I've always wondered why, when making ice cubes, if you use hot water you'll get little peaks in your cube, like a wave. My brother told me it's not true that hot water freezes faster...so how does it peak?

Has anyone seen this as well?

Next time you make hot water ice cubes, peek. ;)

I should replace my freezer door with a microwave door, then catch 'em in the act.

Part of the hot water evaporates.
So
.... there is less water left in the tray to freeze and
.... the evaporation process extracts energy from the water

If you read the Wiki link, they acknowledge that evaporation can play a role, but they also did an experiment where they controlled for evaporation and the hot water still froze faster.

Have the Mythbusters done this yet?

I'll take their word on it, nobody else's.

The question then becomes....




Does it freeze faster on a treadmill?

Yes, hot water pipes freeze faster than the cold. No evaporation there.

Aren't the molecules farther apart in the hot water and thereby more susceptible to temperature change leading to a faster cooling rate?

Yes, and because there are less of them in a given space, there is less total latent heat.

But I think the experiments were done with a given amount (mass) of water.

It is so counter-intuitive, because for a hotter sample to freeze, it must first reach and pass through the colder temperature, and it is tempting to think of it as cooling from there (the colder temperature) just as the cold sample did. Obviously not.
The explanation I found most plausible is that some kind of condition is created by being at higher temperatures which survives the drop to lower temperatures. It could be an internal mixing movement or something weirder at the microphysical level.

Let me get this straight: We can send a man to the moon (don't you love that antique phrase?) but no one can find a definitive answer regarding the science of water?

I found some articles, but still, I would think that they physical properties of water had pretty much been explored.

http://math.ucr.edu/home/baez/physic...hot_water.html

http://itotd.com/articles/521/water-...boiling-myths/

Classic is right: this is not unlike the treadmill arguments.

Mpemba's experiment used identical volume, not mass.

Ahh zen, but there you have hit on it precisely. There is so much about water that we really do not know. It is amazing that so much of our planet and all the very life upon it relies, yet we still don't fully comprehend so many things about it.