Ok here's the short story. A friend of mine is in grad school for physics. I have a BS in physics, however i graduated in 2002 and haven't used anything i learned as i don't work in the field. I always try to think up questions to stump him. This time he got me. Here's what he asked me. In special relativity, At what speed does an object need to travel for its Total energy to be less than its resting energy. This one is way out of my league at this point. If i posted this in the wrong place i apologige. p.s. i asked him about the object having zero mass and didnt get a response.