Thursday, 9 June 2011

dg.differential geometry - Prescribing a Riemannian metric along a given geodesic

Let gamma:[0,1]tomathbbR2 be a finite C2-curve in the plane which does not intersect itself. Let p(z) be a second-degree polynomial in zinmathbbR2. Can we construct a Riemannian metric g along gamma such that

  • gamma is a geodesic of g,


  • gamma has length 1, and


  • p(z) is the 2-jet of g at gamma(0)? (i.e. this prescribes g and its first and second derivatives at gamma(0)) Edit: As per Sergei's comment, assume that p is chosen so that gamma does in fact solve the geodesic equation.

I think so, and my sketch of an argument follows the proof of existence of Fermi coordinates in reverse. I haven't worked through this in detail yet, though, because I'm more concerned about the next question:



Let gamma and eta both be finite curves [0,1]tomathbbR2 which do not intersect themselves, and such that gamma(0)=eta(0) and gamma(1)=eta(1) with no other intersections (i.e. gammacupeta is a piecewise, simple, closed C2-curve in the plane). Can we construct a metric g as above? Note that if so, gamma(0) and gamma(1) will be conjugate points along gamma.

No comments:

Post a Comment