Science: Exploring the World Through Systematic Study

Science Browse the article Science

Introduction to Science

Science, the systematic and unbiased study of the world, including everything that can be seen or detected in nature, man, and society, together with the knowledge that grows out of such study. The word science comes from the Latin scientia, meaning "knowledge."

Scientists try to understand, explain, and predict the way in which everything in the world behaves or acts. In pursuing this goal, they study objects, forces, and events as varied as stars, atoms, microorganisms, earthquakes, climate, chemical reactions, magnetic forces, social groups, and human attitudes.

Science has had a profound impact on daily life. The knowledge scientists accumulate about nature, or the physical world, is used to produce tools and machines and to develop technology for agriculture, medicine, manufacturing, communication, transportation, construction, mining, lumbering, and fishing. Scientific findings about human society and behavior influence the methods used in rearing children, teaching students, and treating the mentally ill.

The scientist's method of inquiry, called the scientific method, is what most distinguishes science from other fields of learning, such as philosophy, literature, and the fine arts. In general, the scientific method involves the following steps: state a problem to be solved; collect pertinent data (information) in an objective way; form one or more hypotheses (trial interpretations or explanations); test the most likely hypotheses through objective observation and experimentation; and form a conclusion. The scientific method is discussed in more detail later in this article.

The scientific method is somewhat harder to follow in the study of human society and behavior than in the study of nature. For example, it is generally more difficult to be unbiased in studying social phenomena, such as marriage or suicide, than in studying physical phenomena, such as rocks or plant diseases. Also, it is usually more difficult to perform experiments involving human beings than experiments involving animals, plants, or nonliving matter.

The difficulties involved in following the scientific method in studying human society and behavior have led some scholars to believe that such studies are less scientific than the study of the physical world. However, other scholars believe that these difficulties can be overcome and that both areas of study are equally scientific.

Classifications

Classification By Subject Matter

The sciences are divided into two main groups—the natural sciences, which deal with nature, or the physical world; and the social sciences, which study human society and behavior, or the social world. The natural sciences, in turn, can be subdivided into the physical sciences, studies concerned with nonliving matter; and the biological, or life, sciences, studies dealing with living matter. Each of these subdivisions is in turn divided into various branches with a number of specialized areas of study.

The physical sciences include such areas of study as physics, chemistry, engineering, astronomy, geology, oceanography, and meteorology. A grouping within the physical sciences, the earth sciences, is made up of geology, oceanography, meteorology, and those parts of astronomy, engineering, and other fields that deal with the earth as a physical object. (Mathematics was formerly regarded as a physical science but is now usually regarded as a tool of science, rather than a science.)

The biological sciences include such fields as botany, zoology, physiology, medicine, forestry, genetics, agronomy, and animal husbandry.

Included within the social sciences are sociology, economics, education, and political science. History is sometimes classed as a social science, sometimes as one of the humanities.

Anthropology, geography, and psychology deal with both physical and social facts. Physical anthropology, physical geography, and physiological psychology are usually called natural sciences. Cultural anthropology, human geography, and the nonphysiological fields of psychology are classed as social sciences.

Another grouping, the behavioral sciences, is made up of major portions of sociology, anthropology, and psychology, and the areas of political science, economics, geography, biology, law, and other fields specifically concerned with human behavior.

Classification By Purpose

When scientists attempt to solve specific problems in order to discover facts of practical use, they are practicing applied science. Examples of applied sciences are engineering, medicine, forestry, and animal husbandry.

Studies that are undertaken to discover facts without regard to their immediate usefulness or value are called pure, or basic, science. Examples of pure sciences are physics, physiology, botany, and zoology. Much of pure science is motivated by scientific curiosity alone. However useless or unrelated to immediate problems pure scientific research may seem to be, scientists recognize that all scientific development is ultimately based on such far-reaching and imaginative studies.

Scientific Method

The scientific method is not a specific set of rules for discovering new scientific knowledge. Rather, it is the general procedure that scientists usually follow.

Stating A Problem

The first step in scientific inquiry is to state a problem, usually by asking a clear, answerable question about physical or social events. The more specific the question, the better the chance of finding an answer. For example, it may be difficult, if not impossible, to answer a broad question such as "What causes juvenile delinquency?" because delinquent behavior seems to be produced by many interacting factors (for example, family relationships, attitudes of friends, level of education, age, social class, size of community). However, it may be possible to answer a narrower question such as "Does the size of a community affect its rate of juvenile delinquency?"

Collecting Data

The second step in scientific inquiry is to collect pertinent data through observation or measurement, or both. Whenever possible, the scientist observes and measures things directly. Such instruments as magnifying glasses or electron microscopes assist scientists in making observations. Many times, however, scientists wish to study things that cannot be seen, such as sound, electricity, atmospheric pressure, human opinions, or attitudes. They then must use instruments that detect the presence of the phenomenon and measure its strength. A physicist, for example, can measure atmospheric pressure with a barometer. A sociologist can gauge public opinion on a subject by asking people carefully worded questions.

Forming Hypotheses

After collecting data, scientists analyze it and form one or more hypotheses about the problem. (In practice, they may be forming hypotheses while they are collecting data.) A hypothesis may be extremely simple and limited. For example, a botany student may measure the length of 100 pin oak leaves and form the hypothesis that all pin oak leaves are three to five inches (8 to 13 cm) in length. A hypothesis may also be broad and complex. For example, the hypothesis that the earth's surface is divided into sections that move in relation to each other helps explain earthquakes, volcanoes, and many other geological phenomena.

In forming a hypothesis, the scientist uses inductive reasoning. Induction is the process of deriving a general, all-encompassing statement from a limited number of particular facts. There is no set procedure for reasoning inductively, and persons vary greatly in their ability to construct useful inductive statements. Successful induction depends upon creative individual insight.

Testing Hypotheses

After a hypothesis is formed, scientists test it. First they determine the consequences of the hypothesis by deductive reasoning. Deduction is the process of drawing particular conclusions from a general, all-encompassing statement. For example, from the hypothesis "All contagious diseases are caused by microorganisms" it might be deduced that "Chicken pox is caused by a microorganism." Scientists test such a hypothesis by making observations or conducting experiments.

Scientists usually follow one of two basic approaches. In one approach, they form deductions about what events should occur and then see if they actually do occur. The occurrence of a deduced consequence provides support for the hypothesis; however, if a supposed consequence does not occur, either the deduction or the hypothesis is incorrect, and has to be changed or rejected.

In the second approach, scientists form deductions about what events should not occur and then see if such events actually do occur. If a deduced impossibility occurs, either the deduction or the hypothesis is incorrect. Repeated failures to disprove a hypothesis, however, only serve to strengthen that hypothesis.

To determine whether or not a supposed event occurs, the scientist uses observation or, more often, experimentation, deliberately manipulating conditions in order to observe what happens. Designing a valid experiment is often the most difficult part of testing a hypothesis. Most experiments are based on the so-called classic experimental design. At the start of a classic experiment, two groups of subjects as identical as possible are set up, and the members of each group are measured for some characteristic. Then one group, called the experimental group, receives the chosen treatment. The other group, called the control group, is left untreated. Afterwards, both groups are re-measured. Any difference in measurement between the experimental and control groups can be attributed to the effect of the chosen treatment.

For example, to determine the effect of fertilizer on plant growth by a classic experiment, scientists might use two groups of seedlings sprouted from the same kind of seeds. First, they would measure the height of each plant. Then they fertilize the seedlings of only one group, while keeping other conditions for both groups constant—that is, making certain each group received the same amount of light, water, etc. After a period of time, they would again measure the height of each plant. The scientists could then attribute differences in height between the plants of one group and the plants of the other group to the application of the fertilizer.

Forming A Conclusion

Depending on the results of observations and experiments, scientists accept, reject, or change their hypotheses. When they believe they have developed a valid new hypothesis, they report it to scientific colleagues through scientific journals. Other scientists, in turn, can perform the same experiments to test their validity and can develop new experiments to further test the hypothesis.

Once adequately tested by the scientific community, the hypothesis may be accepted as a theory, a probable explanation or interpretation. Theories that have stood extensive tests are sometimes referred to as laws. Because of the complexity of natural and social phenomena, and the inductive nature of science, scientific laws are not regarded as absolutely true statements. Rather, they are viewed as approximations of the truth or limited representations of reality that will be changed, extended, and improved as more scientific knowledge is discovered.

History

In ancient and medieval times, people sought scientific knowledge by two different methods that were only partly scientific. Craftsmen and artisans used trial-and-error experimentation to find out about natural events and objects. For example, in ancient Egypt they learned through trial and error how to form a right angle. They divided a rope into 12 equal units and then laid out the rope in the shape of a triangle with sides of 3, 4, and 5 units; the angle between the 3-unit side and the 4-unit side was then a right angle. Craftsmen and artisans used their knowledge for such practical purposes as surveying fields or designing tools, but they did not try to form general conclusions that could be used to solve new problems.

Philosophers, on the other hand, sought general knowledge about the world and the human race. Although philosophers sometimes observed nature and experimented, they generally formed their conclusions by reasoning deductively from assumed premises—by speculation alone. The ancient Greek philosopher Aristotle, for example, made observations in biology, but he used the deductive method of inquiry in physics and astronomy. Like other philosophers who used deduction, Aristotle arrived at many false conclusions because many of his premises were wrong. For example, he accepted the false premise that a heavy object always falls faster than a light object. The quest of philosophers for an understanding of nature was called natural philosophy.

During the Middle Ages, craftsmen and artisans continued to seek knowledge by trial-and-error experimentation. Muslim scholars continued to speculate about nature, frequently combining speculation with observation and experimentation. By contrast, scholars in Christian Europe devoted themselves to theology and largely neglected natural philosophy. In the 13th century, Aristotle's writings, including those on nature, gained acceptance and Christian scholars settled questions about nature by relying on the authority of Aristotle instead of by looking at nature.

Highlights in the history of sciencec. 400 B.C. Hippocrates taught that diseases have natural causes.c. 300 B.C. Euclid organized geometry as a single system of mathematics.200's B.C. Archimedes discovered the laws of the lever and the pulley.A.D. 100's Ptolemy proposed that the earth is the center of the universe.A.D. 100's Galen developed the first medical theories based on experiments.800's and 900's Arab scientists mapped the heavenly bodies and made major advances in mathematics, medicine, and optics.c. 1500 Leonardo da Vinci studied anatomy, astronomy, botany, and geology.1543 Nicolaus Copernicus of Poland published On the Revolutions of the Heavenly Spheres. The book, which proposed a sun-centered theory of the universe, revolutionized astronomy.1543 The first scientific text on human anatomy, On the Fabric of the Human Body by Andreas Vesalius, appeared.1609 Johannes Kepler established astronomy as an exact science.1628 William Harvey published his theory of how the blood circulates.Early 1600's Human vision was explained in geometric terms by Rene Descartes, a French philosopher. He held that mathematics was a model for all sciences.Mid-1600's Robert Hooke used the microscope to uncover the world of cells.Mid-1600's Robert Boyle helped establish the experimental method in chemistry.Late 1600's Experiments with prisms conducted by Sir Isaac Newton of England began the modern study of optics. Newton demonstrated that sunlight is a mixture of light of all colors.Mid 1700's Carolus Linnaeus of Sweden began scientific classification of plants and animals.1770's Carl Scheele and Joseph Priestley independently discovered oxygen.1776 Adam Smith published the first complete work on classical economics.1777 Antonine Lavoisier discovered the nature of combustion.1830's Drawings of cells by Theodor Schwann of Germany helped prove cells make up all organisms.1830 Charles Lyell showed that the earth has changed slowly through the ages.1831 Michael Faraday produced a current with a moving magnet.Mid-1800's Gregor Mendel, an Austrian monk, discovered the basic laws of heredity. He studied the inheritance of various traits in garden pea plants.Mid-1800's Louis Pasteur of France started modern microbiology with his discovery that certain kinds of microscopic organisms cause disease.1859 Charles Darwin set forth his theories of evolution in The Origin of the Species.1860's James Clerk Maxwell developed his electromagnetic theory.1869 Dmitri Mendeleev published his periodic table of the elements.1879 Wilhelm Wundt founded one of the first psychological laboratories.1898 Marie and Pierre Curie and Gustave Bemont discovered the element radium.c. 1900 Sigmund Freud established the field of psychoanalysis.c. 1900 Paul Ehrlich originated the treatment of diseases with chemicals.1900 Max Planck, a Germany physicist, advanced his quantum theory, which states that energy is given off in a stream of separate units called quanta.1905 Albert Einstein, a German-born physicist, published his special theory of relativity, which revolutionized scientific thinking about space and time.1911 Ernest Rutherford put forth his theory of atomic structure.1928 Alexander Fleming discovered penicillin, the first antibiotic.1942 Enrico Fermi and others at the University of Chicago achieved the first controlled nuclear chain reaction, starting the atomic age.1953 Jonas Salk produced the first effective polio vaccine.1953 A ladderlike model of DNA, the substance that controls heredity, was built by James Watson of the United States and Francis Crick of England.1957 The Soviet Union launched the first artificial satellite.1969 Astronauts of the U.S. Apollo 11 mission became the first human beings to walk on the moon.1974 Researchers developed the first successful recombinant DNA procedure.1981 The United States launched the Columbia, the first reusable manned spacecraft.1983 Researchers in France isolated the virus that causes AIDS.1990 Radar aboard the spacecraft Magellan began to map the surface of Venus.Beginning of Modern Science

Modern science developed when the two methods of pursuing scientific knowledge—trial-and-error experimentation and speculation— were combined and systematized to form the scientific method. As early as the 13th century, the Englishman Roger Bacon stressed the need for observation and experimentation in natural philosophy, but he had little influence on his contemporaries. The scientific method did not fully emerge until the late 16th and early 17th centuries during the Renaissance when natural scientists combined observation and induction with deduction tested by experiment. The chief founders of the scientific method were Galileo Galilei and Isaac Newton. The changes in methods and outlook were so great they are often referred to as the scientific revolution.

Two 17th-century scholars who were eloquent spokesmen for the scientific approach—although they made no major scientific discoveries—were the Englishman Francis Bacon and the Frenchman Ren Descartes. Bacon stressed the importance of inductive reasoning in scientific study. Descartes emphasized the need for a critical spirit—an attitude of doubting everything that has not been logically proved.

Scientific investigation in the late 16th and the 17th century was greatly aided by the invention of various instruments for studying nature. Among these instruments were the microscope and telescope, which extended the range of human vision; the pendulum clock, which improved the measurement of time; and the air pump and mercury barometer, useful in the study of the properties of air. Through newly formed scientific societies, such as the Royal Society of England and the French Academy of Science, scholars began to exchange information and cooperate in solving problems.

Science In the 18th and 19th Centuries

Natural philosophy—or science, as it commonly came to be called in the 19th century—began to separate into various branches. First physics and chemistry, then biology, geology, and psychology emerged as distinct sciences. Unable to master the entire field, scientists began to specialize.

As scientific instrumentation and mathematics advanced, science became less qualitative and more quantitative. For example, the use of thermometers enabled scientists to replace vague words such as "hot" and "cold" with precise numbers on a temperature scale. The development of probability theory and statistics helped scientists analyze their observations and experiments.

Throughout the 18th and most of the 19th century, scientists held certain basic assumptions about nature and science. They believed that nature behaves according to the principle of cause and effect—every event in nature has a cause, and a given cause always produces the same effect. The task of science, they believed, is to establish theories that explain the causes of events. Scientific laws, such as Newton's law of universal gravitation, were regarded as true statements about nature. Scientists were confident that in time they would be able to grasp the complete truth about nature.

Late in the 19th century, this outlook began to change. Mathematics, which had been regarded as a collection of true statements about nature, was shown to be a collection of artificial logical systems. For example, Euclid's basic assumptions in geometry were regarded as truths until Nicholas I. Lobachevsky, John Bolyai, Karl Friedrich Gauss, and Georg F. B. Riemann invented non-Euclidean geometries, systems of geometry based on sets of assumptions other than Euclid's. Each non-Euclidean system was internally consistent but contradicted Euclid's system. The discovery of contradictory but internally consistent systems in geometry and other branches of mathematics showed that mathematics by itself revealed no truths about nature.

Another change in outlook was initiated by the Austrian scholar Ernst Mach. He challenged the view that scientific theories should explain the causes of natural events. Instead, he advocated the now widely held view that scientific theories should describe nature in a way that will enable scientists to make accurate predictions.

Science In the 20th Century

A revolutionary discovery early in the 20th century overturned the view that nature proceeds from cause to effect. Physicists discovered that the behavior of subatomic particles of matter—those within the atom—cannot be described with certainty. They found that an event within an atom cannot be described as the certain consequence, but only as the probable consequence, of another event. This discovery led many scientists to believe that the universe consists of complex, uncertain phenomena that will never be fully understood. Scientific theories and laws came to be regarded as statements that are approximately, but not absolutely, true.

Another new view, which became important through the efforts of the American physicist Percy Williams Bridgman, was operationalism. Operationalists tried to rid scientific theories of meaningless terms—"smooth" and "rough," for example—by insisting that each scientific term can be operationally defined, described in terms of the operations that can be performed to measure it. For example, the surface texture of an object might be measured by drawing a phonograph needle and pickup across the object's surface and measuring the electrical signal produced by the needle's vibration. In this example, surface texture could be operationally defined as the magnitude of the electrical signal produced. Most scientists eventually rejected the completely operational approach.

Science in the 20th century has been marked by an increased rate of scientific discovery and the birth of hundreds of specialized fields of scientific study. Many new instruments and techniques have been developed, making possible new kinds of experiments and scientific discoveries. Increasingly, scientists work in teams rather than individually, largely because of the expense and complexity of the equipment required for their experiments. The development of electronics and of the digital computer has greatly assisted scientists in collecting and analyzing data in a large variety of scientific fields. Major new fields of scientific study include the study of the earth with artificial satellites and of outer space with satellites and space probes; the study of nuclear energy and of the interaction of subatomic particles; and the study of the chemical processes within living cells.