Monday, November 26, 2012

Betelgeuse


Betelgeuse 

Betelgeuse (/ˈbiːtəldʒuːz/ or /ˈbɛtəldʒuːz/),[1] also known by its Bayer designation Alpha Orionis (α Orionis, α Ori), is the eighth brightest star in the night sky and second brightest in the constellation of Orion. Distinctly reddish, it is a semiregular variable star whose apparent magnitude varies between 0.2 and 1.2, the widest range of any first-magnitude star. Betelgeuse is one of three stars which make up the Winter Triangle and marks the center of the Winter Hexagon. The star's name is thought to be derived from the Arabic Yad al-Jauzā' meaning "the Hand of al-Jauzā'", i.e. Orion, with mistransliteration into medieval Latin leading to the first character y being misread as a b.
The star is classified as a red supergiant of spectral type M2Iab and is one of the largest and most luminous known stars. If it were at the center of the Solar System its surface would extend past the asteroid belt, possibly to the orbit of Jupiter and beyond, wholly engulfing Mercury, Venus, Earth and Mars. Estimates of its mass are poorly constrained, but have recently ranged from 5 to 30 times that of the Sun. Its distance was estimated in 2008 at 640 light-years from Earth, yielding a mean absolute magnitude of about −6.02. Less than 10 million years old, Betelgeuse has evolved rapidly due to its high mass. Having been ejected from its birthplace in the Orion OB1 Association—which includes the stars in Orion's Belt—this crimson runaway has been observed moving through the interstellar medium at a supersonic speed of 30 km/sec, creating a bow shock over 4 light-years wide. Currently in a late stage of stellar evolution, the supergiant is expected to proceed through its life cycle before exploding as a type II supernova within the next million years.

Betelgeuse was the first star (after the Sun) to have the angular size of its photosphere measured, in 1920. Since then, researchers have used telescopes with different technical parameters to measure the stellar giant, often with conflicting results. Studies since 1990 have produced an angular diameter (apparent size) ranging from 0.043 to 0.056 arcseconds, an incongruity largely caused by the star's perceived tendency to periodically change shape. Due to limb darkening, variability, and angular diameters that vary with wavelength, many of the star's properties are not yet known with any certainty. Adding to the computational challenges, the surface of Betelgeuse is obscured by a complex, asymmetric envelope roughly 250 times the size of the star, caused by colossal mass loss. Possible stellar companions orbiting within this circumstellar nebula may also contribute to the star's enigmatic behavior

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Sunday, November 25, 2012

Grey Cup

From Wikipedia, the free encyclopedia
 
        Grey Cup








Awarded for Winning the

Canadian Football League championship
Country Canada
First awarded 1909
Currently held by BC Lions
Official website greycup.cfl.ca


The Grey Cup (French: La Coupe Grey) is the name of both the championship game of the Canadian Football League (CFL) and the trophy awarded to the victorious team. It is contested between the winners of the CFL's East and West Divisional playoffs and is one of Canadian television's largest annual sporting events. The Toronto Argonauts have 15 championships, more than any other team. The defending champions are the BC Lions. The 2012 game, to be played in Toronto, will be the 100th Grey Cup.

The trophy was commissioned in 1909 by the Earl Grey, then Canada's governor general, who originally hoped to donate it for the country's senior amateur hockey championship. After the Allan Cup was donated for that purpose, Grey instead made his trophy available as the national championship of Canadian football. The trophy has a silver chalice attached to a large base on which the names of all winning teams, players and executives are engraved. The Grey Cup has been broken on several occasions, stolen twice and held for ransom. It survived a 1947 fire that destroyed numerous artifacts housed in the same building.

The Grey Cup was first won by the University of Toronto Varsity Blues. Play was suspended from 1916 to 1918 due to the First World War and in 1919 due to a rules dispute. The game has typically been contested in an east versus west format since the 1920s. Traditionally held on a Sunday at the end of November, the Grey Cup has been played in inclement weather at times, including the 1950 "Mud Bowl," in which a player reportedly came close to drowning in a puddle, the 1962 "Fog Bowl," when the final nine minutes of the game had to be postponed to the following day due to a heavy fog, and the 1977 "Ice Bowl," contested on the frozen-over artificial turf at Montreal's Olympic Stadium. The Edmonton Eskimos formed the Grey Cup's longest dynasty, winning five consecutive championships from 1978 to 1982. Competition for the trophy has been exclusively between Canadian teams, except for a three-year period from 1993 to 1995 when a brief expansion into the United States resulted in the Baltimore Stallions winning the 1995 championship.

Saturday, November 24, 2012

Clean energy for tomorrow

Clean energy for tomorrow


Paula Dobriansky

The world needs affordable and clean energy to fuel economic growth, development, and democracy without harming the environment. The United States is confronting this challenge with transformational technologies, creativity of entrepreneurs, and support for local initiatives in the developing world.

Paula Dobriansky is Under Secretary of State for Democracy and Global Affairs.

Ensuring access to ample, affordable, clean, and sustainable sources of energy is unquestionably one of the greatest challenges facing the modern world. The U.S. government and America's private sector and nongovernmental organizations are confronting it by building on a long tradition of clean energy research to develop transformational technologies that will reduce our reliance on oil and have far-reaching benefits for the entire world.

By embracing the energy challenge, the United States is working to promote energy security, reduce poverty, reduce harmful air pollution, and address climate change. These efforts often strengthen self-governing societies by building a culture of democracy at the grassroots level.

The energy Challenge

Rarely does a day pass without an energy-related issue making the headlines. Whenever world leaders meet, energy is an important and urgent topic of discussion. From the 2002 World Summit on Sustainable Development to the 2005 Gleneagles Group of Eight (G8) Summit to the 2005-2007 energy cycle of the UN Commission on Sustainable Development, energy is front and center.

And for good reason. Supply disruptions and rising prices loom large in day-to-day decisions about how we fuel our vehicles, heat our homes, and power our businesses. What's more, approximately 2 billion people—nearly one-third of the world's population—lack access to the modern energy services that are essential for bringing schools into the 21st century, driving industry, moving water, and boosting crop production, as well as for lighting, heating, and cooling health facilities.

The integrated goals of energy security and poverty alleviation are also inextricably linked with the need to reduce harmful air pollution and address climate change. The World Health Organization estimates that 4,400 people die every day from indoor air pollution, much of which is associated with unhealthy cooking and heating practices.

Developing clean and Affordable energy Technologies

The United States believes that the best way to promote energy security and help nations develop, while protecting the environment and improving public health, is to promote clean and affordable energy technologies. We will need a diversified approach that includes conventional, advanced, and renewable energy and energy-efficiency technologies.

The U.S. government, frequently in partnership with the private sector, is pursuing both domestically and internationally a suite of technologies that should be incrementally deployed by the second half of this century. These include new biofuels from nonfood crops; clean coal technology; commercialization of plug-in hybrid autos; hydrogen fuel cell technology; more efficient, proliferation-resistant nuclear systems; and fusion technology. And these are just the highlights.

In his January 2006 State of the Union address, President George W. Bush outlined a strategy to reduce America's dependence on oil. The president's Advanced energy Initiative proposes a 22 percent increase in funding for clean energy research at the U.S. Department of Energy. This includes greater investment in solar and wind technologies, zero-emission coal-fired power plants, clean nuclear technology, and ethanol.

It is important that we not only develop clean energy technologies but also work to make them more affordable and accessible. That is why the U.S. government has spent more than $11.7 billion since 2001 to develop alternative energy sources. This funding has contributed to a dramatic reduction in the cost of renewable energy. As the costs of conventional energy rise, the private investment community is responding. In 2005, we saw $44 billion of new capital investment in renewable energy technologies in the electricity sector. Renewables now comprise approximately 20 to 25 percent of global power sector investment.

As we strive to develop new sources of energy, we are also working hard to reduce our energy consumption. A leading example of this effort is energy Star, a U.S. government-backed program that helps businesses and individuals protect the environment through superior energy efficiency. With the help of energy Star, Americans saved enough energy in 2005 alone to avoid greenhouse gas emissions equivalent to those from 23 million cars—all while saving $12 billion on their utility bills, or 4 percent of the United States' total annual electricity demand.

Disseminating Technologies Through Public-Private Partnerships

Multi-stakeholder partnerships with governments, civil society, and the private sector are critical to addressing the energy challenge. The United States participates in a broad spectrum of partnerships, with groups ranging from small American nongovernmental organizations building and demonstrating the use of simple solar cookers in African refugee camps to broader regional alliances such as the recently launched Asia-Pacific Partnership on clean Development and Climate. This voluntary partnership with Australia, China, Japan, India, and South Korea—countries that together with the United States represent over 50 percent of global energy use and greenhouse gas emissions—has as its goal the accelerated deployment of cleaner, more efficient technologies and the meeting of partners' respective national pollution reduction, energy security, and climate change objectives. The Asia-Pacific Partnership will engage stakeholders from key economic sectors as full partners in addressing clean development and climate issues in an integrated manner.

In order to foster public-private alliances, the U.S. Agency for International Development (USAID) created the Global Development Alliance in 2001. Through this innovative program, USAID has funded programs with nearly 400 alliances, with more than $1.4 billion in government funding leveraging more than $4.6 billion in partner resources.

The ultimate measure of the partnerships' success is whether they deliver concrete, on-the-ground results. When we talk about measurable results, a really positive story is emerging from some of the partnerships launched almost four years ago at the World Summit on Sustainable Development in Johannesburg. One example is the Partnership for clean Fuels and Vehicles, one of the four performance-based, market-oriented partnerships under President Bush's clean energy Initiative, a multifaceted approach to addressing access to energy and improving energy efficiency and environmental quality. In 2002, leaded gasoline was used in all but one country in sub-Saharan Africa. By the end of 2005, with the assistance of the Partnership for clean Fuels and Vehicles, all 49 sub-Saharan African countries had stopped refining and importing leaded gasoline. This change will have a significant health impact on many of the 733 million people living in these countries.

The United States is committed to transparent reporting on the partnerships in which we participate. Toward that end, we have created a Web site—www.SDP.gov—to provide continuously updated information on U.S. sustainable development partnership efforts.

Building Effective Policy and Regulatory Frameworks
One of the keys to disseminating clean-energy technologies is ensuring the development of markets to receive them. Effective policy and regulatory frameworks at the local and national levels are absolutely necessary to encourage the level of private sector investment that will be needed in the coming decades.

The U.S. government is making significant progress to build capacity throughout the developing world. From our work on providing reliable energy services in poor slum areas in India to setting rules for power trading in Southern Africa to improved public participation in energy sector decision making globally, we are working with developing country ministries, utilities, and end-users to build the kind of institutional and market structures that will encourage investment in the energy sector.

The United States is also proud to work with its G8 colleagues and a number of other partners on the Extractive Industries Transparency Initiative (EITI). The EITI supports improved governance in resource-rich countries through the full publication and verification of company payments and government revenues from oil, gas, and mining.

Fostering Democratic Habits at the Grassroots Level

Increasing access to modern, clean, healthy, and efficient energy services can help lift people out of poverty and protect the environment. Perhaps equally important, the very act of providing energy services offers tremendous opportunities for communities to come together to learn and practice the fine art of democratic decision making.

The roots of strong democracies reach much deeper than the act of voting, resting on a foundation of social cohesion and participatory institutions. For the individual rural villager or urban slum dweller, the quest for energy services hinges on whether or not the institutions that serve the community are accountable to their constituency. Far too often, citizens' needs are not fully incorporated into political decisions about who gets what, when, where, and how.

A number of innovative electrification initiatives across the globe are addressing this problem by fostering local community structures that can bridge the gap between households and service providers. For example, USAID supported an alliance in Ahmedabad, India, in which local nongovernmental organizations served as intermediaries, assisting slum dwellers with financing and acquiring the appropriate documentation regarding land ownership to make them eligible for legal electricity service. The results are impressive. In the pilot project, 820 households were upgraded from illegal and unreliable service to regularized electricity. The utility is now rolling out the program to an additional 115,000 poor urban households. In Salvador, Brazil, the utility COELBA has hired local "community agents" to work with the local citizens and community leaders to identify and resolve problems, as well as to provide education on energy conservation practices. Thus far, COELBA has electrified more than 200,000 households. Building on this success, USAID and the U.S. energy Association are supporting a South-South exchange between COELBA and Angolan electric utility EDEL.

By involving community intermediaries in electrification efforts, these programs are strengthening democratic habits at the grassroots level. They build trust, form social capital, and allow people to voice their concerns. In so doing, they not only connect customers to electricity but also enable citizens to learn what it means to participate in democratic processes. This experience and these newly formed skills can easily be applied to other aspects of social and political life, ultimately contributing to a stronger, more robust, and more secure democratic culture.

Meeting the Challenge

The United States is pursuing a clean energy future that rises to the significant challenge before us. Our approach draws upon the best scientific research, harnesses the power of markets, fosters the creativity of entrepreneurs, and works with the developing world to meet our dual aspirations for vibrant economies and a clean environment.

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Tuesday, November 20, 2012

Great Pyramid of Giza

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Great Pyramid of Giza



The Great Pyramid of Giza (also known as the Pyramid of Khufu or the Pyramid of Cheops) is the oldest and largest of the three pyramids in the Giza Necropolis bordering what is now El Giza, Egypt. It is the oldest of the Seven Wonders of the Ancient World, and the only one to remain largely intact. Egyptologists believe that the pyramid was built as a tomb for fourth dynasty Egyptian Pharaoh Khufu (Cheops in Greek) over a 10 to 20-year period concluding around 2560 BC. Initially at 146.5 metres (481 feet), the Great Pyramid was the tallest man-made structure in the world for over 3,800 years. Originally, the Great Pyramid was covered by casing stones that formed a smooth outer surface; what is seen today is the underlying core structure. Some of the casing stones that once covered the structure can still be seen around the base. There have been varying scientific and alternative theories about the Great Pyramid's construction techniques. Most accepted construction hypotheses are based on the idea that it was built by moving huge stones from a quarry and dragging and lifting them into place.

There are three known chambers inside the Great Pyramid. The lowest chamber is cut into the bedrock upon which the pyramid was built and was unfinished. The so-called[1] Queen's Chamber and King's Chamber are higher up within the pyramid structure. The Great Pyramid of Giza is the only pyramid in Egypt known to contain both ascending and descending passages. The main part of the Giza complex is a setting of buildings that included two mortuary temples in honor of Khufu (one close to the pyramid and one near the Nile), three smaller pyramids for Khufu's wives, an even smaller "satellite" pyramid, a raised causeway connecting the two temples, and small mastaba tombs surrounding the pyramid for nobles.


History and description



It is believed the pyramid was built as a tomb for fourth dynasty Egyptian pharaoh Khufu and was constructed over a 20 year period. Khufu's vizier, Hemon, or Hemiunu, is believed by some to be the architect of the Great Pyramid.[2] It is thought that, at construction, the Great Pyramid was originally 280 Egyptian cubits tall, 146.5 metres (480.6 ft) but with erosion and absence of its pyramidion, its present height is 138.8 metres (455.4 ft). Each base side was 440 cubits, 230.4 metres (755.9 ft) long. The mass of the pyramid is estimated at 5.9 million tonnes. The volume, including an internal hillock, is roughly 2,500,000 cubic metres.[3] Based on these estimates, building this in 20 years would involve installing approximately 800 tonnes of stone every day. Similarly, since it consists of an estimated 2.3 million blocks, completing the building in 20 years would involve moving an average of more than 12 of the blocks into place each hour, day and night. The first precision measurements of the pyramid were made by Egyptologist Sir Flinders Petrie in 1880–82 and published as The Pyramids and Temples of Gizeh.[4] Almost all reports are based on his measurements. Many of the casing stones and inner chamber blocks of the Great Pyramid were fit together with extremely high precision. Based on measurements taken on the north eastern casing stones, the mean opening of the joints is only 0.5 millimetres wide (1/50th of an inch).[5]

Great Pyramid of Giza from a 19th century stereopticon card photo

The pyramid remained the tallest man-made structure in the world for over 3,800 years,[6] unsurpassed until the 160-metre-tall spire of Lincoln Cathedral was completed c. 1300. The accuracy of the pyramid's workmanship is such that the four sides of the base have an average error of only 58 millimetres in length.[7] The base is horizontal and flat to within ±15 mm.[8] The sides of the square base are closely aligned to the four cardinal compass points (within 4 minutes of arc)[9] based on true north, not magnetic north,[10] and the finished base was squared to a mean corner error of only 12 seconds of arc.[11] The completed design dimensions, as suggested by Petrie's survey and subsequent studies, are estimated to have originally been 280 cubits high by 440 cubits long at each of the four sides of its base. The ratio of the perimeter to height of 1760/280 cubits equates to 2? to an accuracy of better than 0.05% (corresponding to the well-known approximation of ? as 22/7). Some Egyptologists consider this to have been the result of deliberate design proportion. Verner wrote, "We can conclude that although the ancient Egyptians could not precisely define the value of ?, in practice they used it".[12] Petrie, author of Pyramids and Temples of Gizeh concluded: "but these relations of areas and of circular ratio are so systematic that we should grant that they were in the builder's design".[13] Others have argued that the Ancient Egyptians had no concept of pi and would not have thought to encode it in their monuments. They believe that the observed pyramid slope may be based on a simple seked slope choice alone, with no regard to the overall size and proportions of the finished building.

Materials


The Great Pyramid consists of an estimated 2.3 million limestone blocks with most believed to have been transported from nearby quarries. The Tura limestone used for the casing was quarried across the river. The largest granite stones in the pyramid, found in the "King's" chamber, weigh 25 to 80 tonnes and were transported from Aswan, more than 500 miles away. Traditionally, ancient Egyptians cut stone blocks by hammering wooden wedges into the stone which were then soaked with water. As the water was absorbed, the wedges expanded, causing the rock to crack. Once they were cut, they were carried by boat either up or down the Nile River to the pyramid.[15] It is estimated that 5.5 million tons of limestone, 8,000 tons of granite (imported from Aswan), and 500,000 tons of mortar were used in the construction of the Great Pyramid.[16]
Casing stones

Casing stone




At completion, the Great Pyramid was surfaced by white "casing stones" – slant-faced, but flat-topped, blocks of highly polished white limestone. These were carefully cut to what is approximately a face slope with a seked of 5½ palms to give the required dimensions. Visibly, all that remains is the underlying stepped core structure seen today. In AD 1300, a massive earthquake loosened many of the outer casing stones, which were then carted away by Bahri Sultan An-Nasir Nasir-ad-Din al-Hasan in 1356 to build mosques and fortresses in nearby Cairo. The stones can still be seen as parts of these structures. Later explorers reported massive piles of rubble at the base of the pyramids left over from the continuing collapse of the casing stones, which were subsequently cleared away during continuing excavations of the site. Nevertheless, a few of the casing stones from the lowest course can be seen to this day in situ around the base of the Great Pyramid, and display the same workmanship and precision as has been reported for centuries. Petrie also found a different orientation in the core and in the casing measuring 193 centimetres ± 25 centimetres. He suggested a redetermination of north was made after the construction of the core, but a mistake was made, and the casing was built with a different orientation.[17] Petrie related the precision of the casing stones as to being "equal to opticians' work of the present day, but on a scale of acres" and "to place such stones in exact contact would be careful work; but to do so with cement in the joints seems almost impossible".[18] It has been suggested it was the mortar (Petrie's "cement") that made this seemingly impossible task possible, providing a level bed which enabled the masons to set the stones exactly.[19][20]
Construction theories
Main article: Egyptian pyramid construction techniques

Many alternative, often contradictory, theories have been proposed regarding the pyramid's construction techniques.[21] Many disagree on whether the blocks were dragged, lifted, or even rolled into place. The Greeks believed that slave labour was used, but modern discoveries made at nearby worker's camps associated with construction at Giza suggest it was built instead by tens of thousands of skilled workers. Verner posited that the labor was organized into a hierarchy, consisting of two gangs of 100,000 men, divided into five zaa or phyle of 20,000 men each, which may have been further divided according to the skills of the workers.[22]

One mystery of the pyramid's construction is its planning. John Romer suggests that they used the same method that had been used for earlier and later constructions, laying out parts of the plan on the ground at a 1 to 1 scale. He writes that "such a working diagram would also serve to generate the architecture of the pyramid with precision unmatched by any other means."[23] He also argues for a 14 year time span for its construction.[24]

A construction management study (testing) carried out by the firm Daniel, Mann, Johnson, & Mendenhall in association with Mark Lehner and other Egyptologists, estimates that the total project required an average workforce of 14,567 people and a peak workforce of 40,000. Without the use of pulleys, wheels, or iron tools, they used critical path analysis to suggest the Great Pyramid was completed from start to finish in approximately 10 years



Interior




The original entrance to the Great Pyramid is 17 metres (56 ft) vertically above ground level and 7.29 metres (23.9 ft) east of the center line of the pyramid. From this original entrance there is a Descending Passage .96 metres (3.1 ft) high and 1.04 metres (3.4 ft) wide which goes down at an angle of 26° 31'23" through the masonry of the pyramid and then into the bedrock beneath it. After 105.23 metres (345.2 ft), the passage becomes level and continues for an additional 8.84 metres (29.0 ft) to the lower Chamber, which appears not to have been finished. There is a continuation of the horizontal passage in the south wall of the lower chamber; there is also a pit dug in the floor of the chamber. Some Egyptologists suggest this Lower Chamber was intended to be the original burial chamber, but Pharaoh Khufu later changed his mind and wanted it to be higher up in the pyramid.[26]

At 28.2 metres (93 ft) from the entrance is a square hole in the roof of the Descending Passage. Originally concealed with a slab of stone, this is the beginning of the Ascending Passage. The Ascending Passage is 39.3 metres (129 ft) long, as wide and high as the Descending Passage and slopes up at almost precisely the same angle. The lower end of the Ascending Passage is closed by three huge blocks of granite, each about 1.5 metres (4.9 ft) long. At the start of the Grand Gallery on the right-hand side there is a hole cut in the wall (and now blocked by chicken wire). This is the start of a vertical shaft which follows an irregular path through the masonry of the pyramid to join the Descending Passage. Also at the start of the Grand Gallery there is a Horizontal Passage leading to the "Queen's Chamber". The passage is 1.1m (3'8") high for most of its length, but near the chamber there is a step in the floor, after which the passage is 1.73 metres (5.7 ft) high.
Queen's Chamber

The Queen's Chamber is exactly half-way between the north and south faces of the pyramid and measures 5.75 metres (18.9 ft) north to south, 5.23 metres (17.2 ft) east to west and has a pointed roof with an apex 6.23 metres (20.4 ft) above the floor. At the eastern end of the chamber there is a niche 4.67 metres (15.3 ft) high. The original depth of the niche was 1.04 metres (3.4 ft), but has since been deepened by treasure hunters.[citation needed]

In the north and south walls of the Queen's Chamber there are shafts, which unlike those in the King's Chamber that immediately slope upwards, are horizontal for around 2 m (6.6 ft) before sloping upwards. The horizontal distance was cut in 1872 by a British engineer, Waynman Dixon, who believed on the analogy of the King's Chamber that such shafts must exist. He was proved right, but because the shafts are not connected to the outer faces of the pyramid or the Queen's Chamber, their purpose is unknown. At the end of one of his shafts, Dixon discovered a ball of black diorite and a bronze implement of unknown purpose. Both objects are currently in the British Museum. [27]

The shafts in the Queen's Chamber were explored in 1992 by the German engineer Rudolf Gantenbrink using a crawler robot of his own design which he called "Upuaut 2". After a climb of 65 m (213 ft),[28] he discovered that one of the shafts was blocked by limestone "doors" with two eroded copper "handles". Some years later the National Geographic Society created a similar robot which drilled a small hole in the southern door, only to find another larger door behind it.[29] The northern passage, which was difficult to navigate because of twists and turns, was also found to be blocked by a door.[30] This research was continued in 2011 by the Djedi Project team.

In 2011 the Djedi Project team used a Micro snake camera (that can see around corners) to penetrate the first door of the northern shaft, and view all the sides of the small chamber behind it. (The National Geographic Society used a camera that was only able to look straight forward.) They discovered hieroglyphs written in red paint. They were also able to scrutinize the inside of the two copper “handles” embedded in the door, and they now believe them to be of an ornamental nature. They also found the reverse side of the “door” to be finished and polished, which suggests that it wasn’t put there just to block the shaft, but rather for a more specific reason.[31][32] A detailed report of the Djedi Project can be found at [1]




Grand Gallery


The Grand Gallery continues the slope of the Ascending Passage, but is 8.6 metres (28 ft) high and 46.68 metres (153.1 ft) long. At the base it is 2.06 metres (6.8 ft) wide, but after 2.29 metres (7.5 ft) the blocks of stone in the walls are corbelled inwards by 7.6 centimetres (3.0 in) on each side. There are seven of these steps, so at the top the Grand Gallery is only 1.04 metres (3.4 ft) wide. It is roofed by slabs of stone laid at a slightly steeper angle than the floor of the gallery, so that each stone fits into a slot cut in the top of the gallery like the teeth of a ratchet. The purpose was to have each block supported by the wall of the Gallery rather than resting on the block beneath it, which would have resulted in an unacceptable cumulative pressure at the lower end of the Gallery.[citation needed]

At the upper end of the Gallery on the right-hand side there is a hole near the roof which opens into a short tunnel by which access can be gained to the lowest of the Relieving Chambers. The other Relieving Chambers were discovered in 1837/8 by Colonel Howard Vyse and J. S. Perring, who dug tunnels upwards using blasting powder.

The floor of the Grand Gallery consists of a shelf or step on either side, 51 centimetres (20 in) wide, leaving a lower ramp 1.04 metres (3.4 ft) wide between them. In the shelves there are 54 slots, 27 on each side matched by vertical and horizontal slots in the walls of the Gallery. These form a cross shape that rises out of the slot in the shelf. The purpose of these slots is not known, but the central gutter in the floor of the Gallery, which is the same width as the Ascending Passage, has led to speculation that the blocking stones were stored in the Grand Gallery and the slots held wooden beams to restrain them from sliding down the passage.[citation needed] This, in turn, has led to the proposal that originally many more than 3 blocking stones were intended, to completely fill the Ascending Passage.[citation needed]

At the top of the Grand Gallery there is a step giving onto a horizontal passage approximately 1.02 metres (3.3 ft) long, in which can be detected four slots, three of which were probably intended to hold granite portcullises. Fragments of granite found by Petrie in the Descending Passage may have come from these now vanished doors.



King's Chamber

The King's Chamber is 10.47 metres (34.4 ft) from east to west and 5.234 metres (17.17 ft) north to south. It has a flat roof 5.974 metres (19.60 ft) above the floor. 0.91 m (3.0 ft) above the floor there are two narrow shafts in the north and south walls (one is now filled by an extractor fan to try to circulate air in the pyramid). The purpose of these shafts is not clear: they appear to be aligned on stars or areas of the northern and southern skies, but on the other hand one of them follows a dog-leg course through the masonry so there was not intention to directly sight stars through them. Longtime believed by Egyptologists to be "air shafts" for ventilation, this idea has now been widely abandoned in favor of the shafts serving a ritualistic purpose associated with the ascension of the king’s spirit to the heavens.[33]

The King's Chamber is entirely faced with granite. Above the roof, which is formed of nine slabs of stone weighing in total about 400 tons, are five compartments known as Relieving Chambers. The first four, like the King's Chamber, have flat roofs formed by the floor of the chamber above, but the final chamber has a pointed roof. Vyse suspected the presence of upper chambers when he found that he could push a long reed through a crack in the ceiling of the first chamber. From lower to upper, the chambers are known as "Davison's Chamber", "Wellington's Chamber", "Nelson's Chamber", "Lady Arbuthnot's Chamber", and "Campbell's Chamber". It is believed that the compartments were intended to safeguard the King's Chamber from the possibility of a roof collapsing under the weight of stone above the Chamber. As the chambers were not intended to be seen, they were not finished in any way and a few of the stones still retain mason's marks painted on them. One of the stones in Campbell's Chamber bears a mark, apparently the name of a work gang, which incorporates the only reference in the pyramid to Pharaoh Khufu.[34][35]

The entrance of the Pyramid




The only object in the King's Chamber is a rectangular granite "sarcophagus", one corner of which is broken. The sarcophagus is slightly larger than the Ascending Passage, which indicates that it must have been placed in the Chamber before the roof was put in place. Unlike the fine masonry of the walls of the Chamber, the sarcophagus is roughly finished, with saw marks visible in several places. This is in contrast with the finely finished and decorated sarcophagi found in other pyramids of the same period. Petrie suggested that such a sarcophagus was intended but was lost in the river on the way north from Aswan and a hurriedly made replacement was used instead.
Modern Entrance

Today tourists enter the Great Pyramid via the Robbers' Tunnel dug by workmen employed by Caliph al-Ma'mun around AD 820. The tunnel is cut straight through the masonry of the pyramid for approximately 27 metres (89 ft), then turns sharply left to encounter the blocking stones in the Ascending Passage. Unable to remove these stones, the workmen tunnelled up beside them through the softer limestone of the Pyramid until they reached the Ascending Passage. It is possible to enter the Descending Passage from this point, but access is usually forbidden.


Pyramid complex



he Great Pyramid is surrounded by a complex of several buildings including small pyramids. The Pyramid Temple, which stood on the east side of the pyramid and measured 52.2 metres (171 ft) north to south and 40 metres (130 ft) east to west, has almost entirely disappeared apart from the black basalt paving. There are only a few remnants of the causeway which linked the pyramid with the valley and the Valley Temple. The Valley Temple is buried beneath the village of Nazlet el-Samman; basalt paving and limestone walls have been found but the site has not been excavated.[36][37] The basalt blocks show "clear evidence" of having been cut with some kind of saw with an estimated cutting blade 15 ft in length capable of cutting at a rate of 11?2 inches (38 mm) a minute. John Romer suggests this "super saw" may have had copper teeth and weighed up to 300 lbs. He theorizes such a saw could have been attached to a wooden trestle and used in conjunction with possibly vegetable oil, cutting sand, or emery or pounded quartz to cut the blocks and would have required at least a dozen men to operate it.[38]

On the south side are the subsidiary pyramids, popularly known as Queens' Pyramids. Three remain standing to nearly full height but the fourth was so ruined that its existence was not suspected until the recent discovery of the first course of stones and the remains of the capstone. Hidden beneath the paving around the pyramid was the tomb of Queen Hetepheres, sister-wife of Sneferu and mother of Khufu. Discovered by accident by the Reisner expedition, the burial was intact, though the carefully sealed coffin proved to be empty.

Group photo of Australian 11th Battalion soldiers on the Great Pyramid in 1915.

Aerial photography, taken from Eduard Spelterini's balloon on 21 November 1904

The Giza pyramid complex, which includes among other structures the pyramids of Khufu, Khafre and Menkaure, is surrounded by a cyclopean stone wall, the Wall of the Crow, and outside of which Mark Lehner has discovered a worker's town, otherwise known as "The Lost City", dated by pottery styles, seal impressions, and stratigraphy to have been constructed and occupied sometime during the reigns of Khafre (2520–2494 BC) and Menkaure (2490–2472 BC).[39][40] In the early 1970s, the Australian archaeologist Karl Kromer excavated a mound in the South Field of the plateau. This mound contained artifacts including mudbrick seals of Khufu, which he identified with an artisans' settlement.[41] Mudbrick buildings just south of Khufu's Valley Temple contained mud sealings of Khufu and have been suggested to be a settlement serving the cult of Khufu after his death.[42] A workers cemetery used at least between Khufu's reign and the end of the Fifth Dynasty was discovered south of the Wall of the Crow by Zahi Hawass in 1990


Boats

There are three boat-shaped pits around the pyramid, of a size and shape to have held complete boats, though so shallow that any superstructure, if there ever was one, must have been removed or disassembled. In May 1954, the Egyptian archaeologist Kamal el-Mallakh discovered a fourth pit, a long, narrow rectangle, still covered with slabs of stone weighing up to 15 tons. Inside were 1,224 pieces of wood, the longest 23 metres (75 ft) long, the shortest 10 centimetres (0.33 ft). These were entrusted to a native boat builder, Haj Ahmed Yusuf, who slowly and methodically worked out how the pieces fit together. The entire process, including conservation and straightening of the warped wood, took fourteen years.

The result is a cedar-wood boat 43.6 metres (143 ft) long, its timbers held together by ropes, which is now currently housed in a special boat-shaped, air-conditioned museum beside the pyramid. During construction of this museum, which stands above the boat pit, a second sealed boat pit was discovered. It was deliberately left unopened until 2011 when excavation began on the boat.


Looting



Although succeeding pyramids were smaller, pyramid building continued until the end of the Middle Kingdom. However, as authors Briar and Hobbs claim, "all the pyramids were robbed" by the New Kingdom, when the construction of royal tombs in a desert valley, now known as the Valley of the Kings, began.[45][46] Joyce Tyldesley states that the Great Pyramid itself "is known to have been opened and emptied by the Middle Kingdom", before the Arab caliph Abdullah al-Mamun entered the pyramid around AD 820.[47]

I. E. S. Edwards discusses Strabo's mention that the pyramid "a little way up one side has a stone that may be taken out, which being raised up there is a sloping passage to the foundations." Edwards suggested that the pyramid was entered by robbers after the end of the Old Kingdom and sealed and then reopened more than once until Strabo's door was added. He adds "If this highly speculative surmise be correct, it is also necessary to assume either that the existence of the door was forgotten or that the entrance was again blocked with facing stones" in order to explain why al-Ma'mun could not find the entrance.[48]

He also discusses a story told by Herodotus. Herodotus visited Egypt in the 5th century BC and recounts a story he was told about vaults under the pyramid built upon an island where lay the body of Cheops. Edwards notes that the pyramid had "almost certainly been opened and its contents plundered long before the time of Herodotus" and that it might have been closed again during the Twenty-sixth dynasty of Egypt when other monuments were restored. He suggests that the story told to Herodotus could have been the result of almost two centuries of telling and retelling by Pyramid guides


The Great Pyramid in modern cultural depictions


Because of their fame, Khufu and his pyramid are object of several modern receptions, similar to kings and queens such as Akhenaten, Nefertiti and Tutankhamen. Khufu's historical figure appears in movies, novels and documentations. Already in 1827, female science fiction author Jane C. Loudon wrote the novel The Mummy! A Tale of the 22nd Century. The story describes the citizens of the 22nd century, which became technically high advanced at one side, but totally immoral on the other side. Only the mummy of Khufu can save them.[50] In 1939, Nagib Mahfuz wrote the novel Khufu's Wisdom, which leans on the stories of Papyrus Westcar;[51] In 1997, French author Guy Brachet composed the novel series Le roman des pyramides, including five volumes, of which the first two (Le temple soleil and Rêve de pierre) are picking out Khufu and his tomb as a theme.[52] In 2004, Page Bryant wrote the Sci-Fi story The Second Coming of the Star Gods, which deals with Khufu's alleged celestial origin.[53] The novel The Legend of The Vampire Khufu, written by Raymond Mayotte in 2010, deals with king Khufu awakening in his pyramid as a vampire.[54]

Well known cinematic movies, which deal with Khufu or at least have the Great Pyramid as a theme, are Howard Hawks' Land of the Pharaohs from 1955, a fictional account of the building of the Great Pyramid of Khufu,[55] and Roland Emmerich's Stargate from 1994, in which an extraterrestrial device is found near the pyramids.

Khufu and his pyramid are furthermore object of pseudoscientific theories which deal with the idea that Khufu's pyramid was built with the help of extraterrestrials and that Khufu simply seized and re-used the monument,[56] ignoring all archaeological evidences or even falsifying them.[57]

Khufu and his pyramid are even thematized in several computer games such as Tomb Raider - The last revelation, in which the player must enter Khufu's pyramid and face the god Seth as the final boss.[58] Another example is Duck Tales 2 for the Game Boy. In this game the player must guide Uncle Scrooge through a trap-loaded Khufu's pyramid

Sports

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Sport in childhood. Association football, shown above, is a team sport which also provides opportunities to nurture physical fitness and social interaction skills.

Sport (or, in the United States, sports) is all forms of competitive physical activity which,[1] through casual or organised participation, aim to use, maintain or improve physical ability and provide entertainment to participants.[2] Hundreds of sports exist, from those requiring only two participants, through to those with hundreds of simultaneous participants, either in teams or competing as individuals.

Sport is generally recognised as activities which are based in physical athleticism or physical dexterity, with the largest major competitions such as the Olympic Games admitting only sports meeting this definition,[3] and other organisations such as the Council of Europe using definitions precluding activities without a physical element from classification as sports.[2] However, a number of competitive, but non-physical, activities claim recognition as mind sports. The International Olympic Committee (through ARISF) recognises both chess and bridge as bona fide sports, and SportAccord, the international sports federation association, recognises five non-physical sports,[4][5] although limits the amount of mind games which can be admitted as sports.[1]

Sports are usually governed by a set of rules or customs, which serve to ensure fair competition, and allow consistent adjudication of the winner. Winning can be determined by physical events such as scoring goals or crossing a line first, or by the determination of judges who are scoring elements of the sporting performance, including objective or subjective measures such as technical performance or artistic impression.

In organised sport, records of performance are often kept, and for popular sports, this information may be widely announced or reported in sport news. In addition, sport is a major source of entertainment for non-participants, with spectator sports drawing large crowds to venues, and reaching wider audiences through sports broadcasting.