In this article, 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.
The 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 simply 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 knowledge 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 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 problems. 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 ofMiletus 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 immense 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 effect 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, that the scientists may or may not be aware of, can all lead different scientists to different conclusions, or even the same scientist to different conclusions, at two different times. Occasionally, this leads to controversy. In the following sections 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 scientists 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 considered part of the domain of science.
Theories
As much as a collection of bricks does not equal a house, a collection 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 established. Scientists need to 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 connection 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 to 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 unimportant. However, it is in human nature to notice and remember more 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 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 misinterpret the nice things that Julie does—it could be a coincidence that Julie sat next to him, and that she called him up just because she needed something. Scientists can't help but to occasionally do the same thing. For example, a scientist who is a smoker 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 pollution 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 well enough trained scientist for her doctoral thesis to be 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 which 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 incorporated into the same theory, often cause controversies among scientists. The controversies can polarize the scientific 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 prevailed 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 prevail until there was enough evidence for 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 generation 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 accumulated and became more specialized. Areas of science today include very specific subjects, such as oceanography, crystallography, and genetic engineering, as well as interdisciplinary subjects, such as biochemistry and biophysics.
Progress in science usually occurs in small incremental 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 contributions to the study of DNA. However, scientists did not solve the structure of DNA until 1953, when Rosalind Franklin, James Watson, and Francis Crick obtained their results. About 20 years later, the first genome sequencing was presented—for a virus, having a relatively small amount of genetic material. More recently, the Human Genome Project was completed. Hundreds of scientists worked on this largest single federally funded project to date with the goal of identifying all human genes and mapping out the human DNA. Scientific advances usually depend on other scientific advances and progress is usually gradual.Many scientists 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 shake the foundations of understanding and lead to new modes of thinking. Thomas Kuhn, philosopher of science, 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.
- 1866: Mendel discovers the laws of heredity.
- 1869: Mendeleyev designs the periodic table of elements.
- 1870: Louis Pasteur and Robert Koch establish the germ theory of disease.
- 1895: Wilhelm Rontgen discovers X-rays.
- 1907: Pavlov demonstrates behavioral conditioning with salivating dogs.
- 1912: Alfred Wegener proposes that all continents once formed a single landmass that separated by continental drift.
- 1915: Einstein publishes his theory of relativity.
- 1928: Alexander Fleming discovers penicillin.
- 1953: Rosalind Franklin, James Watson, and Francis Crick solve the structure of DNA.
- 1969: Neil Armstrong and Buzz Aldrin walk on the moon.
- 2000: A network of scientists completes the Human Genome Project.
"There is a single light in science, and to brighten it anywhere is to brighten it everywhere."
—Isaac Asimov
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