Transcript Document

The Scientific Method
2/18/1996
…lots and lots and lots of math.
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Goal
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What is science?
What is the scientific method?
Does the scientific method work?
What is not a scientific argument.
Does astrology follow the scientific method?
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What is science?
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Science is a tool to understanding the Universe.
You see something happen, you ask why?
You make a model (or hypothesis) that explains what
you see.
A scientific model must do two things:
– Explain what is seen.
– Predict what will happen accurately.
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How do you know if your model is right?
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What is science?
• Science is a tool.
• Medicine: “I have high cholesterol, what should I do?”
– Take cholesterol lowering medication.
– Consult your astrologer.
– Pray to the god Baal and sacrifice a goat.
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The Scientific Method
1. Observe an event.
2. Develop a model (or hypothesis) which makes a
prediction.
model
3. Test the prediction.
4. Observe the result.
5. Revise the hypothesis.
test
6. Repeat as needed.
7. A successful hypothesis becomes a Scientific Theory.
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Medical Science
Scientific Method
High Cholesterol
Observation
Patient has high cholesterol
Hypothesis
(prediction)
Test
Revise hypothesis?
Certain chemicals may dissolve
cholesterol deposits.
Give 100 patients these chemicals,
give 100 patients placebo.
Same number of patients lower their
cholesterol as placebo patients.
Try different amounts of chemicals.
New test?
Re-run medical test. Observe results.
Scientific Theory
Lipitor reduces cholesterol.
Observe result
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Everyday Science
Scientific Method
Car Repair
Observation
Engine won’t turn over.
Hypothesis (prediction)
Predict battery is dead.
Test
Replace battery.
Observe result
Engine now turns over.
Revise hypothesis?
Not needed.
New test?
Not needed.
Scientific Theory
Cars won’t work without a
fully charged battery.
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Everyday Science
Scientific Method
Observation
Making Spaghetti Sauce
Spaghetti sauce should be red.
Hypothesis (prediction) Use tomato sauce.
Test
Heat pot of tomato sauce.
Observe result
Taste the sauce - bland.
Revise hypothesis?
Use tomato sauce and garlic!
New test?
Add garlic, taste - not so bland.
Scientific Theory
The Final Recipe.
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Food Science
• Throwing something together  Hypothesis
• Your grandmother’s time-tested recipe 
Scientific Theory.
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Recap: Theories, Guesses, Laws
• What does the word “Theory” mean to you?
“A conjecture; guess” (Webster’s Dictionary)
• Does it mean the same to a scientist?
“A model which has been born out by
repeated tests and observation.”
• Is a Theory less than a Law?
“Evolution is just a theory, it is not a fact.”
• Do Theories “grow up” to be Laws?
“Einstein’s Theory of Relativity”
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Theories
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So: a theory is a highly successful hypothesis.
All hypotheses make predictions.
All theories make predictions.
All theories can be tested.
Result: Any scientific theory is subject to change
as our ability to make tests, or make observations
of a test’s results, improves with time.
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Non-scientific Theories
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Make no predictions
Un-testable
Can’t be falsified
The chain of events needed for life to arise is too
complicated to have happened by chance, a
divine intelligence must therefore have caused
life to arise (Intelligent Design).
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Non-scientific Theories
• Car won’t work?  Aliens drained the battery.
• Spaghetti is bland?  You were meant to eat
bland food.
• Car won’t work?  Gods must be angry.
• Spaghetti is bland?  At the instant of tasting,
tongue is transported to alternate dimension where
all flavors are rendered nullified. Happens
instantaneously.
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Non-scientific Theories
• The chain of events needed for life to arise are too
complicated to have happened by chance, a divine
intelligence must therefore have caused life to
arise (Intelligent Design).
• Face on Mars.
Viking Orbiter (1976)
Mars Global Surveyor (1998)
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Falsification
• A real Scientific Theory tells you what
observations are necessary to falsify it.
– Not so proponents of:
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Face on Mars
Moon Hoax
Intelligent Design
Astrologers
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Astrology Tests
• What test would falsify astrology?
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Astrology and the President
(TIME, May
16, 1988)
-- Chief of Staff, Donald] Regan and
“[Former
White
House
“The First
Lady
dabbled in astrology
as far
others
make
a compelling
case that
in back
1986 and 1987
as 1967. In 1981 [Joan] Quigley made Nancy a
astrological
influence
dramatically
reduced the
believer …. And
from then
on, no presidential
presidency's
effectiveness,
at leastthepartly, by keeping
public appearance
was slated without
Friend'sReagan
say-so. To
this day,
Nancy's
Ronald
under
wraps
for Friend
much of the time.
continuesintrusions
to influenceinthe
schedule.
Nancy's
thePresident's
scheduling
process, Regan said
Reagan-Gorbachev
Washington
summit,
inFor
anthe
interview
with TIME
last week,
‘began to interfere
she cast the charts of both men and determined
with
normal
that the
2 p.m.
on Dec.conduct
8, 1987, of
wasthe
thepresidency.’”
most propitious moment for
them to sign the intermediate-range nuclear forces treaty. At
Nancy'sMay
behest,
the1988)
entire summit was built around that hour. For
(TIME,
16,
the upcoming Moscow summit, Gorbachev's chart (he is a Pisces)
has been recast alongside Reagan's (Aquarius).”
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Homework #2
• For Thursday 9/12:
• Read Bennett chapter 1.1 – 1.2
– (B1.1 – 1.2 on Physics 103 lecture web page)
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For Monday 9/16:
Read Ty7 and B6.1 – 6.3, B7.1 – 7.5
Do B6: Review Questions 8, 9, and Problems 1, 2
Do B7: Problems 3, 5, 9, 10
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