`Bob Rose light bulb classroom demonstration`

Tom's thesis advisor would stop at Sylvania (Danvers, MA — Corning-licensed light bulb plant) before teaching 3.091, bring fresh light bulbs, throw them at the wall — they bounced. Next day same bulbs shatter. Water-vapor surface corrosion in <24 hours.

But if you go through the fracture toughness of this glass, go back to the Ashby plot and look where the glasses are in terms of fracture toughness and calculate the minimum flaw size — it's like 10⁻⁴ millimeters. We're talking angstroms of critical flaw size, or tens of angstroms. You don't have to have very much corrosion. Just the humidity in there. Now, I've never seen this, but my thesis advisor, Bob Rose, used to do it. He still lives up on the North Shore. Sylvania up in Danvers has a glass manufacturing plant — a light bulb manufacturing plant, part of their lighting division — they used to make light bulbs, I'm sure under license from Corning technology. Bob would stop by before he would lecture 3.091 and pick up some freshly made light bulbs, bring them into class, and an hour later he would throw them against the wall, and they'd just bounce off the wall. Try that the next day, and they shatter. He didn't do it the next day, but freshly made glass is extremely strong, because it has no surface flaws — it hasn't been corroded by the moisture in the air yet. Does that answer your question?