2 The Scientific Method Pushing back the frontiers of human knowledge.

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2 Science as a tool Science is a tool for answering why and how. “I have high cholesterol, what should I do?” –Take cholesterol lowering medication. –Consult my astrologer. –Pray to the god Baal and sacrifice a goat. How do you choose what to do? What is your criteria for the “best” solution?

2 Tyson Episode 1 Test ideas by experiment and observation. Build on those ideas that pass the test. Reject those ideas that fail the test. Follow the evidence wherever it leads. Question everything.

2 The Scientific Method 1.Observe an event. 2.Develop a model (or hypothesis) which makes a prediction. 3.Test the prediction. 4.Observe the result. 5.Revise the hypothesis. 6.Repeat as needed. 7.A successful hypothesis becomes a Scientific Theory. model test

2 Medical Science Scientific MethodHigh Cholesterol ObservationPatient has high cholesterol Hypothesis (prediction) Certain chemicals may dissolve cholesterol deposits. TestGive 100 patients these chemicals, give 100 patients placebo. Observe resultSame number lower their cholesterol as placebo patients. Revise hypothesis?Try different combo of chemicals. New test?Re-run medical test. Observe results. Scientific TheoryLipitor reduces cholesterol.

2 Everyday Science Scientific MethodMaking Spaghetti Sauce ObservationSpaghetti sauce should be red. Hypothesis (prediction)Maybe try a tomato sauce. TestHeat pot of tomato sauce. Observe resultTaste the sauce - bland. Revise hypothesis?Use tomato sauce and garlic! New test?Add garlic, taste - not so bland. Scientific TheoryThe Final Recipe.

2 A Theory’s Power A successful theory means: –Applies to the future (the prediction) –You don’t have to keep doing the test. Example: –Lipitor: No more trials –Recipe: No more trial and error Example from daily life where you followed this method?

2 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”

2 Concept Question Which of these statements is true. a.A theory becomes a Law after it has been proven correct. b.A theory becomes a Law if it is supported by the results of enough experiments. c.A Law that is refuted by experimental results becomes just a theory. d.The movement of the Earth around the Sun and the formation of the Universe in the Big Bang are theories. e.We should withhold judgments on theories until they become Laws.

2 Limitations of Science Key to the scientific method is The Test. Q: What can and cannot be tested? Q: What is and is not reproducible? A: Magic, the Divine, matters of faith cannot be tested and are not reproducible. Result: 1.Science is the search for natural or material explanations to the Universe. 2.Science is limited to those questions of which natural or material explanations can be applied.

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2 Assumptions of Science To what questions are natural or material explanations applicable? –God of the Gaps –The unknown versus the unknowable! Are we justified in assuming that natural or material explanations are sufficient to describe the world? –Personal Experience The Universe isn’t random. –The same test done by you, me, yesterday and tomorrow should all give the same result.

2 Theories 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.

2 Concept Question Which of the following is NOT a hallmark of science? a.A scientific theory is built on logic and common sense to explain observed phenomena. b. Science seeks explanations for observable phenomena using natural causes. c. Science makes progress by testing models that explain observations as simply as possible. d. A scientific model makes testable predictions about natural phenomena and is revised or abandoned if the predictions do not agree with observations.

2 Concept Question The fact that a new test can come along tomorrow and overturn a scientific theory that has been successful for centuries is: a.A strength of the scientific method b.A weakness of the scientific method

2 Non-scientific Theories Make no predictions Un-testable Can’t be falsified

2 Non-scientific Theories Cholesterol too high?  Aliens are clogging your arteries with invisible probes. Spaghetti is bland?  You were meant to eat bland food. Cholesterol too high?  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.

2 Non-scientific Theories Viking Orbiter (1976)Mars Global Surveyor (1998)

2 Falsification A real Scientific Theory tells you what observations are necessary to falsify it. –Not so proponents of: Face on Mars Moon Hoax Astrologers Intelligent Design

2 Question of Belief Which of the following do you believe? 1.God created human beings and all forms of life in their present form at some point in the past. 2.Humans have evolved from earlier forms through a process guided by God or some other Intelligence. 3.Humans have evolved from earlier forms of life through a process of natural selection and random mutation.

2 Evolution & Public

2 Tests and Theories Science is a tool for telling you what works! How do you know if your theory (idea, model, hypothesis) is right? –You can test it! –I make a claim, you can test that too. A scientific theory must do two things: –Explain what is seen. –Predict what will happen in the future.

2 Predictions The Theory of Evolution makes testable predictions and thus is a successful scientific theory. 1.True 2.False

2 Predictions Intelligent Design says that human beings (and life in general) is too complex to have arisen naturally and therefore must have been created. Does this statement make testable predictions? 1.Yes 2.No