Explored is the role of thought experiments in the development of physical theories. Drawing examples from quantum theory it asks how a method that generates no new empirical data can nonetheless exert an influence upon a subject defined by its empiricism. (Author/KR)

A homemade device for testing particle scattering is described. Also described are experiments in zero gravity conducted in free fall in the cargo space of an airplane belonging to the National Aeronautics and Space Administration. (JN)

Explains and illustrates strange events which occur when two pendulums interact through a variety of interconnections. Phenomena addressed include: pendulums coupled by a spring, rod, or string; vertical and rotational oscillations, and synchronous and mirror-image swinging. A resonant-spring pendulum and a Wilberforce pendulum are also discussed.…

Provides a method for correcting the photoemission from a collector when using the photoelectric effect experiment to determine Planck's constant. The problem results from a negative current through the cell and makes the measurement of the cutoff potential difficult. (DH)

Presents a field formula for calculating speed and flight efficiency of soaring birds. By estimating the size of the bank angle and timing the complete circle, the observer can determine the speed and circling radius on a chart provided. Lift coefficients and flight characteristics of several birds are also discussed. (DH)

A retroreflector is a mirror that removes distortion from a light beam. Describes experiments using the retroreflector as well as related phenomena. (JN)

Discusses forces that shape the behavior of water as a drop meanders down a windowpane. A homemade apparatus for studying meanders is described along with several experiments. Contact angles, molecule attraction, surface area, air tension, and gravity drag forces are some of the topics addressed. (DH)

The tendency of a poured liquid to cling to the outside of a container is known as the "teapot effect." The nature of the teapot effect and experiments investigating this phenomenon are described. (JN)

Many properties of new particle field theories can only be tested by comparing their predictions about the physical conditions immediately after the big bang with what can be reconstructed about this event from astronomical data. Facts/questions about big bang, unified field theories, and universe epochs/mass are among the topics discussed. (JN)

Describes experiments using fluidyne engines. These engines (which have liquid pistons), started by external heat sources, are used primarily for pumping water. Examples of various engines built from U-shaped tubes or from coiled tubes in fruit jars are provided. (DH)

Provides the rationale for and examples of experiments designed to test the stability of protons and bound neutrons. Also considers the unification question, cosmological implications, current and future detectors, and current status of knowledge on proton decay. (JN)

Suggests using better materials in fire syringes to obtain more effective results during demonstrations which show the elevation in temperature upon a very rapid (adiabatic) compression of air. Also describes an experiment (using ignition temperatures) which introduces students to the use of thermocouples for high temperature measurements. (DH)

Discusses the physics behind making ice cream in a hand-cranked ice cream maker. Ingredients in the maker are cooled and hardened by a bath of ice, water, and rock salt. Several experiments to investigate the variables involved in preparing the ice cream (and related desserts) are included. (JN)

Computational science is defined as science done on a computer. A computer can serve as a laboratory for researchers who cannot experiment with their subjects, and as a calculator for those who otherwise might need centuries to solve some problems mathematically. The National Science Foundation's support of supercomputers is discussed. (MLW)

Presents a nonmathematical approach to help students understand that there are two types of coherence and to associate coherence as a property of the illumination at an object itself. The approach also lends itself to an introduction to the Fourier approach for analyzing imaging systems. (JN)