My daughter was driving to work and her back windshield shattered. Does anyone know why that would have happened?
It could have been hit by something, but it’s also possible for a window to shatter just due to internal stresses if there’s a defect in the glass, especially if the temperature of the glass changed rapidly.
Tester
It’s possible she poured hot water on the glass to quickly clear it of ice/snow, and it shattered. And she’s just not owning up to that, which is understandable, as it is sort of embarrassing to admit to. That is not an uncommon thing to try, especially for younger drivers who are seeking a method to bypass the scrape the windshield of ice job. Years ago my dad decided it would be a good idea to put an electric heater inside his truck cab, pointed at the windshield. His job required he leave very early in the morning, cold climate. About 10 minutes before he planned to leave he turn the heater on and by the time he was ready to go the windshield would be 100% defrosted, inside & out. It worked for about a month, then a cold spell of several days in a row of below 0 degrees overnight temperatures occurred. Zap, the glass shatters.
So? What color is your sky in your world, George?
Tester
Can’t see the sky, my tin foil hat prevents looking up. 
Really not a nice thing to post.
I agree with @Tester. My son recently had a problem with the glass in the door of his kitchen range. This was a brand new stove in a newly renovated apartment. The range was about six months old. At any rate, he had used the oven to make biscuits for his family’s breakfast. The stove had been turned off, his family had finished breakfast and an hour later, the glass in the oven door shattered. The manager of his apartment building immediately replaced the stove.