> Ideally it would be in a pressure regulated space.
That probably wouldn't do much to help us answer the question of what will happen in our own freezers which aren't pressure regulated. While I'm glad there are and will continue to be all kinds of investigation and exploration around the Mpemba effect what I (and many others) really want to know is if heating water first would help with real world situations like having ice cubes ready in time for an event.
I can accept that it might not always be the case, but considering that at this point we can't say for sure if the effect is real at all it'd be nice if we could get it settled that it worked often enough and potentially decreases freezing time enough to be worth the time and trouble of microwaving our ice cube trays even if all the details and underlying mechanisms aren't well understood.
I should probably just start trying it myself and see what I come up with on my own, but even imperfect lab experiments would be much more accurate and trustworthy. I regularly do things like heat a mug full of water in the microwave, get distracted, and then forget all about it for hours.
> if heating water first would help with real world situations like having ice cubes ready in time for an event.
If the mechanism is that 10% of the water evaporates away, allowing the remaining 90% to freeze smaller by virtue of its reduced mass, the take-away for making ice in a hurry is not to use hot water. It is to use cold water, but a little less of it.
A difference that large should show up in the resulting cubes though right? You wouldn't even need to figure out exactly how long they took to freeze or which tray froze first, just put a heated water tray and a cold water tray in together and compare them after waiting long enough for both to freeze. That'd give you an idea of how much more/less water you'd need to compensate.
Honestly, smaller ice cubes is probably your best bet if you need ice in hurry either way.
> That probably wouldn't do much to help us answer the question of what will happen in our own freezers which aren't pressure regulated
It would do a great deal to answer the question. Knowing the base physics (or at least the outcomes) then allows further experimentation and calculation to answer more complicated (less controlled) conditions.
> I regularly do things like heat a mug full of water in the microwave, get distracted, and then forget all about it for hours.
Under controlled conditions, it would not. Ideally it would be in a pressure regulated space.