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Wallace-Bolyai-Gerwien theory is the theory that any two polygons are equidecomposable.

That is that one can be cut into finitely many polygon pieces and be rearranged to obtain the second polygon.

at around 13.2 degrees Celsius, β-form white tin transforms to α-form grey tin due to

tin pests (or tin disease).The transformation process requires high activation energy but very low temperatures and the presence of Germaniumcan aid in initiation.

A domino can knock over another domino 1.5x larger than itself.

The above Gif shows a domino 5 millimeters tall starting a chain reaction 13 dominos long that eventually knocks over a domino about half a meter tall.

If the reaction was 29 dominos long, the final domino would be the size of the Empire State Building.

"When we know how materials melt, shatter and bend, we can make machines that don’t."

Nice. :D

GIFs of semi-intelligent slime mold growing like crazyJust what is this pretty yellow goo? Delicious, delicious slime mold of course. Heather Barnett makes art from

physarum polycephalum, a eukaryotic microorganism that lives in cool, moist areas. As part of a project on the semi-intelligent slime mold, Barnett captures its behavior “in a game of creative control and authorship,” creating a timelapse film of its growth.In these images, she’s replicated a maze from a 2000 experiment by Toshiyuki Nakagaki that showed how the organism seeks out food sources. The slime mold had already grown into a network throughout the maze, but when Nakagaki and his team at Hokkaido University added agar to two different places within, it withdrew from the empty corners and found the shortest path between the two points of nutrition, spreading into a beautiful web that connected them.

I have wondered about this for so long.

So, convex polygon with n sides can be divided into triangles in multiple ways. Remarkably, triangulations can be sorted and cycled through so that any successive two differ in one flip of the shared edge of a pair of adjacent triangles.

More formally, such graph — in which two triangulations are adjacent if they differ in exactly one flip — is Hamiltonian, and in it exists a cycle that visits each vertex exactly once.

Above: as the 7-gon cycles through all of its 42 triangulations, the 6-gon repeats its 14-cycle three times, the 5-gon repeats its 5-cycle eight times (and waits for two frames), and the quadrilateral repeats its 2-cycle 21 times.

An X-ray recording of metal solidifying under microgravity. The video was recorded on a Maser sounding rocket. In under seven minutes a small furnace was used to cook a metal sample to 700°C turning it liquid before it was frozen inside a cooling chamber to solidify into crystal clusters. An X-ray camera captured this dramatic experiment for analysis.

Credit:NTNU Norway–Prof. Ragnvald Mathiesen