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Advances in science have been termed “revolutions” since the 18th century. In 1747, Clairaut wrote that “Newton was said in his own lifetime to have created a revolution.” A new view of nature emerged, replacing the Greek view that had dominated science for almost 2,000 years.
Greek view was based on faith. It was not based on “Reason” – the new lifeblood of science. Faith replacing “Reason?” What is that?
Take a look at the following in keeping with the Ptolemaic system:
There is talk of a new astrologer who wants to prove that the earth moves and goes around instead of the sky, the sun, the moon, just as if somebody were moving in a carriage or ship might hold that he was sitting still and at rest while the earth and the trees walked and moved. But that is how things are nowadays: when a man wishes to be clever he must . . . invent something special, and the way he does it must needs be the best! The fool wants to turn the whole art of astronomy upside-down. However, as Holy Scripture tells us, so did Joshua bid the sun to stand still and not the earth.” – Martin Luther, 1539
The “new astrologer” Martin Luther is referring to is Copernicus. Martin Luther made negative comments about Copernicus because the idea of the heliocentric universe seemed to contradict the Bible. The new science moved forward with “Reason” plus “Scientific observation.”
The transition from ancient superstition and dogma of the 15th century to Newton’s laws marked the start of the scientific age.
- The Renaissance
- Humanists placed low value on science
- More interested in classical antiquity and the authority of the ancients
- Arabic translations of Greek classics
- Rediscovery of Ptolemy and Archimedes
- The universe as machine
- Developing collaboration between artisans and intellectuals
- Building machines for practical use
- The laws of perspective and optics
- Alchemy and astrology
- Voyages of discovery
- Travelers’ accounts of foreign lands
- Attacking the authority of the ancients
Ptolemaic system with the Earth as the center of the universe.
Ptolemy’s model was accepted as Church doctrine.
Heliocentrism was nothing less than heresy:
-Giordano Bruno was burned at the stake in 1600 for his heliocentric views.
-Galileo was forced to recant and placed under house arrest.
-Many others picked their words carefully to avoid a similar fate
-It was only around the time of Newton that it became safe (even respectable) to express such heretical views.
When we talk about science there are four words we use more often than any others — facts, theories, hypotheses, evidence. But none of these words exist in their modern sense before the Scientific Revolution. This new vocabulary means that something we can recognize as modern science doesn’t exist until the age of Newton. Scientific results must be subjected to scrutiny and be open to refutation. Science does not just require certain ways of gathering and processing information; it requires a critical community which subjects results to scrutiny and a collaborative community which seeks to carry forward the work of others.
The Copernican Revolution
- Medieval science
- Authority of the ancients: Aristotle and Ptolemy
- Heavenly bodies orbit in a hierarchy of spheres
- Heavens and earth composed of different matter
- The “quintessence” (the ether)
- Earth, air, fire, and water
- The “prime mover”
- Late Middle Ages developments
- Ptolemaic system did not conform to observations
- Retrograde motion
- Roman calendar out of alignment with movement of heavenly bodies
- The “problem” of Easter and other holy days
- Nicolaus Copernicus (1473-1543)
- Renaissance Man
- Ptolemaic system had become too messy
- Copernican system
- The earth moved and was not the center of the planetary system
- The earth rotated on its axis and orbited the sun
- Believed he had restored a pure understanding of God’s plan but was troubled by its implications
- New problems and inconsistencies
- On the Revolutions of the Heavenly Spheres (1543)
Nicolai Copernicito Torinensis De Revolutionibus Orbium Coelestium, Libri VI (title page of 2nd edition, Basel, 1566)
Although the medieval model of the universe persisted throughout the Renaissance, a new theory about the shape of the universe arose around 1512, when Polish astronomer Nicholaus Copernicus (1473–1543) wrote De Revolutionibus Orbium Coelestium (Revolution of the Heavenly Spheres), explaining his heliocentric theory. This theory held that the Earth, along with the other planets, rotated around the sun. Copernicus had arrived at this theory using mathematics and observation of the stars and planets. Though he was convinced of his findings, he was reluctant to publicize his ideas, since they contradicted the teachings of the church. According to church leaders the Earth was the center of the universe because the humans who lived there were the constant focus of God’s divine rule. Copernicus waited more than thirty years to have his work published, but many European astronomers knew of his theories and some continued his work.It is traditionally assumed to start with the Copernican Revolution (initiated in 1543) and to be complete in the “grand synthesis” of Isaac Newton’s 1687 Principia. The first scientific society to be established was the Royal Society of England. The major features of Copernican theory are:
- The center of the universe is near the Sun.
- Around the Sun, in order, are Mercury, Venus, Earth and Moon, Mars, Jupiter, Saturn, and the fixed stars.
- The Earth has three motions: daily rotation, annual revolution, and annual tilting of its axis.
Center: Italian physicist Galileo Galilei’s circa 1630-1646 experiment for testing the “force of the vacuum”. Right: The 1641 siphon experiment, done by Gasparo Berti, created by means of an 11 meter high column of water. Demo in Rome, for an invited audience which included Raffaelo Magiotti, Athanasius Kircher, and Nicolo Zucchi.
Galileo’s Dialogue concerning the Two Chief World Systems (1632), which argues for the superiority of the heliocentric Copernican over the geocentric Ptolemaic system, is a classic straw man argument. By 1632, astronomers had all but abandoned the Ptolemaic system, which had become untenable in the light of the evidence from telescopes for more than 20 years, which showed, for example, that Mercury and Venus orbited the sun. Refracting telescopes first appeared in the Netherlands in 1608. Galileo was one of the first scientists to use this new tool for his astronomical observations in 1609.
The Catholic church sanctioned the First Edition of Galileo’s complete works in the 18th century (Roman Inquisition above), considering “the affair” closed. However, Pope John Paul II issued an official church investigation into Galileo’s claims in 1979 and published an official papal pardon for Galileo in 1992. As shown in the figure above, the chapter on Heliocentrism ended in 1992.
Galileo never realised that he had seen the rings of Saturn, but he certainly did see what we now call the rings of Saturn.
(4) Issac Newton: Law of Gravity
Copernicus never uses the word “system” — or rather its equivalent in Latin. After Galileo’s book on the two chief world systems it becomes commonplace to refer to the Ptolemaic, Tychonic, and Copernican systems — the word system here, as in Galileo, just means “model” or “theory” or even “diagram”. The real world is not a system because systems are always things you find in books, and to refer to one of these systems you use the name of the author of the book in which it first appears — just as we say “Einstein’s theory” they write “the Copernican system”.
All this changes with Newton’s theory of gravity. For the first time people start writing about “the solar system”. In other words the real world has now acquired the characteristics of a system. What are the characteristics of a system? It is something where the different parts are connected together. What connects together the different parts of the solar system is gravity, and a change in any of the parameters of one body — its mass, its speed, its direction — has an effect on all the others. No previous intellectual system had been interactive in this way, and no one had previously claimed that the real world consisted of feedback systems of this sort.
Kepler it is true had imagined that the sun might emit some sort of force driving the planets, but he had not claimed that the planets reciprocally affected the sun or each other — his was a physical astronomy, not merely a mathematical astronomy, but his was not a system in this new sense. The term the solar system thus encapsulates an intellectual revolution, and one that isn’t just important in physics — it provides the crucial model for the development of economics as a theory of interactions in what we now call the economy — Quesnay, the first to produce such an account insisted that he took his inspiration from Newton.
In 1727 (84 ME), Isaac Newton, at the time of his death (reaction end), had amassed all the world’s knowledge into a large collected works set, estimates of which, still not yet finalized (Ѻ), indicate 40-volumes±, including: 25-volume set of correspondence, 8-volume plus set of mathematical papers, 3-volume plus set of optics, one volume plus on Philosophical Questions, and untold volumes on alchemical pursuits and religious ventures; the apex of which being his Principia (1686) and Optics (1718), the latter of which, via Query 31, launched the chemical revolution.
(5) William Harvey: Circulation of Blood
Further groundbreaking work was carried out by William Harvey, who published De Motu Cordis in 1628. Harvey made a detailed analysis of the overall structure of the heart, going on to an analysis of the arteries, showing how their pulsation depends upon the contraction of the left ventricle, while the contraction of the right ventricle propels its charge of blood into the pulmonary artery. He noticed that the two ventricles move together almost simultaneously and not independently like had been thought previously by his predecessors.
A line that connects a planet to the sun sweeps out equal areas in equal times.
This is one of Kepler’s laws.This empirical law discovered by Kepler arises from conservation of angular momentum. When the planet is closer to the sun, it moves faster, sweeping through a longer path in a given time.
Since the days of Aristotle science had been based on the belief that all of the Earth’s matter was made up of four elements: earth, water, air, and fire. Human beings were thought to be microcosms, or little worlds, that were smaller versions of the macrocosm, or the world at large. Thus the four elements of the world were thought to correspond to four humors, or body fluids, in humans. These fluids, which were associated with human characteristics, were believed to exist in a state of balance within the body. The four humors had the following corresponding elements and traits:
Blood corresponded to the element of fire and was associated with a cheerful character. Phlegm (mucus) corresponded to earth and was associated with a slow, unexcitable nature. Black bile (digestive juices) corresponded with water and was associated with sadness and depression.
Yellow bile corresponded to air and was associated with anger and bad temper. Renaissance philosophy held that imbalance in the body’s humors resulted in disease. Thus treatments for disease were usually attempts to restore balance by draining off an excess of one of the humors. Elizabethan doctors frequently practiced bloodletting—cutting open a vein to let the blood flow—to cure fevers, infections, and diseases. Sometimes they placed leeches (blood-sucking worms) on prescribed parts of the body to suck out blood. In other cases they induced vomiting. According to modern medicine most of these remedies were harmful, or at least not helpful, to the patient.
In the early Renaissance, some scholars began to study the human body through dissection, cutting the body open in order to examine the organs, and systematic observation. The pioneers of the new science of anatomy were Leonardo da Vinci, whose fascination in the workings of the human body led to masterful sketches of its internal structures, and Belgian anatomist and physician Andreas Vesalius (1514–1564). In 1543 Vesalius wrote a seven-volume text on the structure of the human body illustrated with engravings based on his own drawings. Vesalius rejected the medical theories that had been passed down from the ancient Greeks and Romans. He believed that the only reliable source of information on human anatomy was the close observation of a dissected human corpse. He showed the human body to be composed of internal organs that function together, and his descriptions and drawings were the most accurate study of anatomy ever undertaken up to that time.
Einstein had a new idea about gravity. He thought that gravity is what happens when space itself is curved or warped around a mass, such as a star or a planet. Thus, a star or planet would cause kind of a dip in space so that any other object that came too near would tend to fall into the dip.
This 2-D animation gives an idea of how gravity works in 3-D.
For example, if gravity is a force that causes all matter to be attracted to all other matter, why are atoms mostly empty space inside? (There is really hardly any actual matter in an atom as seen above!) How are the forces that hold atoms together different from gravity? Is it possible that all the forces we see at work in nature are really different sides of the same basic force or structure?
Discovery Of Vacuum
A 1644 rendition of experiments of Torricelli on making a vacuum by means of a mercury column, Florence.
Torricelli used a glass tube about 1 m in length, and filled it with mercury. He sealed the open end of the tube with a fingertip and then flipped the sealed end of the tube facing downwards. He then submerged the tube in a mercury reservoir and removed his finger, allowing the mercury inside the tube to be in contact with the reservoir. The column of mercury in the tube sank to 76 cm, measured from the liquid surface of the reservoir. The space left in the glass tube above the mercury was in fact a vacuum.
The experiment demonstrated that the space left above the mercury after turning the tube upside down was in fact a vacuum: the mercury level was independent of the volume above, and it could be filled completely with water admitted from below. This experiment was the first successful attempt to produce vacuum and subsequently convinced the scientific community.
||Foundations Of Atomic Theory
||1803: He discovered Electron and won a Nobel prize for this.
|J J Thomson
||In 1897, Thomson showed that cathode rays were composed of previously unknown negatively charged particles, which he calculated must have bodies much smaller than atoms and a very large value for their charge-to-mass ratio. J.J. Thomson, a British scientist, discovers the electron, leading to his “plum-pudding” model.
||1904 Hantaro Nagaoka, a Japanese physicist, suggests that an atom has a central nucleus. Electrons move in orbits like the rings around Saturn.
||1911 New Zealander Ernest Rutherford states that an atom has a dense, positively charged nucleus. He called them Protons. Electrons move randomly in the space around the nucleus.
||1913 In Niels Bohr’s model, the electrons move in spherical orbits at fixed distances from the nucleus.
|Louis de Broglie
||1924 Frenchman Louis de Broglie proposes that moving particles like electrons have some properties of waves. Within a few years evidence is collected to support his idea.
1926 Erwin Schrödinger develops mathematical equations to describe the motion of electrons in atoms. His work leads to the electron cloud model (Shown above).
1932 James Chadwick, a British physicist and Student of Rutherford, discovered neutrons, which have no charge. Atomic nuclei contain neutrons and positively charged protons.
||Max Planck suggests that radiation is quantized (it comes in discrete amounts.)
||Albert Einstein, one of the few scientists to take Planck’s ideas seriously, proposes a quantum of light (the photon) which behaves like a particle. Einstein’s other theories explained the equivalence of mass and energy, the particle-wave duality of photons, the equivalence principle, and special relativity.
||Hans Geiger and Ernest Marsden, under the supervision of Ernest Rutherford, scatter alpha particles off a gold foil and observe large angles of scattering, suggesting that atoms have a small, dense, positively charged nucleus.
||Ernest Rutherford infers the nucleus as the result of the alpha-scattering experiment performed by Hans Geiger and Ernest Marsden.
||Albert Einstein explains the curvature of space-time.
||Niels Bohr succeeds in constructing a theory of atomic structure based on quantum ideas.
||Ernest Rutherford finds the first evidence for a proton.
||James Chadwick and E.S. Bieler conclude that some strong force holds the nucleus together.
||Arthur Compton discovers the quantum (particle) nature of x rays, thus confirming photons as particles.
||Louis de Broglie proposes that matter has wave properties.
||Wolfgang Pauli formulates the exclusion principle for electrons in an atom.
||Walther Bothe and Hans Geiger demonstrate that energy and mass are conserved in atomic processes.
||Erwin Schroedinger develops wave mechanics, which describes the behavior of quantum systems for bosons. Max Born gives a probability interpretation of quantum mechanics. G.N. Lewis proposes the name “photon” for a light quantum.
||Certain materials had been observed to emit electrons (beta decay). Since both the atom and the nucleus have discrete energy levels, it is hard to see how electrons produced in transition could have a continuous spectrum (see 1930 for an answer.)
||Werner Heisenberg formulates the uncertainty principle: the more you know about a particle’s energy, the less you know about the time of the energy (and vice versa.) The same uncertainty applies to momenta and coordinates.
||Paul Dirac combines quantum mechanics and special relativity to describe the electron.
||Quantum mechanics and special relativity are well established. There are just three fundamental particles: protons, electrons, and photons. Max Born, after learning of the Dirac equation, said, “Physics as we know it will be over in six months.”
||Wolfgang Pauli suggests the neutrino to explain the continuous electron spectrum for beta decay.
||Paul Dirac realizes that the positively-charged particles required by his equation are new objects (he calls them “positrons”). They are exactly like electrons, but positively charged. This is the first example of antiparticles.
||James Chadwick discovers the neutron. The mechanisms of nuclear binding and decay become primary problems.
||Enrico Fermi puts forth a theory of beta decay that introduces the weak interaction. This is the first theory to explicitly use neutrinos and particle flavor changes.
J J Thompson (1897)
advisors John Strutt (Rayleigh)
Edward John Routh
Charles Glover Barkla
Charles T. R. Wilson –>
Ernest Rutherford –>
Francis William Aston –>
J. Robert Oppenheimer
Owen Richardson –>
William Henry Bragg –>
H. Stanley Allen
Daniel Frost Comstock
Max Born –>
T. H. Laby
Balthasar van der Pol
Geoffrey Ingram Taylor
Niels Bohr —>
George Paget Thomson –>
- Rutherford at McGill University in 1905
- Schematic of Rutherford’s apparatus https://youtu.be/kBgIMRV895w
Chadwick’s neutron detector; replica Science Museum 1932
In 1920, Ernest Rutherford postulated that there were neutral, massive particles in the nucleus of atoms. This conclusion arose from the disparity between an element’s atomic number (protons = electrons) and its atomic mass (usually in excess of the mass of the known protons present). James Chadwick was assigned the task of tracking down evidence of Rutherford’s tightly bound “proton-electron pair” or neutron.
This is Chadwick’s equation:
Chadwick’s Atomic Model
- Scientific Revolution By Boyd
“Reason” plus “Scientific observation”
Formulation of “Scientific Method”
Expansion of Scientific Knowledge
Five theories by
(1) Nicolous Copernicus: Heliocentric Theory
(2) Johannes Kepler: Planetory Motion is elliptical around the sun
(3) Galileo: Invents telescope to look into the planetary system
(4) Issac Newton: Law of Gravity
(5) William Harvey: Circulation of Blood
- Book: Philosophers Of Science
- Pictures of Experimental Set-Ups
- Walkling in Galileo’s Childhood Neighborhood
- A visit to Newton’s birthplace – Woolsthorpe Manor By Greycoat’s Teapot
- Einstein’s Gravity By NASA
Foundations Of Atomic Theory
- Atomic Structure: Discovery of the Neutron By Tyler DeWitt
- Youtube: 6.1 How protons, electrons and neutrons were discovered. Ian Stuart
- Discovery of the Neutron (James Chadwick – 1932) Moof University