Galileo is still in the news. An optical illusion he discovered in the s caused Venus to appear much larger and blurrier—a "radiant crown," as Galileo called it—when seen through a telescope than when viewed with the naked eye. The puzzle was finally understood just this week. Neuroscientists from the State University of New York College of Optometry report that the answer lies in the wiring of our visual brain cells.
The brain responds to light and dark objects differently, so the brightness of a planet distorts its apparent size when it is seen against the dark background of space. Originally he wanted to name the moons after his noble patrons, four brothers of Florence's famed Medici family called Cosimo, Francesco, Carl, and Lorenzo. Other astronomers, perhaps thankfully, assigned more elevated names to the moons, ones taken from mythology for the consorts of Jupiter, king of the gods.
Those moons revealed that some objects revolved around something other than the Earth, which helped Galileo to discover heliocentrism, or the fact that the Earth circles the sun.
This finding, in turn, would earn him the attention of the Inquisition, which investigated religious rebellion and heresy in the world of 16th-century Italy. The Vatican officially apologized in for Galileo's heresy trial, which resulted in the scientist being kept under house arrest for the last eight years of his life.
Galileo's most famous experiment, which he likely never really performed, was the dropping of cannonballs with different masses off the Leaning Tower of Pisa. The goal of this experiment was to show that objects fall at a uniform rate, that gravity doesn't make heavier objects fall faster. That notion was contrary to classic Greek physics, which held that heavier objects fall faster. In the experiment was repeated on the moon to remove the effects of air resistance by Apollo 15 astronauts , who dropped a hammer and a feather to confirm Galileo's observation.
What was notable about the experiment was precisely that it was an experiment. Earlier models of scientific inquiry were reasoned entirely in the mind or argued from theological principles. Galileo, by contrast, advanced the fundamental idea that science relied on experiments to prove its contentions. This simple idea—prove it—was radical at the time. Galileo went even further, pioneering the idea that mathematics are essential to scientific observations, and abjuring the literary hand-waving of ancient texts.
In this work, which he addressed to the Grand Duchess Christina of Lorraine, he argued strongly for a non-literal interpretation of Holy Scripture when the literal interpretation would contradict facts about the physical world proved by mathematical science.
In this Galileo stated quite clearly that for him the Copernican theory is not just a mathematical calculating tool, but is a physical reality:- I hold that the Sun is located at the centre of the revolutions of the heavenly orbs and does not change place, and that the Earth rotates on itself and moves around it. I confirm this view not only by refuting Ptolemy 's and Aristotle 's arguments, but also by producing many for the other side, especially some pertaining to physical effects whose causes perhaps cannot be determined in any other way, and other astronomical discoveries; these discoveries clearly confute the Ptolemaic system, and they agree admirably with this other position and confirm it.
The cardinals of the Inquisition met on 24 February and took evidence from theological experts. They condemned the teachings of Copernicus , and Bellarmine conveyed their decision to Galileo who had not been personally involved in the trial. Galileo was forbidden to hold Copernican views but later events made him less concerned about this decision of the Inquisition.
This happened just as Galileo's book Il saggiatore The Assayer was about to be published by the Accademia dei Lincei in and Galileo was quick to dedicate this work to the new Pope.
The work described Galileo's new scientific method and contains a famous quote regarding mathematics:- Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and read the characters in which it is written. It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures without which it is humanly impossible to understand a single word of it; without these one is wandering in a dark labyrinth.
Galileo, therefore, decided to publish his views believing that he could do so without serious consequences from the Church. However by this stage in his life Galileo's health was poor with frequent bouts of severe illness and so even though he began to write his famous Dialogue in it took him six years to complete the work. Galileo attempted to obtain permission from Rome to publish the Dialogue in but this did not prove easy.
Eventually he received permission from Florence, and not Rome. It takes the form of a dialogue between Salviati, who argues for the Copernican system, and Simplicio who is an Aristotelian philosopher. The climax of the book is an argument by Salviati that the Earth moves which was based on Galileo's theory of the tides. Galileo's theory of the tides was entirely false despite being postulated after Kepler had already put forward the correct explanation.
It was unfortunate, given the remarkable truths the Dialogue supported, that the argument which Galileo thought to give the strongest proof of Copernicus 's theory should be incorrect. Illness prevented him from travelling to Rome until Galileo's accusation at the trial which followed was that he had breached the conditions laid down by the Inquisition in However a different version of this decision was produced at the trial rather than the one Galileo had been given at the time.
The truth of the Copernican theory was not an issue therefore; it was taken as a fact at the trial that this theory was false. This was logical, of course, since the judgement of had declared it totally false. Found guilty, Galileo was condemned to lifelong imprisonment, but the sentence was carried out somewhat sympathetically and it amounted to house arrest rather than a prison sentence. He was able to live first with the Archbishop of Siena, then later to return to his home in Arcetri, near Florence, but had to spend the rest of his life watched over by officers from the Inquisition.
In he suffered a severe blow when his daughter Virginia, Sister Maria Celeste, died. She had been a great support to her father through his illnesses and Galileo was shattered and could not work for many months.
When he did manage to restart work, he began to write Discourses and mathematical demonstrations concerning the two new sciences. After Galileo had completed work on the Discourses it was smuggled out of Italy, and taken to Leyden in Holland where it was published. It was his most rigorous mathematical work which treated problems on impetus, moments, and centres of gravity. Much of this work went back to the unpublished ideas in De Motu from around and the improvements which he had worked out during - In the Discourses he developed his ideas of the inclined plane writing:- I assume that the speed acquired by the same movable object over different inclinations of the plane are equal whenever the heights of those planes are equal.
He then described an experiment using a pendulum to verify his property of inclined planes and used these ideas to give a theorem on acceleration of bodies in free fall:- The time in which a certain distance is traversed by an object moving under uniform acceleration from rest is equal to the time in which the same distance would be traversed by the same movable object moving at a uniform speed of one half the maximum and final speed of the previous uniformly accelerated motion. After giving further results of this type he gives his famous result that the distance that a body moves from rest under uniform acceleration is proportional to the square of the time taken.
One would expect that Galileo's understanding of the pendulum, which he had since he was a young man, would have led him to design a pendulum clock. In fact he only seems to have thought of this possibility near the end of his life and around he did design the first pendulum clock. Galileo died in early but the significance of his clock design was certainly realised by his son Vincenzo who tried to make a clock to Galileo's plan, but failed. It was a sad end for so great a man to die condemned of heresy.
His will indicated that he wished to be buried beside his father in the family tomb in the Basilica of Santa Croce but his relatives feared, quite rightly, that this would provoke opposition from the Church. His body was concealed and only placed in a fine tomb in the church in by the civil authorities against the wishes of many in the Church.
On 31 October , years after Galileo's death, Pope John Paul II gave an address on behalf of the Catholic Church in which he admitted that errors had been made by the theological advisors in the case of Galileo. He declared the Galileo case closed, but he did not admit that the Church was wrong to convict Galileo on a charge of heresy because of his belief that the Earth rotates round the sun.
References show. Biography in Encyclopaedia Britannica. S Drake, Galileo Oxford, P Machamer ed. C A Ronan, Galileo W R Shea, Galileo's intellectual revolution. Middle period, - New York, E Agazzi, Was Galileo a realist? Storia Sci. U Baldini, Additamenta Galilaeana. M Biagioli, Galileo the emblem maker, Isis 81 , - M Biagioli, Galileo's system of patronage, Hist. V Cappelletti, Galileo's trial Italian , Arch. E Carruccio, Galileo precursore della teoria degli insiemi Italian , Boll.
Proposal for a new interpretation of his works Italian , Rend. XL Mem. Vie Sci. S Drake, Galileo's first telescopic observations, Journal for the history of astronomy 7 , - S Drake, Galileo, Kepler, and the phases of Venus, Journal for the history of astronomy 15 , - S Drake, Galileo and satellite prediction, Journal for the history of astronomy 10 , 75 - S Drake, Galileo's constant, Nuncius Ann.
S Drake, Galileo and mathematical physics, in Science and philosophy Milan, , - S Drake, Galileo's steps to full Copernicanism, and back, Stud. Simply put, all hell brakes loose in Galileo's world. The Pope, infuriated at the content of "Dialogo," places him on trial for one thing after another. February Galileo is eventually placed on trial and at his old age, is forced to make the journey to Rome. He is under suspicion of "vehement suspicion of heresy," but is convicted of holding and teaching the Copernican belief.
He is placed under house arrest for eight years until his death. Despite his house arrest Galileo publishes Discorsi e dimostrazioni mathematiche intorno a due nuove scienze attenenti alla meccanica Dialogue Concerning Two New Sciences, a work about the principles of mechanics.
Galileo makes the discovery, months before he went completely blind, that the moon makes monthly wobbles on its axis, called liberations. January 8, Galileo Galilei dies from a long illness. The moon is an irregular, rough body, not smooth as scientists thought.
The Milky Way is composed of many stars. Jupiter has many small satellites that he named, "Sidera Medicea," after his favorite pupil. He made observations about Saturn, sunspots, and the phases of Venus. The advocate of Aristotelian belief comes across as the simpleton, getting caught in his own arguments. In addition to the telescope and his numerous mathematical and scientific discoveries, in Galileo constructed a hydrostatic balance for measuring small objects.
That same year, he also refined his theories on motion and falling objects, and developed the universal law of acceleration, which all objects in the universe obeyed.
He also devised a type of simple thermometer. A simple glass-bulb thermometer known as a Galileo thermometer wasn't invented by Galileo, but was based on his understanding that the density of liquids changes based on its temperature. A thermoscope that Galileo designed or helped to design is similar to modern-day thermometers.
Inside the thermoscope, a liquid rises and falls in a glass tube as the temperature of the liquid rises or falls. After Galileo built his telescope in , he began mounting a body of evidence and openly supporting the Copernican theory that the earth and planets revolve around the sun. The Copernican theory, however, challenged the doctrine of Aristotle and the established order set by the Catholic Church.
In , Galileo wrote a letter to a student to explain how Copernican theory did not contradict Biblical passages, stating that scripture was written from an earthly perspective and implied that science provided a different, more accurate perspective.
The letter was made public and Church Inquisition consultants pronounced Copernican theory heretical. Galileo obeyed the order for seven years, partly to make life easier and partly because he was a devoted Catholic.
He allowed Galileo to pursue his work on astronomy and even encouraged him to publish it, on condition it be objective and not advocate Copernican theory. Church reaction was swift, and Galileo was summoned to Rome. During most of this time, Galileo was treated with respect and never imprisoned. However, in a final attempt to break him, Galileo was threatened with torture, and he finally admitted he had supported Copernican theory, but privately held that his statements were correct.
He was convicted of heresy and spent his remaining years under house arrest. Though ordered not to have any visitors nor have any of his works printed outside of Italy, he ignored both. In , a French translation of his study of forces and their effects on matter was published, and a year later, copies of the Dialogue were published in Holland.
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