Bob Rose light bulb classroom demonstration

Thesis advisor Bob Rose stopped at the Sylvania Beverly plant before 3.091 lectures to collect freshly made light bulbs, which he then threw across 10-250 — they bounced because moisture had not yet attacked the surface.

The story I know is, my old thesis advisor Bob Rose lives up on the North Shore. Sylvania had a glass light bulb manufacturing plant up there in Beverly. He used to lecture 3.091 back in the days when I was a student, and he would stop and get freshly made light bulbs on the way in before his lecture. He would take the light bulbs in 10-250 and throw them across the room, and they'd bounce. They wouldn't shatter, because they were freshly made. They did not have surface imperfections that caused them to fracture.

Rose's 3.091 demonstration — fresh light bulb from Sylvania Danvers plant bounces off wall; day-old light bulb fractures. The point: sodium/potassium oxide corrosion by atmospheric humidity within hours creates fracture-mechanics-relevant surface flaws.