Friday, March 14, 2014

Happy Pi Day


The number π is a mathematical constant, the ratio of a circle's circumference to its diameter, approximately equal to 3.1415926. It has been represented by the Greek letter "π" since the mid-18th century and it is commonly spelled as "pi."

Pi - π - is a so called irrational number and cannot be expressed exactly as a common fraction. Consequently its decimal representation never ends and never settles into a permanent repeating pattern. The digits appear to be randomly distributed although no proof of this has yet been discovered. Also, π is a transcendental number – a number that is not the root of any nonzero polynomial having rational coefficients. This transcendence of π implies that it is impossible to solve the ancient challenge of squaring the circle with a compass and straight-edge.

For thousands of years mathematicians have attempted to extend their understanding of π, sometimes by computing its value to a high degree of accuracy. Before the 15th century mathematicians such as the Greek Archimedes and the Chinese Liu Hui used geometrical techniques, based on polygons, to estimate the value of π. Starting around the 15th century, new algorithms based on infinite series revolutionized the computation of π. In the 20th and 21st centuries mathematicians and computer scientists discovered new approaches that, when combined with increasing computational power, extended the decimal representation of π to, as of late 2011, over 10 trillion (1013) digits. Scientific applications generally require no more than 40 digits of π so the primary motivation for these computations is the human desire to break records but the extensive calculations involved have been used to test supercomputers and high-precision multiplication algorithms. 

Because its definition relates to the circle π is found in many formulae in trigonometry and geometry, especially those concerning circles, ellipses or spheres. It is also found in formulae used in other branches of science such as cosmology, number theory, statistics, fractals, thermodynamics, mechanics and electromagnetism. The ubiquity of π makes it one of the most widely-known mathematical constants both inside and outside the scientific community: Several books devoted to it have been published, the number is celebrated on Pi Day and record-setting calculations of the digits of π often result in news headlines. Attempts to memorize the value of π with increasing precision have led to records of over 67,000 digits.

If mathematics is not exactly your forte, maybe cooking is. All over the United States people celebrate π with an ever increasing number of pie recipes.

The Shepherd's Pie recipe comes from Williams-Sonoma blog taste and makes an excellent use of leftover short ribs which probably is a rare, but probable occurrence.  

  • 4 beef short ribs, each 2 1/4-2 1/2 lb.
  • Sea salt and ground pepper
  • 2 Tbs. extra-virgin olive oil
  • 1 large onion, chopped
  • 2 celery stalks, chopped
  • 6 cloves garlic, crushed
  • 1 carrot, chopped
  • 3 1/2 cups dry red wine, such as Syrah
  • 3 bay leaves
  • 1 Tbs. fresh thyme leaves
  • 4 cups beef stock, or as needed
  • 1 1/2 lb. Yukon gold potatoes, peeled and quartered
  • 1/4 cup milk
  • 4 Tbs. unsalted butter
  • 1 egg yolk, beaten
  • Season ribs with salt and pepper and refrigerate for at least 6 hours or up to overnight. Bring to room temperature and season again with salt and pepper.
  • Preheat oven to 350 degrees F. Heat a large saute pan over high heat until hot. Add olive oil and heat until shimmering. In batches, sear ribs on all sides, turning as needed, until well browned. Transfer to a Dutch oven. Pour off all but 2 tablespoons fat from saute pan and return to medium heat. Add onion, celery, garlic and carrot and saute until beginning to caramelize, about 5 minutes. Add wine, bay leaves and thyme, raise heat to medium-high, and boil to reduce wine by half. Add stock, bring to a boil, and pour contents of pan over ribs. They should be just covered with liquid; add stock as needed.
  • Cover tightly and braise in oven, adding stock as needed to maintain liquid level, until a fork slides easily through meat, about 2 1/2 hours. Skim off any fat from surface, let ribs cool in liquid until they can be handled, then remove ribs from pot and pull meat from bones. Shred meat into bite-sized pieces, return to Dutch oven, and discard bones.
  • While ribs are cooling, in a saucepan, cook potatoes in boiling salted water until tender, about 15 minutes. Drain, dry in pan over low heat, then pass through ricer back into warm pan. In a small saucepan, heat milk and butter until mixture is steaming. Pour into potatoes, add egg yolk and fold to mix well.
  • Raise oven temperature to 400 degrees F. Transfer contents of Dutch oven to a 9-by-13-inch baking dish or divide among individual gratin dishes. Cover top(s) evenly with potatoes. Bake until topping is golden, 35-40 minutes. Serve at once and enjoy! Serves 6-8.

Recipe source Williams-Somoma blog taste

Article source here