The mysterious pentagon… explained?

Around 2 weeks ago I posted a note about a “pentagon” I saw in some boiling lentils in my kitchen. There have been some interesting responses to this… but before I get to that, here is the original image, if you missed the original posting:

Interestingly enough, a few readers questioned the very presence of the pentagon! They saw paws and hands and soccer balls … rather than a simple geometric shape. My first response was, “you must be kidding me, how can you NOT see a pentagon?” But as I thought about it a bit more, I began to “see” their point of view. I think, now, that I was too quick to latch onto the “pentagon” rather than consider other shapes. Whether this is a cultural matter (as some people suggested) or an individual quirk (as some others did), I am not sure.

That said, the fact that some kind of a 5-sided, pointed figure was visible was not in doubt. Whether a pentagon was the best way to label it maybe a fair question to ask. The “fiveness” of it, however, is not really under question here.

So… what caused this “five-based” shape?  To cut a long story short, those of you who predicted this pattern had something to do with the heat source below were right, pretty much. I must add though that the lentils had NOT been stirred, and that this pattern emerged because they had not been stirred. Anyway, here is a photo of the heat source. I tried to take this picture from approximately the same location as the first one…

The first thing you notice are the five prongs that hold the pot up. And these five prongs align quite perfectly with the lines of bubbles that come inwards from the other edge of the vessel. The five prongs that hold the pot up prevent direct heat from hitting the base of the vessel and I suppose lead to less “boiling” activity in these areas, making them ideas spots for the bubbles to collect.

As to why  we get the lines between these prongs (what I called the pentagon) is still not clear to me. My suspicion is that the convection currents that move through the water move the bubbles as they form to points where there is less “bubbling.” That explains the lines coming from the side towards the center – but does not fully, at least to my mind, explain the lines that join these prongs together – the pentagon that I first noticed.

Some more experimentation may be in order… I will keep you posted as and when opportunity arises for me to study this further :-)

Thanks for all those of you who chose to comment.

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