1. Lecture 1: Our Evolving View of the Universe
4/6/2019
Lecture 1: Our Evolving View of the Universe
Dr. Michael Burton
GENS X1
Evolving View of the Universe

2. History of Science & Astronomy: The Greeks
4/6/2019
History of Science & Astronomy: The Greeks
550BC Pythagoras: Natural phenomena described by mathematics.
300BC Aristotle: Universe governed by physical laws.
(Aristarchus proposed heliocentric model.)
200AD Ptolemy: Geocentric cosmology.
Epicycles and Deferents, as explained in the Almagest
GENS X1
Evolving View of the Universe

3. History of Science & Astronomy: The Renaissance
4/6/2019
History of Science & Astronomy: The Renaissance
1543 Nicolaus Copernicus: Heliocentric cosmology in De Revolutionibus (circles).
1573 Tycho Brahe: De stella nova in Cassiopeia - precise observations.
1619 Johannes Kepler: Three (empirical) laws of planetary motion (ellipses).
1610 Galileo Galilei: Telescope shows an imperfect, non-geocentric universe.
Dialogue on the Two New Sciences

4. History of Science & Astronomy: Physics
4/6/2019
History of Science & Astronomy: Physics
1687 Isaac Newton: Principia: Physical laws to explain the observations.
Laws of Motion and Gravity allow predictions.
1905 Albert Einstein: Special and General theories of Relativity explain nature of light and gravity.
???? You ???? Quantum Gravity and a Unified Field theory for Forces of Nature.
GENS X1
Evolving View of the Universe

5. Scientific Method & Astronomy
4/6/2019
Scientific Method & Astronomy
The universe is comprehensible.
Scientific method is a procedure for formulating theories, which can be tested by experiment to build models to describe phenomena in the universe.
Observations of the heavens have led to the discovery of some fundamental laws of nature.
GENS X1
Evolving View of the Universe

6. Evolving View of the Universe
4/6/2019
Key Ideas
The heliocentric theory simplified the explanation of planetary motions compared to geocentric theory.
In it the Earth is but one of several planets orbiting the Sun
Ellipses describe the paths of planets around the Sun more accurately than circles do.
The invention of the telescope lead to new discoveries about the universe around us.
Newton based his explanation of the universe on three assumptions called the Laws of Motion.
GENS X1
Evolving View of the Universe

7. Evolving View of the Universe
4/6/2019
Key Ideas
Together with the law of gravity, they explained Kepler’s empirical laws with great accuracy.
Einstein’s theories of relativity accounted for small discrepancies in Newton’s Laws which were only apparent through careful observation.
The theory of relativity, which explains the universe on the largest scales, is incomplete and has yet to be reconciled with quantum theory, which explains it on the smallest scales.
GENS X1
Evolving View of the Universe