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