Module 1: The Physical World PDF

05/09/2024 MODULE 1: The Physical World SEPTEMBER 3, 2024 1 1 WHAT IS THE PHYSICAL WORLD? 2 2...

05/09/2024 MODULE 1: The Physical World SEPTEMBER 3, 2024 1 1 WHAT IS THE PHYSICAL WORLD? 2 2 1  05/09/2024 WHAT IS THE PHYSICAL WORLD? Classical Greece: Geocentric model o Perfectly circular orbits o Perfectly uniform speed o The Earth is spherical, motionless, and positioned at the center of the universe 3 3 WHAT IS THE PHYSICAL WORLD? Hipparchus: Precession of the Equinoxes 4 4 2  05/09/2024 WHAT IS THE PHYSICAL WORLD? Eratosthenes: Circumference of the Earth 5 5 WHAT IS THE PHYSICAL WORLD? Ptolemy: Retrograde motion 6 6 3  05/09/2024 7 7 MODELS OF THE PHYSICAL WORLD Eudoxus, Aristotle: Geocentric Model Cannot explain changes in the planets’ brightness Cannot explain apparent changes in the size of the moon (perigee, apogee) Motion of the moon, sun, and other planets is not visually uniform Aristarchus: Heliocentric model Ptolemy: Ptolemaic model The orbital center is not the Earth (deferent, epicycle, eccentric, equant) Galileo Galilei Craters of the moon Copernicus: Heliocentric model New explanation for retrograde motion Cannot explain stellar parallax Cannot explain motion within the Earth 8 8 4  05/09/2024 MODELS OF THE PHYSICAL WORLD Tycho Brahe: Planetary Positions Found no stellar parallax Galileo Galilei: Observation of the stars Motion (falling, horizontal, projectile) Moon craters, sunspots, Jupiter moons, Venus phases, Star size, supernova Johannes Kepler: Laws of Planetary Motion Law of Orbits (elliptical orbits) Law of Areas (perihelion, aphelion) Law of Periods (𝑇 ~𝑎 ) Isaac Newton Elliptical orbits from laws of gravitation 9 9 WHAT IS GRAVITY? 10 10 5  05/09/2024 WHAT IS GRAVITY? 11 11 WHAT IS GRAVITY? 12 12 6  05/09/2024 WHAT IS GRAVITY? Newton's Law of Universal Gravitation Centripetal Force 13 13 14 14 7  05/09/2024 WHAT IS GRAVITY? Albert Einstein: General Theory of Relativity 15 15 16 16 8  05/09/2024 UNDERSTANDING THE PHYSICAL WORLD Law vs Theorem vs Model Model: representation of reality Theory: explanation for a phenomenon Law: results from experiments Features of a Good Model Elegant Few arbitrary elements Agrees and explains existing observations Detailed predictions for future possible observations Features of a Good Theory Logically sound Consistent ideas Plausible results Quantitative predictions Repeated comparison 17 17 UNDERSTANDING THE PHYSICAL WORLD Temporal 18 18 9  05/09/2024 UNDERSTANDING THE PHYSICAL WORLD Spatial 19 19 UNDERSTANDING THE PHYSICAL WORLD Scientific Method Formulating a theory and doing an experiment Gathering facts Observing patterns Making a hypothesis Testing the hypothesis Predicting and further tests Formulating a theory Applying the theory 20 20 10  05/09/2024 DIAGNOSTIC FEATURES OF SCIENCE Objectivity Reliability Verifiability Precision Ethical Neutrality Accuracy Systemic Exploration Predictability 21 21 REQUIRED READINGS Chapter 3 – What is Reality? Of the book The Grand Design by Hawking and Mlodinow Chapter 1 – The Cosmic Calendar in Dragons of Eden by Carl Sagan Chapter 1.3 and 1.5 in Basic Physics by Kenneth W. Ford Chapter 4 – Public Attitudes towards Science in Stephen Hawking’s Black Holes and Baby Universes and Other Essays 22 22 11