Can you speak English for a lowly S/W Developer, please... I have always had an interest in physics, and have done some reading, on it, and will do much more. I'm not a mathematician, nor a Physicist, but I can catch on to ANYTHING well explained! Here is the preliminary to the question I have concerning the increase in mass, as velocity increases. BUT first, I want to point to some Web Pages that confirm that a photon DOES have mass, as I'm not sure if it is part of my confusion or not. 1) "What is the Mass of a Photon?" See: http://math.ucr.edu/home/baez/physi...hoton_mass.html 2) For a discussion of it, in another String Theory Forum, See: http://superstringtheory.com/forum/...sages10/23.html (Many other Web Sites can be found stating the Mass of a Photon). If I recall correcly, I read on one Web Site that the mass of a photon is estimated at 10^-48th of the mass of an electron. Now for my questions... THIS MUST BE VERY BASIC STUFF FOR YOU FOLKS PLEASE excuse my ignorance. 1) What is meant by "infinite mass", when speaking of the mass of an object traveling at light speed. 2) Since a photon is traveling at light speed, why does it not have infinite mass; if not infinite mass, then at least the mass of a planet? 3) Along with infinite mass should come an infinite gravitational pull. So, why wouldn't an object with "infinite mass", have "infinite gravity", which leads to two questions: 3a) What is infinite gravity? 3b) Why wouldn't the gravitational pull of the photon (which is supposed to have "infinite mass"), cause the entire planet to be swallowed into it, just like a Black Hole would do??? Again, I appologize for my ignorance, but these are the words used in physics books I've read, and I'm just following what I think is supposed to happen for a particle with mass travelling at light speed. Thanks for your patience. I look forward to reading a reply that doesn't flame my ignorance. Thanks again.