War Along with advances in technology came a different kind of warfare—mass destruction and complete disregard for the environment. To end World War II and test a new weapon, the United States dropped two atomic bombs on Japan, instantly ending countless lives. Chemical and biological weapons, and cluster bombs containing depleted uranium, present another danger. All these weapons affect not only the humans involved in wars now, but future generations, and plant and animal life. Solar Power Solar power refers to the conversion of solar energy to another, more useful form. Sunlight can be harnessed and collected in special greenhouses. Photosensitive cells can produce electricity when sunlight hits them. The sun produces about ten times the energy fossil fuels create each year. Many scientists are convinced that this form of energy will one day replace ordinary fossil fuels. Cur- rently, one reason that we still do not see solar-powered cars and houses is because fossil fuels are cheaper to col- lect and use. But technology is slowly catching up—solar plants are now being constructed in some parts of the United States. Scientists are hopeful that these new plants will be able to produce enough energy to power our cities in the future. Genetic Engineering One of the fastest growing fields in science, and also pos- sibly the most controversial, genetic engineering, has been making headline news. The first thing that comes to mind is cloning. But there is more to genetic engineering than that. Genetic engineering is used to produce every- day products such as fruits, grains, plants, and even ani- mals like fish. This might be a bit pointless, you might say. Certainly, we have had fruits, plants, and animals before. Why do we have to genetically engineer these products? We do not make these products from scratch. Genetic engineering allows us to modify the product to bring out certain qualities or to embed qualities that the product would not normally have. For example, Florida oranges grow best in Florida because oranges prefer lots of sun and warm temperatures. Genetic engineering can mod- ify the trees so that the oranges can grow in colder cli- mates, like further north. While making an orange tree that can grow anywhere seems like a good idea, we must look at the flip side and examine other projects. What effect would an orange tree in Alaska have on other plant and animal life in Alaska? In China, scientists concerned with overpopulation and hunger developed a strain of rice that will grow twice as fast as normal rice. This means that more food can be produced faster. Unfortunately, the faster-growing rice has half the nutrients of normal rice. Is this a step up? Now there is more rice available for the population, but it is less nutritious than natural rice. Environmental Quality Many factors contribute to environmental quality. Pol- lution, the introduction of substances that affect or harm the environment, is one of the biggest environmental concerns scientists face today. There are many different forms of pollution. Some are natural, like volcanic eruptions. Humans, however, cause most other forms of pollution. Air Pollution Air is polluted by the introduction of harmful contami- nants into the atmosphere. In and around big cities, smoke produced from factories and car emissions is called smog. Smog in the atmosphere can cause acid rain. Recently, people with allergic reactions to smog have found the need to catch the smog alerts commonly read with the weather reports. In addition to causing allergies, smog has been known to cause numerous health prob- lems, damage habitats, and disrupt ecosystems. Water Pollution Many companies dispose their waste by pumping it into rivers, causing pollution in our water systems. Sewage and pesticides are also factors that contribute to water pollution. About one in three rivers in the United States is polluted. This presents serious problems to all life that depends on clean water for survival. Oceans also get polluted. Garbage dumping, oil spills, and contaminated rivers are the biggest con- tributing polluters for our oceans. This can be devastat- ing for countries that depend heavily on fishing for food. In 1989, the oil tanker Exxon Valdez smashed into some rocks and spilled 260,000 barrels of oil in Alaska. The – PERSONAL AND SOCIAL PERSPECTIVES IN SCIENCE– 255 consequences of this ocean contamination were felt by land mammals and shore life in and around the area. Because the Earth is a closed system, all the pollution we create eventually makes it back to our bodies or back- fires in some other way. It seems easier to dump mercury waste, used in the extraction of gold from its ores, into the ocean. But the mercury waste can kill fish. The fish that survive contain the mercury we just spilled. If we eat the fish or a fish that had eaten a fish that survived, the mercury enters our bodies. Mercury causes brain damage. Soil Pollution Soil pollution occurs when chemicals such as pesticides, fertilizers, toxic chemicals, or radioactive wastes are introduced into the soil. Considering that we all eat pro- duce, this form of pollution directly affects us. Hazardous Waste This type of waste refers to all kinds of substances that are harmful to life, the environment, or is difficult to break down. Hazardous waste can cause cancer, genetic disorders, and death. Natural and Human-Induced Hazards Floods, earthquakes, hurricanes, and drought are all examples of natural hazards. All these conditions pro- duce stresses on the environment. ■ Floods can erode the topsoil, destroy trees, grass, and crops, and even tear down homes. Floods can also contribute to the spread of disease by damag- ing sewage and waste disposal mechanisms. The results of a flood can take years to undo. ■ Earthquakes can tear up the land and produce rock slides. They can even cause flooding if a river is redirected. The effects of an earthquake in a big city can be devastating. ■ Hurricanes can wreak havoc along the coasts, destroying plants, trees, and even highways. Human-induced hazards include global warming, forest depletion, pollution, and nuclear waste. Air pollu- tion that humans create directly affects global warming. It results from increased levels of carbon dioxide and other gases (greenhouse gases), which produce a green- house effect. The greenhouse effect occurs when the sun’s rays, after hitting the Earth’s crust and bouncing back into space, get trapped in the atmosphere because of the greenhouse gases. The trapped heat causes a rise in global temperature. – PERSONAL AND SOCIAL PERSPECTIVES IN SCIENCE– 256 T HE WORLD’S MOST renowned scientists once believed that the Earth was flat, that the sun revolved around the Earth, and that human beings were already fully formed within a woman’s body and sim- ply had to grow to full size in the womb. Science has a rich and often tumultuous history. Driven by curiosity and desire to help humanity, scientists have made great progress in understanding nature. This knowl- edge was, in most cases, accumulated incrementally, with one small discovery leading to another. Theories were developed to unify and explain available facts. Different interpretation of facts by different scientists has lead to controversies in the past. Some major scientific discoveries created dramatic paradigm shifts—revolutions in our understanding of nature. Science as a Human Endeavor What can possibly get someone to study for years, read science journals, repeat experiments countless times, write applications for funding, and present results? Just like a child reaches for a new object, touches it, looks at it, takes it apart, and tries to make it work again, so the scientist looks at nature and tries to understand it. The curiosity CHAPTER History and Nature of Science IN THIS chapter, you will read about what drives science, the nature of scientific knowledge, and how the body of scientific knowledge grows and changes over time. You will also find a brief description of some foundation-shaking advances in science. 28 257 almost seems to be innate, and the thrill that comes from understanding nature or making a new experiment work is well expressed in the following quote: “I do not think there is any thrill that can go through the human heart like that felt by the inventor as he sees some creation of the brain unfolding to success Such emotions make a man forget food, sleep, friends, love, everything.” —Nikola Tesla, physicist and inventor Scientists are driven by curiosity and the thrill that comes from understanding or creating something. At the same time, they are motivated by the desire to improve the quality of life—making everyday chores easier, curing diseases, and solving global and environmental prob- lems. Scientists also seek to use, predict, and control nature—to use sunlight and water for electrical power generation, to forecast the weather and earthquakes, to prevent floods, and to prevent infection of crops and cattle. The result is that over the years, our understanding of science has greatly improved. Humanity has gone from attributing disease to supernatural beings to developing vaccines, antibiotics, and gene therapy to prevent and cure disease. Since Thales of Miletus proposed in 625 B.C. that the Earth is a disc that floats on water, humans have discovered the true nature of their planet, have observed other galaxies, and have landed on the moon. The im- mense progress people have made in science is well expressed in this quote: “The simplest schoolboy is now familiar with truths for which Archimedes would have sacrificed his life.” —Ernest Renan, philosopher The Nature of Scientific Knowledge Scientific knowledge is rooted in factual information that is compiled and interpreted to develop theories. While scientists can’t help believing and hoping—that their experiments or inventions will work; that they will solve a problem; that their theories are correct—experiments are designed to eliminate, as much as possible, the effects of the beliefs and hopes of the scientist performing them. Different scientists often get conflicting data. Even the same scientist’s data is not always consistent. Differences in experimental procedure, which the scientists may or may not be aware of, can all lead different scientists to different conclusions or even the same scientist to dif- ferent conclusions at two different times. Occasionally, this leads to controversy. In the sections below, we will briefly describe the nature of scientific knowledge and how beliefs and controversies play a part. Facts Scientific knowledge is dependent and inseparable from facts. The principles of the scientific method guide sci- entists to observe facts and to propose hypotheses that can be tested by observing other facts. A hypothesis that can’t be verified by collecting scientific facts is not con- sidered part of the domain of science. Theories Just as a collection of bricks does not equal a house, a col- lection of facts does not equal science. Scientific facts, like bricks, need to be sorted and stacked properly. Their relationships to each other matter and need to be estab- lished. Scientists must be able to envision the end result, the way an architect needs to have an idea of what a house should look like. For scientists, the house is the theory—something that unites the facts and makes them meaningful and useful. Theories are formed when a con- nection between facts is first observed. The theories are then developed by looking for more facts that fit into the theory and by modifying the theory to include or explain the facts that do not fit. Beliefs One of the most difficult tasks of a scientist is to remain objective and prevent beliefs from affecting observations. This is not to say that scientists purposely hide facts that don’t support their hypotheses or that are in conflict with their beliefs. Most scientists are well trained to report everything they observe, even if it’s inconsistent with what was previously observed and even if it seems unim- portant. However, it is in human nature to notice and remember the things that we believe in and that we expect. This is a form of intellectual prejudice. If Bob believes that Julie hates him, he will tend to notice only Julie’s negative behavior toward him such as not saying – HISTORY AND NATURE OF SCIENCE– 258 hello and making a joke about him. He will also tend to interpret Julie’s actions in a negative way. For example, if Julie says that she can’t go to the movies, Bob will take that as evidence for his hypothesis that Julie hates him. However, this is not necessarily true—Julie may have too much homework. Bob could also disregard or misinter- pret the nice things that Julie does—it could be a coinci- dence that Julie sat next to him and that she called him (maybe she just needed something). Scientists can’t help but occasionally do the same thing. For example, a sci- entist who smokes may note the great number of people who smoke and don’t get cancer, and attribute the fact that some people who smoke and do get cancer to pol- lution sensitivity or lack of proper nutrition. Marie Curie, a two-time Nobel Prize winner, refused to note overwhelming data that suggested that radium, an element she had discovered, was a health hazard. This inability to see was not caused by lack of training, as Curie was a sufficiently trained scientist whose doctoral thesis was considered the greatest single contribution to science by a doctoral student. The inability to see is caused by a blindfold made of hopes and beliefs that scientists, like all other people, can’t help having once in a while. “Man can’t help hoping even if he’s a scientist. He can only hope more accurately.” —Karl Menninger, psychiatrist Controversies Conflicting data, or facts that seemingly can’t be incor- porated into the same theory, often cause controversies among scientists. The controversies can polarize the sci- entific community, as well as the general population, especially in matters of public or social importance. In the past, controversies also sprang up between scientists and religious establishments. Copernicus shook up the church when he proposed that planets revolved around the sun. Similarly, Darwin caused a lot of controversy when he presented his theory of evolution. There is still some debate on whether evolution theory should be taught in public schools. The nature of light was not very well understood for a long time. There were observations that suggested that light is a stream of particles, as well as that light is a wave. Newton’s belief that light was a series of particles pre- vailed from the 1700s until 1873, when James Clerk Maxwell showed that light is an electromagnetic phenomenon. Although many scientists before Maxwell found evidence for the wave nature of light, Newton’s great reputation and social class allowed his ideas to pre- vail until there was enough evidence to the contrary. Max Planck’s theory about the resolution of controversies is slightly more cynical: “A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new genera- tion grows up that is familiar with it.” —Max Planck, physicist Historical Perspectives All sciences are rooted in philosophy, which they stemmed from, as knowledge in different sciences accu- mulated and became more specialized. Areas of science today include very specific subjects, such as oceanogra- phy, crystallography, and genetic engineering, as well as interdisciplinary subjects, such as biochemistry and bio- physics. Progress in science usually occurs in small incremen- tal steps. For example, nucleic acids (building blocks of DNA) were discovered in the nuclei of cells in 1869. After that, progress was made. Different scientists made con- tributions to the study of DNA. However, scientists did not solve the structure of DNA until 1953, when Ros- alind Franklin, James Watson, and Francis Crick obtained their results. About twenty years later, the first genome sequencing was presented—for a virus that had a relatively small amount of genetic material. More recently, the Human Genome Project was completed. Hundreds of scientists worked on this largest single fed- erally funded project to date with the goal of identifying all human genes and mapping out the human DNA. Sci- entific advances usually depend on other scientific advances, and progress is usually gradual. Many scien- tists put in a lot of time before a new concept becomes completely understood and before a new area of science develops. Occasionally, however, there are leaps in scientific progress. Such leaps represent major discoveries that – HISTORY AND NATURE OF SCIENCE– 259 shake the foundations of understanding and lead to new modes of thinking. Thomas Kuhn, philosopher of sci- ence, called such discoveries paradigm shifts. Here are some major advances in science. ■ 420 B.C.: Hippocrates begins the scientific study of medicine by maintaining that diseases have common causes. ■ 260 B.C.: Archimedes discovers the principle of buoyancy. ■ 180 A.D.: Galen studies the connection between paralysis and severance of the spinal cord. ■ 1473: Copernicus proposes a heliocentric system. ■ 1581: Galileo finds that objects fall with the same acceleration. ■ 1611: Kepler discovers total internal reflection and thin lens optics. ■ 1620: Francis Bacon discusses the principles of the scientific method. ■ 1687: Newton formulates the laws of gravity. ■ 1789: Lavoisier states the law of conservation of energy. ■ 1837: Darwin uses natural selection to explain evolution. ■ 1864: James Clerk Maxwell shows that light is an electromagnetic phenomenon. – HISTORY AND NATURE OF SCIENCE– 260