1.5 mm per year; an analy-sis of the situation showed that a collapse was to be expected within some decades. After having described the monument and its subsoil, the paper reviews its history and all the data available on the progress of its inclination. Studies and investigations carried out since the early XX cen-tury are recalled, and finally the activity of the International Committee appointed in 1990 is reported. After the underexcavation carried out by the Committee, and the decrease of the overhang by about 0,4 m, at present the tower is practically motionless. In conclusion, the possible future scenarios are briefly addressed. 1 INTRODUCTION The monuments of the Piazza dei Miracoli in Pisa (consisting of the Tower, the Cathedral, the Baptis-tery and the Monumental Camposanto) were erected in the Middle Ages, in the period of maximum splendour and power of the Pisa Republic. Piazza dei Miracoli is the wonderful symbol of the pro-found unity prevailing at those times among the religious, spiritual and political powers. The history of Art and the civil history intertwine in the monuments enhancing it, giving them an outstanding character of sign and symbol of the city.

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