Is it possible for glass to randomly crack?

[Deleted User]

There was one time, I was at a shopping centre. I heard a sound and the window of a nearby store suddenly cracked. I was not paying attention before I heard the sound but I did not see anything or anyone hit the glass. At that time I assumed that kinetic energy between the atoms (heat) in the glass caused the atoms to arrange themselves in some very unlikely formation which caused the crack to occur.

Assuming that the glass wasn't physically hit by something I didn't see, is this assumption reasonable? Are there any other reasonable explanations for this occurrence? Maybe my assumption while possible is so statistically unlikely that in practice it wont happen therefore I'm an idiot for not paying attention at the time.

 

[ChaosEternal]

Glass can randomly shatter, yeah. I'm not really sure why it happens though.

 

[Crazynoob458]

screetching ladies

 

[Ryccardo]

Yeah, it is theoretically possible - but fairly more common is for repeated heating and cooling to enlarge preexisting micro cracks
(a bit like why halogen lamps have a self-repairing filament yet in practice still break like conventional ones, not even that much later: wear is uneven, so is redeposition AND it can't privilege where it's needed the most)

 

[sarkwalvein]

Yes, it's likely to happen if it is heated or made cold too fast just due to non-uniform expansion/contraction.

 

[slaphappygamer]

Yes, it's likely to happen if it is heated or made cold too fast just due to non-uniform expansion/contraction.

This is why you never use water to melt the ice on your windshield.

 

[VinsCool]

Glass stress induces forces that could make a piece of glass to randomly shatter, yes.

It's not that rare to see a glass fine a day and the next day see it cracked, or often a piece detach from it.

Use, heat and cold over the time does do that.

 

[Ericthegreat]

I think it can be cause by the glass having stress on it over a period of time, like if it was installed incorrectly, then a very hot or cold day (or many)

 

[Sicklyboy]

Did the store have a swinging door or an automatic sliding door? If it was a swinging door it's possible the sudden pressure differential could have shattered it, with the glass being weakened from other factors over time - such as heat/cold cycles and impurities in the glass.

Happened on my truck once - closed my door after placing my laptop inside and it just straight up blew out my back window.

 

[TheCasualties]

Other answers here seem reasonable to me. Could have even been a defect from manufacturing. Might not have annealed properly too (heated evenly so the molecules realign into the strong crystal structure).

Interesting side note, glass eventually 'droops' even at room temps. It takes a really long time, much longer than what the window in your story had. Some old stained glass has started to droop, for example.

I've also made some things that have no visible cracks and then next week there is a crack. Sometimes from heat, but it's usually just unseen stresses that finally give. A "polariscope" is cool for seeing these invisible stresses.

 

[JuanMena]

Absolutely, under certain frequencies.

Did you attended Physics classes?

The Kinetic energy thing is only true in King Rupert's Glass.

 

[Deleted User]

Did the store have a swinging door or an automatic sliding door? If it was a swinging door it's possible the sudden pressure differential could have shattered it, with the glass being weakened from other factors over time - such as heat/cold cycles and impurities in the glass.

Happened on my truck once - closed my door after placing my laptop inside and it just straight up blew out my back window.

It had an automatic sliding door.

 

[linuxares]

Believe it or not, but glass is actually not a solid, nor a liquid. It's amorphous solid. That will say it's between them. So yes, glass can infact just randomly explode.

Most common tho is stress from example heat or cold, vibrations in the facility or pressure even. And of course by causing force to it.