¶ Tetrahedron: Coordinate Symmetry (1)
← Tetrahedron: Coordinate Symmetry | Tetrahedron: Coordinate Symmetry (2) →
Index Entry
Tetrahedron: Coordinate Symmetry:
“Let me then take a tetrahedron of cheese and I am going to press in on one of the faces instead of slicing it. It remains symmetrical all right. But I am going to pull out on a second face at the same rate that I pushed in on the first face; so now it remains the same size. It is still symmetrical but the pushing of the first face made it get a little smaller, but pulling out on the second face made it get larger. By pushing and pulling at the same rate it remains the same size, but its center of gravity has to change because the tetrahedron moves. As a consequence, then, of the tetrahedron moving it receives a couple of alterations. It receives one positive and one negative alteration, remains symmetrical and the same size, and apparently moves. I have only used up two of the four faces, so I am going to push in on the third face at a rate different from the couple that are already operating, and I am going to pull out on the fourth face at the rate I was pushing in on the third face. I am making another completely different rate of change: one being very fast and the other slow; one very hard and the other quite soft. These completely different rates are coupled, and so it remains symmetrical and the same size, but now it has to change its position to satisfy two alterations to the center of gravity and so it is moving in a kind of helix. It is one of our precessional results.”
¶ Citations
- OREGON Lecture #6, pp. 208-9. 10 Jul’62
