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What is Inquiry in the Natural World”?
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What is a “physical object”?
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What are physical objects made of?
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Aristotle (384 – 322 BC) http://www.chem.uidaho.edu/~honors/history.html
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Another early idea: “atomism” Leucippus & Democritus (~ 500 BC) John Dalton, 1808. A New System of Chemistry
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http://snobear.colorado.edu/Markw /SnowHydro/mol.html The quantum physics model of matter
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How easy is it to measure physical objects?
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What can’t we see?
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Modern instruments have greatly extended our detection abilities
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Why do physical objects behave the way they do?
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Anthropomorphic explanation
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Mechanistic explanation
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Can we make predictions about the natural world?
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Given a knowledge of the “laws” of physics, can you predict what will happen if I drop this ball? Given a knowledge of the “laws” of physics, can you predict what will happen if I drop this ball?
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Do the results support your prediction? Do the results support your prediction?
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Chaos Theory Chaos Theory
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Types of Inquiry
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Curiosity
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Curiosity-driven science Basic or “pure” often leads to surprisingly practical discoveries
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Problem Solving
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Problem-solving science Applied or “practical” Gives us power over the natural world http://www.colostate.edu/programs/lifesciences/TrangenicCrops
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How do we investigate the natural world?
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Francis Bacon (1561 – 1626) if we understand nature we can dominate it Questioned authority Emphasis on incompleteness of knowledge Proposed a new method of studying nature observation over philosophical speculation
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Hypothetico-deductive scientific method
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Step 1: Observations
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The “Where’s Waldo” problem
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Step 1b: look for a general pattern This step uses a process called Inductive Reasoning ~ in which we develop a rule based on many individual examples
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Step 2: Think up explanations (hypotheses) for the patterns observed 3. is generally applicable A useful hypothesis: 1. leads to accurate predictions 2. is as simple as possible
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Step 3: Make a testable prediction This step uses a process called Deductive reasoning ~ in which we use the rules of logic to generate a prediction
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Step 4: Make observations or do experiments to test our explanations
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How can you tell if someone is a Witch?
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A Witch! A Witch! We’ve got a Witch
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What’s the general pattern here?
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If she looks like a Witch and acts like a Witch she is a Witch - Nose like a Witch - Hat like a Witch - Wart like a Witch -Turned someone into a newt Must be a Witch!
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What do you do with Witches? Burn them!
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What do you burn other than Witches? Wood
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Why do Witches burn? Because they’re made of wood? How can you tell she is made of wood? Build a bridge out of her
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But can’t you also build bridges out of stone? Oh Yeah!
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Does wood sink in water? It Floats Throw her in the pond
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What else floats? Bread! Apples! Very small rocks! Gravy! A Duck Cider! Cherries! Mud! Churches! Lead!
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So, logically... If she weighs the same as a duck She’s made of wood And therefore... SHE’S A WITCH!
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Bring my large scales She DOES weigh the same as a duck SHE’S A WITCH!
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Witch Wood Witch burns Wood burns -------------------------------
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Duck Wood Wood Floats Duck Floats ------------------------------
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Duck Wood Girl’s weight Duck’s weight Witch Wood Girl Wood ------------------------------ Girl Wood --------------------------------- Girl Witch
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William of Ockham (1280 – 1347) “ Pluralitas non est ponenda sine necessitate” Translation Entities should not be multiplied unnecessarily Ockham’s Razor “keep it simple”
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Description of Motion of Planets around the Sun
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Two Competing Models with Different Predictions
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Kepler - elliptical Shape of Planetary Orbits Copernicus - circular
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More accurate prediction is “better” Perform Experiment
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Two Competing Models with the Same Predictions
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Model # 1 Planets move around sun in ellipses
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decreases as the square of the distance force between them and the sun
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Model # 2 Planets move around sun in ellipses
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decreases as the square of the distance force between them and the sun
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Model # 2 Force is generated by will of powerful aliens
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Models # 1 and # 2 Force between planets and sun determines motion of planets
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Models # 1 and # 2 same type of force
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Models # 1 and # 2 predicted motion of planets identical for both Models
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Model # 2 has additional baggage (the will of aliens) that is unnecessary for description of system
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Ockham’s Razor reject’s 2 nd model
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motion of planets can be explained by simple idea of force Solar system may be permeated by alien intellect BUT no evidence of alien’s presence nor their absence
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It does not guarantee that the simplest model is correct, it merely establishes priorities Application of Ockham’s Razor directs us to look to simplest model
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Scientific Theories keep changing so where is the Truth?
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Newton & Theory of Gravitation Newton’s theory “The Truth” 1666 – explained all the observed facts Predictions later tested and found correct to within accuracy of instruments used
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Einstein & Theories of Relativity 19th century – more accurate instruments Slight discrepancies in Newton’s theories Einstein’s theory explained newly observed facts Found to be correct with accuracy of instruments used Einstein’s theory “The Truth”
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Has the Truth changed? Theories can be shown to be incomplete No it hasn’t - Universe is still the same “Truth” means it agrees with all known experimental evidence
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New Theories Devour and assimilate its predecessors Explain old and new data
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Acknowledgements I would like to thank Dr. Ted Georgian for the use of a number of his slides and especially his idea to use Monty Python as a humorous example of the scientific method
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