and, foom, send out its own light wave. that catches the next atom. when that light wave hits that atom, what's that atom do? how many say, "oh, it probably don't vibrate"? come on, it vibrates, too, all right? so, boom, it's absorbed. now, what's the vibrating atom do? boom, spit, burp, bam, bam, bam--it cascades, when it gets to the end. here's your piece of glass like this, yeah. here's your first atom just sitting like that. here comes a wave--choo, choo-- okay, hoop, i spit. next atom, boom, okay, boom. hit, boom. here's the atom right on the edge over here. whip, boom. this one, hit, boom, and then foom, free space. how fast did it throw it out? free space. you know what the speed of the light was in between atoms? 300,000 kilometers per second, the speed of light that you get in a vacuum. 'cause guess--we think of a vacuum as void, right? take a piece of glass, take a piece of water, what's in between the atoms? how many say airspace? no, no, no, no, no. no airspace. what's in between there, gang? begin with a v end with oid. try it. - void. -