You have a glass jar. You pour in water with a pitcher until it is half filled. You then seal the jar with an air-tight lid. (The only other thing in the jar is regular air). Assuming that the water in the jar is not already boiling after attaching the air-tight lid, how do you make the water boil?

boiling: the state in which liquid water is rapidly changing to water vapor (ie, the water is accually bubbling, not just steaming)

For clarification, the water is plain distilled H20. It is not heavy water, water with impurities, etc...

You cannot transfer or use anything that transfers light, heat, magnetic, electric, or chemical energy into the jar. (and no, shaking the jar till the water friction causes the water to boil does not work)

You cannot open or break the glass jar.

The area in the jar cannot increase or decrease. (You can try but the jar will not shrink, grow, or deform in any way)

You cannot insert anything into the water.

You must be able to conduct this experiment with easily attainable equipment, chemicals, and other materials. (ie, no radioactive chemicals, no superpowers, no multi-million dollar scientific equipment, you get my drift...)

(Note: although it is hard for it to succeed, you can conduct this experiment at home and get the water to boil without any special equipment.)

This interested me a lot when it was in the qeue and  Haruki chnaged the rules such that none of the solutions given to change the difficulty setting stayed valid. 

Up till now, I saw only S4tD and Charlie's solution.  The latter one, although being technically correct seems to me as violating the idea of the problem.  Indeed, the lid is not explicitely mentionned and could be deformed.  With S4tD (andGoFish) solution, I also have a problem:  although te problem statement only limits energy transfers into the jar, I wonder if energy transfers outside the jar are allowed.  If not, then this solution is no more valid.

A general thought is: to get the water boiling, there must be either a transfer of energy or a change in the conditions of boiling, so I'd guess one of the above ways must be the solution.  Certainly if you can do it at your kitchen and do not have to wait to proton decay or something like that.

I'm pretty good at www searches and only a couple of times the solution to a problem escaped me, but this???  I haven't found anything else then Charlie's solution (The www experiment used a handkerchief  over the jar's opening.  The surface tension of the water kept it in.  Then you'd had to push the handkerchief in, turn the jar upside down and pull the handkerchief out.  The vacuum created should suck in surrounding air, thus creating a boiling/bubbling effect)  and S4tD' solution, nearlyt identical to GoFish's description, except liquid nitrogen was used as cooling in the experiment.

Edited to add:

To GoFish's solution, the www added that the cooling let condense the hot air above the water, thus creating the vacuum. I have some doubts about it (I think you can't create high enough a vacuum).

 

Edited on December 6, 2005, 5:38 pm

Posted by Hugo on 2005-12-06 17:29:14