Galileo and the Copernican Revolution

Contemporaries: Galileo Galilei (G) and Johannes Kepler (K) were contemporaries in the field of astronomy.
Impressions in their Lifetimes:
- G overshadowed K during their lifetimes, yet K’s significantly improved astronomical charts and the simplicity of his version of the Copernican theory were essential to the Copernican revolution.
- Both played pivotal roles in shaping modern astronomy.

G's Role:
- G is recognized as crucial for uniting the fields of astronomy and physics following the Copernican revolution.
- His work integrates astronomy, physics, theology, and philosophy.
Shift in Scientific Views:
- In the Aristotelian/Ptolemaic system, physics and astronomy were interconnected, only to become distinct in the late Middle Ages.
- G’s achievements can be seen as a replacement of Aristotelian natural philosophy's components with a more updated perspective.

Replacement of Elements:
- G replaced the classical five elements (earth, air, fire, water, aether) with a single element – matter.
- He transformed the Aristotelian explanations for change (such as circular motion and growth) into perspectives akin to Kepler’s clockwork metaphor.
- This transformation marks a critical shift away from experiential understanding towards a more mathematical-based framework.
Primary vs. Secondary Qualities:
- G made the vital distinction between primary qualities (such as shape and quantity) and secondary qualities (like taste and sound).
- A notable line from his work, The Assayer, states: "The book of the universe is written in the language of mathematics."

Opposition by Aristotelians:
- Due to his reliance on mathematics, G's work was perceived by Aristotelian scholars as overly abstract and disconnected from tangible experiences.

Telescope Development:
- The principles of the telescope were discovered accidentally in 1608 by boys experimenting in a lens shop.
- G quickly improved upon the design, being among the first to employ it for astronomical purposes, publishing his results starting in 1610.
Unity of Terrestrial and Celestial Mechanics:
- G concluded that mountains on the moon share similarities with those on Earth, challenging Aristotle's separation of terrestrial and celestial phenomena.
- He posited that if there is only one type of matter, there must be a single type of natural motion.
- G questioned the meaning of “weight” with respect to celestial bodies and noted that a physical cause was necessary for planetary and rotational motion.

Progress in Terrestrial Physics:
- Although G recognized the need for a physical understanding of celestial motions, his primary advancement was in terrestrial physics, where he viewed earthly motions as logical and predictably mathematical.
- Introduced the notion that the path of an arrow could be described mathematically, paralleling celestial dynamics; he recognized the parabola as a model for motion.
- G shifted the scientific inquiry from "why do rocks fall?" to "how do rocks fall?" marking a profound progression in scientific methodology.

Comparison of Models:
- G’s model was mathematical and mechanical, diverging from Aristotle’s qualitative and organic explanation of physics.
- His models drew from Archimedes’ simple machines, such as levers and inclined planes, paving the way for a mechanical interpretation of science.
Unexplored Terrains:
- Acknowledgement that a full exploration of the implications of these ideas would require more detailed examination than provided in this brief note.

Concept of Matter:
- It was initially counterintuitive for G to conceptualize generic matter, as Aristotle identified four types of terrestrial substances categorized by heaviness and lightness.
- G aimed to define weight similarly to heaviness, struggling to form a clear, measurable notion due to the lack of a defined concept of mass.

Measurement Techniques:
- G resorted to experiments involving inclined planes and water flow for timing, since he recognized the need to establish a method to quantify motion.
Mathematical Laws:
- He endeavored to derive a mathematical relationship connecting the speed of falling objects with the distance they fall, eventually discovering the law that distance is proportional to time squared d \ ext{ } \ ext{proportional to} ext{ } t^2 (independent of its weight).

Thought Experiments:
- G engaged in significant thought experiments, which raise questions about the nature of experimentation and argumentation in science.
- Illustrations of these thoughts included discussions about vertical and horizontal motions, leveraging scenarios such as a ball dropped from a tower and frictionless planes to challenge established notions of motion.
Observation and Independence of Motion Types:
- G highlighted how an object's fall directly downward does not confirm either the earth's stationary state or its uniform motion, emphasizing the independence of vertical and horizontal motion.

Initial Acceptance:
- Initially, G's discoveries, including the moons of Jupiter and the phases of Venus, were received with interest by the Church, who saw them consistent with Scripture and supportive of the divine creation of a vast universe.
Growing Suspicion from the Church:
- Over time, the Church adopted a more intolerant and authoritarian stance towards scientific advancement due to rising pressures from Protestant heresies.
- Their initial willingness to allow Copernican views for instructional purposes was retracted; it needed to be presented as merely instrumental rather than the truth.

Conflict Development:
- G experienced conflicts due to derogatory comments against Aristotelian scholars in his work Dialogue, leading to additional tensions with authority figures in the Church.
- The Inquisition eventually led to his condemnation when he was forced to recant his beliefs concerning the motion of the earth.
Consequences:
- G suffered public humiliation and was placed under house arrest, although he faced threats of torture, he was never tortured.
- His later explanations and attempts at compromise did not ease the Church's condemnation, revealing a profound struggle between emerging scientific perspectives and established religious doctrines.