# Piet Hein (scientist)

Piet Hein (16 December 1905 – 17 April 1996) was a Danish polymath (mathematician, inventor, designer, writer and poet), often writing under the Old Norse pseudonym Kumbel, meaning "tombstone". His short poems, known as gruks or grooks (Danish: gruk), first started to appear in the daily newspaper Politiken shortly after the German occupation of Denmark in April 1940 under the pseudonym "Kumbel Kumbell". He also invented the Soma cube and the board game Hex.

## Biography

Hein, a direct descendant of Piet Pieterszoon Hein, the 17th century Dutch naval figure, was born in Copenhagen, Denmark. He studied at the Institute for Theoretical Physics (later to become the Niels Bohr Institute) of the University of Copenhagen, and Technical University of Denmark. Yale awarded him an honorary doctorate in 1972. He died in his home on Funen, Denmark in 1996.

## Resistance

Piet Hein, who, in his own words, "played mental ping-pong" with Niels Bohr in the inter-War period, found himself confronted with a dilemma when the Germans occupied Denmark. He felt that he had three choices: Do nothing, flee to neutral Sweden or join the Danish resistance movement. As he explained in 1968, "Sweden was out because I am not Swedish, but Danish. I could not remain at home because, if I had, every knock at the door would have sent shivers up my spine. So, I joined the Resistance."
Taking as his first weapon the instrument with which he was most familiar, the pen, he wrote and had published his first "grook" (Danish: gruk). It passed the censors who did not grasp its real meaning. The Consolation Grook reads:
CONSOLATION GROOK
Losing one glove is certainly painful, but nothing
 compared to the pain, of losing one, throwing away the other, and finding
 the first one again.
The Danes, however, understood its importance and soon it was found as graffiti all around the country. The deeper meaning of the grook was that even if you lose your freedom ("losing one glove"), do not lose your patriotism and self-respect by collaborating with the Nazis ("throwing away the other"), because that sense of having betrayed your country will be more painful when freedom has been found again someday.
One of Hein's best-known grooks is A Maxim for Vikings:
A MAXIM FOR VIKINGS
Here is a fact  that should help you fight  a bit longer: Things that don't act-  ually kill you outright  make you stronger.

## Recreational mathematics

In 1959, city planners in Stockholm, Sweden announced a design challenge for a roundabout in their city square Sergels Torg. Piet Hein's winning proposal was based on a superellipse. He went on to use the superellipse in the design of furniture and other artifacts. He also invented a perpetual calendar called the Astro Calendar and marketed housewares based on the superellipse and its three-dimensional analog, the superegg.
He invented the Soma cube and devised the games of Hex, Tangloids, Tower, Polytaire, TacTix, Nimbi, Qrazy Qube, and Pyramystery.
Hein was a close associate of Martin Gardner and his work was frequently featured in Gardner's Mathematical Games column in Scientific American. At the age of 95, Gardner wrote his autobiography and titled it Undiluted Hocus-Pocus. Both the title and the dedication of this book come from one of Hein's grooks.