CERN

Coordinates: 46°14′03″N 6°03′10″E / 46.23417°N 6.05278°E / 46.23417; 6.05278

The European Organization for Nuclear Research (French: Organisation européenne pour la recherche nucléaire), known as CERN (/ˈsɜːrn/; French pronunciation: ​[sɛʁn]; derived from the name "Conseil Européen pour la Recherche Nucléaire"; see History), is a European research organization that operates the largest particle physics laboratory in the world. Established in 1954, the organization is based in a northwest suburb of Geneva on the Franco–Swiss border, (46°14′3″N 6°3′19″E / 46.23417°N 6.05528°E / 46.23417; 6.05528) and has 21 member states.Israel is the first (and currently only) non-European country granted full membership.

The term CERN is also used to refer to the laboratory, which in 2013 had 2,513 staff members, and hosted some 12,313 fellows, associates, apprentices as well as visiting scientists and engineers representing 608 universities and research facilities.

CERN's main function is to provide the particle accelerators and other infrastructure needed for high-energy physics research – as a result, numerous experiments have been constructed at CERN as a result of international collaborations.

Flat Earth

The flat Earth model is an archaic conception of the Earth's shape as a plane or disk. Many ancient cultures subscribed to a flat Earth cosmography, including Greece until the classical period, the Bronze Age and Iron Age civilizations of the Near East until the Hellenistic period, India until the Gupta period (early centuries AD) and China until the 17th century. That paradigm was also typically held in the aboriginal cultures of the Americas, and the notion of a flat Earth domed by the firmament in the shape of an inverted bowl was common in pre-scientific societies.

The idea of a spherical Earth appeared in Greek philosophy with Pythagoras (6th century BC), although most Pre-Socratics retained the flat Earth model. Aristotle accepted the spherical shape of the Earth on empirical grounds around 330 BC, and knowledge of the spherical Earth gradually began to spread beyond the Hellenistic world from then on.

Historical development

Ancient Near East

In early Egyptian and Mesopotamian thought the world was portrayed as a flat disk floating in the ocean. A similar model is found in the Homeric account of the 8th century BC in which "Okeanos, the personified body of water surrounding the circular surface of the Earth, is the begetter of all life and possibly of all gods." The Israelites likely had a similar cosmology, with the earth as a flat disc floating on water beneath an arced firmament separating it from the heavens.

Black hole

A black hole is a geometrically defined region of spacetime exhibiting such strong gravitational effects that nothing—including particles and electromagnetic radiation such as light—can escape from inside it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of the region from which no escape is possible is called the event horizon. Although crossing the event horizon has enormous effect on the fate of the object crossing it, it appears to have no locally detectable features. In many ways a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe.

Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958. Black holes were long considered a mathematical curiosity; it was during the 1960s that theoretical work showed they were a generic prediction of general relativity. The discovery of neutron stars sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.