Yeah, I remember the same thing, although not from physics class. I was a fine arts major and took classes that had topics like "our friend, the 7". However, if it is impossible to change directions without changing speed, then refraction and reflection prove the speed of light is not constant (at least I thought it did.) Also, it would seem logical to me that light would slow down after so long. If this is the case, wouldn't it be possible that the red shift in all the stars might mean NOT that the stars were moving away from us, but that the light was slowing down as it crossed the galaxy?
Light used to be seen in the park playing chess all afternoon, but lately it has become forgetful about even feeding pigeons, just sitting and watching, going home when it starts growing cold.