SETTING UP MODELS OF THE UNOBSERVABLE IF YOU WERE BLIND: Would you think an elephant was like a wall, a spear, a snake, a tree, a fan, or a rope? Would you think an elephant was like a wall, a spear, a snake, a tree, a fan, or a rope?

A Model is used to help us a get a mental picture of something that cannot be directly observed because it is: A Model is used to help us a get a mental picture of something that cannot be directly observed because it is: Too fast or too slow Too big or too small Too far away Past or future etc. Too fast or too slow Too big or too small Too far away Past or future etc. A model is not necessarily testable. It just helps us to “wrap our minds around an idea.”

LAWS OF SCIENCE: Gravity, thermodynamics, planetary motion, etc. 1. Derived from observation. If exceptions ever observed, the law must be corrected. 2. Accurately predict the behavior of the systems they describe. 3. Can often be expressed mathematically. tells us how strong the force of gravity is, but doesn’t tell us why gravity exists in the first place. A law of science simply describes WHAT happens, without trying to explain WHY it happens. For instance, the law of gravity A law of science simply describes WHAT happens, without trying to explain WHY it happens. For instance, the law of gravity F grav = G m 1 m 2 d2d2

1. In science, a “Theory” is a very powerful term. It means that a hypothesis idea has been tested over and over and has never failed a single test. Calling an idea a Theory is a high compliment. 2. The idea that humans came from apes is not a scientific theory because it is impossible to test! There is no way we could perform an experiment to make apes evolve into humans. It is a HYPOTHESIS or MODEL instead. Likewise, the idea of a “big bang” is not testable. It relies on computer models rather than experimentation. It, too, is a hypothesis or model rather than a theory. BIG MISTAKE: saying “Evolution is only a theory.” BIG MISTAKE: saying “Evolution is only a theory.”

SUMMARYSUMMARY A MODEL is a description, object, drawing, set of equations, etc. that helps us get a mental picture of something we cannot directly observe. A LAW has also been tested by many experiments (usually for many years). It describes WHAT happens, without trying to say WHY it happens. A HYPOTHESIS is a tentative explanation for something observed in nature. A THEORY is a hypothesis that has been thoroughly tested by many experiments. It is an attempt to explain WHY something happens.