The Sigil
Mr. 3000 (Words per post)
BVB said:
Let's see here - we'll keep things to an order of magnitude.
1 gallon = 231 cubic inches.
Assume a sphere of one-inch internal diameter. Its volume is 4/3piR^3 or about 1/2 of a cubic inch.
That means, to an order of magnitude, we are compressing the water to 1/500th its normal size.
Let us further assume that water behaves "only" as an ideal gas (obviously, it exerts a lot more push than a gas does, but let's play with this for a moment). A sudden expansion (not out of line with reduce/expand spells) means that there is no time for the temperature to adjust initially.
Ideal gases obey the law PV=kT. Since k is a constant, and we are holding T constant for the moment of expansion, we know that since the water is contained in a container that is 500 times too small for it, the pressure must by 500 times greater than normal (again, one order of magnitude here).
Now, we'll hold V constant when compared with a sphere filled with 1/2 cubic inch of water and see what will quickly happen to temperature in the instant after the water "expands." Since P is 500 times that of a sphere with 1/2 cubic inch of water, and we are holding V constant, that means the temperature will rapidly rise - in fact, it will increase 500-fold since P(magically uncompressed water) = 500 P (water). Room temperature is around 300 degrees K, so this leads us to a result of about 150,000 degrees K - or ten times hotter than most stars!!! This would (obviously) immediately boil the metal away and allow the water to escape long before it hit star-like temperatures - which would mean you would get a spray of hot liquid metal (OUCH!) immediately followed by immersion in superheated water if you were holding the sphere. If you were not within a few feet of the sphere, you'd still be in danger of being hit with the liquid metal, but the water temperature would cool rapidly (back to room temperature) as it expanded - meaning by the time the water had created a globe sufficient to hold its 231 cubic inch size (roughly 3.75 inches in diameter), it would be back to normal temperatures.
Result: Effectively a painful "chrome plating bath" (or whatever metal is used) for anyone in the vicinity, a wickedly burned hand and lower arm for the person holding the globe, and a big "splash" of water drenching that hand and the as the water returns to normal size and falls to the ground.
If (using magic) you instead "unshrank" the water in an impenetrable globe of force 1 inch in diameter (the force will not melt, etc.) you would produce a body so hot (150,000 K, remember?) that it would instantly sear your hand and then drop to the floor, melting its way all the way through to the center of the planet (probably doing slight oscillations once it got there) and heating the planet from the interior. The intense heat and light thusly emitted (yes, it would emit some light as a black body) would cause severe planetary problems. I haven't done the math to figure out how long it would take such an object to "burn down" to normal temperatures, but it's a good bet that life on the planet would be summarily toasted - if not blown away entirely by the prospect of having something far hotter than a star sitting in the center of the planet.
And that's just with water "pressing back" with the force of a gas. My guess is that water actually "pushes back" with at least 1,000 times as much force as a gas (a conservative estimate) which would peg the temperature of the object created in the 150,000,000 degree range - which is so hot it's just stupid. It would vaporize the entire planet instantly.
NOW, if by some quirk you were able to do this in an isolated area so as to not destroy the world (a bag of holding or portable hole, perhaps?) and let the thing blast that destructive energy out over a long period of time (eventually, it will cool down, but it will likely take hundreds to millions of years), and THEN pull it out when it has cooled to room temperature and then crack it open...
Well, the exact reverse of the process will happen... you'll have to "put back" all the heat that you radiated away earlier. If the heat you had before was enough to vaporize a planet, what you wind up with is instant deep-frozen planet (we're talking the entire planet instantly goes to within a degree or two of absolute zero). Again, completely impractical for making ice armor or anything else.
Long story short... there are not a lot of possible outcomes for this.
1.) The ball almost instantly cracks and water sprays out. Ball is launched in the opposite direction at high speed, possibly with a spin (different coefficient of friction at spots where you were holding it). Unless all the water is out almost instantly, it will heat up too fast and turn into #2 (below).
2.) The ball holds together long enough to get so hot that the metal vaporizes - it only has to hold for a few hundredths of a second, so I think this is the most likely scenario - the water simply can't escape fast enough to stop the superheating. You get an explosion of liquid metal in every direction at once, anything within about 2 inches is hit with superhot water, and then the 4" water ball (assumes it expands in all directions at once) drops onto the ground, making a big wet splash (at normal temperatures).
3.) The ball is made of force (or other material) and is not compromised. Instant "mega-hot-to-the-tune-of-ten-times-hotter-than-a-star" ball that vaporizes the planet.
4.) The ball is not compromised per #3 above and is allowed to "burn out" of temperature changes. Then the ball is cracked open. Instant deep freeze of entire planet.
#2 is the most likely - and will do more damage to the poor sap holding the ball than anyone else. #1, though MUCH less likely, is a vague possibility - but you'd probably need to have a sizable hole in the sphere to get it to work. #3 and #4 are, quite simply, apocalyptic planet-destroyers either way.
Those are really your only four choices. No matter what, the person most likely to suffer any damage is the poor sap trying this stunt... though taking out the planet as collateral damage is not great either.
I'm in the camp of "expand/reduce in D&D stops before damage accrues" so you'd wind up with a sphere of "partially unshrunk" water - it unshrinks until it fills the sphere but does not exert abnormal pressure on the sphere.
Again, my calculations were with a GAS - a LIQUID will have FAR more pressure (and far more heat).
--The Sigil
I'm just throwing out some "order of magnitude" guesstimates. All of the compression necessary to overcome Electromagnetic and Quantum forces, let alone the lack of viscosity in compressed water, would add even more energy to the "blast."
