Re: question about matter in space and music in space

From: Ian Stirling (root_at_mauve.demon.co.uk)
Date: 01/22/05 

Date: 22 Jan 2005 23:49:51 GMT

Jana Cole <quikscor@ix.netcom.com> wrote:
> On Sat, 22 Jan 2005 15:41:01 -0500, John Popelish <jpopelish@rica.net>
> wrote:
>
>>Jana Cole wrote:
>>>
>>> I'm not a scientist. I have some "laymen's" questions:
>>>
>>> 1. What would happen if a dollar bill were instantly dropped into
>>> outer space? Would it "stick together".
>>
>>I don't understand the question.
>
> For example, I imagine that water in space would not flow but would
> float apart in little droplets......

This is an interesting one.
If you take a 'large' droplet (say a meter in diameter) a perfect sphere
of pure water at 20C, and put it in space.

For a few microseconds the outside of the drop evaporates, with the
evaporation providing enough pressure to support the inside of the drop
at a higher pressure and stop it flash boiling.

The outside of the drop supercools during this time, and then
ice forms around the outside.
The shock from either the ice formation, or the cracking of the ice under
thermal stresses, causes bubbles to nucleate in the middle of the
sphere.
These expand, as the outside is no longer supported, and similar processes
cause shock waves through the whole mass, so it foams and boils outwards,
with rimes of ice on the outside.
The droplets continue to fission until they are small enough that the
surface tension on the drop causes the internal pressure to be higher than
the vapour pressure of the water at the temperature it's at.
These then freeze rapidly, then will cool further as the ice sublimates to
space.
In a cold enviroment, they will last a long time, as the ice loses maybe a
third of its mass in the first few hours, then is supercooled to a few K,
at which time evaporation almost stops.

(I think, this is from first principles, I'd like to confirm by experiment)

A question for Uncle Al, if he's read this far...

What is the energy released/absorbed by going from ice I to ice IX?
Are the vapour pressures similar?

<snip>
> Music is created when vibrating material is percieved by the ear.
> Could we hear things in outer space?

As the pressure drops, the frequency at which sound can be heard drops too.
In space, it's too low to be perceptible to humans.