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.)

I propose a reexamination of the problem, without resorting to some of the more creative solutions (meant as a compliment)<o:p></o:p>

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Many have stated, and I agree that to cause a liquid to boil under the circumstances of the problem statement one must either raise its temperature or reduce the local pressure at the liquid surface to be equal or below the vapor pressure of the water at that temperature.  Since great pains are taken to disallow energy addition of any kind, let’s explore the second possibility<o:p></o:p>

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The problem statement essentially creates a closed system that allows no mass transfer from the outside world.  Therefore an air pump I fear would be disallowed.  The handkerchief trick is not boiling; it is outside air migrating through the cloth, while the surface tension of the water prevents reverse leakage.<o:p></o:p>

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As stated, one could rapidly cool only that portion of the jar in cntact with the air inside, perhaps specially shaped to enhance this effect, thus lowering the pressure.  However, cooling the system is energy transfer “out”.  Is this allowed?  No transfer “in” is allowed.  Do not know.<o:p></o:p>

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Given the pains to describe the lack of energy input and a rigid jar, the fact that the lid is not so mentioned may be significant.  As Charlie and other have noted, let’s change the paradigm of a “lid”, perhaps making it flexible.  A flexible lid could remain airtight yet be manipulated in many ways to expand the air volume and thus lower the pressure.  A handle and rapidly moving to a higher altitude have been mentioned by others.  There may be more methods. However, in each case, work is done on the system (= energy).  Is this Haruki’s “energy”?  Do not know.<o:p></o:p>

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Speaking of air pumps, imagine an airtight lid, connected to an air pump, which exits not to the atmosphere, but to another tank through a one way valve.  This “pump system” would be just a fancy lid that could move air out of the jar and trap it in the tank, yet remain completely air tight (allowing no intermixing of air form the jar to the environment).  Now that I have proposed this, it has two problems.  It is likely too complicated, per my first paragraph, and also, working the pump would require energy, which technically is going “into” the closed system.<o:p></o:p>

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Haruki, either you have some ingenious method, or the problem statement is lacking.  I await the solution posting.<o:p></o:p>

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Any comments?<o:p></o:p>

Posted by Kenny M on 2005-12-10 14:29:46