why does popcorn seem to pop at a somewhat consistent rate regardless of the amount, instead of all of them popping closer to at the same time?
In: Physics
The corn pops when pressure from the internal moisture boiling gets too high for the strength of the hard outer shell. There is natural variation from kernel to kernel in how much moisture there is, and how thick/strong the shell is, plus possible weaknesses/defects in the shell, plus uneven heating from whatever you’re using to heat the kernels in. Add all of those factors together and you get a wide range of popping times. Thin-shelled high-moisture kernels that happen to pass through a hot spot in the microwave are going to pop a long time before drier, heavy-shelled kernels passing mostly through cool spots in the microwave. Of course, the vast majority of kernels will lie somewhere between these two improbable extremes – so you get roughly a [normal distribution](https://getnave.com/blog/wp-content/uploads/2018/08/frequency-distribution-types-normal-distribution.png) (bell curve) of popping times, with middle-length times being the most common. You usually get a few early pops, then a faster popping region, then a few late pops again slower.
Side note: Things that depend on many variables, with an element of randomness, often end up looking like a bell curve. The classic example is test grades. The kids that are naturally smart AND study hard AND correctly guessed what’s on the test do super well. The not-smart kids who ALSO don’t work hard AND didn’t know there was a test that day do super poorly. However most students are some middle combination of those factors not either extreme, so you get a bell curve shape, with [middle-ground grades being more likely for most people](https://community.alteryx.com/t5/image/serverpage/image-id/70245i5975B12143193352?v=v2).
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