I'm over the Mariana(s) Trench and want to throw some objects overboard.

[Hostile_Dialect]

If Hitler, having been revived and bionically implanted with gills, were at the bottom of Marianas Trench, holding a bottle of glue and a gun and plotting to take over the world, would a 2000s-style “Death Sphere” thrown from the side of a Carnival cruise ship kill him?

[Flander]

What if the ocean were made of molasses?

[zut]

@RedSwinglineOne

From a practical standpoint, we usually say liquids don’t compress. What happens at those pressures? Where does that 4% come from? Do the molecules actually compress, or do they align themselves into a more space efficiant pattern?

I should emphasize that this thread (and my earlier statement that you quoted) is an example of why, from a practical standpoint, we usually say liquids don’t compress. The pressure at the bottom of the Marianas trench is higher than what you’ll see in most applications, and yet the effect of ignoring compressibility is a change in descent time of probably 1%, which is on the order of other uncertainties in the problem.

This is, of course, in contrast to gasses, where the density change is substantial and significant at much lower pressures.

Anyway, to answer your question: I dunno. Water molecules aren’t little round spheres, but rather electron-shelled conglomerations, so I suspect they’re just squarshed together more tightly, with the something-something-elecromagnetic-something balanging out the forces. But I admit my intuition is fuzzy down at molecular levels, so I’d be interested in a better answer, too.

[Santo_Rugger]

@RedSwinglineOne

From a practical standpoint, we usually say liquids don’t compress. What happens at those pressures? Where does that 4% come from? Do the molecules actually compress, or do they align themselves into a more space efficiant pattern?

I’m not sure the answer to your last question, but the first part can be found here:

http://hyperphysics.phy-astr.gsu.edu/hbase/tables/compress.html

Compressibility is the fractional change in volume per unit increase in pressure. For each atmosphere increase in pressure, the volume of water would decrease 46.4 parts per million. The compressibility k is the reciprocal of the Bulk modulus, B.