2019/06/28 by Louis Crane, Crane, Louis, David N. Yetter +1
Mathematics · Physics and Astronomy · #51M04 #51M20 #51M25 #Black Holes and Theoretical Physics #FOS: Mathematics #FOS: Physical sciences #General Mathematics (math.GM) #General Relativity and Quantum Cosmology (gr-qc) #Mathematics and Applications #Noncommutative and Quantum Gravity Theories
paper · pdf · doi:10.48550/arxiv.1906.12224
openalex publication_date 2019/06/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We solve a very classical problem motivated by considerations in quantum gravity: providing a description of the geometry of a Euclidean tetrahedron from the initial data of the areas of the faces and the areas of the medial parallelograms of Yetter or equivalently of the pseudofaces of McConnell. In particular, we derive expressions for the dihedral angles, face angles and (an) edge length, the remaining parts being derivable by symmetry or by identities in the classic 1902 compendium of results on tetrahedral geometry of Richardson. We also provide an alternative proof using (bi)vectors of the result of Yetter that four times the sum of the squared areas of the medial parallelograms is equal to the sum of the squared areas of the faces. The updated version corrects several errors and provides better historical context for the result.