IMPORTANT WORDS IN SCIENCE

HYPOTHESIS This is an educated guess based upon observation. It is a rational explanation of a single event or phenomenon based upon what is observed, but which has not been proved. Most hypotheses can be supported or refuted by experimentation or continued observation.

Example: If you see no difference in the cleaning ability of various laundry detergents, you might hypothesize that cleaning effectiveness is not affected by which detergent you use.

You can see this hypothesis can be disproven if a stain is removed by one detergent and not another.

THEORY A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. A theory is valid as long as there is no evidence to dispute it.

Therefore, theories can be disproven. Basically, if evidence accumulates to support a hypothesis, then the hypothesis can become accepted as a good explanation of a phenomenon. One definition of a theory is to say it's an accepted hypothesis.

Example: It is known that on June 30, 1908 in Tunguska, Siberia, there was an explosion equivalent to the detonation of about 15 million tons of TNT. Many hypotheses have been proposed for what caused the explosion. It is theorized that the explosion was caused by a natural extraterrestrial phenomenon, and was not caused by man.

Is this theory a fact? No. The event is a recorded fact. Is this this theory generally accepted to be true, based on evidence to-date? Yes. Can this theory be shown to be false and be discarded? Yes.

Development of a Simple Theory by the Scientific Method: Observation State a possible answer, called a Hypothesis Perform an experiment or Test Publish your findings Verification Other scientists read about your experiment and try to duplicate it In time, and if experiments continue to support your hypothesis, it becomes a Theory

Development of a Simple Theory by the Scientific Method: Broth spoils when I leave it out for a couple of days. Why? Tiny organisms floating in the air must fall into the broth and start reproducing. After boiling some broth, I divide it into two containers, one covered and one not covered. I place them on the table for two days and see if one spoils. Only the uncovered broth spoiled. "Only broth that is exposed to the air after two days tended to spoil. The covered specimen did not." Scientists try other methods to make sure your experiment was measuring what it was supposed to. Again, they get the same results every time. Microorganisms from the air cause broth to spoil.

LAW A law generalizes a body of observations. At the time it is made, no exceptions have been found to a law. Scientific laws explain things, but they do not describe them.

LAW is generally accepted to be true and universal, and can sometimes be expressed in terms of a single mathematical equation.

A law is a general description of a pattern or a relationship.

scientific laws must be simple, true, universal, and absolute

Example: Consider Newton's Law of Gravity. Newton could use this law to predict the behavior of a dropped object, but he couldn't explain why it happened.

MODEL A model is a representation containing the essential structure of some object or event in the real world.

The scientific method is basically one of creating, verifying, and modifying models of the world. The goal of the scientific method is to simplify and explain the complexity and confusion of the world.

Example: the particle model of matter is a theory (a set of ideas) that explains how particles are arranged in solids, liquids and gases and how they behave in different conditions. The particle model uses diagrams to help explain what happens.

BIBLIOGRAPHY ry101/a/lawtheory.htm /introbook/sbk04m.htm