Tetrahedra: From Aristotle’s Mistake to Unsolved Problems

Lecture

Speaker

  • A smiling middle-aged man with a bald head and light skin, wearing a white shirt, is photographed indoors with a softly blurred background.
    Bjorn Poonen Principal Investigator, Simons Collaboration on Arithmetic Geometry, Number Theory and Computation

When

  • – ET

Tetrahedra are three-dimensional shapes with four triangular faces. Which tetrahedra can tile to fill a three-dimensional space? Which tetrahedra have rational dihedral angles (the angle between two intersecting planes)? Which tetrahedra can be sliced and reassembled into a cube? Each of these three problems has been around for at least 45 years, and one of them is over 2300 years old. In this lecture, Bjorn Poonen will discuss the status of these problems and explain how he solved one of them in collaboration with K. Kedlaya, A. Kolpakov, and M. Rubinstein.

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October 15–16, 2026

October 15, 2026

1–5 p.m. ET

Speaker

Sookkyung Lim, Ph.D.