Week 4 — Tycho, Kepler, Galileo, and the Telescope¶
Tycho Brahe¶
Contribution¶
Tycho produced the most accurate astronomical measurements before the telescope.
Discoveries¶
Supernova and comet observations demonstrated that the heavens were not immutable.
Philosophical Significance¶
Tycho's work shows how empirical evidence can challenge deeply entrenched metaphysical beliefs.
The Aristotelian assumption of perfect heavens collapsed under observational pressure.
Kepler¶
Three Laws of Planetary Motion¶
- Planets move in elliptical orbits.
- Equal areas are swept in equal times.
- Orbital period relates mathematically to distance.
Philosophical Significance¶
Kepler abandoned the ancient commitment to perfect circles, which had philosophical roots in Greek ideals of perfection.
His work shows an important methodological shift:
Scientific theories must follow empirical evidence, even if it means abandoning long-standing philosophical ideals.
Kepler also moved astronomy toward the idea that celestial motion results from physical forces, not purely geometric descriptions.
Galileo¶
Telescope Discoveries¶
Galileo observed:
- mountains on the Moon
- moons orbiting Jupiter
- phases of Venus
- sunspots
These discoveries undermined Aristotelian cosmology.
Development of Mechanics¶
Galileo introduced mathematical analysis of motion.
He discovered laws describing:
- acceleration
- projectile motion
- inertia
Philosophical Significance¶
Galileo helped establish the mathematization of nature.
Nature becomes something that can be described through mathematical laws rather than philosophical speculation.
Galileo also emphasized:
- controlled experimentation
- idealized models
These practices are foundational to modern science.
The Galileo affair also illustrates the interaction between science and social authority, showing that scientific change can conflict with religious and institutional power.