okay, so in Einstein's theory of relativity, E=mc^2 states that energy is equal to mass time the speed of light squared.. right? sooo...
if we transpose that into terms of mass(m) m=E/(c^2) meaning that mass is energy divided by the speed of light squared.. meaning if you have energy, you MUST have mass, if you have no mass, then you are multiplying the speed of light squared by 0, and the equation states you have no energy. when you say photons are massless, you are either A: ignoring general reletivity, or B: saying Einstein was wrong.
Well basically matter is everything that takes up space, and it doesn't necessarily need to have mass.
there are other particles streaming off of the sun, not just photons. however I know scientists have allegedly trapped a photon and transported a photon. if there is no mass what is there to trap or transport. what if photons are what happens to matter if it is ever accelerated to that velocity. maybe matter is shed to accomodate the increase in velocity leaving only subatomic particles of some kind.
okay. if photons don't have mass. explain solar sails.
sonic boom that goes faster than sound...+1
OOH! Remembered. @Sandwichlizard, perhaps the E=mc^2 is the same as in ohms law (I don't look into the math part of science too much yet) but if I were to make an equation where m is mass and another where m is momentum, they could technically be correct as math is just math. you can assign a variable to anything that has a value and that variable can be anything. This is what happens in communication and as communication, contexts can be required hence english, all of language, so on.
Photons can have mass if you consider there energy as mass (in which case it's tiny and technically incorrect) and something else I forgot. My train of thought is more like a rollercoaster...