light may have no mass but it has energy and momentum and has shown to move things, that is the transfer of energy, which is what primarily what lasers are for, it has plenty of evidence that it is light speed because of how it works, 15 million degrees is for the Sun's core which is only achieved by it's mass and gravitational pressure, so no, 100 million is the key here. Wall is Large Country level. Technically that is not all off, even Invel showed feats of Absolute Zero, such as frozen mass breaking down by itself from it's own weight