Changing Understanding of the Universe

Homocentric

Belief that all rotations in the universe are centred on the Earth

Empiricism

Knowledge can only come as a result of experience, seek out experience and experiments to formulate theories - key development of the Scientific Revolution

Natural Philosophy

Study of the natural world

Concerned with providing philosophical reasoning to explain the workings of nature - adopted scientific method during the Scientific Revolution

Aristotelian Beliefs

Work of Aristotle (384-322 BC), homocentric circular view of the universe

Empiricism approach through observation and experience

Platonic Beliefs

Work of Plato (427-347 BC), theoretical approach through knowledge based thought

Applied Mathematics

The use of mathematical methods and theories to solve practical problems in science, engineering, and other fields

Theoretical Mathematics

A branch of mathematics focused on abstract concepts and theoretical frameworks, studying structures and proofs that inform future discoveries.

Why are spheres and circles such an attractive philosophical idea?

Spheres and circles symbolize perfection and unity due to their symmetrical shape. They are often associated with the heavens and the divine in philosophical thought, embodying the idea that the universe is orderly and harmonious. In various philosophical traditions, these shapes represent the ultimate form or ideal, suggesting that reality is structured and that these geometric forms reflect deeper truths about existence.

Why does it matter if theory is based on pure theory rather than empiricism?

The distinction between pure theory and empiricism is significant because pure theory relies on abstract reasoning, mathematical models, or logical deductions without direct reference to observable data. This can lead to theoretical frameworks that might not accurately reflect the complexities of the real world. In contrast, empiricism emphasizes the necessity of observation and experimentation to validate theories, ensuring they are grounded in reality and can be tested against actual phenomena. This empirical approach fosters a more reliable understanding of nature, allowing for theories to evolve based on new evidence rather than remaining static in ideological assumptions.

What did Ptolemy believe was the centre of the universe?

Earth

What did he produce to track the position of the sun, stars and planets?

Tables of astronomical data known as the Almagest.

What sort of model was it?

Mathematical

What did it lack?

Observed evidence

What did Ptolemy predict would exist using his model?

Extra planets and stars might exist

How did Ptolemy believe planets moved?

In perfect circles around the Earth - theory of Epicycles

What assumption did he have to make to make his theory work?

Epicycles didn’t move around the Earth but instead at another point not far from Earth

Why were equants important?

Accounted for uneven speeds of planets in their orbits and maintain perfect circles

Why was it important that all spheres and orbits were perfect?

It aligned with the philosophical belief in perfection and harmony in the universe, reflecting the divine order

What did Copernicus write in 1543?

De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spears)

Who was the book dedicated to?

Pope Paul III

What does this suggest about this belief system?

Celestial bodies followed precise paths, reinforcing the idea of a divine creator and following Christianity strongly

What practical problem did the Copernican system have?

Unable to accurately set a date for Easter each year

What was Copernicus’ revolutionary idea?

Heliocentric universe, Sun at the centre

To what extent did Copernicus agree with Aristotle and Ptolemy?

Agreed that heavenly bodies moved in perfect circles

How many spheres did Copernicus propose existed?

Eight spheres

How did Copernicus try to avoid accusations of blasphemy?

Presented his work as Platonic theory rather than observed

What did the church do to the book?

1616, banned by the Catholic Church and placed on their Index Librorum Prohibitorum (Index of Forbidden Books)

1758, removed from the Index, hugely influential after his death

Was Copernicus theoretical or empirical?

Theoretical

What did he incorrectly believe about planets?

Moved on a round tradjectory

What did he incorrectly believe about planetary motion?

Perfectly circular

How many thinkers accepted Copernicus ideas as a description of physical reality?

Very few during his lifetime - counter-intuitive that Earth moved and contradicted biblical accounts

Only 10 prior to 1600

To what extent was Copernicus’ impact limited by the church?

Andreas Osiander, Protestant minister, stated the book acted as an aid to astronomical calculations and were unlikely to be accurate

Catholic Church Index

To what extent was his impact limited by describing it as a philosophical theory?

His ideas were dismissed as speculative and not taken seriously by the scientific community, limiting their acceptance and influence.

What position did Tycho Brahe have in 1597, who took over after him?

Imperial astronomer for the Holy Roman Emperor, taken up by Kepler after his death

What compromise position did Brahe develop between Ptolemy and Copernicus?

All planets circled the Sun, but the sun circled the Earth which was stationary

What was the problem with it?

Inaccurate

How does this demonstrate the limited impact of purely theoretical ideas at this point?

This demonstrates the limited impact of purely theoretical ideas as Brahe's model, while innovative, was ultimately inconsistent with observational evidence and the heliocentric theory that later became widely accepted.

What did he observe in 1572?

Supernova

How did this challenge the pre-existing ideas of the universe?

It challenged the notion of an unchanging cosmos by providing evidence of new celestial phenomena, suggesting that the heavens were not immutable as previously thought.

What did he publish in 1588?

His findings, included observations of comets and detailed descriptions of the supernova

How did this change his view of existing models of the universe?

They existed outside the atmosphere of the Earth

How did he refute the idea of the perfect sphere?

Path taken by the comets meant that all heavenly bodies could not travel in perfect spheres