A science teacher's view of Science
by Paul Doherty
Through a few deacdes as a science teacher I have extracted a few pieces of philosophy about science that I use over and over again to help students to understand some of what science is. Here are my selections of ideas that are most useful to science teachers.
I Doubt it
When you read about science in books, magazines, newspapers, and on the Web, or hear about science in lectures or on television or radio I urge you to keep a healthy amount of skepticism. Good science will withstand your sketicism.
Scientists must be professional doubters.
The Royal Society finally sorted out how to do science at the end of the 17'th century. Their motto is: Nullius in Verba.
In other words, don't believe something just because it is stated by an authority, check statements yourself. This is how the first modern scientists &emdash; Galileo and Newton for example &emdash; broke free of the teachings of Aristotle.
It is an amazing self-contradiction to stand in front of a class of students and tell them that Aristotle was wrong. It is easy to show that Aristotle's ideas about motion are in error by an experiment. Just have your students drop a medium-weight ball and a heavy-weight ball, Aristotle claimed that the heavy ball would fall faster and hit the floor first. Allow the experimental result to speak for itself. Many of your students have the same idea about motion as Aristotle, by doing an experiment they can begin to question their own assumptions.
It has been suggested that bumper stickers for Aristotelian science would be "Minds-on, Hands-off!" and "Just take our word for it!"
There is a spectrum of doubting among scientists, some believe the most outlandish reports on the skimpiest of evidence, others doubt even the most well tested theories. It is important to understand this lack of unanimity. One good rule to remember is that in science: "extraordinary claims require extraordinary proof."
As a teacher, when I answer a question I use scientific models accepted by the vast majority of scientists.
How do you know that?
A scientist must be an expert in one small part of science.
What does the expertise mean to you as a student of science?
It means that when a scientist makes a statement, you can always ask, "How do you know that?" They must answer you by showing an experiment, or a referring to the published result of an experiment that supports their statement..
I don't know
Teachers on the other hand need not, and can not, know everything about all of the topics they introduce to students. Instead, teachers need to know the overview of the topics they teach, what is important and why. Teachers are guides, taking students through unfamiliar landscape. Teachers also need to know how to find out answers through research. With the coming of computer terminals to classrooms teachers may be able to find answers more quickly. (aside &emdash; you need to be particularly doubtful of science from the un-edited and un-reviewed World Wide Web.) If you don't know the answer to a question, admit it, and then find the answer for the next day. If you think you know an answer give it, and then check. Give yourself a day to find answers.
It's more complicated than that
Scientists answer questions from other scientists with mathematical models, graphs, tables and drawings, accompanied by very precisely worded verbal arguments. Their answers must be so precise that they are often difficult to follow and take a long time to state.
Teachers, on the other hand, answer questions from students using the simplest models of science that work to answer each particular question. Students should keep in mind that such an answer always carries an asterisk* with it:
*It's more complicated than that.
Ask me a question, I will give you an answer based on the simplest scientific model I can use. If you then refine your question I may have to switch my answer to use a more complicated model.
Choosing the correct model to use in answering a science question is one of the most difficult things to do.
For example, if you ask me about the orbit of the moon I'll answer you by using Newton's laws, however if you ask me about two neutron stars orbiting each other I'll have to switch to Einstein's general relativistic model. There is no need to use general relativity in a high school class when discussing the orbit of the moon.
The quantitative nature of science
"If it can't be expressed in figures it's not science it's opinion." R. Heinlien
Science is Quantitative, concepts are expressed in precisely defined mathematical terms so that they can be tested. e.g. Einstein's theory of general relativity predicted that light would bend under gravity twice as much as Newton predicted. Measurements showed that Einstein was correct.
In general, people have a very poor perception of numbers, ask someone which is more dangerous an airplane flight of 1000 miles, or the 50 mile drive to and from the airport in their automobile. If they don't base their answer on numerical probability they might answer that the airplane flight is less safe even though it is over 100 times safer.
Science begins with Observation
Believe only half of what you see, and nothing of what you hear.
Dinah Craik 1858
You must understand human perception to understand the observations behind science and also the observations which lead to pseudoscience.
Some scientists, such as Percival Lowell, saw Canals on Mars others did not. The straight lines on Mars were a human perception, when the eye and brain are presented with a row of fuzzy blobs the resulting perception is a straight line.
In one UFO encounter, pilots of a commercial airliner sketched a green spacecraft with windows. Photos show that the pilots saw a meteor. Of course pilots are always looking for other aircraft so it isn't surprising that they saw windows. Scientific observers must always be careful about self deception. You can honestly report what you see, but you might be mislead by your perceptual system, as Dr. Lowell and the pilots mentioned above were.
Honesty in reporting observations is one of the most important qualities in science. If you lie or cheat, you'll be caught - eventually, the punishment for a scientist caught lieing is ostracism, forever.
As reported in the Exploratorium's Exploring Fakes magazine. One scientist painted black skin patches onto a white mouse to fake the results of an experiment. He was caught and is no longer a scientist. Because of the severity of the punishment for lieing scientists trust other scientists to tell the truth. Unfortunately, the habit of trusting the honesty of other scientists may lead them to trust the reports of non-scientists who are lieing. Many scientists have been mislead by non-scientist charlatans.
If it can't possibly be proven wrong then it isn't science
Scientific hypotheses must be Testable, that is capable of being proved wrong. (Proving a hypothesis correct is harder, and often impossible.) e.g.
"Life probably exists on Mars" cannot be proved wrong, it is not a scientific statement." As Paul Hewitt points out, the statement,"the moon is entirely made of green cheese," is a scientific statement, it can, and has, been proven wrong.
Science works with models
Scientists create models to help them predict the results of future experiments. These models are continuously refined and occasionally replaced with entirely new models. When faced with two different models both of which explain all known experimental results, scientists choose the simpler one. This principle is known as Occam's Razor.
You must be careful with models.
If you feel that scientific models are absolute truth then substitute the word "lie" for model for a while to help you to gain a better perspective.
Consider three examples of scientific models:
1. We model light as a wave but light is not a wave &emdash; Light is light.
Light behaves like a wave when it travels.
Light is not a particle, although we sometimes model it as a particle.
Light behaves like a particle when it is created or absorbed (as a whole quantized chunk of energy named a photon.)
2. The atomic theory organizes a tremendous amount of chemical information in a simple statement: All ordinary matter is made of atoms, small indivisible particles which attract each other when a little ways apart and repel each other when close. (this is Feynman's statement of the atomic theory) The atomic theory provides a conceptual basis for the periodic table.
The atomic theory is a useful model, independent of whether atoms actually exist.
At the beginning of the 20'th century there were scientists who believed that atoms did not exist, although many admitted that atoms provided a good model for explaining a lot of chemistry. It was Einstein and his theory of Brownian motion who finally convinced many of them of the existence of atoms. Today, scanning tunneling microscopes produce images of atoms.
3. These days the Standard Model of particles and fields provides an organizational framework to a tremendous amount of information. The organization is useful, it actually predicted several particles before they were found, part of it uses quarks as a constituent of protons and other elementary particles. No one has ever found a single quark by itself, some scientists wonder how much quarks can be thought to really exist, maybe they are just convenient models, as atoms were 100 years ago.
Scientific Models Change
Scientists must posses a willingness to change their theories with time to accommodate new observations.
Established theories are usually modified to accommodate new observations, less often they are completely revised. However, remember that an existing theory is supported by many observations, a new theory must explain all of the previous observations plus the new ones, before it replaces the old one.
Evidence for Change
As we mentioned before, extraordinary claims require extraordinary proof. If a claimed observation goes against models which explain all previous scientific observations it has the possibility of starting a scientific revolution, therefore it requires extraordinary proof.
Two example immediately come to mind.
1. High temperature superconductivity. For decades hardly a year went by without someone claiming to have discovered hints of high temperature superconductivity, these reports never made it to the press because when another group attempted to repeat the experiment it was always found to be flawed. However, when a group of scientists from IBM labs announced the discovery of high temperature superconductors, two other laboratories were able to verify their claims within a week. The result became an excellent example of revolutionary science. A decade later, there is still no scientific model to explain these high temperature superconductors quantitatively.
2. Cold Fusion, was clacaimed verbally by Stan Pons and Martin Fleischmann. As a scientist should, I immediately doubted their report, however, after a few days, two other laboratories reported confirming observations and I began to give credence to their report. After a couple of more weeks other laboratories began to report results which disagreed with those of Pons and Flieschmann. When Pons and Flieschmann published their scientific paper I was appalled by its poor quality, if they were students of mine and submitted the report in Junior physics laboratory I would have given them a C. Today almost no scientists believe in their cold fusion model.
Getting to the truth takes time often years.
In a wonderful summary about what science is, in the American Scientist March/April 1996 Harold B. Hopfenberg says:
"The enterprise of science might be viewed optimistically as an onion whose gossamer layers are peeled away through the ages. Waiting to be revealed within, we like to imagine, lies a distant but pristinely pure central core. Would that it were so! At best the fundamental truths of one age are typically found to be the oversimplifications of another. Sometimes it's worse. From Newton to Carnot to the early middle of the 20'th century, the bedrock principle of the physical sciences was the notion that neither matter nor energy could be created or destroyed. Under clear skies, the 1945 summer inhabitants of Hiroshima witnessed the cataclysmic and public refutation of the 19'th century Universal laws. The science of each century, history shows, is a well-intended cartoon of the state of humankinds knowledge of nature; it is not a compendium of systematically uncovered absolutes. Science is simply the best understanding that we can provide at the time."
Almost every sentence of this paragraph contains an important nugget of truth about science.
Beware of science obtained on the World Wide Web
Many "scientific" articles posted on the Web are not reviewed by other scientists as they are in scientific journals. This leaves he work of checking their accuracy to you! At a minimum get three opinions on any scientific answer you find on the web.
This is the variation on the statement that when you have a physics question you should always ask an odd number of physicists so you can compare their answers and pick the best two.My editor jokes that any number of physicists is odd.
A scientist, G. Landis, published in1987 in the American Journal of Science that bubbles trapped in amber preserved samples of ancient air.
His publication was refuted in Science magazine in 1988 by H. Hopfenberg who showed that amber is permeable to gas and that the author of the original article had reported his CO2 measurements as O2.
In 1995, the original author republished his erroneous conclusions on the Web.
And now for something completely different
There is plenty more to learn to understand what science is. But the best way to learn is to do so do some of the science activities I will present you, then return to these ideas to see which are useful to you.
Return to the Summer Institute
Scientific Explorations with Paul Doherty
22 Feb 99