Harry Potter and the Philosopher's Stone is a fantasy novel written by British author J. K. Rowling; the first novel in the Harry Potter series and Rowling's debut novel, it follows Harry Potter, a young wizard who discovers his magical heritage on his eleventh birthday, when he receives a letter of acceptance to Hogwarts School of Witchcraft and Wizardry. Harry makes close friends and a few enemies during his first year at the school, with the help of his friends, Harry faces an attempted comeback by the dark wizard Lord Voldemort, who killed Harry's parents, but failed to kill Harry when he was just 15 months old; the book was first published in the United Kingdom on 26 June 1997 by Bloomsbury. It was published in the United States the following year by Scholastic Corporation under the title Harry Potter and the Sorcerer's Stone, it won most of the British book awards that were judged by children and other awards in the US. The book reached the top of the New York Times list of best-selling fiction in August 1999 and stayed near the top of that list for much of 1999 and 2000.

It has been translated into at least 73 other languages, has been made into a feature-length film of the same name, as have all six of its sequels. Most reviews were favourable, commenting on Rowling's imagination, simple, direct style and clever plot construction, although a few complained that the final chapters seemed rushed; the writing has been compared to that of one of Rowling's favourite authors. While some commentators thought the book looked backwards to Victorian and Edwardian boarding school stories, others thought it placed the genre in the modern world by featuring contemporary ethical and social issues, as well as overcoming obstacles like bullies. Harry Potter and the Philosopher's Stone, along with the rest of the Harry Potter series, has been attacked by some religious groups and banned in some countries because of accusations that the novels promote witchcraft under the guise of a heroic, moral story. Other religious commentators have written that the book exemplifies important viewpoints, including the power of self-sacrifice and the ways in which people's decisions shape their personalities.

The series has been used as a source of object lessons in educational techniques, sociological analysis and marketing. Harry Potter has been living an ordinary life abused by his surly and cold aunt and uncle and Petunia Dursley and bullied by their spoiled son Dudley since the death of his parents ten years prior, his life changes on the day of his eleventh birthday when he receives a letter of acceptance into Hogwarts School of Witchcraft and Wizardry, delivered by a half-giant named Rubeus Hagrid after previous letters had been destroyed by Vernon and Petunia. Hagrid details Harry's past as the son of James and Lily Potter, who were a wizard and witch and how they were murdered by the most evil and powerful dark wizard of all time, Lord Voldemort, which resulted in the one-year-old Harry being sent to live with his aunt and uncle. Voldemort was not only unable to kill Harry, but his powers were destroyed in the process, forcing him into exile and sparking Harry's immense fame among the magical community.

Hagrid introduces Harry to the wizarding world by bringing him to Diagon Alley, a hidden street in London where Harry uncovers a fortune left to him by his parents at Gringotts Wizarding Bank, receives a pet owl, various school supplies, a wand. There, he is surprised to discover how famous he is among witches and wizards. A month Harry leaves the Dursleys' home to catch the Hogwarts Express from King's Cross railway station's secret Hogwarts platform, Platform ​9 3⁄4. On the train, he befriends fellow first-year Ronald Weasley and the two boys meet Hermione Granger, whose snobbiness and affinity for spells causes the two boys to dislike her. There, Harry makes an enemy of yet another first-year, Draco Malfoy, who shows prejudice against Ron for his family's financial difficulties. Arriving at Hogwarts, the first-years are assigned by the magical Sorting Hat to Houses that best suit their personalities, the four Houses being Gryffindor, Slytherin and Ravenclaw. Harry hears from Ron about Slytherin's dark reputation, known to house potential dark witches and wizards, thus objects to being sorted into Slytherin despite the Hat claiming that Harry has potential to develop under that House.

He winds up in Gryffindor with Ron and Hermione, while Draco is sorted into Slytherin like his family before him. As classes begin at Hogwarts, Harry discovers his innate talent for flying on broomsticks despite no prior experience, is recruited into his House's team for Quidditch as a Seeker, he comes to dislike the school's Potions master, Severus Snape, the Head of Slytherin House who acts with bias in favour of members of his House while perpetually looking for opportunities to fail Harry and his friends. Malfoy tricks Harry and Ron into a duel in the trophy room to get them out of their rooms at night and secretly tells Filch, the school's caretaker, where they will be. Hermione unintentionally is forced to come along after her failed attempts to stop them, they find Gryffindor student Neville Longbottom asleep outside the common area because he had forgotten the password to get in. After realizing the duel was a set-up to get them in trouble, they run away, they discover a huge three-headed dog standing guard over a trapdoor in a forbidden corridor.

The school's Halloween celebrations are interrupted by the

Martlet House is a Scottish baronial style building at 1430 Peel Street in Downtown Montreal, Quebec. The building was completed in 1928 by architect David Jerome Spence, with additions in 1931, 1947 and 1955; the Montreal headquarters of Seagram Company Ltd. the building was donated to McGill University by Vivendi Universal, which had acquired the property in 2002 after its merger with Seagram. The university spent $1.5 million renovating the site in order to house its Development and Alumni Relations department, which moved there in 2004. Prior to 2004, the Martlet House designation had been applied to two properties in succession: one on University Street, followed by a move in 1971 to a stone mansion at 3605 Mountain Street, designed by architect Robert Findlay; the house was built in 1925 for Alice Graham Hallward, the wife of Bernard Marsham Hallward and the only child of Canadian newspaper magnate Hugh Graham, 1st Baron Atholstan. Media related to Seagram House, Montreal at Wikimedia Commons McGill – University Advancement

In geometry, tetrahedron packing is the problem of arranging identical regular tetrahedra throughout three-dimensional space so as to fill the maximum possible fraction of space. The best lower bound achieved on the optimal packing fraction of regular tetrahedra is 85.63%. Tetrahedra do not tile space, an upper bound below 100% has been reported. Aristotle claimed. In 2006, Conway and Torquato showed that a packing fraction about 72% can be obtained by constructing a non-Bravais lattice packing of tetrahedra, thus they showed that the best tetrahedron packing cannot be a lattice packing; these packing constructions doubled the optimal Bravais-lattice-packing fraction 36.73% obtained by Hoylman. In 2007 and 2010, Chaikin and coworkers experimentally showed that tetrahedron-like dice can randomly pack in a finite container up to a packing fraction between 75% and 76%. In 2008, Chen was the first to propose a packing of hard, regular tetrahedra that packed more densely than spheres, demonstrating numerically a packing fraction of 77.86%.

A further improvement was made in 2009 by Torquato and Jiao, who compressed Chen's structure using a computer algorithm to a packing fraction of 78.2021%. In mid-2009 Haji-Akbari et al. showed, using MC simulations of random systems that at packing densities >50% an equilibrium fluid of hard tetrahedra spontaneously transforms to a dodecagonal quasicrystal, which can be compressed to 83.24%. They reported a glassy, disordered packing at densities exceeding 78%. For a periodic approximant to a quasicrystal with an 82-tetrahedron unit cell, they obtained a packing density as high as 85.03%. In late 2009, a new, much simpler family of packings with a packing fraction of 85.47% was discovered by Kallus and Gravel. These packings were the basis of a improved packing obtained by Torquato and Jiao at the end of 2009 with a packing fraction of 85.55%, by Chen and Glotzer in early 2010 with a packing fraction of 85.63%. The Chen and Glotzer result stands as the densest known packing of hard, regular tetrahedra.

Because the earliest lower bound known for packings of tetrahedra was less than that of spheres, it was suggested that the regular tetrahedra might be a counterexample to Ulam's conjecture that the optimal density for packing congruent spheres is smaller than that for any other convex body. However, the more recent results have shown. Packing problem Disphenoid tetrahedral honeycomb - an isohedral packing of irregular tetrahedra in 3-space; the triakis truncated. Packing Tetrahedrons, Closing in on a Perfect Fit, NYTimes Efficient shapes, The Economist Pyramids are the best shape for packing, New Scientist