I know this is a stupid questionÑI’ve seen all the remote underwater footage of the behavior of water up to several thousand feet deepÑbut still somehow, the sight of all those strange fish swimming blithely around as if in a 10-gallon aquarium puzzles me.
Not to mention “why” the water doesn’t freeze solid at those depths, notwithstanding the salt contentÑwhy don’t the molecules become pushed so close together under the awesome pressure of so much water above make the water thickerÑa gel maybeÑand make it more difficult for the fish to swim through? (let alone a submersible.)
I thought extreme pressure and cold made things harder. (This is not to comment on my date the other night in a loft in Montreal where she left the windows open and complained about my “performance.”)
if you squeeze water enough it will indeed go solid (see http://www.sbu.ac.uk/water/phase.html ). This happens at about 10^9 pascals or about 10,000 atmospheres. As one atmosphere corresponds to 10 m of water, that works out to about 1000 km depth. No danger there.
The point is that atomic bonds “pressure” if I may use such a term is much greater than the pressures we think are important.
One of the cool things about water is that it expands upon freezing.
If some water froze at the bottom of the ocean, it would tend to float toward the surface, creating a sort of “reverse convection current” in which cold things rise.
The ice would rise until conditions of temperature and pressure no longer allowed it to be solid.
Also note that even under relatively “normal” pressures, water density undergoes an inversion point at 4 C. That is, at relatively normal temperatures, water has its greatest density at 4 C. This is one of the reasons why lakes freeze from the top-down, rather than from the bottom up.
I had no idea someone had posted a similar question just a week ago. Extremely interesting answers. Now how do the fish swimming around the Titanic feel? Wouldn’t they rather be sipping hot chocolate in front of a roaring fire? =+)
Note that atmospheric pressure of 15psi is equivalent to sleeping under a lead blanket… if the lead blanket was three feet thick!
Organisms made of water and solids cannot “feel” pressure. Fish swim around happily at depths where carbon dioxide remains liquid at room temperature.
One interesting aspect of great ocean depths: the maximum “suction” produced by a pump or by your lips is related to ambient pressure. At sea level you can suck on a pressure gauge and get it down near -15psi relative to ambient (try it!) If you dive deep under the ocean you might not be able to feel the pressure, but you can “suck” with far greater degree. Killer hickies! A vacuum pump or even a suction cup might be able to pull chunks out of your flesh if you were a few thousand feet down.