brief history of modern science discovery - a new method of acquiring knowledge was invented by a...

Brief History of Modern Science

• Discovery - A new method of acquiring knowledge was invented by a series of European thinkers from 1500 to 1700. Among these thinkers are Copernicus, Galileo, Descartes, Kepler, and Newton

• Definition of Science- A special method and knowledge executed by practitioners of science called scientists.

Aristotelian Science Theory of MatterMatter stuff out of which things are madeIn sublunary world (below the moon) thereare four elements or essences: earth, water, air, and fire.These four elements never found pure always mixed.Heavy things made out of earthLight things made mix of water,air, and fire

Aristotelian Science

• Above sun, planets are stars imbedded in the crystalline sphere

• The crystalline sphere made out of pure quintessence ( 5th essence)

• Different laws pertain the sublunary world than to the world above the moon

Archimedes (287-212 BCE )

Sicilian geometrician who calculated an accurate value for , demonstrated the relationship between the volume of spheres and cylinders, discovered methods for determining the center of gravity of plane figures, and provided a foundation for the science of hydrostatics. Archimedes also invented many ingenious machines, including a pump for raising water, effective levers and compound pulleys, and a mechanical planetarium. He died defending Syracuse against a Roman seige during the

second Punic war.

Ptolemy & Epicycles more accurate measurement required more epicycles

From World Book © 2002 World Book, Inc., 233 N. Michigan Avenue, Suite 2000, Chicago, IL 60601. All rights reserved. World Book diagram by Precision Graphics

Thomas Aquinas (1224-1274 )

• Although matters of such importance should be accepted on the basis of divine revelation alone, Aquinas held, it is at least possible (and perhaps even desirable) in some circumstances to achieve genuine knowledge of them by means of the rigorous application of human reason. As embodied souls ( hylomorphic composites ), human beings naturally rely on sensory information for their knowledge of the world. Reading hint: Although the rigidly formal structure of the Summa articles can be rather confusing to a modern reader, the central portion beginning with the words, " I answer that ..." is always a direct statement of Aquinas's own

position.

Roger Bacon

• Bacon, Roger (1214-1292 )English philosopher who translated many Aristotelean treatises from Arabic into Latin. Although passionately interested in alchemy and magic, Roger defended reliance upon mathematics and experimental methods for the improvement of human knowledge generally and theological understanding in particular in the Opus Maius (Greater Work ) (1267) { at Amazon.com } and On Experimental Science (1268). His novel educational doctrines were supposed to violate the condemnation of 1277 , and much of Roger's later work, including the Compendium Studii Theologiae (1292) was

suppressed.

Roger Bacon

Against authority of…

Church

State

Commonly held opinion

Obstacles to truth:

Frail and unsuitable authority

Long-held custom

Uninstructed popular opinion

Concealment of ignorance in apparent wisdom

Roger Bacon

Bacon’s advice: To study Natural Philosophy, use;

“External experience, aided by instruments, and made precise by mathematics.”

Roger Bacon:“The result of all true philosophy is to

arrive at a knowledge of the creator through knowledge of the created world”

“He who wishes to rejoice without doubt in regard to the truths underlying phenomena must know how to devote himself to experiment. For authors write many statements, and people believe them through (deductive) reasoning, which they formulate without experience. Their reasoning is wholly false” (Opus Majus)

William of Ockham,

• Ockham, William of (1285-1349 )English philosopher who defended the logic, physics, and metaphysics of Aristotle in Summa Logicae (The Whole of Logic ) (1328) vol. 1 { at Amazon.com } and vol. 2 { at Amazon.com } and the Dialogus . An extreme nominalist , Ockham held that general terms are signs that indefinitely signify discrete (though similar) particulars. Ockham is best known for his statement of the law of parsimony as the ontological principle often called Ockham's Razor : " Frustra fit per plura quod potest fieri per pauciora " ["It is pointless to do with more what can be done with less"]. Thus, according to Ockham, we ought never to postulate the reality of any entity unless it is logically necessary to do so.

William of Ockham

Ockham’s Razor:

“What can be accounted for by fewer assumptions in explained in vain by more.”

His philosophy of science:

“Nothing is assumed as evident unless it is known per se or is evident by experience, or is proved by authority of scripture.”

Paracelsus (Phillippus Aureolus Theophrastus Bombastus von Hohenheim) ( 1493-1541 )

• Swiss chemist and physician. Rejecting the ancient reliance on concern for bodily "humours," Paracelsus transformed the practice of medicine by employing careful observation and experimentation. Although his chemical knowledge was rudimentary by modern standards, Paracelsus envisioned using pharmaceutical methods for treating disease and something like inoculation for preventing it.

Scientific Development From 1543 to 1789

• 1543: Nicolas Copernicus (1473-1543) publishes De Revolutionibus Orbium Coelestium, which argues that the Sun is the center of the Solar System.

• 1543: Andrea Vesalius (1514-1564) publishes Concerning the Structure of the Human Body, the first modern anatomical text.

• 1600: William Gilbert (1540-1603) publishes Concerning the Magnet.

• 1605: Francis Bacon (1561-1626) publishes Advancement of Learning.

• 1609: Astronomia Nova is published by Johannes Kepler (1571-1630), in which he presented his first two Laws of Planetary Motion.

• 1610: Galileo Galilei (1564-1642) publishes Sidereal Messenger, describing his observations using the telescope.

• 1619: Kepler publishes his Third Law in Harmonia Mundi.


`

*1628: William Harvey (1578-1657) publishes On the Motion of the Heart and Blood in Animals, in which he proves that the heart circulates blood throughout the body. *1632: Galileo publishes Concerning the Two Chief World Systems, in which he compares the Copernican and Ptolemaic solar systems. *1637: Rene Descartes publishes his Discourse on Method, in which he lays the foundation for modern philosophy. *1660: Robert Boyle (1627-1691) publishes New Experiments Physico-Mechanical Touching the Spring of the Air, in which he states his laws of gases. *1662: The Royal Society of London is founded.


*1666: The French Academy of Science is founded. *1677: Anton von Leeuwenhoek (1632-1723), using a microscope,

discovers male spermatoza. *1678: Christian Huygens (1629-1695) proposes the wave theory of light. *1687: Isaac Newton (1642-1727) publishes his Principia Mathematica. *1704: Isaac Newton publishes his Optics. *1735: Carolus Linnaeus publishes his Systema Naturae, which

establishes the science of taxonomy. *1789: Antoine Lavoisier publishes his treatise on chemistry, laying the

foundation for the modern theory of chemical elements.

Copernicus b. 1473 Poland• Polish astronomer who developed the theory that the

earth is a moving planet. In Copernicus's time, most astronomers accepted the theory the Greek astronomer Ptolemy had formulated nearly 1,400 years earlier.

• Some astronomers before Ptolemy had suggested that the earth did in fact move. Copernicus decided that the simplest and most systematic explanation of heavenly motion required that every planet, including the earth, revolve around the sun. The earth also had to spin around its axis once every day. The earth's motion affects what people see in the heavens, so real motions must be separated from apparent ones.

• Copernicus skillfully applied this idea in his masterpiece, On the Revolutions of the Heavenly Spheres (1543). In this book, he demonstrated how the earth's motion could be used to explain the movements of other heavenly bodies. Copernicus could not prove his theory, but his explanation of heavenly motion was mathematically strong and was less complicated than Ptolemy's theory. By the early 1600's, such astronomers as Galileo in Italy and Johannes Kepler in Germany began to develop the physics that would prove Copernicus' theory correct.

Nikolai Copernicus

Wrote:

“On the Revolution of Celestial Orbs”

His philosophy of Science:

“True assumptions must save the appearances.”

Tycho Brahe b. 1546• Danish astronomer. Brahe developed a systematic approach for observing the planets and stars. He

stressed the importance of making such observations on a regular basis. The telescope had not yet been invented, and so Brahe used his eyesight and such instruments as astrolabes and quadrants to estimate the positions of celestial objects. His observations were far more precise than those of any earlier astronomer.

• Brahe's observations of planetary motion revealed that the tables then in use to predict the positions of the planets were inaccurate. His sighting of a supernova (type of exploding star) in 1572 helped disprove the ancient idea that no change could occur in the heavens beyond the orbit of the moon.

• Like many astronomers of his time, Brahe refused to accept the Copernican theory of the solar system. According to this theory, the earth and the other planets move around the sun. Brahe reasoned that if the earth revolved around the sun, he should have been able to measure changes in the positions of the stars resulting from the earth's movement. He did not realize that such changes were too small for his instruments to detect. However, Brahe's observational data later enabled Johannes Kepler, a German astronomer and mathematician, to confirm the Copernican theory.

• Brahe was born in Knudstrup (then a Danish city but now in Sweden), near Malmo. As a member of the nobility, he attended universities in Denmark, Germany, and Switzerland. Brahe built an elaborate observatory on the island of Hven (now called Ven), where he made many of his

observations.

Tycho Brahe b. 1546• Danish astronomer. Brahe developed a

systematic approach for observing the planets and stars. He stressed the importance of making such observations on a regular basis. The telescope had not yet been invented, and so Brahe used his eyesight and such instruments as astrolabes and quadrants to estimate the positions of celestial objects. His observations were far more precise than those of any earlier astronomer.

• Brahe's observations of planetary motion revealed that the tables then in use to predict the positions of the planets were inaccurate. His sighting of a supernova (type of exploding star) in 1572 helped disprove the ancient idea that no change could occur in the heavens beyond the orbit of the moon.

Tycho Brahe (1546-1601)

Johannes Kepler b. 1571• Discovered three laws of planetary motion.

• Newton later used Kepler's three laws to arrive at the principle of universal gravitation • Kepler's laws are:

(1) Every planet follows an oval-shaped path, or orbit, around the sun, called an ellipse. The sun is located at one focus of the elliptical orbit. (2) An imaginary line from the center of the sun to the center of a planet sweeps out the same area in a given time. This means that planets move faster when they are closer to the sun. (3) The time taken by a planet to make one complete trip around the sun is its period. The squares of the periods of two planets are proportional to the cubes of their mean distances from the sun.

• Kepler formed an association with Tycho Brahe, which shaped the rest of his life. His most significant discoveries trying to find an orbit to fit all Brahe's observations of the planet Mars. Earlier astronomers thought a planet's orbit was a circle or a combination of circles. However, Kepler could not find a circular arrangement to agree with Brahe's observations. He realized that the orbit could not be circular and resorted to an ellipse in his calculations. The ellipse worked, and Kepler destroyed a belief that was more than 2,000 years old.

• Kepler was the first astronomer to openly uphold the theories of the Polish astronomer Nicolaus Copernicus.

Johannes Kepler b. 1571

• Kepler formed an association with Tycho Brahe, which shaped the rest of his life. His most significant discoveries trying to find an orbit to fit all Brahe's observations of the planet Mars. Earlier astronomers thought a planet's orbit was a circle or a combination of circles. However, Kepler could not find a circular arrangement to agree with Brahe's observations. He realized that the orbit could not be circular and resorted to an ellipse in his calculations. The ellipse worked, and Kepler destroyed a belief that was more than 2,000 years old.

• Kepler was the first astronomer to openly uphold the theories of the Polish astronomer Nicolaus Copernicus.


FIRST LAW• The orbits of the planets are

ellipses, with the Sun at one focus of the ellipse.


SECOND LAW• The line joining the planet to the

Sun sweeps out equal areas in equal times as the planet travels around the el


THIRD LAW• The ratio of the squares of

the revolutionary periods for two planets is equal to the ratio of the cubes of their semi-major axes:

• T^2/R^3 = constant for all planets

Gilbert, William (1540-1603),

• Gilbert, William (1540-1603), an English doctor and scientist, was the first person to use the word electricity. He has been called the "Galileo of Magnetism" because of his celebrated book De Magnete, which he published in 1600. It was concerned with the properties of magnetism, with electricity, and with the use of compasses in navigation.

• Gilbert's most important discoveries in the field of magnetism were the laws of attraction and repulsion, magnetic dip, and the properties of loadstones. Gilbert based his findings on observation and practical experiments. This practice differed greatly from that of most of the scientists of his time, who developed only abstract theories, unsupported by experiments.

• Gilbert was born in Colchester, in Essex, England, and was educated at St. John's College, Cambridge. He was physician to Queen Elizabeth I and

attended her during her last illness. Gilbert died on Nov. 30, 1603.

Rene Descartes 1596-1650

• Rene Descartes was one of the founders of modern philosophy. In this painting, Descartes conducts a scientific experiment for Queen Christina of Sweden shortly before his death in 1650.

From World Book © 2002 World Book, Inc., 233 N. Michigan Avenue, Suite 2000, Chicago, IL 60601. All rights reserved. Detail of Rene Descartes Conducts a Demonstration Before Queen Christina of Sweden (about 1700) oil on canvas by Dumesnil (The Art Archive)

Descartes 1596 - 1650French philosopher, mathematician, and scientist. He is often called the father of modern philosophy. Descartes invented analytic geometry and developed a detailed account of the physical universe in terms of matter and motion.

“I think, therefore I am.”

Wrote “Discourse on Method.”

“The need to experiment is an expression of the failure of the ideal”

Concerning Galileo:

“Without having considered the first causes of nature, he has looked only for the reasons for certain particular effects, and that thus he has built without foundation.”

Bacon, Francis (1561-1626)Bacon believed the mind could attain truth if it followed the inductive method of investigation. He developed four steps of doing so: (1) listing all known cases in which a phenomenon occurs; (2) listing similar cases where the phenomenon does not occur; (3) listing the cases in which the phenomenon occurs in differing degrees; and (4) examination of the three lists. These steps would lead to the cause of a phenomenon.

Bacon suggested the use of preliminary hypotheses (assumptions) to aid scientific investigation. His treatment of hypothesis is still a subject of study. Bacon also wrote an unfinished romance called New Atlantis (published in 1627, after his death). The book describes an imaginary island where the inhabitants dedicate themselves to the study of science.

Francis Bacon

“Nature, to be commanded, must be obeyed.”

Wrote “Novum Organum”

“The end of our foundation is the knowledge of causes, and the secret motions of things, and the enlarging of the bounds of human empire, to the affecting of all things possible.”

“Knowledge ought to bear fruit in work, that science ought to be applicable to industry, that men ought to organize themselves as a sacred duty to improve and transform the conditions of life.”

“I am fitted for nothing so well as the study of truth.”

Galileo Galilei

From World Book © 2002 World Book, Inc., 233 N. Michigan Avenue, Suite 2000, Chicago, IL 60601. All rights reserved. Uffizi Gallery, Florence, Italy (Art Resource)

Pendulum

• The Simple Pendulum

• If a pendulum of mass m attached to a string of length L is displaced by an angle from the vertical, it experiences a net restoring force due to gravity:

• In this small angle approximation, the amplitude of the pendulum has no effect on the period. This is what makes pendulums such good time keepers. As they inevitably lose energy due to frictional forces, their amplitude decreases, but the period remains constant.

GALILEO GALILEI

1610 Published “The Starry Messenger”

‘The Bible was written to show us how to go to heaven, not how the heavens go”

“In discussions of physical problems we ought to begin not from the authority of scriptural passages, but from the sense-experiences and necessary demonstrations.”

“For the Holy Bible and the phenomena of nature proceed alike from the divine Word, the former as the dictate of

the Holy Spirit and the latter as the observant executor of God’s commands.”

GALILEO (cont.)

“To ban Copernicus now that his doctrine is daily reinforced by many new observations would seem in my judgment to be a contravention of truth, and an attempt to hide and supress her the more as she revealed herself the more clearly and plainly…And to prohibit the whole science would be but to censure a hundred passages of

holy scripture which teaches us that the glory and greatness of Almighty God are marvelously discerned in

all his works and divinely read in the open book of heaven.”

1632 “Dialogue of the two Chief World Systems

William Harvey (1578-1657)

• An English physician who became famous for his discovery of how blood circulates in mammals, including human beings. He described his discovery in An Anatomical Study of the Motion of the Heart and of the Blood in Animals (1628). This work became the basis for all modern research on the heart and blood vessels.

Robert Boyle (1627-1691)

• He helped establish the experimental method in chemistry and physics.

• Boyle is best known for his experiments on gases that led to the formulation of Boyle's law. Boyle also helped improve the air pump, and with it he investigated the nature of vacuums.

• Boyle disproved the theory that air, earth, fire, and water were the basic elements of all matter. Boyle argued that all basic physical properties were due to the motion of atoms, which he called "corpuscles."

• Boyle was a founding member of the Royal Society of London, the first publicly recognized scientific organizations.

Robert Boyle (1627-1691)

ROBERT BOYLE

Wrote “The Excellence of Theology or The Preeminence of the Study of Divinity Above That of Natural

Philosophy”

Wrote “The Skeptical Chymist”

Scientist should “Set themselves diligently to make experiments and collect observations, without being

overtoward to establish principles and axioms.”

Theories are never final, but should be thought of as “the best we have, but capable of improvement.”

Boyle (cont.)

• We assent to experience, even when its information seems contrary to reason.

• Objects have color by virtue of “ a certain disposition of the superficial particles which are capable of refracting and reflecting light” (ie. color is a secondary property)

Robert Hooke

• The Science of Nature has been already too long made only a work of the brain and the fancy. It is now high time that it should return to the plainness and soundness of observations on material and obvious things.

Sir Isaac Newton,

1642-1727

Mathematician, Philosopher, Alchemist, Deist and Scientist

Isaac Newton 1642 - 1727

• Explained motion of planets and moon

• Proposed law of universal gravitation

• Explained tides

• Assumed laws on Earth were same as in the heavens

• Discovered light composed of different colors

• Invented reflector telescope

• Invented calculus

• Wrote “Principia” 1687

• Directed English Mint

SIR ISAAC NEWTON

“Whence is it that nature does nothing in vain; and whence arises all that order and beauty which we see in

the world?”

The best and safest method of philosophizing seems to be, first to inquire diligently into the properties of things, and

to establish those properties by experiences and then to proceed more slowly to hypothesis for the explanation of

them. For the hypothesis should be employed only in explaining the properties of things, but should not be

assumed in determining them.

1687 Published “Principia”

Newton’s Laws of Motion

• #1 Objects with no net external force applied to them will move with a constant velocity

• #2 The acceleration of an object is directly proportional to the net force applied to the object and inversely proportional to its mass.

• #3 Whenever an object exerts a force on a second object, the second object exerts an equal but opposite force on the first.

Corpuscular Theory of Light (1704)

• Isaac Newton proposed that light consists of a stream of small particles, because it

– travels in straight lines at great speeds

– is reflected from mirrors in a predictable way

Wave Theory of Light

• Hooke, Grimaldi and Huygens (idea of a wave front)

• Thomas Young (1802) showed that light is a wave, because it

– undergoes diffraction and interference

(Young’s double-slit experiment)

Thomas Young (1773-1829)

Particles

• Position x

• Mass m

• Momentum p = mv

Waves

• Wavelength

• Amplitude A

• Frequency f

– number of cycles per second

(Hertz)

f = c /

Waves versus Particles

• A particle is localized in space, and has discrete physical properties such as mass

• A wave is inherently spread out over many wave-lengths in space, and could have amplitudes in a continuous range

• Waves superpose and pass through each other, while particles collide and bounce off each other

Diffraction

Interference

applet

http://www.colorado.edu/physics/2000/schroedinger/big_interference.html

Interference Fringes on a Screen

applet

Joseph Priestley 1733-1804

Phlogiston Theory

Henry Cavendish 1731-1810

Experiments on Air 1766

Measured G the universal gravitational constant

Antoine Lavoisier 1743 - 1794

French chemist who, through a conscious revolution, became the father of modern chemistry. He won a prize on lighting the streets of Paris, and designed a new method for preparing saltpeter. He also married a young, beautiful 13-year-old girl named Marie-Anne, who translated from English for him and illustrated his books. He burnt phosphorus and sulfur in air, and proved that the products weighed more than he original. Nevertheless, the weight gained was lost from the air. Thus he established the Law of Conservation of Mass.

Antoine LaVossierre

“I have tried to arrive at truth by linking up facts; to suppress as much as possible the use of [deductive]

reasoning, which is so often an unreliable instrument which deceives us, in order to follow as much as possible

the torch of observation and experiment.”

John Dalton 1766-1844

John Dalton’s Atomic Theory (1804)

• Elements are composed of identical atoms

• The atoms of an element cannot be changed into atoms of another element.

• Compounds form when the atoms of two or more elements combine in a definite (exact) integer ration. (in other words, compounds have a formula)

Michael Faraday, b. Sept. 22, 1791 d. Aug. 25, 1867

The English chemist and physicist Michael Faraday, b. Sept. 22, 1791, d. Aug. 25, 1867, is known for his pioneering experiments in electricity and magnetism. Many consider him the greatest experimentalist who ever lived. Several concepts that he derived directly from experiments, such as lines of magnetic force, have become common ideas in modern physics.

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