What is Inquiry in the Natural World”?
Dec 20, 2015
What is Inquiry in the Natural World”?
What is a “physical object”?What is a “physical object”?
What are physical objects made of?What are physical objects made of?
Aristotle (384 – 322 BC)Aristotle (384 – 322 BC)http://www.chem.uidaho.edu/~honors/history.htmlhttp://www.chem.uidaho.edu/~honors/history.html
Another early idea: “atomism”Leucippus & Democritus (~ 500 BC)
John Dalton, 1808. A New System of Chemistry
http://snobear.colorado.edu/Markw/SnowHydro/mol.html
The quantum physics model of matter
How easy is it to measure physical objects?How easy is it to measure physical objects?
What can’t we see?What can’t we see?
Modern instruments have greatly Modern instruments have greatly extended our detection abilitiesextended our detection abilities
Why do physical objects behave the way they do?Why do physical objects behave the way they do?
Anthropomorphic explanationAnthropomorphic explanation
Mechanistic explanationMechanistic explanation
Can we make predictions about the natural Can we make predictions about the natural world?world?
• Given a knowledge of Given a knowledge of the “laws” of physics, the “laws” of physics, can you predict what will can you predict what will happen if I drop this happen if I drop this ball?ball?
• Do the results support Do the results support your prediction?your prediction?
• Chaos TheoryChaos Theory
Types of Inquiry
CuriosityCuriosity
Curiosity-driven scienceCuriosity-driven science
Basic or “pure”Basic or “pure”often leads to often leads to surprisingly practical surprisingly practical discoveriesdiscoveries
Problem Solving
Problem-solving scienceProblem-solving science
Applied or “practical”Applied or “practical”Gives us power over the natural Gives us power over the natural worldworld
http://www.colostate.edu/programs/lifesciences/TrangenicCrops
How do we investigate the natural world?
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
Hypothetico-deductive scientific method
Step 1: Observations
The “Where’s Waldo” problemThe “Where’s Waldo” problem
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
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
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
Step 4: Make observations or do experiments to test our explanations
How can you tell if someone is a Witch?
A Witch! A Witch! We’ve got a Witch
What’s the general pattern here?
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!
What do you do with Witches?
Burn them!
What do you burn other than Witches?
Wood
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
But can’t you also build bridges out of stone?
Oh Yeah!
Does wood sink in water?
It Floats
Throw her in the pond
What else floats?Bread!
Apples!
Very small rocks!
Gravy!
A Duck
Cider!
Cherries!
Mud!
Churches!
Lead!
So, logically . . .
If she weighs the same as a duck
She’s made of wood
And therefore . . .
SHE’S A WITCH!
Bring my large scales
She DOES weigh the same as a duck
SHE’S A WITCH!
Witch Wood
• Witch burns
• Wood burns-------------------------------
Duck Wood
• Wood Floats
• Duck Floats
------------------------------
• Duck Wood
• Girl’s weight Duck’s weight
• Witch Wood
• Girl Wood
------------------------------ Girl Wood
---------------------------------
Girl Witch
William of Ockham (1280 – 1347)
•“Pluralitas non est ponenda sine necessitate”
• Translation Entities should not be multiplied unnecessarily
• Ockham’s Razor
• “keep it simple”
Description of Motion of Planets around the
Sun
Two Competing Models with Different Predictions
Kepler - elliptical
Shape of Planetary Orbits
Copernicus - circular
More accurate prediction is “better”
Perform Experiment
Two Competing Models with the Same Predictions
Model # 1
• Planets move around sun in ellipses
• decreases as the square of the distance
• force between them and the sun
Model # 2
• Planets move around sun in ellipses
• decreases as the square of the distance
• force between them and the sun
Model # 2
Force is generated by will of powerful aliens
Models # 1 and # 2
• Force between planets and sun determines motion of planets
Models # 1 and # 2
• same type of force
Models # 1 and # 2
• predicted motion of planets identical for both Models
Model # 2
• has additional baggage (the will of aliens) that is unnecessary for description of system
• Ockham’s Razor reject’s 2nd model
• 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
• 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
Scientific Theories keep changing so where is the
Truth?
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
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”
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
New Theories
• Devour and assimilate its predecessors
• Explain old and new data
AcknowledgementsAcknowledgements
I would like to thank Dr. Ted Georgian for the use of I would like to thank Dr. Ted Georgian for the use of a number of his slides and especially his idea to use a number of his slides and especially his idea to use
Monty Python as a humorous example of the Monty Python as a humorous example of the scientific methodscientific method