Scientists solve 400-year-old mystery of Prince Rupert's drops | Hacker News Reader

Scientists solve 400-year-old mystery of Prince Rupert's drops

phys.org

41 pointsdnetesn11 comments

The Smarter Every Day YouTube channel has done several high-speed videos about Prince Rupert's drops, including a couple released just last week.

* 2013-03-22 https://www.youtube.com/watch?v=xe-f4gokRBs

* 2016-12-29 https://www.youtube.com/watch?v=24q80ReMyq0

* 2017-04-26 https://www.youtube.com/watch?v=F3FkAUbetWU

* 2017-04-30 https://www.youtube.com/watch?v=k5MORochIDw

Just wanted to point out that he's pretty active on Reddit

https://www.reddit.com/r/SmarterEveryDay/

calling it a "400-year-old mystery" is nonsense; the mechanism has been understood and exploited in heat-tempered glass for decades [1].

Ironically, this article fails to explain the origin of the forces on which the properties depend, which is due to the slow-cooling interior continuing to contract after the surface has hardened. I had read somewhere that the slow-cooling interior tends to find a more compact structure than the exterior, as the rapidly-cooled exterior tends to get locked into the expanded structure exhibited above its transition temperature. I have not found a source saying this, but the behavior above and below the transition temperature is described here [2].

1. http://www.breakglass.org/How-is-glass-made.html

2. https://en.wikipedia.org/wiki/Glass_transition

Could you create a glass shape as strong as the drop, but without the easy to break tail?

Take a whole bunch of them and stick the tails in the center, to form an unbreakable sphere.

Kind of like a Rat King of Prince Rupert drops.

You'd want a hollow centre otherwise compressive forces would pass through and initiate the collapse of the tails.

I guess you could do it in space as long as you could have a sphere of molten glass floating, then immediately surround it with water from all sides.

My reasoning is that the tail is formed because the molten glass is dropped into the water, hence forming the tail. So if you could have a sphere and cool it down from all sides simultaneously then it should form a sphere based version.

Of course there's also a chance of explosion.

but is the internal tension in the head not partially a result of the combination of rapid cooling and rapid deceleration from water resistance? Dousing a molten glass bead in space would only produce one of these two effects.

If you could have the tail inside of the drop like a jellyfish.

I believe this is somewhat how gorilla glass works, except by s different process called ion exchange, where large ions are forced in to the glass in place of smaller ones at high temperature, causing the glass matrix to have to compress to accommodate them once cooled and thus creating residual compressive stresses.

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