APAKAH ILMU PENGETAHUAN? ( What is Science? )

1. APAKAH ILMU PENGETAHUAN?(What is Science?)

2. Science: [scientia, knowledge] • Knowledge gained through experience… • Accumulated and accepted knowledge that has been systematized and formulated with reference to the discovery of general truths or the operation of general laws • Branch of study that is concerned with observation and classification of facts concerned with the physical world and its phenomena

3. In order to do science we have to make the following assumptions: • There is order to the universe (even if it is chaotic order) • The human mind is capable of comprehending this order • If conditions are the same, the results of any study will be the same

4. Which of the following statements can be tested scientifically? • Most of the energy coming from the sun is in the form of visible light. • Unicorns exist. • Shelley wrote beautiful poetry. • The Earth was created over four billion years ago. • Diamond is harder than steel. • Diamonds are more beautiful than rubies.

5. The claim is sometimes made that the scientific method produces closer and closer approximations to "reality." • Is this a scientific statement? Why or why not?

6. The Scientific Method

7. Scientists develop their knowledge by observation and experimentation Observation is used in two ways: 1. Inductive reasoning - discovering general principles by the careful examination of specific cases. Here the scientist organizes data (facts) into categories and asks what they have in common 2. Deductive reasoning starts with general cases and proceeds to specific cases - it makes relationships clearer and allows predictions to be made

8. Scientific knowledge advances by a method known as "strong inference" Strong inference works as follows: 1. Make an observation or measurement 2. State an hypothesis 3. Test the hypothesis 4. Publish the results 5. Restate the hypothesis, test again

9. Observation Semmelweis (1856), observed in hospitals in Vienna, that 5X the number of women died during childbirth if they were attended by a physician as compared to being attended by a nurse (“childbed fever”). One of his colleagues died of childbed fever after cutting his hand with a scalpel during an autopsy. Doctors are often doing autopsies before attending to childbirths.

10. Observation (inductive reasoning) Hypothesis Semmelweis hypothesized that “cadaveric matter” was transmitted from the autopsy room to the delivery room.

11. Observation (inductive reasoning) Hypothesis (Deductive Reasoning) Prediction Washing hands would eliminate the cadaveric matter and reduce childbed fever. null hypothesis vs. alternative hypothesis

12. Observation (inductive reasoning) Hypothesis (Deductive Reasoning) Experimental design •controls •dependent variable (what’s affected) •independent variable (what’s the “cause”) •predicted data (must be able to differentiate between null and alternative hypotheses) Prediction Experiment Observation correlation ≠ causation

13. correlation ≠ causation

14. Observation (inductive reasoning) Hypothesis (Deductive Reasoning) Prediction [Experiment] Experiment Observation Childbed fever deaths absent when physicians washed their hands Analysis (Observation = Prediction?)

15. Observation (inductive reasoning) Hypothesis (Deductive Reasoning) Prediction [Experiment] Experiment Observation Analysis (Observation = Prediction?) Transmission of cadaveric matter causes childbed fever Conclusion

16. Observation (inductive reasoning) Hypothesis (Deductive Reasoning) Prediction What other hypotheses could be made from the conclusion? [Experiment] Experiment Observation Analysis (Observation = Prediction?) Conclusion

17. Observation (inductive reasoning) Hypothesis (Deductive Reasoning) Prediction What would you predict from your hypothesis? [Experiment] Experiment Observation How would you test it experimentally? Analysis (Observation = Prediction?) Conclusion

18. Observation (inductive reasoning) Hypothesis (Deductive Reasoning) Prediction Theory Law Fact [Experiment] Experiment Observation Analysis (Observation = Prediction?) Generalization (Deductive Reasoning) Conclusion

19. Scientific method is a repetitive process that leads to the building of theories Initial Observation reasoning? New Hypothesis Hypothesis New Experiment Experiment New Observation Observation/ Data Analysis Hypothesis not Supported Interpretation Final Hypothesis Supported Theory

20. Identifying Patterns Observations Experimentation Data Hypothesis Prediction Preconceptions can influence scientific method Preconceptions “vapors”, spontaneous generation, women as “weak”

21. accumulated scientific data formulation of hypothesis observation and experimentation new data conclusions 1 2 3 etc Theories in science build from the accumulation of multiple investigative efforts theory communicable disease

22. Summary • The scientific method is in essence a process of observing natural phenomena which leads to the asking of questions about those phenomena which leads to the offering of explanations that can subsequently be tested

23. Mystery Box • Hand out mystery boxes • Do hypothesis testing exercise

24. Types of hypotheses: • Conjectural hypotheses: something that is surmised based on reasonable evidence, but that offers nothing testable. "I believe that there is intelligent life somewhere in the universe other than earth." • Explanatory hypotheses: a proposed explanation that needs to be tested. "Salmon swim up streams to breed so that predation on their young is reduced."

25. Explanations can be of three different types of claims: 1. Causal mechanisms – cause: men who take a single buffered aspirin each day have a 50% lower chance of heart attack than men who do not take aspirin.

27. Laws – When heat is applied to a container of gas, the pressure increases. Why? Guy-Lussac’s Law – If volume is held constant, the pressure exerted by a gas will vary directly with the temperature.

29. Underlying processes - A tungsten bulb is only 10% efficient, but a fluorescent bulb is 90% efficient. Tungsten filament is heated until it glows – 90% of the energy is lost as heat. Mercury vapor in an enclosed tube is energized by electrons, causing it to be absorbed by a phosphorescent coating, causing the coating to fluoresce – only 10% of the energy lost as heat.

30. Before beginning to test an explanation.... • Is there an accurate description of the phenomenon to be explained? • Are more plausible rival explanations available?

31. Occam’s Razor Given competing explanations – any of which would, if true, explain a given puzzle – we should initially opt for the explanation that itself contains the least number of puzzling notions.

32. Types of hypotheses: • Conjectural hypotheses: something that is surmised based on reasonable evidence, but that offers nothing testable. • Explanatory hypotheses: a proposed explanation that needs to be tested.

33. How to test an explanatory hypothesis • We must devise a set of experimental conditions under which something specific will occur if the hypothesis is correct but will not occur if the hypothesis is incorrect. • Therefore our test must meet two exacting criteria: • 1. It must predict what will happen if the explanation is correct • 2. It must predict what will not happen if the explanation is wrong.

34. Francesco Redi He who experiments increases knowledge. He who speculates piles error upon error. – Arabic epigraph quoted by Redi

35. Spontaneous generation of vermin?

36. Done in 1668

37. Redi’s experiment only used open and sealed jars. The jar with a screen was from a repeat of his work.