Scientific method

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What do you see in the photograph?

http://biology.clc.uc.edu/courses/bio104/sci_meth.htm

– Is there a spider hiding under here?– Somebody up above must have dropped this banana.– Something left droppings in this bird bath

• If you were really in that place and trying to figure out what you were seeing,you could use the scientific method to study the “problem. Think about whatyou might do, what steps you might follow, to test your idea to see if it’s right.”

• For centuries, people based their beliefs on their interpretations of what they saw going on in the world around them without testing their ideas to determine the validity of these theories — in other words, they didn’t use the scientific method to arrive at answers to their questions. Rather, their conclusions were based on untested observations.

Spontaneous generation?

• Among these ideas, since at least the time of Aristotle (4th Century BC), people (including scientists) believed that simple living organisms could come into being by spontaneous generation. This was the idea that non-living objects can give rise to living organisms. It was common “knowledge” that simple organisms like worms, beetles, frogs, amd salamanders could come from dust, mud, etc., and food left out, quickly “swarmed” with life. For example:

Right conclusions?

• Observation: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times.

• “Conclusion”: It was perfectly obvious to people back then that muddy soil gave rise to the frogs.

Right conclusions?

• Observation: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs (like Shakespeare’s house). As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and of course there were lots of mice around.

• “Conclusion”: It was obvious to them that the mice came from the moldy grain.

Right conclusions?• Observation: In the cities, there were no sewers nor garbage

trucks. Sewage flowed in the gutters along the streets, and the sidewalks were raised above the streets to give people a place to walk. In the intersections, raised stepping stones were strategically placed to allow pedestrians to cross the intersection, yet were spaced such that carriage wheels could pass between them. In the morning, the contents of the chamber pots were tossed out the nearest window. When people were done eating a meal, the bones were tossed out the window, too. A chivalrous gentleman always walked closest to the street when escorting a woman, so if a horse and carriage came by and splashed up this filth, it would land on him, and not the lady’s expensive silk gown. Most of these cities also had major rat problems which contributed to the spread of Bubonic Plague (Black Death) — hence the story of the Pied Piper of Hamelin, Germany.

• “Conclusion”: Obviously, all the sewage and garbage turned into the rats.

Right conclusions?

• Observation: Since there were no refrigerators, the mandatory, daily trip to the butcher shop, especially in summer, meant battling the flies around the carcasses. Typically, carcasses were “hung by their heels,” and customers selected which chunk the butcher would carve off for them.

• “Conclusion”: Obviously, the rotting meat that had been hanging in the sun all day was the source of the flies.

Right conclusions?• From this came a number of

interesting recipes, such as:

• Recipe for bees: Kill a young bull, and bury it in an upright position so that its horns protrude from the ground. After a month, a swarm of bees will fly out of the corpse.

• Jan Baptista van Helmont’s recipe for mice: Place a dirty shirt or some rags in an open pot or barrel containing a few grains of wheat or some wheat bran, and in 21 days, mice will appear. There will be adult males and females present, and they will be capable of mating and reproducing more mice

Right conclusions?• With the development and refinement of the

microscope in the 1600s, people began seeing all sorts of new life forms such as yeast and other fungi, bacteria, and various protists. No one knew from where these organisms came, but people figured out they were associated with things like spoiled broth. This seemed to add new evidence to the idea of spontaneous generation — it seemed perfectly logical that these minute organisms should arise spontaneously. When Jean Baptiste Lamarck proposed his theory of evolution, to reconcile his ideas with Aristotle’s Scala naturae, he proposed that as creatures strive for greater perfection, thus move up the “ladder,” new organisms arise by spontaneous generation to fill the vacated places on the lower rungs.

Is this an artistic or a scientific drawing?

Look at this series of photographs!

• Needham's Science and Civilization in China uses the 'flying gallop' image as an example of observation bias: In these images, the legs of a galloping horse are shown splayed, while the first stop-action pictures of a horse's gallop by Eadweard Muybridge showed this to be false. In a horse's gallop, at the moment that no hoof touches the ground, a horse's legs are gathered together—not splayed. Earlier paintings show an incorrect flying gallop observation.

What is Scientific Method?• Scientific method refers to a

body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge.

• To be termed scientific, a method of inquiry must be based on gathering empirical and measurable evidence subject to specific principles of reasoning

What is Scientific Method?• The Oxford English

Dictionary says that scientific method is: "a method of procedure that has characterized natural science since the 17th century, consisting in – systematic observation,

– measurement, and

– experiment, and the

– formulation, testing, and modification of hypotheses."

Scientific Method Steps

Scientific Method Steps• A linearized, pragmatic scheme of the four points above is

sometimes offered as a guideline for proceeding:1. Define / Ask a question 2. Gather information and resources (Observe & Research) 3. Form / Construct an explanatory hypothesis 4. Perform an experiment and collect data, testing the

hypothesis 5. Analyze the data. Interpret the data and draw conclusions

that serve as a starting point for new hypothesis 6. Publish / Report results 7. Retest (frequently done by other scientists)

http://www.sciencebuddies.org/science-fair-projects/project_scientific_method.shtml

01 Ask a Question

• The scientific method starts when you ask a question about something that you observe: How, What, When, Who, Which, Why, or Where?

• And, in order for the scientific method to answer the question it must be about something that you can measure, preferably with a number.

02 Do Background Research:

• Rather than starting from scratch in putting together a plan for answering your question, you want to be a savvy scientist using library and Internet research to help you find the best way to do things and insure that you don't repeat mistakes from the past.

03 Construct a Hypothesis

• A hypothesis is an educated guess about how things work:"If _____[I do this] _____, then _____[this]_____ will happen."

• You must state your hypothesis in a way that you can easily measure, and of course, your hypothesis should be constructed in a way to help you answer your original question.

04 Test Your Hypothesis by Doing an Experiment

• Your experiment tests whether your hypothesis is true or false. It is important for your experiment to be a fair test.

• You conduct a fair test by making sure that you change only one factor at a time while keeping all other conditions the same.

• You should also repeat your experiments several times to make sure that the first results weren't just an accident.

05 Analyze Your Data & Draw a Conclusion

• Once your experiment is complete, you collect your measurements and analyze them to see if your hypothesis is true or false.

• Scientists often find that their hypothesis was false, and in such cases they will construct a new hypothesis starting the entire process of the scientific method over again.

• Even if they find that their hypothesis was true, they may want to test it again in a new way.

06 Communicate Your Results

• To complete your science fair project you will communicate your results to others in a final report and/or a display board.

• Professional scientists do almost exactly the same thing by publishing their final report in a scientific journal or by presenting their results on a poster at a scientific meeting.

Homework: Which falls faster?

• Design an experiment to determine which falls faster, an unfolded sheet of paper, a sheet of paper folded in fourths, or a crumpled sheet of paper.

• Be sure to develop a hypothesis, design a controlled experiment, and collect data.

• Do your data support your hypothesis?

• Discuss your results with your team.

The beginning of Scientific Method: A little of story

Additional material

The beginning of Scientific Method

• In contrast to just guessing based on simple observations, what may well be the first recorded use of the scientific method to conduct an experiment occurred in about 587 bce. To give a bit of background and put this in historical perspective, in that year, the Babylonians under Nebuchadnezzar won a victory over the kingdom of Judah, and the people of Judah were incorporated into the Babylonian empire — or at least that was the Babylonian plan. One of the reasons the Babylonians were such a successful world power is that it was their policy that whenever they conquored another nation, they did away with those people’s cultural identity by assimilating/absorbing those people into their own culture.

The beginning of Scientific Method

• Some of the newly-conquored people were forced to migrate to other areas of the Babylonian empire, including Babylon itself, while people from other areas of the Babylonian empire were sent to live and mingle with those of the newly-conquored people who were left behind. Young male relatives of the conquored ruling family were often taken to King Nebuchadnezzar’s palace in Babylon, where they were taught Babylonian history, culture, language, and astrology/science, and in general, assimilated into the lower ranks of Babylonian royalty, serving in various roles within the palace. As part of this assimilation process, these young men were also fed the rich food that was the typical diet in Nebuchadnezzar’s palace.

The beginning of Scientific Method

• However, in the case of the newly-conquored Judeans, unlike the other cultures which Babylon had conquored, the plan did not work, and the Judeans found ways to maintain their own cultural heritage despite the attempted assimilation. The story is told of four young Judean noblemen whose Hebrew names were Daniel, Hananiah, Mishael, and Azariah, who were given new, Babylonian names of Belteshazzar, Shadrach, Meshach, and Abednego, respectively, and who were brought into Nebuchadnezzar’s palace.

The beginning of Scientific Method

• Determined to not eat anything that was not in accord with the dietary rules of Judean religious culture, they requested that they be given a vegetarian diet. However, the palace official in charge of them was skeptical of their request, knowing that if they began to look less robust and healthy than the young men from other cultures who were also in training, he would be killed for not taking good care of them. Daniel suggested that they try an experiment. He asked that for ten days, the four of them be fed a vegetarian diet, and at the end of that time, be compared with the other young men to see who looked healthier

The beginning of Scientific Method

• Question: – Will eating a vegetarian diet make us unhealthy?

• Hypothesis: – Eating a vegetarian diet is healthy (or as health as or more

healthy than a rich-food diet). • Prediction:

– After eating a vegetarian diet for ten days, we will look at least as healthy by visual examination, if not healthier, than those who consume a diet of rich foods.

• Testing: – For ten days, we will eat a vegetarian diet, while the other young

men eat their normal rich-food diet. They are, thus, the control group, and the four of us are the experimental group. Because there are four of us, that both makes us a true group and makes sure there is adequate replication in this experiment.

The beginning of Scientific Method

• Data: – Here, by our modern standards, the experiment is a bit weak. All

that is specified, data-wise is a general physical inspection at the end of the ten days to see who, subjectively, looks the most robust. Now, we would expect some concrete, numerical data to be gathered, perhaps weight, blood pressure, pulse, etc., and averages calculated for each group. However, in 587 bce, sphygmomanometers and stethoscopes hadn’t been invented, yet, so they did the best they could with the tools they had available. Based on the physical inspection at the end of the ten days, the “data” were that the four Judean young men appeared “healthier and better nourished” (Dan. 1:15) than those who had consumed the rich-food diet.

• Conclusion: – Based on the data (the observed differences in appearance), it was

concluded that not only was the vegetarian diet not harmful to their health, but that, in fact, it made them healthier than those in the control group, and thus it was not only safe but advantageous to continue feeding them the vegetarian diet they had requested.