(Roughly) Daily

“The world… gives back to every man the reflection of his own face”*…


In Chichibu, Japan, two hours northwest of Tokyo, there’s an odd museum; perhaps the only one of its kind. It’s called the Chinsekikan (which means hall of curious rocks) and it houses over 1700 rocks that resemble human faces.

The museum houses all kinds of jinmenseki, or rock with a human face, including celebrity lookalikes like Elvis Presley [below]. And according to a 2013 post on Kotaku, there are also movie and video game character rocks like E.T., Donkey Kong and Nemo…

Learn the back story and take the tour at “The Japanese Museum of Rocks That Look Like Faces.

* William Makepeace Thackeray


As we practice being stone-faced, we might spare a thought for Christian Goldbach; he died on this date in 1764.  A mathematician, lawyer, and historian who studied infinite sums, the theory of curves and the theory of equations, he is best remembered for his correspondence with Leibniz, Euler, and Bernoulli, especially his 1742 letter to Euler containing what is now known as “Goldbach’s conjecture.”

In that letter he outlined his famous proposition:

Every even natural number greater than 2 is equal to the sum of two prime numbers.

It has been checked by computer for vast numbers– up to at least 4 x 1014– but remains unproved.

(Goldbach made another conjecture that every odd number is the sum of three primes; it has been checked by computer for vast numbers, but also remains unproved.)

Goldbach’s letter to Euler (source, and larger view)

Written by LW

November 20, 2016 at 1:01 am

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