This is a great example of "what happens at the edge". It's predictable but no one predicts it because no one considers it.

Reminds me of the John Carmack quote someone added on another discussion yesterday: "A large fraction of the flaws in software development are due to programmers not fully understanding all the possible states their code may execute in."

Also reminds me of a line from a book (I can't remember which one), that was quoting an NSA representative in a meeting saying something along the lines of "our business is in the gaps between systems". My memory / interpretation taking it as: where one process ends and another one begins - that's where there's ambiguity, wiggle room, it's not process A's problem now, but it's not yet process B's problem, so what can we do to get in there and "make the ice spike".

The interesting things happen at the edges (in this case it's the middle, but that's missing the point).

> The interesting things happen at the edges

True in biology also. Much more diversity at the boundary between ecosystems.

So happy to have this small mystery solved. I lived in SE Asia for years where we avoided the local tap water, including for ice at home.

My kids and I observed these ice spikes every morning when I took out the trays to for iced coffees, and I always wondered why I'd never seen them anywhere else in the world.

It's almost a nice retroactive confirmation that the water delivery service we relied on was selling distilled water as advertised!

You shouldn’t drink distilled water. It’s devoid of minerals so when you drink it, the distilled water sucks minerals from your body to equalise which can cause issues.

That's a myth. Distilled water is perfectly safe to drink, it just doesn't taste very good.

https://www.healthline.com/health/can-you-drink-distilled-wa...

The mineral content in even mineral water (never mind tap water) is miniscule.

Your source confirms that exactly.

"Since distilled water doesn’t contain its own minerals, it has a tendency to pull them from whatever it touches to maintain a balance. So when you drink distilled water, it may pull small amounts of minerals from your body, including from your teeth."

... and then explains that the effect is small enough to not be a problem, so no, it does not confirm that "you shouldn't drink distilled water".

But that it could be a problem. So its not a myth, that it is demineralizing your body. Its a small effect - but its there, and it could have a negative effect on the body.

"The gamma radiation from distant galaxies is not a myth. It's a small effect - but it's there, and it could have a negative effect on the body."

No - some things are small enough that they cannot.

It's better to drink distilled water than contaminated tap water, though.

I also live in SEA. While distilled water is pretty popular (gaining more popularity these days), spring waters are even more popular and widely available (also tastes better IMO).

"The graphs on this page were produced by Kevin Lui (right), a undergraduate student at Caltech who spent a summer growing thousands of ice cubes to investigate the physics behind ice spike formation."

interns get to do some of the coolest things

ba-dum-ta

>interns get to do some of the coolest things

Like take the blame when things go wrong like testing a major email notification system.

Reminds me of tin whiskers which can happen in electronic solder and cause shorts. https://en.m.wikipedia.org/wiki/Whisker_(metallurgy)

Also by Kenneth Libbrecht checkout "The Snowflake: Winter's Secret Beauty." You can buy it for cheap on AbeBooks.

This interview with Kenneth Libbrecht is wonderful, https://www.youtube.com/watch?v=ao2Jfm35XeE

Aw man, so glad to have had that explained. Took this photo [1] in my back garden about 10 years ago and was never quite sure...

[1] https://capture.dropbox.com/Fw1tQrHnfH3pDTRt?src=ss

I neglected to take a picture of it before picking it up, but I found one of these growing out of a neighbors yard. It had picked up a little baby plant that was frozen in the top. I have seen a lot of crazy ice formations but never this, thanks for solving the mystery (I think)!

Ooooooh, that's what that is. I always thought something was dripping from a shelf above and forming an icy stalagmite, but I could never figure it out.

Anecdata point: I use RO water which is run through a final carbon filter. This water doesn't produce spikes.

But does distilled water make spikes in your freezer? If not, then it's not the water, it's the freezer environment.