Make your own free website on

Theory and Experiment
Back to the main page/Back to the previous page

Theory and experiment:

If you talk to a physicist, sooner or later you will find out that he or she considers him/her self to be either a theorist or an experimentalist, especially if the physicist is rather young. Age and circumstance tend to blur the distinction. (When I. I. Rabi, who won the 1944 Nobel Prize in physics in recognition of his resonance method for recording the magnetic properties of atomic nuclei, was asked if he were a theorist or an experimentalist, he replied "well, I'm just a physicist"). Both theory and experiment are necessary ingredients in science. Generally, a phenomenon is observed or contemplated, and experiments are conducted to allow, through observation and measurement, a consistent pattern to emerge from the experimental data. From the data, or sometimes in anticipation of the data, a theory in the form of a physical or mathematical model evolves. The model is then used to predict more general results, and experiments are devised to test the theory (i.e. the scientific method!). Which comes first: theory or experiment? Usually, an idea comes first - an idea often triggered by curiosity about an observation of some physical process. Then the idea is tested by experiment, and finally a theory is formulated. Galileo wondered about the way objects fell under the influence of gravity. He devised experiments involving dropping objects from various heights (Remember the leaning tower of Pisa?) and then with balls rolling down inclined planes since the descent of freely falling objects were not easily timed using his crude clocks, and thus formulated his theory of the motion of falling bodies. There are also notable examples of theory preceding experiment: From a troubling inconsistency in electromagnetic theory Einstein formulated the special theory of relativity. Experimental verification came later. Both theory and experiment are necessary and complementary ingredients in the recipe of scientific investigation. Any scientist, whether theorist or experimentalist,  must have a good understanding of both.