# Plato's Shadow Problem

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This Demonstration is based on a problem proposed by Plato more than 2000 years ago in Book VII of the celebrated work, *The Republic*, in a dialogue called "Allegory of the Cave". Imagine a film running inside a black box with a thin slit. Outside the box there is a source of parallel rays of light—the sun, for example. Between the source and the slit there is a prismatic object that can rotate on its axis, which is orthogonal to the slit and the direction of the light.

Contributed by: Antonio Candido Faleiros, Luiz Bevilacqua, Adilson J. V. Brandão, and Rodney C. Bassanezi (Universidade Federal do ABC - UFABC, Santo André, Brazil) (August 2009)

Open content licensed under CC BY-NC-SA

## Snapshots

## Details

References:

1. Plato, *The Republic*, Book VII, 514a–517c, circa 385 BCE.
2. L. Bevilacqua, A. J. V. Brandão, and C. Bassanezi, "A Mathematical Approach to the Plato's Problem," arXiv 0805.4596v1, May 2008.

## Permanent Citation

"Plato's Shadow Problem"

http://demonstrations.wolfram.com/PlatosShadowProblem/

Wolfram Demonstrations Project

Published: August 10 2009