Glow-In-The-Dark Ponderings

Do you ever wonder what makes glow-in-the-dark stuff glow? Why is there such a limited supply of things that glow? First off, does it ever not glow? I mean maybe the glowing never stops, even when the lights are on.

Speaking of things that glow, there should be more of them. Glow-in-the-dark paper, undies, bras, pool cues, fishing line...really, how cool would that be to have a fishing pole with glow-in-the-dark line...even picture frames would be neat. Imagine having a book that you can actually read in the dark. Black paper, glowing words...it would be like invisible ink. Imagine how great it would be to have invisible ink for a journal or diary. Better yet, how about glow-in-the-dark food? Now that would be interesting. Glowing silverware and plates...there's an investment in itself.