My wife and I attended the Perimeter Institute for theoretical physics. We watched the public lecture called: THE COSMIC GIFT OF NEUTRON STARS by VICTORIA KASPI. I thought it was a decent lecture (perimeter has had some outstanding ones in the past). On the way to work this morning I was pondering something she said. She talked about and showed an animation of a binary pulsar where the magnetic field was essentially "blocking" the radio light from the background object. Herein lies my question; I was under the impression magnetic fields do not effect photons in that way. The animation clearly wasn't showing a warping of space time. Was this referring to vacuum polarization? Or some other effect? I attempted a google search and came up fairly inconclusive. Can anyone help me out? Here is a link to the video (which isn't in their video library yet) I hope links are allowed! The part I'm referring to is at the 46 minute mark. Their video library with past public lectures can be found here: http://perimeterinstitute.ca/video-library?qt-videos=1#qt-videos Thanks! Ben edit: I completely forgot! Congratulations to Victoria for her recent award!