CONCEPTUAL PHYSICS › CHAPTER 1, ABOUT SCIENCE
What Science Is and How We Know Things
This is the only chapter of the year that is not about the physical world. It is about how anybody came to know any of it, which turns out to be a stranger and more demanding business than most people are told.
1.A Say what makes a claim scientific, and apply the test to claims you have not seen before.
1.B Use the words hypothesis, fact, law and theory the way scientists use them, and explain why the everyday meanings cause so much trouble.
1.C Tell science from technology, and either from pseudoscience.
1. Science is organized doubt
Every field of study collects claims. What makes science different is not the subject matter and not the equipment. It is that a scientific claim arrives with instructions for destroying it.
When Galileo said that heavy and light objects fall together, he was not asking to be believed. He was telling everyone in earshot exactly what to do to prove him wrong: drop two different weights and watch. The claim survived because people tried and failed to break it, which is a completely different kind of confidence than being told something by an authority.
2. Four words you already use wrongly
Most of the confusion the public has about science comes from four words that mean one thing in ordinary speech and something much more specific here.
A fact is an agreement among competent observers about something they have observed. Note what that does not say. It does not say a fact is permanent. Facts have been revised, because observation gets better.
A hypothesis is an educated guess, offered so it can be tested. It is the smallest unit of science, and it is disposable on purpose.
A law is a description of a pattern that has been observed so consistently that it can be stated compactly, usually as an equation. A law says what happens. It does not say why.
A theory is the big one, and the one that causes the most damage. In everyday speech a theory is a hunch. In science a theory is a tested explanation that ties together a large body of facts and laws. Atomic theory and the theory of gravitation are not guesses about whether atoms and gravity exist. They are the explanations of how they behave, and they are the most substantial things science produces.
Sort these into the right box
Each statement below is a fact, a hypothesis, a law or a theory as scientists use those words. Pick a box. The feedback explains the distinction rather than just marking you.
3. Science, technology, and why the difference matters
Science is the business of finding out how the world works. Technology is the business of using that knowledge to make things. They are not the same activity, they are not done by the same reasoning, and they are not judged by the same standard.
Science asks whether something is true. Technology asks whether something works, and then a separate question, which science cannot answer for you, of whether it should be built at all. Knowing how nuclei split is science. Building a reactor is technology. Deciding whether to build one is neither, and pretending it is a scientific question is a way of avoiding the argument.
4. Pseudoscience, which is comfortable for a reason
Pseudoscience wears the costume: technical vocabulary, confident claims, sometimes numbers. What it does not do is take the risk. A scientific claim tells you in advance what would sink it. A pseudoscientific claim is arranged so that nothing can.
Watch for the moves. Predictions vague enough to fit any outcome. Failures explained away afterward rather than counted. Evidence that consists only of testimonials. And the appeal to being suppressed, which converts the absence of supporting evidence into further proof.
Is this claim testable?
A claim, and one question: could any observation you can describe show it to be false? Say yes or no, and the feedback names what a test would have to look like.
5. What the scientific method actually looks like
Textbooks print a tidy numbered list: observe, hypothesize, predict, test, conclude. Real science is messier than that, and the list is better read as a set of standards than as a recipe.
The standards are the part that does not bend. Say what you expect before you look. Report what you actually saw, including the parts that went against you. Describe your method well enough that a stranger who dislikes your conclusion could repeat it. And treat the result as provisional no matter how much you like it.
That last standard is the hard one, and it is the reason science works at all. Everything in it is held loosely enough to be dropped when the evidence says so.
Check yourself
1. A friend says evolution is “just a theory” and should be taught alongside other guesses. Explain what has gone wrong in that sentence, using the definitions above.
The word theory is being read in its everyday sense of hunch. In science a theory is a tested explanation supported by a large body of facts and laws, and it is the highest standing a scientific idea reaches. A hunch is a hypothesis. The sentence swaps the two, which makes the strongest kind of scientific claim sound like the weakest.
2. “There is an invisible, weightless dragon in my garage that cannot be detected by any instrument.” Is this a scientific claim? Say why, and say whether that means it is false.
Not scientific, because nothing you could observe would count against it. Every test you propose has already been ruled out by the claim itself. That does not make it false. It makes it a claim science has no tools for, which is a different and more honest verdict. The useful follow-up question is why someone would frame a claim so that it can never fail.
3. Give an example of a scientific fact that was later revised, and say why that is not an embarrassment for science.
Competent observers once agreed the atom was indivisible, and the number of planets has been counted differently at different times. Facts are agreements among observers, and better observation changes what competent observers agree on. A system that never revised anything would not be tracking the world. Revision is the mechanism working, not failing.
4. Sort these three into science, technology, or neither: measuring how fast a signal travels down a nerve; designing a hearing aid; deciding whether hearing aids should be covered by insurance.
Measuring the signal is science, a question about how the world is. Designing the device is technology, applying that knowledge to make something. The insurance question is neither: it is a question about what we owe each other, and evidence informs it without settling it. Notice that the third question is the one people most often try to disguise as the first.
Chapter 3, Linear Motion. The first thing to find out how to know is where something is and how fast it is going, and the first surprise is that neither question has an answer until you say what you are measuring against.