Astronomy: Big Bang Theory
Biology: Cell Theory; Theory of Evolution; Germ Theory of Disease
Chemistry: Atomic Theory; Kinetic Theory of Gases
Physics: General Relativity; Special Relativity; Theory of Relativity; Quantum Field Theory
Earth Science: Giant Impact Theory; Plate Tectonics
Currently Unverifiable Theories
The term theory is sometimes stretched to refer to theoretical speculation which is currently unverifiable. Examples are string theory and various theories of everything. String theory is a model of physics, which predicts the existence of many more dimensions in the universe than the four dimensions that current science understands (length, width, height, and space-time). A theory of everything is a hypothetical theory in physics that fully explains and links together all known physical phenomena.
For a scientific theory to be valid it must be verified experimentally. Many parts of the string theory are currently untestable due to the large amount of energy that would be needed to carry out the necessary experiments as well as the high cost of conducting them. Therefore string theory may not be tested in the foreseeable future. Some scientists have asked if it even deserves to be called a scientific theory because it is not falsifiable.
Superseded Theories
A superseded, or obsolete, scientific theory is a theory that was once commonly accepted, but for whatever reason is no longer considered the most complete description of reality by mainstream science. It can also mean a falsifiable theory which has been shown to be false. Giraffes, shown in Figure below, are often used in the explanation of Lamarck's superseded theory of evolution. In Lamarckism, a giraffe is able to lengthen its neck over its life time, for example by stretching to reach higher leaves. That giraffe will then have offspring with longer necks. The theory has been superseded by the understanding of natural selection on populations of organisms as the main means of evolution, not physical changes to a single organism over its lifetime.
Figure 1.11
Superseded theories like Lamarcks theory of evolution are theories that are now considered obsolete and have been replaced by newer theories that have more evidence to support them; in Lamarcks case, his theory was replaced by Darwins theory of evolution and natural selection, which will be discussed in the chapter on .
Scientific Laws
Scientific laws are similar to scientific theories in that they are principles which can be used to predict the behavior of the natural world. Both scientific laws and scientific theories are typically well-supported by observations and/or experimental evidence. Usually scientific laws refer to rules for how nature will behave under certain conditions. Scientific theories are more overarching explanations of how nature works and why it exhibits certain characteristics.
A physical law or law of nature is a scientific generalization based on a sufficiently large number of empirical observations that it is taken as fully verified.
Isaac Newton's law of gravitation is a famous example of an established law that was later found not to be universal—it does not hold in experiments involving motion at speeds close to the speed of light or in close proximity of strong gravitational fields. Outside these conditions, Newton's laws remain an excellent model of motion and gravity.
Scientists never claim absolute knowledge of nature or the behavior of the subject of the field of study. A scientific theory is always open to falsification, if new evidence is presented. Even the most basic and fundamental theories may turn out to be imperfect if new observations are inconsistent with them. Critical to this process is making every relevant part of research publicly available. This allows peer review of published results, and it also allows ongoing reviews, repetition of experiments and observations by many different researchers. Only by meeting these expectations can it be determined how reliable the experimental results are for possible use by others.
Lesson Summary
Scientific skepticism questions claims based on their scientific verifiability rather than accepting claims based on faith or anecdotes. Scientific skepticism uses critical thinking to analyze such claims and opposes claims which lack scientific evidence.
Science is based on the analysis of things that humans can observe either by themselves through their senses, or by using special equipment. Science therefore cannot explain anything about the natural world that is beyond what is observable by current means. Supernatural things cannot be explained by scientific means.
Scientific investigations involve the collection of data through observation, the formation and testing of hypotheses by experimentation, and analysis of the results that involves reasoning.
In a controlled experiment, two identical experiments are carried out side-by-side. In one of the experiments the independent variable being tested is used, in the other, the control, or the independent variable is not used.
Any useful hypothesis will allow predictions based on reasoning. Reasoning can be broken down into two categories: deduction and induction. Most reasoning in science is formed through induction.
A variable is a factor that can change over the course of an experiment. Independent variables are factors whose values are controlled by the experimenter to determine its relationship to an observed phenomenon (the dependent variable). Dependent variables change in response to the independent variable.
Scientific theories are hypotheses which have stood up to repeated attempts at falsification and are thus supported by much data and evidence.
Review Questions
What is the goal of science?
Distinguish between a hypothesis and a theory.
The makers of two types of plant fertilizers claim that their product grows plants the fastest and largest. Design an experiment that you could carry out to investigate the claims.
Identify how hypotheses and predictions are related.
What is the difference between the everyday term “theory” and the term “scientific theory?”
Identify two ways that scientists can test hypotheses.
Outline the difference between inductive and deductive reasoning.
What is the range of processes that scientists use to carry out a scientific investigation called?
To ensure that their results are not due to chance, scientists will usually carry out an experiment a number of times, a process called replication. A scientist has two types of plants and she wants to test which plant produces the most oxygen under sunny conditions outdoors. Devise a practical experimental approach, incorporating replication of the experiment.
In taking measurements, what is the difference between accuracy and precision?
Name two features that a hypothesis must have, to be called a scientific hypothesis.
Identify two features that a theory must have, to qualify as a scientific theory.
Give an example of a superseded theory.
Can a hypothesis take the form of a question? Explain your answer.
Why is it a good idea to try to reduce the chances of errors happening in an experiment?
Further Reading / Supplemental Links
http://www.nap.edu/readingroom/books/obas/
http://www.project2061.org/publications/sfaa/online/chap1.htm#inquiry
http://www.nasa.gov/mission_pages/station/science/experiments/PESTO.html#applications
http://biology.plosjournals.org/perlserv/?request=index-html&issn=1545-7885&ct=1
http://biology.clc.uc.edu/courses/bio114/spontgen.htm
http://www.estrellamountain.edu/faculty/farabee/biobk/diversity.htm
http://www.nasa.gov/mission_pages/station/main/index.html
http://books.nap.edu/html/climatechange/summary.html
http://www.cisci.net/about.php?lang=1
http://www.aaas.org/news/releases/2006/pdf/0219boardstatement.pdf
Vocabulary
control
Something that is not tested during the investigation.
controlled experiment
Two identical experiments are carried out side-by-side; in one of the experiments the independent variable being tested is used, in the other experiment, the control, or the independent variable is not used.
controlled variables
Variables that are kept constant to prevent influencing the effect of the independent variable on the dependent variable.
deduction
Involves determining a single fact from a general statement.
dependent variable
Changes in response to the independent variable.
experiment
A test that is used to eliminate one or more of the possible hypotheses until one hypothesis remains.
hypothesis
A suggested explanation based on evidence that can be tested by observation or experimentation.
independent variable
Factor(s) whose values are controlled by the experimenter to determine its relationship to an observed phenomenon (the dependent variable).
induction
Involves determining a general statement that is very likely to be true, from several facts.
observation
The act of noting or detecting phenomenon through the senses. For example, noting that a room is dark is an observation made through sight.
Occam’s razor
States that the explanation for a phenomenon should make as few assumptions as possible.
phenomenon
Is any occurrence that is observable.
scientific methods
Based on gathering observable, empirical (produced by experiment or observation) and measurable evidence that is critically evaluated.
scientific skepticism
Questions claims based on their scientific verifiability rather than accepting claims based on faith or anecdotes.
variable
A factor that can change over the course of an experiment.
Points to Consider
The Points to Consider section throughout this book is intended to have students think about material not yet presented. These points are intended to lead students into the next lesson or chapter.
Science is a particular way in which people examine and ask questions about the world. Can you think of other ways in which people examine and ask questions about the world?
Consider the importance of replication in an experiment and how replication of an experiment can affect results.
Scientists often disagree among themselves about scientific findings, and communicate such disagreement at science conferences, through science articles in magazines, or science papers and in scientific journals. Can you think of other ways in which scientists could communicate so that the public can get a better idea of what the “hot topics” in science are?
Communicating Ideas
Lesson Objectives
Outline the need for scientists to be able to share their ideas and findings with each other.
Identify the role of graphics in presenting results of an investigation.
Identify the role of peer review in the communication of ideas.
Examine how ethics are applied to communicating ideas and research.
Compare scientist to scientist communication to scientist to public communication.
Identify the benefits of studying science, even if you do not intend on becoming a scientist.
List three things that can influence scientific research.
Identify two ways that biotechnology has affected our lives.
Introduction
The reliability of scientific knowledge comes partly from the objectivity of scientific methods, and also from scientists discussing ideas with each other. In talking with each other, researchers must use more than just their scientific understanding of the world. They must also be able to convince a community of their peers of the correctness of their concepts and ideas.
Scientist to Scientist Communication
A wide range of scientific literature is published and it is a format where scientific debates are properly carried out and reviewed. This includes scientific publications that report original research within a scientific field and can comprise of the following:
scientific articles published in scientific journals
books written by one or a small number of co-authors who are researchers
presentations at academic conferences, especially those organized by societies (for example, the American Association for the Advancement of Science)
government reports
scientific publications on the internet
books, technical reports, pamphlets, and working papers issued by individual researchers or research organizations
Scientific journals communicate and document the results of research carried out in universities and various other research institutions. They are like a type of magazine that contains many articles which are written by different researchers about their ideas and discoveries. Most scientific journals cover a single scientific field and publish the research within that field; the research is normally expressed in the form of a scientific paper.
An academic conference is a conference for researchers (not always academics) to present and discuss their work. Together with scientific journals, conferences are an important channel for exchange of ideas between researchers. Generally, work is shared in the form of visual posters or short presentations lasting about 10 to 30 minutes. These are usually followed by discussion. A researcher is presenting his work to his peers in Figure below.
Figure 1.12
A presentation at an academic conference. At conferences, scientists are able to share ideas and their research results with many people at one time, and can talk directly to other researchers and answer their questions.
Types of Scientific Publications: Scientific Journals
A scientific journal is a publication that reports new research, and sometimes contains general science news articles. Most journals are highly specialized for a particular field of research such as biochemistry, microbiology, or botany. However, some of the oldest journals such as Nature publish articles and scientific papers across a wide range of scientific fields. The journals shown in Figure below have a similar look and layout to science journals.
Scientific journals contain articles that have been peer reviewed in an attempt to ensure that articles meet the journal's standards of quality, and scientific validity. A scientific journal is not usually read casually as you would read a magazine. Some of the content can be very dense and detailed.
The publication of the results of research is an essential part of the scientific process. The researcher who has written the paper must give enough details about their experiments so that an independent researcher could repeat the experiment to verify the results.
The significance of these different parts of scientific literature differs between science disciplines and has changed over time. Peer-reviewed journal articles remain the most common publication type and have the highest level of trust. However, journals vary enormously in their prestige and importance, and the value of a published article depends on the journal, review process and the degree that it is referenced by other scientists.
Some well known and well respected science and medical journals include:
Science
Nature
Proceedings of the National Academy of Sciences of the United States of America (PNAS)
Public Library of Science (PLoS)
Cell
Journal of the American Medical Association (JAMA)
The Lancet
Journal of Theoretical Biology
Figure 1.13
These research journals publish research papers written by economists, people who study the economy, and related issues. However, the layout of research journals is very similar.
Science Articles
New research is usually written up in the form of a scientific article, which often appear in journals. A scientific article has a standardized structure
, which varies only slightly between the different sciences. This format can also be used for your lab reports as part of this class.
It is not really the format of the article that is important, but what lies behind it or the content. However, several key format requirements need to be met by every science article:
1. The title should be short and indicate the contents of the article.
2. The names of all authors that were involved in the research should be given. Where the authors work or study should also be listed.
3. The first section is normally an abstract: a one-paragraph summary of the work. The abstract is intended to serve as a quick guide for the reader as to the content of the article.
4. The format should be able to be stored in a library so that scientists years later will be able to recover any document in order to study and assess it
5. The content of the study should be presented in the context of previous scientific investigations, by citing related documents in the existing literature. This is usually in a section called an introduction.
6. Observations that were made, and measurements that were taken are described in a section usually called Materials and Methods. The experiments should be described in such a way that other scientists in the same or related fields can repeat the experiments and observations and know whether he or she gets the same results. This is called reproducibility.
7. Similarly, the results of the investigation are given in a section called, results. Data should be presented in tabular or graphic form (images, charts, graphs, photos, or diagrams, shown in Figure below. Graphics should have a caption to explain what they are showing.
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