First, I did understand Jon Fong's post to be in a humorous vein. Just thought I'd see if I could make it work. Sorry if this is a thread drift, but it seems to follow naturally from the topic to discuss if a set up actually works.
If there's an engineer or someone fluent with the math of thermodynamics it would be great to have them weigh in on this. IMO rocks, bricks, it makes little difference, neither is much of a heat sink. They conduct heat poorly and therefore don't absorb much. Probably more of a factor would be how much surface area of the pan they are blocking from direct contact with the Esbit flames. So I drew lines to show how much contact there was with the bricks, then cut the contact areas so I could estimate their area. About 1.75 square inches, out of 38.5 square inches of bottom surface area for the 7" diameter pie pan (4.5%). I just don't think it's a significant factor.


Nevertheless, I went and borrowed three rocks from my neighbor's low-water yard and re-did the experiment. Essentially the same results as before. There is a "local" boil about 2-3" in diameter directly above the flame but the water at the edges is much cooler, and at no point does all of the water reach boiling temperature. When I observed the local boil I measured the temperature as 175* at the edges. Then I stirred the water for awhile to get an average temperature and got 188.5*.




Clearly there is a limit at some point to how wide and flat a "pot" can be and still effectively heat all of the water in it. There's probably an equation or something. But I think the pie pan is over the limit.







