After a colleague sent me a link on the subject, my boyfriend and I spent an evening watching YouTube videos about supercooled water. The principle is that you can cool water bellow its freezing point without it actually turning into ice. But once disturbed, it causes a chain reaction and freezes instantly, as you can see in the following video:
It's so cool, I had to try! I didn't know about this property of water. It's amazing to see that you can still learn from something that we use -and take for granted- every day. And it's a simple experiment too: all you need is a bottle of water, a freezer and a timer. Timing is extremely crucial because if you leave it too long, ice will form. And if you don't leave it in the freezer long enough, it won't work.
This is my third success. It wasn't as good as the other two times because the chain reaction was a little fuzzy. When I shook the bottle, you can see some slush being thrown around and the freezing didn't spread quite evenly. For this experiment I keep reusing the same bottle over and over again. I just make sure that there is no ice present in the bottle when I put it in the freezer as the water will form ice around those "seeds". I'm using a 1 L bottle of unopened filtered water. So far, I've had the most success keeping it in the freezer for 2 hours and 45 minutes. Can't tell ya how cold it is in there though. Obviously, different freezers and other variants will produce different data. I'm hoping to make a video where you can see the same chain reaction as you can see in the YouTube video above.
After the cooling time, I admit I might've taken the bottle out of the freezer a little too slow! It does take a bit of... persuation for the reaction to start. I suspect the colder the water is, the faster it freezes.
Once I'll have this down to a (ahem) science, I'll make a video using the glass of water with ice cubes. What happens in that instance is that the supercooled water freezes instantly as it touches the ice. The point of contact is where the chain reaction begins. This is the reason why the water needs to be free of particules. Even bubbles of water can help ice form crystals.
I think I'm starting to understand what I need to do instead of shaking and beating the bottle! Something about the top part of the bottle..