1. The Scientific Method …lots and lots and lots of math. 2/18/1996

2. Learning Objectives What are the steps in the scientific method? What does the scientific method assume? Does the scientific method work? What is not a scientific argument.

3. What is science? Science is a tool. Medicine: “I have high cholesterol, what should I do?” –Take cholesterol lowering medication. –How do we know this is the best treatment? Science has improved our lives GREATLY.

4. The Scientific Method 1. Observe an event / Problem 2. Think of a question to test. 3. Develop a hypothesis which makes a prediction. 4. Test the prediction using experiments. 5. Make a conclusion based on your data. –Repeat as needed. –A successful hypothesis becomes a Scientific Theory. model test

5. 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.

6. Everyday Science Scientific MethodCar Repair ObservationEngine won’t turn over. Hypothesis (prediction)Predict battery is dead. TestReplace battery. Observe resultEngine now turns over. Revise hypothesis?Not needed. New test?Not needed. Scientific TheoryCars won’t work without a fully charged battery.

7. Food Science Throwing something together  Hypothesis Your grandmother’s time-tested recipe  Scientific Theory.

8. Hypothesis, Theories, and Laws A hypothesis is an educated guess that needs to be tested with experiments. If a hypothesis stands up to much testing and can make useful predictions, it is called a Theory. –This does NOT mean “hunch” or “guess” in science –Scientific theories in science are the strongest ideas (in terms of explanation power) A Law is a mathematical explanation that science uses. Laws are NOT “higher” than theories.

9. Theories So: a theory is a highly successful hypothesis. All hypotheses make predictions. All theories make predictions. All theories can be tested by anyone, anywhere. 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.

10. Does it work? Scientific Method is a tool. Does this tool work? –Life expectancy 38 years old in 1850 81 years old in 2004 –Mortality rates 200 people per 100,000 died from tuberculosis in 1900 0.2 people per 100,000 died from tuberculosis in 2000 152 babies per 1000 died at birth in 1950 47 babies per 1000 died at birth in 2005 Are there better tools?

11. 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? “Atomic Theory” – Foundation of modern chemistry

12. Non-scientific Theories Make no predictions – I like Pepsi better than Coca-Cola. Un-testable – Rain is caused by invisible ghosts flying around in the sky crying. Can’t be falsified – All swans are not green.

13. Non-scientific Theories Car won’t work?  Aliens drained the battery. Feel sick?  Invisible, undetectable fairies put a spell on you. Spaghetti is bland?  At the instant of tasting, tongue is transported to alternate dimension where all flavors are rendered nullified. Happens instantaneously.

14. Science? Or Not? Face on Mars. What do you think? Viking Orbiter (1976)Mars Global Surveyor (1998)

15. Falsification A real Scientific Theory tells you what observations are necessary to falsify it. Falsify – prove it wrong. –Not so proponents of: Face on Mars Moon Hoax Astrologers / Horoscopes (how could you prove these wrong?)