how is it that some strings have mass (spin 1/2 particles) while others have no mass at all (spin 2 particles and force carrying particles)? all strings are the same, its just how they move and vibrate that they change from particle to particle, but wouldnt this mean that all strings either have mass or dont? also, string theory is supposed to calm the quantum fluctuations at plank scales so that the standard model and GR mix. but wouldnt there not be any quantum fluctutions at that level because there arent any point particles? does this mean that virtual strings hitting each other release less energy than if they where point particles?