Thanks everyone. It is an honor to be a helper.

I'm always looking for better ways to explain physics so I have a question for all of you. Someone recently made the assertion that if you give someone more than a simple yes or no answer to a simple question then the person asking the question is overwhelmed. I find that to be a silly assertion. Here is the example I used.

Suppose someone asks you the question "Does light have mass?" One person answers "No". I find that to be misleading. Here is how I wold answer it "A photon has zero rest mass, since it can't be at rest, non-zero relativistic mass since it has momentum, non-zero passive gravitational mass, since its effected by a gravitational field and non-zero active gravitational mass since it can generate a gravitational field."

Are any of you overwhelmed by that answer? I could have gotten more precise since "light" and "photon" are different things and the answer can be more complicated depending on the exact nature of the light.