HS-102 Readings

Scientific Revolution


The 17th century Scientific Revolution broke new ground in the understanding of the physical world.;   Ancient Greek, Arabic, and medieval European philosophers were handicapped by lack of instruments and were unable to verify their ideas by observation and experimentation. They relied upon authority figures from the Church and from the ancient world. Aristotle, Ptolemy and St. Augustine, among others, were considered to be the sources of truth. Medieval painters and sculptors were not interested in portraying the physical reality of this world. Rather, they were concerned with expressions of religious belief. In a largely illiterate world, pictures told a story where words could not.

     The Renaissance involved a different attitude about the world, one which focussed upon the human being rather than the gods, a humanistic natural viewpoint as opposed to a supernatural one. This change in attitude was essential to the scientific revolution.

     Also essential was a deepening skepticism about religion and about authority figures of the past. The invention of the printing press, the development of vernacular languages, the continued growth of a literate middle class in urban areas produced larger numbers of people who were not willing to blindly accept the teachings of the Church and its clergy; rather, they read the Bible and came to their own understanding. This increase in independent thinking among the intellectual elite of Europe was expressed in the Renaissance and in the Protestant Reformation. The Church was being challenged as the fountain of wisdom and the center of authority.

An important aspect of the advances made in science in the 17th century was the invention of instruments of measurement. The  Dutch glass industry was responsible for developing the necessary skills to producepolished lenses needed for fine microscopes and telescopes.  As early as 1590, a Dutchman, Zacharias Jannsen produced a compound microscope employing a double convex and a double concave lens.

In 1609, Galileo, hearing of a similar Dutch idea useful for seeing objects at a great distance, developed a telescope which he used initially to observe ships approaching port.  When he turned the telescope to the heavens, he found great numbers of stars which were not visible to the naked eye. He was able to distinguish the moons of Jupiter and to make other fine discriminations. His latest version magnified the view by 1,000 times.

A few years before, Galileo had invented a simple thermometer.  Years later, in 1643, a pupil of Galileo, Torricelli, employed a dish and an inverted tube of mercury, to make the first barometer in order to measure atmospheric pressure.

Another important component needed for scientific progress was an improved knowledge of mathematics. The introduction of logarithms, the invention of the slide rule, and the development of a decimal system had been accomplished by the beginning of the 17th century. Algebra and
geometry were among the essential foundations. These tools, mathematics and instruments of measurement and observation, permitted science to develop as a pursuit independent from philosophy.

The continuing and increasing overseas voyages undertaken by Europeans in the 16th and 17th centuries created a demand for more accurate map-making.  In a long life devoted to cartography, Mercator developed the"Mercator" projection and, in 1585, issued a world atlas. An increasing
knowledge of geography widened the horizons of knowledge for Europeans.The need to improve navigation stimulated developments in mathematics and astronomy.

Significant progress was also made in the study of botany. A systematic classification of plants was carried out, and governments and universities sponsored the development of botanical gardens.  In about 1560, an obscure plant, the potato, was brought from Peru to Spain. The Spanish
aristocrats who performed that service could hardly have been aware of the revolutionary consequences. The potato would, in subsequent generations, become a major source of food for Europeans, and contribute substantially to an unprecedented increase in population.

In 1628, a major breakthrough in medicine was achieved when a London physician, William Harvey, announced his theory that blood circulated continuously in the body.  He had found a way of measuring the amount of blood pumped by the heart and it was obvious that the body could not
possibly manufacture all the blood that was being pumped. It had to be continuously recirculated. Servetus and Colombo, half a century earlier, had theorized that the heart pumped blood to the lungs where it was aerated and returned to the heart for circulation to the rest of the body. Harvey proved that theory to be correct, but was unable to explain how the blood flowed from arteries into veins. That would be left to Marcello Malpighi, who, in 1661, discovered capillaries in the lungs of a frog.

During the first half of the 17th century, Francis Bacon, in England, and Descartes, on the continent, began a transition from an uncoordinated assault on ignorance and superstition to more disciplined and logical methods. Both were ecumenical in their approach in a time when many specialties had not yet developed. Both advised a new beginning in scientific endeavors which involved disposing of preconceived notions and principles.  That included the ideas of Plato, Aristotle, and other

Bacon was actively involved as a minister of King James I, and was too distracted to extensively use the experimental method which he advocated. His primary contribution was to insist upon an "inductive study of nature through experience and experiment."1  His name has, ever since, been identified with the inductive process which is essential to scientific progress. "The true method of experience first lights the candle (byhypothesis), and then by means of the candle shows the way, commencing
as it does with experience duly ordered.....and from it educing axioms (first fruits, provisional conclusions), and from established axioms againnew experiments.....Experiment itself shall judge."2

Descartes, educated by Jesuits and trained in mathematics, rigorously attempted to wipe the mental slate clean, begin from a position of doubting everything, and then deduce by logic what was known.  He began with the now famous premise: "I think, therefore, I am."  The process of deductive reasoning which followed, led him to conclusions which could be challenged by critics using his own method. He, like Bacon, though for different reasons, must be considered as a philosopher of science rather than as a scientist. He was also a mathematician. His development of analytic geometry, a wedding of algebra with geometry, was an important contribution. As a result of his influence, Cartesian doubt dominated scientific endeavor on the continent throughout the 17th century.

Also in the early 17th century, the pseudo-science of alchemy (the effort to manufacture gold and silver from baser metals) was beginning to stimulate progress in chemistry. The word was derived from the Greek word "chaos", first coined by Jan Baptista van Helmont, a wealthy nobleman who, among other works, isolated and analysed the gases contained in air.

The needs of the metallurgical and dyeing industry encouraged research, and began a long, complementary inter-relationship between science andindustrialization. "Coking", a process for purifying bituminous coal so that it could be used as an alternative to charcoal in the iron industry, was
invented in 1612, at a time when available forests were being depleted. A less expensive glass-making process made it practical to produce windowpanes in quantity for the first time. The screw lathe, the knitting frame, the threshing machine and the fountain pen were all first heard of in the
late 16th and early 17th centuries.

In astronomy, Copernicus had begun a revolution by stating, as early as 1514, that the sun, not the earth was the center of the universe.  Although this theory was largely rejected at the time, and Copernicus had not been able to produce sufficient evidence to decisively refute the Ptolemaic
theory, it stimulated doubt and later investigation. When Galileo, a century later, could observe the solar system with his telescope, he provided conclusive evidence in support of the Copernican theory.

In the late 16th century, the Danish astronomer, Tycho Brahe, although he did not have a telescope, spent a few decades of his life observing theheavens with the help of his students. Meticuluously recording his observations, he was able to pass on a wealth of information to hisassistance, Johann Kepler.  Kepler, using these observations, tested hundreds of hypotheses, before arriving at a theory involving elliptical orbits of the planets around the sun. "Kepler,s Laws", made public in 1619,
clarified difficulties in the Copernican theory and paved the way for the works of Isaac Newton.

Meanwhile Galileo's experiments with gravity and inertia provided another major foundation for Newton's work. These involved the principles that objects fall at the same rate regardless of their weight, that theyaccelerate their fall uniformly, and that objects at rest or in motion will continue as such, unless affected by an outside force.

Important research was also done with sound and light.  Sound was recognized as a variation in air pressure and its speed was measured. Studies in optics led to an explanation of the rainbow in terms of the reflection and refraction of light. Improved knowledge of the effect oflenses upon light led to the manufacture of better telescopes andmicroscopes.  It would be left to Newton to discover how a prism divides white light into the spectrum of colors.

By 1650, the pace of scientific research was quickening. Private academies were formed in Florence, Paris, and London in order to share and publish scientific research. In 1662 and 1667, the French and English monarchies issued royal charters. An international community of scholars began to fulfill the vision of Francis Bacon. The Royal Society of London was particularly influential.

The following developments took place in rapid succession in the last half of the 17th century:

Improved microscopes, barometers, and thermometers were developed. Guericke invented the air pump by which to study vacuums. Newton invented the sextant for improved navigation. Fermat developed the modern theory of numbers. Leibniz and Newton developed differential calculus. Christian Huygens established the "Law of Inverse Squares", an important principle utilized in Newton's astronomy. The application of statistics to population studies was begun by John Graunt and Sir William Petty.  Edmund Halley drew up mortality tables which were utilized by the first life insurances companies in London in the 18th century. Jean Picard measured a degree of longitude and the circumference of the earth at the equator with considerable accuracy. A collaboration of several scientists demonstrated that the earth, indeed, bulged at the equator. The Greenwich observatory was established as zero degrees longitude. Edmund Halley studied and catalogued the stars from the southern hemisphere. He predicted the periodic return (every 75 years) of the comet which has
since been named after him. Thomas Boyle formulated the law of Physics that with temperature constant, the pressure of a gas, multiplied by its volume is also constant. Leeuwenhoek discovered sperm and bacteria with his microscope. Swammerdam dissected insects and discovered the
bacterial cause for decay. Edward Tyson described the orangutan as a "man of the woods", compared the anatomy of man with that of the monkey, and saw the chimpanzee as intermediary between the two. Athanasius Kirchner, a Jesuit, discovered microorganisms in the blood of plague victims, and
stated that the transfer of noxious organisms from one person to another was the cause of infectious disease. In 1712, Thomas Newcomen manufactured the first reliable steam engine. The industrial age had begun and the world would never be the same again.3

The man who has come to symbolize this age of scientific progress was an absent-minded professor by the name of Isaac Newton.  Working as a scholar at Cambridge University, he combined experimentation with mathematics, and  pulled together the works of several of his scientific predecessors and colleagues, to establish a comprehensive explanation of the physical laws that govern gravitation and astronomy. Along the way, he discovered that different elements, when subject to heat, gave off a characteristic color in the light spectrum. The spectrum of light coming from each star
was therefore useful in revealing the chemical composition of that star. It was also useful in determining how the star was moving with respect to the earth, and gave some suggestions about the distance of stars from the earth.
A principal feature of his gravitational theory was that the force which caused objects to fall to the earth was the same force which kept the planets in their orbits.

On the occasion of Newton's funeral in 1727, Alexander Pope said of him:

"Nature and Nature's laws lay hid in night;
 God said, Let Newton be! and all was light."4

Newton himself, said, shortly before his death:

"I do not know what I may appear to the world; but to myself I seem to
have been only like a boy playing on the seashore, and diverting myself in
now and then finding a smoother pebble or a prettier shell than ordinary,
while the great ocean of truth lay all undiscovered before me."5

1. Durant, The Age of Reason Begins, Simon & Schuster, N.Y., 1961, p.174

2. Ibid, p.175

3. Ibid, pp.498-526

4. Ibid, p.546

5. Ibid, p.547