archive-org.com » ORG » S » SCIENTUS.ORG

Total: 32

Choose link from "Titles, links and description words view":

Or switch to "Titles and links view".
  • Francesco Redi and Controlled Experiments
    Redi and Galileo Galilei demonstrated their methods using very simple experiments then explained their procedures in clear and compelling ways This is why both are so important But scientists before Redi and Galileo had recognized the need to control variables and had described the sequence of steps described in Galileo s experimental method When Galileo was still a young boy Giuseppe Moletti a professor at the University of Padua conducted a series of experiments on free fall by dropping weights in different media see Timeline of Classical Mechanics His test with free fall in water and air specified that the balls must be of the same substance weight and figure in order to remove doubt In the same book when Moletti described dropping balls of wood and lead from a tower to demonstrate that free fall doesn t depend on weight as Aristotle had said he was careful to eliminate size as a nuisance variable by conducting the experiment with wooden balls of different sizes 1 Being careful to control for the known variables doesn t guarantee that you will get the correct results That is because you don t know what you don t know There might be variables that need to be controlled that you don t even know exist This is why the famous Tower of Pisa experiment actually came up with incorrect results Many consider the legend of the Tower of Pisa experiment to be a myth The experiment did occur It was conducted by Vincenzio Renieri a Catholic monk see Galileo s Battle for the Heaven s and not Galileo as is commonly thought Vincenzio was a friend of Galileo s Like Moletti before him Renieri controlled for size when he dropped two balls of the same size one of wood and one of lead He came up with the wrong results There was almost 2 metres difference between the heavier and lighter balls when they hit the ground Galileo described similar results in some of his works These scientists could not have known that they needed to control for human physiology as well Modern experiments with humans dropping balls of markedly different weights show that there is a tendency to grip the heavier ball more tightly and release it more slowly 2 Francesco Redi and the Galileo Affair Francesco Redi lived during the time of the Galileo Affair This event is presented as evidence for the the recurring clash between religion and science see Galileo s Battle for the Heaven s Francesco Redi s experiences counter this interpretation Francesco Redi lived a comfortable life in Florence walking the same streets and working for the same people that Galileo did the Medicis He died without encountering any problems with the Church Galileo s use of Italian instead of Latin was supposed to be a problem with the Church But with Francesco Redi it wasn t Any challenge to Aristotle was supposed to be a problem for the Church It was Aristotle who proposed life forms

    Original URL path: http://www.scientus.org/Redi-Galileo.html (2016-02-10)
    Open archived version from archive


  • Mendel, Darwin and Evolution
    This is significant as well This ratio can be explained if the inheritance of traits depended on paired elements that are recombined not blended as Darwin believed in the offspring In this experiment a Yellow Green pair would show as a yellow pea But if we crossed many Yellow Green plants we could get only 4 different permutations Yellow Yellow Yellow Green Green Yellow and Green Green Three of them result in yellow peas and only one the Green Green results in green peas The diagram below taken from a early book by Thomas Hunt Morgan illustrates Mendelian genetics through two generations F 1 and F 2 of the yellow green trait Why did Mendel use such large numbers of crosses in his experiments Mendel needed large samples to produce higher confidence in the 3 1 ratio If Mendel had used smaller sample sizes his work would have been of little value Charles Darwin had conducted similar experiments with snapdragons but because of his poor understanding of sampling had only used 125 crosses His result of 2 4 1 could have been interpreted as a 2 1 ratio or a 3 1 ratio Darwin Mendel and Statistics Mendelian genetics helped support a trend toward a more mathematical approach in biology Gregor Mendel s work on genetics was finally published in the the Proceedings of the Natural History Society of Brünn in 1866 No one seemed to care The paper was rarely mentioned over the next 35 years It would dramatically change the field of biology when it was rediscovered around 1900 Mendel s Laws of Inheritance There was more to Mendel s work than a brilliant set of experiments He also developed a set of laws It is good to review Gregor s experiments to understand these laws It seems from the experiments that there were two components used to code for each trait The individual component is known as an allele The first law the Law of Segregation states that during fertilization each parent passes on one allele for each trait Which allele the offspring would get from the parents is random The second law the Law of Independent Assortment states that transmission of one trait does not affect the transmission of other traits We only described the experiments for one trait pea color In fact Mendel and his fellow monks conducted experiments on six other traits pea shape round or wrinkled seed color gray or white stem length color of unripe pod green or yellow position of the flower terminal or axial and form of the ripe pod inflated or constricted The second law means that the inheritance of a green unripe pod should not influence the inheritance of a terminal flower The third law the The Law of Dominance states that one type of allele the dominant could mask the other the recessive This is now considered a general principle and not a law Mendel s Laws of Inheritance helped revive Darwin s theory They would also

    Original URL path: http://www.scientus.org/Mendel-Darwin.html (2016-02-10)
    Open archived version from archive

  • Galileo's Battle for the Heavens
    him to expect pushback from other astronomers 4 When the manuscript was finally published it contained a copy of Schonberg s Letter the imprimatur of the pope and an expression of thanks to the pope and Geise Kepler and the Jesuits Kepler is usually credited with our modern view of the solar system Kepler was not a Catholic Born a Lutheran he had been excommunicated from the Lutheran church for some of his beliefs He remained a devout Christian but outside of any formal tradition Nothing seemed to come easy for Kepler Early in his career Kepler had trouble borrowing a telescope Galileo ignored his requests It would be left to the Catholic bishop of Cologne to lend him one Over time Kepler developed a close relationship with the Austrian Jesuits especially Paul Guldin Kepler would use the Jesuit network of institutions as his private postal service The Jesuits chased down and returned a manuscript that was stolen from him Niccolo Zucchi a master Jesuit telescope builder built a telescope for Kepler at Guldin s request Kepler acknowledged the help with a gushing thank you to the Jesuits in his last book the Somnium Galileo Kepler and some Jesuits disagreed on the design of telescopes Galileo s preferred design used a convex objective and a plano concave eyepiece A few years after Galileo introduced his telescopes Kepler proposed a design with a convex objective and a convex eyepiece This design was largely ignored except for a group of Jesuits led by Christopher Scheiner Scheiner started building and using telescopes using Kepler s design He detailed this in his work Rosa Ursina in 1630 Astronomers remained skeptical But not for long Shortly after Galileo s death astronomers discarded the Galilean design in favour of Kepler s Scheiner was only one of many church scientists who made important contributions to the early development of telescopes This included building the first crude reflecting telescope inventing a telescope mount that is still used widely today and proposing the reflecting telescope design that would dominate in the twentieth century Fathers of the Telescope details some of the contributions of church scientists to the early development of the telescope The Galileo Myths Narratives such as Galileo s Battle for the Heavens do Galileo a tremendous disservice Galileo s greatness could be argued using only one of his works Discourses and Mathematical Demonstrations Relating to Two New Sciences Yet Galileo narratives unnecessarily embellish his record with myth and hyperbole As a result it is difficult to know where the real Galileo ends and where the mythical Galileo begins There are several examples of myth making from Galileo s Battle for the Heavens This from an award winning documentary that is used widely in science education in the United States The program s accompanying website stated Despite myriad embellishments however most optical telescopes in use in the 21st century derive from the two types developed in the 17th century by Galileo and Newton on whose shoulders all astronomers both amateur and professional stand today Astronomical telescopes are based on Kepler s design not Galileo s The quote exaggerates Newton s importance as well Newton s designs are still used by amateurs but for about a century almost all major research reflecting telescopes have been based on a design proposed by a 17th century Catholic priest Laurent Cassegrain see Reflecting on History In an ironic twist Isaac Newton was the most important early critic of the design Galileo was not working from scratch Galileo was not the first to apply mathematics to nature as the program s website suggests This tradition had been established centuries before in Oxford see The Oxford Calculators and Paris the Doctores Parienses but had spread through Europe We know that Galileo had been exposed to their work from his own notes as a student 5 Galileo s time squared law for free fall distance is related to the square of time is the same as Bishop Oresme s time squared law for objects undergoing constant acceleration distance is related to the square of time Galileo s geometric proof for his theory is very similar to Oresme s geometric proof for his Bishop Oresme was a Parisian academic Galileo was not a lone voice for experimentation or a lone voice against Aristotle Sadly the program s educational materials use Galileo s Tower of Pisa experiment as an example of his belief in experimentation We are still waiting for any evidence that the experiment ever happened see Galileo s Contemporaries We do know that several of Galileo s predecessors and contemporaries Borro Varchi Moletti Stevin Philiponus Renieri had conducted free fall experiments from towers Neither was Galileo able to determine the rate of acceleration due to gravity unless you consider a 50 error close enough 6 Galileo s contemporaries amongst the Jesuits were the first to derive an accurate estimate of the acceleration due to gravity see Galileo s Contemporaries Several myths surround Galileo s time at the Vatican One of the documentary s myths seems to be pure invention According to the program Galileo was remanded to a small room in the Palace of the Inquisition The floor plan below was done by a nineteenth century historian who had visited Galileo s five room suite in the Palace 7 It shows 3 large rooms for Galileo s personal use one room for Galileo s valet and an ante room to receive visitors One side of the apartment looked out on the Vatican Gardens and from one corner Galileo had a view of St Peter s The small room was a suite of approximately 2500 square feet 230 square metres This is larger than the average size of a home in the United States While at the Palace Galileo was provided with a personal valet and the finest of Tuscan cuisine courtesy of the Tuscan Embassy Galileo Science and the Church The Galileo Affair has become a symbol for the conflict between church and science This

    Original URL path: http://www.scientus.org/Galileo-Battle-for-Heavens.html (2016-02-10)
    Open archived version from archive

  • Galileo's Contemporaries
    the date for the vernal equinox to what it would have been in 325 C E That was enough reduce the error from 10 minutes a year in the Julian calendar to 26 seconds a year in the new Gregorian calendar Initially only Catholic countries adopted the calendar but by 1760 most of Europe Catholic or Protestant had adopted it From then its use spread around the world The importance of having a common calendar for commerce and communication is typically overlooked Important experiments are not always done by important scientists One important experiment was conducted by Carmelite friars in Seville Spain before Galileo had reached the age of 10 They had acquired an exotic tuber native to the equatorial mountain regions of South America They wanted to see whether the plant could be used to feed the poor in the region There were risks the stem and leaves of the plant were poisonous and if the tubers themselves were allowed to go green they also became poisonous But it was known that the Native Americans in South America were using the tuber as food and that Spanish sailors had used the tuber as rations on trips across the Atlantic The other problems with the plant was that it had a bland taste and that the plant was adapted to 12 hours of daylight not the long summer days of Europe The experiment was successful enough that the Carmelite friars took the plant to Northern Italy and started growing it there Within two centuries hybrids had been developed that could handle the long summer days of Northern Europe Today the tuber now known as the potato is the fourth largest cash crop in the world It is being used to feed many more than just the poor of Seville Optics is important in our daily lives due to cameras and projectors not telescopes Modern cameras and projectors derive from the camera obscura and pin hole cameras Several of Galileo s contemporaries both scientists and artists made productive use of this technology Camera obscura had been around for centuries but their use with lenses was new Christopher Scheiner and his Jesuit colleague Grienberger used an astounding combination of camera obscura telescope and the newly invented equatorial mount to observe sunspots The device shown below was 22 metres long The Early Telescope Galileo is commonly associated with the telescope It was Galileo who demonstrated that the telescope was much more than a toy for the rich It was a valuable instrument for astronomy and an early warning system for the military He also raised the bar on telescope manufacture very quickly producing telescopes that were much more powerful than the telescopes of the Dutch originators But there was a serious flaw in Galileo s designs A flaw so great that the design had met its practical limit even before his death As astronomers attempted to increase the power of the Galilean telescope the field of view quickly decreased to the point where the telescope was of little use see Jesuits and the Telescope The picture of the moon below shows what would be seen by a 20x Galilean telescope the inner circle and what would be seen by a 20x Keplerian telescope the outer circle The problems with the Galilean telescope meant that the future of the telescope lay in the hands of Galileo s contemporaries Johannes Kepler proposed a design that would so dominate in astronomy that it became known as the astronomical telescope Kepler s design was initially ignored It was the Jesuit Christopher Scheiner and his colleagues that were the early champions of the design Two priests Marin Mersenne and Bonaventura Cavalieri would propose telescope designs employing mirrors instead of lenses see Reflecting on History During the nineteenth century important reference works identified Marin Mersenne as the inventor of the reflecting telescope 3 Today we have the awkward situation where astronomers are using reflecting telescopes based on a design Mersenne published in 1636 see Reflecting on History while textbooks assign the invention of the reflecting telescope to Isaac Newton in 1668 or James Gregory in 1663 The designs below are taken from Mersenne s 1636 publication Kepler is important to science for more than his telescope design He developed an important treatment of optics and a set of laws for planetary motion that is still taught in schools today He also advocated that the tides were caused by the moon Sadly he was largely ignored by Galileo Had he recognized Kepler s work it may have saved him the embarassment of trying to use tides to prove the motion of the earth and the futility of trying to make a planetary model work with perfect circles when ellipses were required Nothing was going to change Galileo s mind about Kepler Kepler s planetary model made very specific predictions One was that Mercury should pass directly between the sun and earth on November 7 1631 this is known as a Transit of Mercury This was about a year before Galileo s trial Pierre Gassendi had arranged an international experiment by sending brochures to important astronomers warning about the upcoming event The transit was witnessed by Gassendi and others on November 7 1631 within minutes of the time predicted Galileo did state why he chose to ignore Kepler He did not want to seek out the nuggets of real gold in Kepler s heap of dross 4 The Real Tower of Pisa Experiment Perhaps the most famous experiment in the history of science is the Tower of Pisa experiment Most people know the legend Galileo when a young professor at the University of Pisa climbs the Tower of Pisa in front of an audience of professors and students In a direct challenge to the stodgy Aristotelian professors of the day he proceeds to drop balls of unequal weight to show that they hit the ground at the same time There is a growing consensus that this experiment was a myth There

    Original URL path: http://www.scientus.org/Galileo-Contemporaries.html (2016-02-10)
    Open archived version from archive

  • The Jesuit's Bark
    in the Americas and partly from pure luck Augustino Salumbrino a Jesuit apothecary in Lima had noticed the Quecha natives in the foothills of the Andes using the bark of the cinchona tree to fight off chills The center of the period map below is the area where Augusto observed the Quechas Thinking that the bark might be used to fight off the chills that accompany malaria he arranged for samples to be sent to Rome The doctors in Rome discovered that the bark did more than fight off chills it was actually a remedy for the disease The active ingredient of cinchona was quinine which is still used to fight off the disease New medicines need a champion The first champion of the Jesuit s bark was a Spanish Jesuit Cardinal Cardinal Lugo In fact early names for the medicine was Cardinal s Powder and de Lugo s Powder There was resistance to the remedy Miracle cures are met with suspicion because they are often scams And miracle cures do not work if they are applied to the wrong subjects or with the wrong dosages The Jesuits seemed to take a reasoned approach to this resistance Cardinal Lugo asked Gabrielle Fonseca physician to the pope to conduct an efficacy study in 1643 The Jesuits were sufficiently satisfied by its efficacy that they recommended its wider use Cardinal Lugo used his own funds to provide the drug for the poor of Rome By 1649 there were instructions on proper dosages and application in the Schedula Romana The efficacy study and the recommendations of the Jesuits did not mean that the remedy stopped being controversial The association of the remedy with the Jesuits made it more controversial There was considerable anti Catholic sentiment in Northern Europe and England at the time and many suspected anything associated with the Church Oliver Cromwell who hated all things Catholic is an example of this resistance When he fell ill to malaria in 1658 he refused to take the popish powder and died as a result The confusion over proper application of the bark continued to be a problem as well Jean Jacques Chifflet a famous doctor wrote a pamphlet critical of the powder when his own application of the remedy failed There was another reason for controversy The Jesuit s Bark was a serious challenge to the status quo in medical practice At the time Galen was to medicine what Aristotle was to physics Galen believed that all fevers could be treated the same way that they were the result of an imbalance of humours and that correcting this imbalance took several months Jesuit s Bark only acted on specific fevers The Bark also acted much more quickly than Galenic remedies Popular histories often caricature the Church and Jesuits as blind defenders of the status quo In this case they were the ones leading the challenge The story of the Jesuit s Bark is an interesting backstory to the Galileo Affair But which story

    Original URL path: http://www.scientus.org/Jesuits-Bark.html (2016-02-10)
    Open archived version from archive

  • Copernicanism and Stellar Parallax
    year Nearer stars should seem to move relative to more distant stars The relative positions of nearer and farther stars seemed to remain the same No one in Galileo s time or for almost 200 years after his death was able to demonstrate this necessary effect of earth s motion around the sun Stellar parallax was finally observed in 1838 by Friedrich Bessel a German scientist But it is not Bessel that is credited with finally proving that the earth moved around the earth In 1729 James Bradley while searching for the elusive stellar parallax detected motion of the stars over the course of the year which did not fit the pattern of stellar parallax He had discovered stellar aberration which is also related to the motion of the earth Regardless proof of the earth s motion was not available in the seventeenth century and those arguing for it s motion had no answer for why stellar parallax could not be observed It is a huge problem when a consequence of a theory is expected and it cannot be observed It is enough to keep a hypothesis from being accepted as a proven theory regardless of the number of positive arguments in its favor This applies as much today as it did in the seventeeth century These scientists were correct that a moving earth required that there must be stellar parallax They were also correct that this parallax could not be observed However their rejection of the hypothesis was based on more than this it was also based on the assumption that the stars were millions of miles away These stars were billions of miles away Given the instrumentation of the day one could expect to detect stellar parallax if the stars were millions of miles away but not if

    Original URL path: http://www.scientus.org/Copernicus-Stellar-Parallax.html (2016-02-10)
    Open archived version from archive

  • Timeline of Galileo's Contemporaries

    (No additional info available in detailed archive for this subpage)
    Original URL path: /timeline/Galileo-Contemporaries-Timeline.html (2016-02-10)


  • The Church and the Early Telescope
    first to construct a modern astronomical telescope using theory proposed by Johannes Kepler Christopher Grienberger another Jesuit proposed an advanced method of mounting telescopes that made it easier to follow objects as the arc through the sky Father Nicolo Zucchi another Jesuit demonstrated that creating telescopes out of lenses and mirrors was possible This was in 1616 50 years before Newton s famous reflecting telescope He was the master craftsman who also built refracting telescopes for Johannes Kepler see Jesuits and the Telescope The early adoption of the telescope by Jesuit scientists might explain why 35 lunar craters are named after Jesuit scientists see Jesuit Lunar Craters After Galileo The advances in telescope making continued in the decades after Galileo s death The lenses of Giuseppe Campani have spherical curvatures as good as can be made today 1 Giuseppe Campani was first noticed when he and his brother Matteo a Catholic priest entered their telescope in a competition against the greatest telescope makers of the day The Campani telescope won Campani and his most famous competitors were very secretive about their methods and tools It was left to a Capuchin Monk Cherubin d Orleans to spread knowledge of the craft of telescope making Cherubin d Orleans wrote two important works on optical instruments and optics La Dioptrique Oculaire and De visione perfecta De visione perfecta documents his invention of the binocular microscope La Dioptrique Oculaire included detailed descriptions of the tools and techniques involved in the manufacture of lenses The monk s work continues to impress today These descriptions are so good and show such thoughtful personal knowledge of the subject that they would be suitable to place in the hands of an optical apprentice today 2 The lathes he used for grinding and polishing were very sophisticated An image of one of Cherubin D Orleans lathes is shown below modified from here Other priests from the time who published important works on telescope construction were Niccolo Zucchi and Anton Rheita For the last one hundred years almost all of the largest optical telescopes have been Cassegrain reflectors Father Laurent Cassegrain a French priest and contemporary of Isaac Newton and Cherubin D Orleans was the first to propose this popular design In an ironic twist that is so common in history Isaac Newton was one of the leading critics of the young priest s design Here is what Newton had to say about the Cassegrain design You see therefore that the advantages of this design are none but the disadvantages so great and unavoidable that I fear it will never be put in practise with good effect 3 More information on the early history of the reflecting telescope is found at Reflecting on History Unsung Heroes Church scientists from the 17th century made very important contributions to the early development of the telescope They are rarely mentioned The narratives on 17th century science focus on the story of two great scientists Galileo and Newton These narratives commonly portray the church

    Original URL path: http://www.scientus.org/Church-Early-Telescope.html (2016-02-10)
    Open archived version from archive



  •