Galileo and the Origins of the Modern World David Banach Department of Philosophy

Galileo and the Origins of the Modern World David Banach

Discoverer of new worlds

Proponent of New Theories

Saint for Science

Galileo at Arcetri

Galileo and Milton at Arcetri

Galileo at Arcetri

Galileo Discourse on the Two New Sciences (1638)

Galileo and Scientific Method  1602-Pendulum experiments.  Inclined plane experiments of natural acceleration.  1607-Systematic manipulation of shapes and weights of wax balls to study flotation.  Investigation of projectile motion. Discovery of parabolic character of projectile motion.

Science and the Modern World  Scientific Method as a model for Reason: The new method of knowledge introduced by Galileo and the Scientific Revolution increased the confidence in the power of human reason and its ability to transform civilization. The hundred or so years following the Scientific Revolution (the 1700’s, the Enlightenment) saw an unprecedented revision of the forms of human government and culture on the basis of the application of this new method. The Post-Modern world will ask whether Science can deliver on the promise of objectivity and whether a society can be ordered on the basis of reason.  The Mechanistic world view: The Scientific revolution introduced a radically new view of the world as a mechanism composed of inert parts, whose configuration and mechanical relations determine all of its properties. The Post-Modern world will ask whether human values and the human soul can find a place in this mechanistic world. This is the real conflict between science and religion.

The Scientific Method  Science does not trust the senses. It mistrusts and re-interprets them.  Science does not aim at understanding the particular, but at isolating how nature acts under ideal conditions  Scientific discovery involves more than merely looking in the right place. It requires uncovering the hidden order within appearances.

The Scientific Method  Purifying the Appearances  Separating the Relative from the Absolute

Separating Relative and Absolute: The Copernican Revolution  The senses tell us that the sun is moving. Using our minds we can see that the motion of the sun in the sky is really our motion, merely relative to us.

Copernicus’s Revolution: The Motion we see outside us in the Sun

Is not in the sun but in us; Is not real but merely relative

The Laws of Terrestrial Motion  1. Free fall: Aristotle believed heavy objects fell faster than light objects, since they had more earth than air or fire or water in them. Galileo saw that all objects fall at the same rate. The senses supported Aristotle. Galileo’s experiments aimed at purifying the senses and isolating only the effects of weight from all the other causes involved such as air resistance, friction, and buoyancy.  2. Inertia: Aristotle thought that an object in natural motion moved to its natural place and stopped and that to keep it moving in violent motion required energy. Galileo formulated the law of inertia: that an object in motion tends to stay in motion. The senses supported Aristotle. Only Galileo’s purification of the senses in experiments proved him to be correct.

Aristotle on Terrestrial Motion: Natural Place

Purifying the appearances Simple unified motions often arise from an impure conglomeration of forces such as friction and air resistance. The scientific method systematically manipulates properties to isolate the real source of phenomena.

Only in a vacuum do objects fall at the same rate

The Law of Inertia  The senses tell us that objects require force to keep them moving and eventually slow down.  Only under ideal conditions does an object in motion tend to stay in motion

Three Experiments  1. The Pendulum: Used to demonstrate the law of inertia and that heavy and light bodies fall at the same rate. Galileo also discovered the mathematical laws governing the length of the string, the period of the motion, and the amplitude of the swing. 2. The Inclined Plane and the Rate of Acceleration: Galileo used the inclined plane to slow the motion of falling objects enough to accurately measure how their speed increased.  3. Projectile Motion: Galileo also used the inclined plane to control the speeds and heights of projectiles in order to discover the mathematical properties of their paths.

1. Pendulum

Pendulum  "...repeat many times the fall through a small height in such away that I might accumulate all those intervals of time that elapse between the arrival of the heavy and light bodies respectively at their common terminus, so that this sum makes an interval of time which is not only observable, but easily observable."  "...two balls, one of lead and one of cork, the former more than a hundred times heavier than the latter, and suspended them by means of two equal fine threads, each four or five cubits long. "This free vibration repeated a hundred times showed clearly that the heavy body maintained so nearly the period of the light body that neither in a hundred swings nor even in a thousand will the former anticipate the latter by as much as a single moment, so perfectly do they keep step." Galileo

Pendulum  Momentum is conserved

Pendulum  1. Robust Regular motion remains independent of impurities in environment.  2. Demonstrates regular fall of bodies and law of inertia.  3. Allows mathematical study of dependence of motion on string length and mass of pendulum.

2. Inclined Plane

Inclined Plane "...in such a plane, just as well as in a vertical plane, one may discover how bodies of different weight behave..." Galileo

Total distance traveled is proportional to the square of time.

Inclined Plane Slows down motion to enable the measurement of mathematical relationships. Corrects for the effects of air resistance. Simplifying and purifying the appearances allows discovery of first mathematical law of motion.

3. Projectile Motion

Projectile Motion  Purifying the appearances: Separating and Analyzing the Components of motion.

All Projectile paths are Parabolas

Parabola is a Conic Section

Vertical motion can be separated from the horizontal motion

Projectile Motion

The apparent single motion is actually composed of two different motions

Which function independently even when united

Separating the Relative and the Absolute

Projectile Motion  Purifying the appearances allows the different components of motion to be separated and describe mathematically.  The Scientific method is reductionistic. It breaks down complex things into their simple parts.

Primary and Secondary Properties The Assayer 1623  Separating the relative from the absolute  2° feelin g 1° real properties of matter

All our sense perceptions are relative to the five senses

Sensible properties are relative  Once we separate the relative from the absolute within our perceptions, we find that most of the properties we found to be indicative of unities that required a single nature as their source are really not in the external world at all, but are the effects that the primary qualities of objects have on our constitutions.

Sensible properties are relative  1. Primary properties are the properties really in the object such as the size, shape, number, or speed of the atoms or particles of matter. 2. Secondary properties are the effects that the object has on us and exist only in us, not in the object itself. (E.g. the tickle of the feather.) Galileo saw that all sensible qualities such as color, sound, warmth, taste, and smell were really only in the mind.

The world is made of numbers  Galileo in The Assayer  “Philosophy is written in this grand book, the Universe, which stands continually open to our gaze.... It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures without which it is humanely impossible to understand a single word of it.”

May God us keep/ From single vision, and Newton's sleep! (William Blake)

Galileo and the Modern World  1. Science is a model for how impartial human reason works. Science is objective. It forms the basis for our hopes of a rationally organized society. (Jefferson)  2. We are no longer at home in the world revealed by science. Science unweaves the rainbow. There is no room for the human spirit in the purified appearances. (Beethoven)

1. Science as a model for human reason  Science is objective. Purifying the appearances and separating the relative from the absolute means that science eliminates us, our biases, our prejudices, our point of view, from the appearances.

The Scientist separates the relative from the absolute

Does the Scientist separate themselves from their humanity?

The Mad Scientist

2. Mechanistic Reductionism and the Human Soul  Mechanism: The World is a Machine. The world consists of matter in motion and the mathematical laws that govern its motion.  Reductionism: The qualities of complex objects, such as squirrels, persons, or countries, can be explained completely by an examination of the basic forms of the components that make them up and the scientific laws that govern them.

Mechanism

Reductionism

May God us keep/ From single vision, and Newton's sleep! (William Blake)

Do not all charms fly/ At the mere touch of cold philosophy?/ There was an awful rainbow once in heaven: We know her woof, her texture; she is given/ In the dull catalogue of common things./ Philosophy will clip an Angel’s wings, Conquer all mysteries by rule and line,/ Empty the haunted air, and gnomed mine –/ Unweave a rainbow…(John Keats)

Two Questions  Is Science objective? Do Science and Reason really give us absolute and complete knowledge of the world? Can all questions be solved scientifically through the application of the scientific method? Are humans capable of being completely objective?  Does Science leave room for the human spirit? Does Science oversimplify and rob the world of its beauty and grandeur? Are human beings more than machines, and are there limitations to the applicability of the views and methods of science? Is science a savior of mankind, or are the pervasive applications of Galileo’s methods an enemy to human values.