Dark matter makes up most of the matter in the universe but very little of a standard introductory physics curriculum. Here we present our construction and use of a spandex sheet-style gravity simulator to qualitatively demonstrate two aspects of modern physics related to dark matter. First, we describe an activity in which students explore the dependence of orbital velocities on the central mass of a system, in a demonstration of how scientists first discovered dark matter. Second, we discuss the use of the gravity simulator as a visualization of gravitational lensing, a current astronomical technique for mapping dark matter in the sky. After providing the necessary background for the phenomena of interest, we describe our construction of the gravity simulator and detail our facilitation of these two activities. Together, these activities provide a conceptual visualization of gravitational phenomena related to indirect detection techniques for studying dark matter.

Topics
General relativity, Dark matter, Galactic properties, Galaxies, Gravitational lenses, Telescopes, Polymers, Optical imaging, Education, Astronomers
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Here we used a localized central mass to investigate orbital rotation speeds. A more accurate model of dark matter would be to use an extended object—perhaps a flexible sheet of lead—attached to the underside of the spandex, since the dark matter is known to extend far beyond the visible matter of a galaxy (see Fig. 1). However, our students do not appear to suffer misconceptions about dark matter detection because of this model limitation.
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For elementary school students it could be a model of the solar system, while for more advanced students it could be a visualization of Einstein's curved spacetime.
© 2015 American Association of Physics Teachers.
2015
American Association of Physics Teachers
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