What is science?
That's a broad question and is perhaps central to some of our most heated debates regarding science and religion.
The American Physical Society (APS) answers this question in the following way:
Science is the systematic enterprise of gathering knowledge about the universe and organizing and condensing that knowledge into testable laws and theories.
The success and credibility of science are anchored in the willingness of scientists to:
- Expose their ideas and results to independent testing and replication by others. This requires the open exchange of data, procedures and materials.
- Abandon or modify previously accepted conclusions when confronted with more complete or reliable experimental or observational evidence.
Adherence to these principles provides a mechanism for self-correction that is the foundation of the credibility of science.
In the APS definition, I notice the following characteristics:
- observing (i.e. experimenting)
- developing a model for understanding and predicting
- testing the model
- doing this in a systematic way
There's a definite "method" that scientists use to figure things out. The credibility of this method is established by what we know about our universe today; its credibility is also established in the success of this method--from technology to medicine; its credibility is also established in our ability to make accurate predictions. This "method" is called the scientific method. It's not really a single method, but rather it is a collection of lots of methods used to understand the physical world.
Generally, scientists, especially astronomers, use models to understand physical systems. A physical system is just the "thing" you are studying. Perhaps it's a hurricane or a car or Earth or a star. A model is a simplified system that has the essential characteristics of the real system but is far simpler and far less complex than the real system.
For example, consider Earth's orbit around Sun. You may have heard that the planets' orbits are ellipses. This is correct. But, take a look at the following accurate picture of Earth's orbit. (Units of the axes shown are called Astronomical Units, or AU.)
Does this look like an ellipse? It looks more like a circle because Earth's orbit is in fact nearly a circle. It's an ellipse that is not very elongated. Therefore, in some models we assume that Earth's orbit is a circle with Sun at the center. Though this is an assumption that is not exactly correct, it is much simpler to assume a circular orbit when doing certain calculations. Furthermore, it's enough like the real system that for many calculations the model is quite accurate and valid.
In astronomy, we will use many models. Models are never perfect. Often, they are only valid under certain circumstances. It's very important to define the model, state its assumptions, and use it in a valid way.
I believe that Richard Feynman best explains the process of science in The Feynman Lectures on Physics. He says (italics and quotation marks are in the original quote):
Each piece, or part, of the whole of nature is always merely an approximation to the complete truth, or the complete truth so far as we know it. In fact, everything we know is only some kind of approximation, because we know that we do not know all the laws as yet. Therefore, things must be learned only to be unlearned again, or more likely, to be corrected.
The principle of science, the definition, almost, is the following: The test of all knowledge is experiment. Experiment is the sole judge of scientific "truth." But what is the source of knowledge? Where do the laws that are to be tested come from? Experiment, itself, helps to produce these laws, in the sense that it gives us hints. But also needed is imagination to create from these hints the great generalizations-to guess at the wonderful, simple, but very strange patterns beneath them all, and then to experiment to check again whether we have made the right guess.
Answer the following questions
on paper. The reason you should answer on paper is that writing clarifies one's thoughts.
A scientist might say, "We really do not know anything." This is intentionally a vague statement. In what way is it right and in what way is it wrong? Use what you have read on this page to support your answer.
Feynman refers to two important uses for experiments. What are they?
You have undoubtedly heard a weather report. Typically in those reports, the meteorologist refers to predictions of various weather models. Are these weather models perfect? Are these weather models useful?
What should scientists do when their models are found to not work; that is, the models make predictions that are not verified by experiment?
Your answers will not be collected but will be discussed in class.