1. Consider each of the following hypotheses. Is the hypothesis measurable? Falsifiable? I. Maggots spontaneously generate when raw meat is exposed to air. II. Intelligent life exists on other planets in the universe. III. Souls are standing waves with antinodes at synapses in a human's brain. IV. If the length of an electrical wire increases, the resistance of the wire will increase in proportion to the length.

Measurement Corner #15: Testable hypotheses You have been told since grade school that you should make a hypothesis before you do an experiment. Why is this so important? If you make a hypothesis first, you are much more likely to learn from your experiment. If your experiment confirms your hypothesis your confidence in your model grows. On the other hand, if your experiment contradicts your hypothesis, you know that your model is wrong so you can brainstorm modifications to your model or new and better models. If you don't have a hypothesis, you won't know whether your model is right or wrong. Any learning that occurs is then purely accidental. Making hypotheses is also important because it helps you decide what experiment to do. For example, one of Galileo's discoveries was that all objects, provided that air resistance is negligible, fall with the same acceleration under the influence of gravity. The experiment to test this is very simple, yet for thousands of years people had not discovered this simple fact. (In fact, some of you probably believed that heavier objects fall faster at the beginning of this class.) What allowed Galileo to make his discovery was that he made a hypothesis. His hypothesis was that two objects would fall through the same distance in exactly the same amount of time. Let's look a little closer at this hypothesis. What makes it useful for scientific experimentation? The hypothesis is testable; an experiment can be performed to conclusively confirm or reject the hypothesis. In order for a hypothesis to be testable, it must be measurable and falsifiable. Anything that is not measurable is not scientifically testable. Measurements might be as simple as visual observations or extremely complicated, but in all scientific tests some experiment measures a property of a material object. For example, consider the following hypothesis "When an object enters a black hole, it emerges from a corresponding black hole in another universe with a velocity equal to the object's velocity before it entered the black hole." Is this hypothesis plausible? Is it testable? Are we likely to gain any scientific knowledge from pursuing this hypothesis? A falsifiable hypothesis can be proved to be incorrect when some measurement directly contradicts the predictions made by the hypothesis. Falsifiability is important because it allows us to definitively reject incorrect hypotheses. For example, when Newton was studying optics, his model of light propagation required that all of space be filled with a material called "luminiferous aether" through which light travels, just like sound travels through air. Michelson and Morley used this model to develop a hypothesis. They hypothesized that since Earth would be moving relative to the luminiferous aether, the speed of light would be different depending on the direction that the light travels. Is Michelson and Morley's hypothesis falsifiable? Is it testable? In fact, Michelson and Morley designed an experiment to test their hypothesis and found that their hypothesis was untrue