In school yesterday my teacher told me that we could not travel at the speed of light because the faster we go the more our mass increases and that we would reach infinite mass before we reached the speed of light so there could never be enough energy to propel us that fast. I asked my teacher if we can't go the speed of light because of infinite mass then how come light can? She couldn't tell me. I also asked her if we were in a place that had no gravity to pull on us then would mass even matter when it came to moving us? So given enough time of constant pushing couldn't we get to the speed of light then? I understand that the photons are really small and have almost no mass but even if it had a mass of 1 with ten billion zeros in front of it wouldn't infinite mass still give the light the same problem? Oh also. Someone told me that light speed isn't constant?