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In this lesson, we will review what science encompasses, how it works, and cover some of the diversity of its fields, spanning all human knowledge.
The word science comes from a Latin word that means, “to know.” However, science is more than just a collection of facts and knowledge. It is the method of observing nature and the universe, and of testing explanations for how and why things are the way they are. Scientists search for the truth. They try to uncover facts and get a better understanding of the natural world and how its parts are interrelated. Scientific knowledge and understanding are built on the principle that the universe can be explained in terms of cause and effect. Although there are many definitions of science, only two are useful in our modern understanding: empiricism and realism. According to empirical philosophy, scientific theories are objective, testable, and predictive of results that can be checked and possibly falsified through proper experimentation. On the other hand, scientific realism is more akin to identifying objects and processes; their causes, constituents, or origins; and the manner in which the causes or origins work. In short, empiricism is more about asking questions about reality; realism is more about identifying structure and cause. It may seem to be a subtle difference and the two are tightly linked in an everyday-real-world definition of science.
An important philosopher of science, Karl Popper, argued that verification is impossible in science and that scientific hypotheses can only be falsified. Thomas Kuhn also stated that human bias taints all observations with preconceptions that are based on the current paradigm. Kuhn argued that science involves paradigms and assumptions, and that scientific progress is mainly gained through the falsification or modification of paradigms. He also stated that the emergence of newer and more powerful paradigms occurred in a cycle that never ends. Kuhn pointed out that science has never historically proceeded as a steady accumulation of facts, but as a series of dramatic (and sometimes cataclysmic) paradigm shifts that precipitate scientific revolution.
There are no arbitrary decisions that control our lives. Storms occur not because of angry supernatural beings, but rather because a certain amount of energy from the sun has heated parts of Earth more than others. Energy flows between these places in a predictable way that follows natural laws. This flow of energy causes the storms and other atmospheric phenomena. We employ science as a powerful tool; observations are used to make predictions about how the universe works. Almost every part of our daily lives is based on scientific knowledge and its applications.
Because science covers a lot of conceptual ground people separate it into different branches of knowledge. The term branches might indicate that the fields of science can be shown in a tree-like diagram. However, as our storehouses of knowledge expand, a web of knowledge may display science more accurately. No matter how you prefer to visualize the complexity of science, you should realize that all of scientific progress is interrelated and there are no isolated disciplines within science — everything is connected.
Broad fields of scientific study include:
Most scientific investigations do not fall strictly within one of these classifications. There is tremendous overlap and interconnection among them. Within and between these broad fields, there are many other classifications of science. These include fields such as biochemistry and geophysics, that combine concepts from two or more of the broad fields. Others, for example, botany and organic chemistry, are specialties within one of the broad fields. In addition, the principles of science are used by sociologists, economists, psychologists, and others who study human behavior. The main idea to remember is that science is a process that encompasses the whole range of causes and effects in the natural world and our systematic attempts to understand it all.
Science is
The correct answer is B. Science is a method for learning about the universe. It is more than data or a list of subjects.
All of us know what a stereotypical “mad scientist” is. You may have pictured such a person as a middle-aged, white male with an indeterminate European accent, glasses, a beard, bad haircut, and a somewhat rumpled white lab coat. Like most stereotypes, this stereotype is far removed from reality. Science is a worldwide undertaking that involves people of all types, colors, and creeds doing many different kinds of jobs. Although many scientists work in laboratories, the settings for scientific research are diverse. Engineers, teachers, computer scientists, doctors, nurses, farmers, and even cooks do scientific research every day. Some scientific fields, such as astronomy, actively encourage amateur observers to contribute their data, observations, and interpretations. The bottom line is that anyone can perform scientific work.
Scientific research has several purposes. In its most basic form, science is the search for greater understanding. People are curious about how things work, why the sky is blue, and whether it will rain tomorrow. Science also has a practical aspect, known as technology. Technology is the application of scientific knowledge to solve practical problems. Farmers, for example, use a wide variety of technologies to produce food. After early farmers observed that certain seeds grew better when the soil was loosened, they applied this knowledge to the design of the plow. Modern farm equipment now includes global positioning systems to help control precise application of fertilizer, water, and pesticides.
Modern technologies are built on the results of past scientific research that have occurred over many thousands of years. Think about all of the knowledge that went into building your car, for example. Building an engine requires an understanding of the chemistry of fuel combustion and of the materials that can handle the heat generated by internal combustion. Brakes are designed to distribute massive forces of a thousand-kilogram auto body moving at high speeds. Safety systems apply the results of biological investigations to prevent damage to human bodies during an accident. Even the process of designing an appealing shape uses the scientific study of aerodynamics and human aesthetics.
In this lesson, we will review the ethical traditions of science and the ways that scientists work to assure reliability in their investigations.
Science is a method of learning about the universe, not just a collection of facts.
Science covers and is largely responsible for the entire range of human knowledge. This diversity can be thought of as an interconnected web or as a tree of knowledge with various branches.
Technology is the application of scientific knowledge to solve practical problems.
Because science is based on relationships between causes and effects in nature, an experiment performed under the same conditions will always yield the same results. This is the basic assumption on which all scientific investigations and scientific knowledge are built. Reproducibility of results is the core of science; while exact data will undoubtedly be slightly different, the results should be the same and show the same conclusions. When scientists report their findings to the scientific community, there is a process called peer review that entails other scientists looking at their methods and determining if their results are reproducible.
The reliability of scientific results is based on researchers following a code of ethical behavior. Elements of this code include:
Accurately recording and reporting results is necessary so that an experiment can be repeated in exactly the same way by anyone. Scientific research depends on careful documentation so independent researchers can reproduce the experiment. When results are not reproducible, they cannot be accepted by the scientific community. This happened in 1989 when the results of a now-famous “cold fusion” experiment were announced. The potential new source of energy received wide coverage in the press, but when other scientists attempted to reproduce the results from the experiment, they obtained entirely different results. What happened? No one is sure exactly why the cold fusion results were not reproducible. There may have been a problem with the experimental design that was overlooked. Perhaps a second independent variable was introduced or some condition was not controlled, so that the exact procedure could not be determined. Whatever the cause of the error, the results have not been accepted as valid because they are not reproducible. Needless to say, this did nothing positive for the professional integrity of the scientists involved.
It is also important that all results be reported. Sometimes an experiment produces data that are not expected or appear to be inconsistent with earlier data. These inconsistencies must be recorded and analyzed just like all the rest of the data. Frequently, unexpected data leads to new questions and research directions. As a result, it is important to accurately record the exact methods used and all data obtained in an experiment. Scientists generally report their results at conferences or in scientific journals that are reviewed by other scientists. One of the problems encountered by the cold fusion researchers was that results were released to the general media prior to review by other scientists.
Perhaps the most important ethical consideration in scientific research is to avoid influencing, or biasing, the results of an experiment. Bias is the often inextricable quality of affecting the results of your experiments. Results are often skewed by the expectations of the scientists to a particular outcome. Bias can be as innocuous as accidentally avoiding running experiments when it is cold outside, but also include the blatant changing of recorded data to obtain the expected or desired result. The latter case constitutes fraud and it is a very serious breach of scientific ethics. Often times, however, bias is more subtle. If the experimenter expects a particular result, he or she may tend to accept results that support the result and reject results that do not, perhaps without any conscious realization of having done so. The design of many medical experiments prevents bias by using a “double-blind” technique. Because the results can be influenced by an expectation that a drug will work, neither the patients nor the doctors know which patients receive the real drug being tested. Because of an effect broadly termed Heisenberg’s Uncertainty Principle (first developed in attempting to measure the location of electrons), we know now that there is ALWAYS bias in all human endeavors, but scientists try to minimize this bias. It is not always an easy task.
In this lesson, you will learn:
A key part of any scientific investigation is the hypothesis – a possible explanation for a phenomenon that can be tested. A hypothesis is sometimes referred to as an educated guess, but it is actually more than that—it is a tentative explanation for something that has been observed. In the early 1600s, most people believed that all celestial bodies revolved around Earth. Nicolas Copernicus carefully observed the motions of the planets and formulated a hypothesis that the sun, not Earth, was the center of the Solar System—a heliocentric system. His hypothesis, or possible explanation, was based on observations. Of course, not everyone was immediately convinced. Other explanations of the motions of stars and planets already existed. More observations and data were needed. One observation that supported the heliocentric hypothesis was that the planets sometimes appear brighter and sometimes dimmer. The relative positions of the sun, the planets, and the Earth change in different ways in a heliocentric system than in a geocentric system and the observed patterns of brightness also corresponded to a heliocentric system. The fundamental change from a geocentric universe to a heliocentric solar system was a paradigm shift that brought a scientific revolution.
A hypothesis is useful for a scientific investigation if it has certain features. First, it must make a prediction that can be tested. How does Copernicus’s heliocentric universe stack up to this requirement? He could predict the positions of the planets far into the future (that could be falsified) and later observations supported the hypothesis. Second, the hypothesis must be falsifiable. If the hypothesis is not correct, there are tests or experiments that will show it to be incorrect. If the motion of the celestial bodies is not consistent with the hypothesis, it can be shown to be incorrect. In fact, parts of the Copernican hypothesis (that planets move in uniform circular motions around the sun) were later falsified. The observed motions of the planets are not consistent with these circular orbits; planets actually move in elliptical orbits around the sun. The Copernican hypothesis, although not completely correct, eventually led to an understanding of the solar system that allowed people to walk on the moon and robots to explore Mars.
Science is based on testable hypotheses, using the scientific method, and always questioning the status quo. Pseudoscientific fields, such as astrology, fortune telling, therapeutic touch, Intelligent Design, and studies of UFOs are generally built on a foundation of hypotheses that are not falsifiable or based on beliefs, not hypotheses. When the observations support the “hypothesis,” they are presented as proof. When they do not, there is always an explanation—which cannot be tested. This is not science and there is no confusion about what is and what is not scientific.
Check your understanding of hypotheses.
Which of the following could be a scientific hypothesis?
The best answer is C. Choice C makes a prediction that can be tested. It can also be falsified, if cats are demonstrated to have hearing that is as good as, or better than that of dogs. Choice D is not falsifiable because there is no way to prove that I don’t know what my dog is thinking. (You can ask him, but he won’t answer. He only communicates with me.) Choices A and B do not make testable predictions.
Forming a hypothesis is only one step of the scientific method.
The hypothesis is a tentative explanation, but it is not really useful until there are data to support it. Using a prediction based on your hypothesis, you can design an experiment to test the prediction. An experiment is a set of controlled tests and observations of the results that determine whether the prediction is correct. Although an experiment can show that you were unable to disprove the hypothesis, you can never truly verify hypotheses beyond further testability. In other words, the best you can do in scientific inquiry is to NOT refute hypotheses. Skepticism always remains and empowers science to achieve hypotheses that can later become theories and perhaps even laws. More on those later.
The experiment must be designed to actually test the hypothesis, providing an answer that will support it or disprove it. For example, how can you design an experiment to test a hypothesis showing that a species of small mammals are equally likely to eat sunflower seeds and thistle seeds? If you place only thistle seeds in a feeder and count the number of small mammals that eat them, your data does not test the hypothesis. What if no small mammals show up? That could either mean that small mammals do not like thistle seeds or, perhaps, that there are no small mammals in the area. In addition, it provides no data about whether they eat sunflower seeds. However, if you place two identical feeders side by side, one holding sunflower seeds and the other holding thistle seeds, and there are small mammals in the area, your experiment can test the hypothesis. If the small mammals spend equal time at the two feeders, the hypothesis is supported. Keep in mind that a single test does not prove the hypothesis to be true. If no small mammals arrive at either feeder, you still do not have useful data, because there are several possible explanations for the observation that do not have anything to do with your hypothesis. On the other hand, if all the small mammals go wild over the sunflower seeds and ignore the thistle seeds altogether, the hypothesis is not supported by the observations.
Which observation supports the hypothesis that fire ants produce a substance that is harmful to humans?
The Correct Answer is C. The hypothesis predicts some kind of adverse reaction, so observation C supports the hypothesis. Choices A and B are observations that are unrelated to toxicity. There are nontoxic red insects. Although people may be afraid of fire ants because they inflict pain, the fear itself is not evidence of toxicity. In fact, many people are afraid of insects that do not produce toxins.
An experiment must produce unambiguous results. You can accomplish this by designing the test so that only one variable is changed at a time. Let’s go back to the birds and their seeds. Notice that the paragraph above refers to placing different types of seed in two identical feeders. Why is the word “identical” italicized? There must be some reason for the emphasis. Well, what if you placed the sunflower seeds in a platform feeder and the thistle seeds in a tube feeder? Now you observe the small mammals eating sunflower seeds, but you still don’t have support for the hypothesis. Why? It’s possible that the animals don’t have a preference for one seed over the other, but instead, a preference for one type of feeder over the other. The experiment doesn’t test the hypothesis because two variables were changed. One change — the type of seed — tests the hypothesis. The other variable — the type of feeder — does not. You don’t know whether your experimental results are because of one change or the other or both.
The table below shows some examples in which an independent variable — a factor that is controlled by the experimenter — affects the dependent variable — a factor that changes in response to changes of the independent variable.
| Experiment | Independent Variable | Dependent Variable |
|---|---|---|
| How does temperature affect the reaction rate of a chemical reaction? | temperature | amount of reaction product forms in a given time period |
| How is the parent eye color related to offspring eye color in fruit flies? | color of parents’ eyes | ratio of eye colors in offspring |
| How is the speed of an electric motor affected by the voltage? | voltage | motor speed |
| Which direction are tectonic plates moving? | direction of magnetic poles | orientation of magnetic materials in rock as it forms |
| How does the mass of an object affect the rate at which it falls? | object mass | amount of time to fall a given distance |
| Do all metals absorb light energy at the same rate? | type of metal | temperature of metal after a given period of exposure to sunlight |
In well designed experiments, all factors, except the independent variable, should be identical in each test. For example, to test the prediction that plants grow bigger if they have more light, expose several plants to different amounts of light (independent variable) and measure growth (dependent variable). Other parameters, such as temperature, water, and fertilizer, must be the same for each plant in order to ensure that the change in the growth rate is a result of the difference in the amount of light. These factors are the controlled variables. In the small mammal feeding experiment, identical feeders were chosen — a controlled variable.
Which of these sets of variables could be used in an experiment to test the hypothesis that different metals absorb different amounts of energy from sunlight?
The correct answer is C. Because you want to determine the effect on different type of metals, your independent variable (the one you change) is the type of metal. The effect on the dependent variable tests your hypothesis. The temperature of the metal is related to energy absorption. Other variable, such as type and amount of lighting and the size of the metal pieces must be controlled.
After data are collected, the results of the test are analyzed to reach a conclusion. The conclusion may be that the experiment supports the hypothesis because the prediction is unable to be refuted. Keep in mind that this does not prove the hypothesis—it only shows that the hypothesis is not NOT true (that it might be true). An interesting thing about experiments is that the results often don’t match the prediction and that’s not necessarily a bad thing. The data are still useful. The scientific method is a cycle, not a linear progression. When the data do not match the hypothesis, you modify or replace your hypothesis and design a new experiment. What will you do if all of the small mammals flock to the sunflower seeds? Time for a new hypothesis: small mammals prefer sunflower seeds to thistle seeds.
Frequently an investigation not only tests the hypothesis, but leads to new questions and further investigations. While observing the small mammals, you may have noticed that the thistle feeder attracts birds. Why does one type of bird prefer one food and another prefer a different food? There may be a new hypothesis and series of experiments just waiting for the right scientist.
How does the scientific method work?
The correct Answer is D. The scientific method is based on the testing of falsifiable hypotheses that are based on observations. If these hypotheses are shown to be untrue, new hypotheses are developed and tested. When hypotheses are unable to be refuted, they are tested in new experiments. Although we commonly assume some very well known hypotheses, they can never strictly be proven.