# Patterns, Theories, and the Scientific Process

In the last activity, you predicted what was going to happen before trying out a scenario for real. How did you make your prediction? You had never tried scenario B before, so you could not rely solely on your past experience. You had tried a very similar scenario in scenario A, but the two scenarios are slightly different.

If your prediction was fairly accurate, it may have been because you had noticed a pattern when trying scenario A. In scenario A, you started the plunger at 35, pushed it down to 20, and then released it. After releasing the plunger, it moved back up to almost 35 again — not quite 35, but very close to it (I got 34).

It would be reasonable to predict that in scenario B, when you started the plunger at 25, pushed it down to 15, and then released it, the plunger would move back up to almost 25 again — maybe 24. Do you begin to see a pattern? How many different scenarios would you have to test in order to feel confident that you could accurately predict where the plunger would end up after being released?

Scientists are constantly looking for patterns and testing those patterns by making predictions. Once enough scientists have tested a pattern and feel confident in it, the pattern may be considered a “law.” Scientific laws have not been proven. For example, Newton’s first law of motion states that, in the absence of a net force, the center of mass of a body either is at rest or moves at a constant velocity. Someone may come up with a scenario tomorrow where Newton’s first law of motion fails, in which case a new and better pattern will need to be found. Of course, this is very unlikely to occur because Newton’s first law of motion has been tested in thousands of ways by thousands of scientists, and so far it has not failed once. That’s not proof, but a reason for scientific confidence.

You may have noticed that Newton’s first law of motion does not explain how or why, in the absence of a net force, the center of mass of a body either is at rest or moves at a constant velocity. It’s simply a pattern that has been reliably observed over and over again. In science, an attempt to explain how or why a pattern occurs is called a theory. Theories are not stronger or weaker than laws, and like laws, can never be completely proven. You will learn more about patterns, theories, and the scientific process throughout this unit.

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