Don Frazier, a NASA chemist, conducting an experiment using a laser imaging system.
In science, we need to make observations on various phenomena to form and test hypotheses. Some phenomena can be found and studied in nature, but scientists often need to create an experiment. Experiments are tests under controlled conditions designed to demonstrate something scientists already know or to test something scientists wish to know. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results. The process of designing and performing experiments is a part of the scientific method.
The Scientific Method
The scientific method is the process used by scientists to acquire new knowledge and improve our understanding of the universe. It involves making observations on the phenomenon being studied, suggesting explanations for the observations, and testing these possible explanations, also called hypotheses, by making new observations. A hypothesis is a scientist's proposed explanation of a phenomenon which still must be tested. The scientific method is employed by scientists around the world, but it is not always conducted in the order above. Sometimes, hypothesis are formulated before observations are collected; sometimes observations are made before hypothesis are created. Regardless, it is important that scientists record their procedures carefully, allowing others to reproduce and verify the experimental data and results. After many experiments provide results supporting a hypothesis, the hypothesis becomes a theory. Theories remain theories forever, and are constantly being retested with every experiment and observation. Theories can never become fact or law.
In science, a law is a mathematical relationship that exists between observations under a given set of conditions. There is a fundamental difference between observations of the physical world and explanations of the nature of the physical world. Hypotheses and theories are explanations, whereas laws and measurements are observational.
