content_image/366443.jpg content_image/366450.jpg content_image/366449.jpg
(i.e. x = x $^{1}$), we get 

<img src='content_image/366443.jpg'>

<img src='content_image/366450.jpg'>

where the turning points are x = r$_{max}$ and x = − r$_{max}$ . On setting x$_{0}$ = − r$_{max}$ we can write the trajectory explicitly as 

<img src='content_image/366449.jpg'>

where T = 4 r max c is the period of oscillations of a massless particle between the turning points x = r$_{max}$ and x = − r$_{max}$ , and [ a ] is the biggest integer in a . The trajectory (2.23) is 

