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Post date: Jan 20, 2020 3:23:27 AM
i like quanta magazine. it's not hard to read and i still learn from it. for this iteration, these are the articles that caught my eye:
arguably, there are continents that live "underground" ... or, as the title suggests, continents of the underworld:
"Assuming that the blobs are distinct, they could be old — the last surviving remnants of the infant Earth. One leading idea is that they formed when the entire lower mantle was an ocean of magma, shortly after the planet’s birth. Rock began to cool and crystallize, but iron stayed melted in the magma ocean, said Nicolas Coltice at the École Normale Supérieure in Paris. Then, when the last dregs of magma crystallized, they were so dense and iron-rich that they sank to the bottom of the mantle, forming the blobs ...
... hot, heavy, stable blobs would have more of a back-and-forth dialogue with the tectonic system on the surface. Cold currents from sinking plates would push the blobs around like Silly Putty; in turn, upwelling heat from the warm blobs would push the plates right back."
and to take a geometric turn, there is a discussion of minimal coverings [1] that is rather reminiscent of old-school straight-edge-&-compass constructions:
"Below we show Pál’s hexagon covering various shapes of diameter 1. The shape in the middle is a Reuleaux triangle, a curve of constant width closely related to the example covers we constructed above. (We can construct a Reuleaux triangle from our example covers by centering our compass at the top intersection of the two circles, opening it to a width of 1, and making an arc from A to B.)"
lastly, this is exciting news: steven strogatz, the mathematician behind the NYT column "me, myself, and math" and the author of the book "the joy of x" is developing a new conversational podcast series!
among the guests will be ...
Janna Levin, an astrophysicist;
Moon Duchin, a topologist who is known for her study of geometrically-verifiable gerrymandering;
John Urschel, a former NFL player who is now pursuing a Ph.D. at MIT;
... and many more, some of a rather technical background.
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[1] my only gripe about this article is that their use of the term "universal cover" is inconsistent with what most mathematicians would refer to as a universal cover. however, in their use of colloquial language, they do a pretty good job of explaining why (and how hard) it is to create a minimal shape.
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