What is the Nature of Science?

1. What is the Nature of Science? What qualifies as scientific knowledge and what processes characterize the development of scientific knowledge?

2. IThere is no single set or sequence of steps that always directs a scientific investigation. There is no such thing as “the scientific method.”

3. The question of “Scientific Method” Pick up any science book. Look at the Table of Contents or the Index and you will probably find a reference to “The Scientific Method.” The “Method” may include anywhere from 4 to 7 steps that represent a procedure for investigating questions of a scientific nature. The next two slides are examples of how two different texts represent the Scientific Method.

4. The Scientific MethodAdapted from Krauskopf, K B. & Beiser, A. (2000) The Physical Universe, McGraw Hill Statement of Problem What is the question being asked of Nature? Experiment and Observation Collecting the data that bear upon the problem Testing and Interpretation Predicting the results of new experiments on the basis of the hypothesis Interpretation Explaining the data in terms of a hypothesis about how nature works

5. The Scientific Method Taken from Starr, C, & Taggart, R. (1989) Biology: The Unity and Diversity of Life, Wadsworth • 1. Ask a Question (or identify a problem). • 2. Make one or more hypotheses, or educated guesses, about what the answer (or solution) might be. • 3. Predict what the consequences might be if the hypothesis is valid • 4. Devise ways to test those predictions by making observations, developing models, or performing experiments. • 5. Repeat the tests as often as necessary to determine whether results will be consistent and as predicted • 6. Report objectively on the tests and on conclusions drawn from them • 7. Examine alternative hypotheses in the same manner.

6. WHAT DO YOU THINK? Is there really a universal way of doing science? • What similarities and differences do you see in these two presentations of the Scientific Method? • How do these presentations compare, contrast with your own ideas of the Scientific Method based on your past science experiences?

7. Is there really a universal way of doing science? Well, yes and no. There are guiding principles, but scientists study nature in a variety of ways. What you may have learned in school science as “The Scientific Method” is not necessarily the only way that scientists do science. The next two slides describe how some well known scientists have conducted their own studies.

8. Jane Goodall: An Extraordinary Life • In the summer of 1960, 26-year-old Jane Goodall arrived on the shore of Lake Tanganyika in East Africa to study the area's chimpanzee population.Although it was unheard of for a woman to venture into the wilds of the African forest, the trip meant the fulfillment of Jane Goodall's childhood dream. • At first, the Gombe chimps fled whenever they saw Jane. But she persisted, watching from a distance with binoculars, and gradually the chimps allowed her closer. • It is hard to overstate the degree to which Dr. Goodall changed and enriched the field of primatology. She defied scientific convention by giving the Gombe chimps names instead of numbers, and insisted on the validity of her observations that animals have distinct personalities, minds and emotions. She wrote of lasting chimpanzee family relationships http://janegoodall.org/jane/default.asphttp://www.rootsandshoots.org /

9. Marie Curie and the Science of Radioactivityhttp://www.aip.org/history/curie/contents.htm • Two mysterious discoveriesled Marie Curie to her life’s work. In December 1895, a German physicist, Wilhelm Roentgen, had discovered rays that could travel through solid wood or flesh. A few months later a French physicist, Henri Becquerel, discovered that minerals containing uranium also gave off rays. Roentgen’s X-rays amazed scientists, who took to studying them with great energy. They mostly ignored Becquerel’s rays, which seemed much the same, only weaker. Marie decided to investigate the uranium rays.Marie Curie started off by studying a variety of chemical compounds that contained uranium. With numerous experiments Marie confirmed Becquerel's observations that the electrical effects of uranium rays are constant, regardless of whether the uranium was solid or pulverized, pure or in a compound, wet or dry, or whether exposed to light or heat. Her study of the rays emitted by different uranium compounds also validated Becquerel's conclusion that the minerals with a higher proportion of uranium emitted the most intense rays. • She went beyond Becquerel's work, however, in forming a crucial hypothesis: the emission of rays by uranium compounds could be an atomic property of the element uranium--something built into the very structure of its atoms. • MARIE'S SIMPLE HYPOTHESIS would prove revolutionary. It would ultimately contribute to a fundamental shift in scientific understanding. At the time scientists regarded the atom--a word meaning undivided or indivisible -- as the most elementary particle

10. IIScientific knowledge, both theories and Laws is subject to change. All scientific knowledge is tentative.

11. Science knowledge is tentative • So why should I learn science if everything I learn today is going to change in the future? • First, not every thing is necessarily that tentative. Observable facts such as that the earth revolves around the sun will not change. Much of what we understand about how nature works today will remain consistent in our understanding in the future. Science will not be turned upside down in your lifetime. • But if we view scientific knowledge as proven beyond a shadow of a doubt we have no room for improving our knowledge in the future. • We need to learn (and teach) scientific knowledge as it exists today because the world in we live and decisions made in that world are based on what we know today. • To be able to participate actively in society and make personal decisions about your own life and your family’s lives you need to understand what is known today.

12. How Knowledge Changes I • Sometimes knowledge changes because new discoveries are made.

13. Marie Curies’ study of uranium led her to an hypothesis that atoms were not indivisible entities, a belief that had been considered “true” from the time of Democritus in 300 B.C. Based on research proceeding from the knowledge generated in Curies’ study today we understand that not only are atoms divided into protons, neutrons and electrons, but that even these smaller particles are composed of still smaller particles. A whole new generation of scientific knowledge is being generated in a study area of science called Quantum Theory.

14. How Knowledge Changes II • Sometimes knowledge changes because someone looks at an old problem in a new way. • This is evidenced in the development of scientific knowledge related to how the planets orbit the sun.

15. The beginning of a Theory

16. A New Approach to an Old Idea • Copernicus (1473-1543) suggested a different approach to the same problem – create a model with the sun at its center around which planets travel in circular orbits. Although it was not an accurate model because at the time it was difficult to measure speeds and positions precisely, his calculations were the beginning of change in scientific knowledge. \Invention of better instruments for measuring movements of the planets led to Tycho Brah’s (1546-1601) making records of the movement of stars and planets with great accuracy.

17. Keplar (1571-1630) took Copernicus’ idea of the sun centered solar system, and combined this idea with Brah’s data base of measurements. He found that Copernicus model did not quite fit the data and so created a new model that did fit the data in which planets traveled in elliptical orbits. All this when there were as yet no telescopes invented.

18. The Current Theory • Finally Isaac Newton (1642-1727) developed his law of gravity as an explanation for what causes the planets to move as they do in these ellipses. Using Newton’s ideas scientists have constructed our current model of the solar system • Although we currently have a pretty good understanding of how the planets move, there is still much to be learned. Today physicists and astronomers are still studying planetary movements within distant solar systems and in our own. In July 2005 a new planet was observed beyond Pluto in our own solar system and scientists are now studying its movement to see if it meets the predictions of the theory.

19. IIIScientific knowledge must be at least partially supported by empirical evidence. Scientific knowledge must involve the collection of data, be consistent with what we “know” about the world, and be testable.

20. What is Empirical Evidence? • Empirical evidence can take many forms. • Evidence may be collected from the observations we make with our naked senses of of sight, hearing, taste, touch, and smell. • Sometimes better evidence is collected using tools that aid our senses in making observations such as microscopes, telescopes, x-ray machines, MRI’s, infra-red cameras microphones and so on. • Sometimes evidence that can be expressed as a measurement is best. This evidence is collected using tools such as balances, graduated cylinders, rulers, spectrometers, chromatography instruments, and so on to make measured observations.

21. How do we know our empirical evidence is correct? • We never can be sure our observations are absolutely correct. All we can tell is whether our observations can be repeated in all similar tested cases and that others also get the same measurements when they do the same tests. • Knowledge derived from observations made with our senses and the instruments we use is only as good as the human brain is capable of interpreting. Our interpretations of optical illusions is a good demonstration that sometimes our observations fool us.

22. Optical Illusions Etc... Perceived Distance Optical Illusion Below is an optical illusion that seems simple enough. Which distance is longer? Is the distance between the tips of the first two opposing triangles pointing away from each other (A-B) on the left longer? Or is the distance between the points of the second two triangles facing each other (B-C) on the right longer Which distance (tip to tip) is longer (A-B) or (B-C)?You don't need me to tell you that it appears that the tips of the second two triangles (B-C) are further apart. It also seems that the tips of the first two triangles (A-B) are closer together.If it was that easy though this image wouldn't be here would it? The truth is that the distance between the two sets (A-B) and (B-C) are exactly the same

23. IV Scientific knowledge is partially the product of the creative imagination of the scientists. All scientific knowledge combines both empirical evidence and the creative interpretation of data by scientists.

24. Marie Curie’s hypothesis that the behavior of uranium rays occurred because uranium atoms were made of several particles rather than being indivisible was a new idea. She imagined a new way of interpreting the data that others before her had not considered. Her ideas sparked a whole new field of research. Jane Goodall interacted with chimpanzees in the wild to try to develop new understandings of their behavior. Previously chimp behavior had only been studied in zoos or preserves where natural activity was inhibited. She imagined a new way of conducting research on these animals that generated new knowledge.

25. VGiven the importance of scientists’ individual creativity, scientific knowledge is necessarily subjective to some degree. Scientific knowledge is not totally objective as is commonly believed.

26. Ethical scientists do not interpret data based on personal bias (they don’t try to manipulate data to support their hypothesis), but because they design experiments and interpret their data based on what they already know, their cultural background and their previous experiences their designs and interpretations are limited by their own existing knowledge. • Knowledge of the world around us is not “out there” waiting to be discovered. What becomes “scientific knowledge” depends on what questions the scientist decides to ask, how he or she decides to investigate the questions, the inferences he or she makes from the data, and all are influenced by the prior knowledge and sensory limitations of the individual scientist. • Because the generation of scientific knowledge is a human endeavor it must be to some degree subjective. We will never know what the world is really like, all we can know is our interpretation of it based on careful observation or experimentation, and the inferences we construct from empirical data.

27. VIScientific knowledge is a product of both observation and inference.

28. You have learned that atoms are constructed of protons, neutrons and electrons. Yet no one has ever observed an atom much less a proton or an electron. The scientific knowledge we have that these particles do exist is founded on inferences we make about atoms based on observations and measurements of chemical reactions and radioactivity, and because we can photograph “tracks” in fog made by particles when atoms are smashed in accelerators. From these and other observations we infer that these particles do exist. These inferences are part of our current scientific knowledge about atoms.

29. Time to ReflectWhat is your personal understanding of the Nature of Science? What do you believe about What scientists do when they do science? How knowledge about the natural world is generated? The relationship between the process of doing science and the knowledge that is generated by that process? How you should teach children science?