I have been researching a question I have concerning the speed of light in magnetic AND electric fields. I came across an article in arvix but could not quite understand what they were saying. I am not a scientist I am just curious. There was a statement in which was shrouded in a strange nomenclature. Can someone please decipher what they are saying. They said, "In the experimental setup described there, this would mean a birefringence with 0 n (small triangle which I think means delta) <. Sorry that I could not find the delta symbol. This experiment was referring to measuring the speed of light in a magnetic field and in a vacuum. What does 0 n small triangle followed by a less than sign mean?