> I just thought of something: If you put a container of water in a freezer, it will crystallize from the outside and inwards, causing the core to freeze last. But since water expands when it freezes, this must seriously mess up the crystalline structure, since the expanding liquid core will be "shut in" by the surrounding ice. How would it look if you were able to freeze it from the center and outwards? Would it be much different?
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> Trav"inquisitive mind"holt.

Well, in general, the idea of getting the water to freeze from the outside inward would be the hard part. Where gravity exists (i.e. anywhere on earth) the water would freeze from the top down, because as individual bits if ice form, they would float upwards and accumulate at the top of the container, and you would never get a section of water completely surrounded by ice-- the bottom of the jar would be the last part to contain ice.

To replicate the first system you describe (freezing from the outside inward) we would need to perform the experiment in 0-G. Without gravity, the ice would freeze and stay where it first froze, so a container of ice in a freezer would freeze from the outside inward. I'm not too sure what would happen to the crystal structure in this case, but I do know that crystal structures can deform to some extent, and the ice would likely deform as much as possible before breaking the container. As with the 1-G ice jar, though, this would likely happen long before the water had all frozen. In the case of the 0-G system, though, the breaking jar would make no mess, since all the remaining water would be contained inside a hollow ice block.

For freezing from the inside out, I think it would be quite different. First, we would have to come up with a means of of accomplishing this unique form of freezing. I would think that a thin metal wire extending into the center of the container would be a start, with the wire hooked up to a heat sink of some sort to produce the cooling. The wire would need to be heat insulated along its length right up to the tip in order to create a point source heat sink. Now, in a 1-G environment, this would work just like normal-- the ice would form from the top down, although some buildup might occur at the point source. In the 0-G environment, though, ice would form in a sphere surrounding the point source, and the crystalline structure would be very well defined. Again, our container would break before the water had all frozen, but we would have a perfect ice sphere (with a small hole where the point source had been inserted). I think that would be pretty cool.

Don "Likes to be verbose when it comes to science" Monkey