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Dec 30, 2022 at 14:26 history edited rob CC BY-SA 4.0
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Mar 8, 2018 at 20:58 comment added NVZ @jwg While the question started off with the 3-year-old asking about circles, I don't think OP's intent is merely to convey this to the kid. It would be a worthwhile question for us all.
Mar 8, 2018 at 14:18 comment added jwg @rob I have. The three year olds I have met appreciate being told "I don't know" when I don't know. I would never say "the details of how that works are a little more involved than I can get into at the moment" to a three year-old.
Mar 8, 2018 at 12:46 comment added rob @jwg Have you ever met a three-year-old?
Mar 8, 2018 at 10:44 comment added jwg This is a terrible answer. A complete failure to make a valid assertion about the actual question (if you are too busy to explain how the heat exchange works, why are you posting an answer?), combined with a suggestion to throw some mock science at an inquisitive young child "Look, brownies have corners too! The center of a brownie square works the same way! Isn't science yummy?'
Mar 6, 2018 at 18:27 comment added Bob Jarvis - Слава Україні @AndersSandberg: when dealing with 3-year-olds distraction is a key strategy. You say: "It's kind of like brownies. Want to bake some brownies?" - three-year old replies, "YAY!" and you're good. :-)
Mar 6, 2018 at 12:47 comment added rob @BlueRaja I believe I called that the basic reason, and I did propose an experiment in an analogous system. But there's plenty of room for other contributing factors. I used to own a set of sandstone drink coasters which were shockingly good at sucking up puddles from their surfaces. I don't think that's the major driver here (though I did mention absorption) but a couple of the other upvoted answers suggest that plays a larger role.
Mar 6, 2018 at 12:35 comment added rob @jpmc26 I actually like a little contrast between the center brownies and the edge brownies, but perhaps "gooey" wasn't the best word for the center ones.
Mar 6, 2018 at 0:10 comment added jpmc26 If you're getting gooey brownies at the middle, perhaps you should try lowering the temperature a little and cooking a little longer?
Mar 5, 2018 at 20:01 comment added WoJ Excellent analogy (+1). I would have replaced "explanation" by "experiment" :)
Mar 5, 2018 at 18:58 comment added BlueRaja - Danny Pflughoeft @rob: Then it's ironic that you said with such certainty that the "reason that the center and the edges of the tile evaporate differently is that the gaps between the tiles change the way that heat is exchanged there". Did you run an experiment to determine that?
Mar 5, 2018 at 17:12 comment added can-ned_food I guess the only thing I would say in commentary is that children, even those less than five years old, deserve better than to presume that they couldn't understand something. Better that you make the attempt and they don't than you don't and they could've.
Mar 5, 2018 at 15:17 comment added rob @BlueRaja That's one possibility, but there are some others. In good science, we don't come up with one possible explanation and say "that's it"; we come up with at least one possible explanation and test it. I can't do that from a photo, so I left those speculative details out.
Mar 5, 2018 at 14:26 comment added BlueRaja - Danny Pflughoeft The edges are warmer because the sides contact the air/sunlight while the inside does not. Does the explanation need to be more complicated than that?
Mar 5, 2018 at 8:58 comment added Chris H They look very close to squircles (i.e. superellipses) but the fact that they're offset with respect to the tiles, and not all offset the same points to an interesting further effect.
Mar 4, 2018 at 7:07 comment added akhmeteli @Yly : I had "the same thought" (please see my answer), but it is not obvious to me that this thought is necessarily wrong. First of all, porosity (or some other properties) of the surface of the "grey and red" tiles can be different, but, for the sake of the argument, let us assume that they only differ in color (and, therefore, albedo). So the grey tiles can dry faster, but this mechanism can work in parallel with the porosity/runoff mechanism.
Mar 4, 2018 at 5:50 vote accept user138719
Mar 4, 2018 at 4:03 comment added Yly My first guess at an explanation for this phenomenon was that it was due to porosity of the tiles, which could allow water near the edge of the tile to ooze through to the cracks between tiles more quickly than water in the center. Upon reflection, though, I prefer the explanation given in this answer, attributing the effect to differential heating of the tile, because otherwise I would expect the grey and red tiles to have the same water spots (which they don't). I'm posting this observation as a comment in case anyone else has the same thought I did.
Mar 4, 2018 at 0:35 comment added rob @Nathaniel I came up with some arguments for the edges being warmer and some arguments for the edges being cooler, depending on some details of the construction that I don't have access to and that I don't find interesting. The point is just that heat flow near the edges and near the middle are different.
Mar 4, 2018 at 0:31 comment added N. Virgo "However the details of how that works are a little more involved than I can get into at the moment" -- honestly that sounds like a bit of a non-explanation. There must be a reason for the temperature to be uneven, and if we don't know what that is, we can't really explain the pattern. (I suspect it's because the gout between the tiles absorbs more heat from sunlight because it's darker, but that's just conjecture.)
Mar 4, 2018 at 0:12 comment added Asher +1 for including a demonstrative and practical yet tasty experiment for kids of all ages (including mine).
Mar 3, 2018 at 23:17 comment added Anders Sandberg If we assume it is dominated by the diffusion equation and starts from a square initial condition one can probably make an analytic expression for the shape. But explaining boundary value problems to 3-year olds is a tricky.
Mar 3, 2018 at 22:18 history answered rob CC BY-SA 3.0