Skip to main content
1 of 8
Ali Taghavi
  • 356
  • 8
  • 31
  • 123

Some dynamical and Bundle questions arising from certain map $P:TS^{n}\to S^{n}$

Define the map $$P:TS^{n}\to S^{n} \;\;\;\text{by}\;\; P((x,v))=\frac{x+v}{\parallel x+v \parallel}$$ where $$TS^{n}=\{(x,v)\in S^{n} \ \times \mathbb{R}^{n+1}\mid v \perp x \}$$

This map is used in the book of Alain Hatcher, Algebraic topology to give a proof for the fact that every vector field on even spheres must vanish on at least one point of the sphere.

Question:

  1. Does $P$ define a (nontrivial) fiber Bundle?
  1. Define the Hamiltonian $H:TS^{n} \to S^{n}$ with $H(x,v)={\parallel P(x,v)-x \parallel}^{2} $ where the later is the standard Euclidean norm on $\mathbb{R}^{n+1}$. What can be said about the dynamical behavior of the corresponding hamiltonian vector field $X_{H}$? Are there periodic orbits?
Ali Taghavi
  • 356
  • 8
  • 31
  • 123