Minimal submanifolds of spheres and cones
M. I. Zelikin,
Yu. S. Osipov Lomonosov Moscow State University
Abstract:
Intersections of cones of index zero with spheres are investigated. Fields of the corresponding minimal manifolds are found. In particular, we consider the cone
$\mathbb{K} =\{x_0^2+x_1^2=x_2^2+x_3^2\}$. Its intersection with the sphere
$\mathbb{S}^3=\sum_{i=0}^3x_i^2$ is often called the Clifford torus
$\mathbb{T}$, because Clifford was the first to notice that the metric of this torus as a submanifold of
$\mathbb{S}^3$ with the metric induced from
$\mathbb{S}^3$ is Euclidian. In addition, the torus
$\mathbb{T}$ considered as a submanifold of
$\mathbb{S}^3$ is a minimal surface. Similarly, it is possible to consider the cone $\mathcal{K} =\{\sum_{i=0}^3x_i^2=\sum_{i=4}^7x_i^2\}$, often called the Simons cone because he proved that
$\mathcal{K}$ specifies a single-valued nonsmooth globally defined minimal surface in
$\mathbb{R}^8$ which is not a plane. It appears that the intersection of
$\mathcal{K}$ with the sphere
$\mathbb{S}^7$, like the Clifford torus, is a minimal submanifold of
$\mathbb{S}^7$. These facts are proved by using the technique of quaternions and the Cayley algebra.
Keywords:
minimal surface, gaussian curvature, quaternions, octonions (Cayley numbers), field of extremals, Weierstrass function.
UDC:
523.46/.481
MSC: 49Q05,
11R52 Received: 11.02.2019
Revised: 11.03.2019
Accepted: 18.03.2019
DOI:
10.21538/0134-4889-2019-25-3-100-107