Cosmology is a branch of astronomy concerned with the studies of the origin and evolution of the universe, from the Big Bang to today and on into the future. It is the scientific study of the origin and eventual fate of the universe. Physical cosmology is the scientific study of the universe's origin, its large-scale structures and dynamics, its ultimate fate, as well as the laws of science that govern these areas; the term cosmology was first used in English in 1656 in Thomas Blount's Glossographia, in 1731 taken up in Latin by German philosopher Christian Wolff, in Cosmologia Generalis. Religious or mythological cosmology is a body of beliefs based on mythological and esoteric literature and traditions of creation myths and eschatology. Physical cosmology is studied by scientists, such as astronomers and physicists, as well as philosophers, such as metaphysicians, philosophers of physics, philosophers of space and time; because of this shared scope with philosophy, theories in physical cosmology may include both scientific and non-scientific propositions, may depend upon assumptions that cannot be tested.
Cosmology differs from astronomy in that the former is concerned with the Universe as a whole while the latter deals with individual celestial objects. Modern physical cosmology is dominated by the Big Bang theory, which attempts to bring together observational astronomy and particle physics. Theoretical astrophysicist David N. Spergel has described cosmology as a "historical science" because "when we look out in space, we look back in time" due to the finite nature of the speed of light. Physics and astrophysics have played a central role in shaping the understanding of the universe through scientific observation and experiment. Physical cosmology was shaped through both mathematics and observation in an analysis of the whole universe; the universe is understood to have begun with the Big Bang, followed instantaneously by cosmic inflation. Cosmogony studies the origin of the Universe, cosmography maps the features of the Universe. In Diderot's Encyclopédie, cosmology is broken down into uranology, aerology and hydrology.
Metaphysical cosmology has been described as the placing of humans in the universe in relationship to all other entities. This is exemplified by Marcus Aurelius's observation that a man's place in that relationship: "He who does not know what the world is does not know where he is, he who does not know for what purpose the world exists, does not know who he is, nor what the world is." Physical cosmology is the branch of physics and astrophysics that deals with the study of the physical origins and evolution of the Universe. It includes the study of the nature of the Universe on a large scale. In its earliest form, it was, the study of the heavens. Greek philosophers Aristarchus of Samos and Ptolemy proposed different cosmological theories; the geocentric Ptolemaic system was the prevailing theory until the 16th century when Nicolaus Copernicus, subsequently Johannes Kepler and Galileo Galilei, proposed a heliocentric system. This is one of the most famous examples of epistemological rupture in physical cosmology.
Isaac Newton's Principia Mathematica, published in 1687, was the first description of the law of universal gravitation. It provided a physical mechanism for Kepler's laws and allowed the anomalies in previous systems, caused by gravitational interaction between the planets, to be resolved. A fundamental difference between Newton's cosmology and those preceding it was the Copernican principle—that the bodies on earth obey the same physical laws as all the celestial bodies; this was a crucial philosophical advance in physical cosmology. Modern scientific cosmology is considered to have begun in 1917 with Albert Einstein's publication of his final modification of general relativity in the paper "Cosmological Considerations of the General Theory of Relativity". General relativity prompted cosmogonists such as Willem de Sitter, Karl Schwarzschild, Arthur Eddington to explore its astronomical ramifications, which enhanced the ability of astronomers to study distant objects. Physicists unchanging. In 1922 Alexander Friedmann introduced the idea of an expanding universe that contained moving matter.
Around the same time the Great Debate took place, with early cosmologists such as Heber Curtis and Ernst Öpik determining that some nebulae seen in telescopes were separate galaxies far distant from our own. In parallel to this dynamic approach to cosmology, one long-standing debate about the structure of the cosmos was coming to a climax. Mount Wilson astronomer Harlow Shapley championed the model of a cosmos made up of the Milky Way star system only; this difference of ideas came to a climax with the organization of the Great Debate on 26 April 1920 at the meeting of the U. S. National Academy of Sciences in Washington, D. C; the debate was resolved when Edwin Hubble detected Cepheid Variables in the Andromeda galaxy in 1923 and 1924. Their distance established spiral nebulae well beyond the edge of the Milky Way. S
General relativity is the geometric theory of gravitation published by Albert Einstein in 1915 and the current description of gravitation in modern physics. General relativity generalizes special relativity and Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time, or spacetime. In particular, the curvature of spacetime is directly related to the energy and momentum of whatever matter and radiation are present; the relation is specified by the Einstein field equations, a system of partial differential equations. Some predictions of general relativity differ from those of classical physics concerning the passage of time, the geometry of space, the motion of bodies in free fall, the propagation of light. Examples of such differences include gravitational time dilation, gravitational lensing, the gravitational redshift of light, the gravitational time delay; the predictions of general relativity in relation to classical physics have been confirmed in all observations and experiments to date.
Although general relativity is not the only relativistic theory of gravity, it is the simplest theory, consistent with experimental data. However, unanswered questions remain, the most fundamental being how general relativity can be reconciled with the laws of quantum physics to produce a complete and self-consistent theory of quantum gravity. Einstein's theory has important astrophysical implications. For example, it implies the existence of black holes—regions of space in which space and time are distorted in such a way that nothing, not light, can escape—as an end-state for massive stars. There is ample evidence that the intense radiation emitted by certain kinds of astronomical objects is due to black holes; the bending of light by gravity can lead to the phenomenon of gravitational lensing, in which multiple images of the same distant astronomical object are visible in the sky. General relativity predicts the existence of gravitational waves, which have since been observed directly by the physics collaboration LIGO.
In addition, general relativity is the basis of current cosmological models of a expanding universe. Acknowledged as a theory of extraordinary beauty, general relativity has been described as the most beautiful of all existing physical theories. Soon after publishing the special theory of relativity in 1905, Einstein started thinking about how to incorporate gravity into his new relativistic framework. In 1907, beginning with a simple thought experiment involving an observer in free fall, he embarked on what would be an eight-year search for a relativistic theory of gravity. After numerous detours and false starts, his work culminated in the presentation to the Prussian Academy of Science in November 1915 of what are now known as the Einstein field equations; these equations specify how the geometry of space and time is influenced by whatever matter and radiation are present, form the core of Einstein's general theory of relativity. The Einstein field equations are nonlinear and difficult to solve.
Einstein used approximation methods in working out initial predictions of the theory. But as early as 1916, the astrophysicist Karl Schwarzschild found the first non-trivial exact solution to the Einstein field equations, the Schwarzschild metric; this solution laid the groundwork for the description of the final stages of gravitational collapse, the objects known today as black holes. In the same year, the first steps towards generalizing Schwarzschild's solution to electrically charged objects were taken, which resulted in the Reissner–Nordström solution, now associated with electrically charged black holes. In 1917, Einstein applied his theory to the universe as a whole, initiating the field of relativistic cosmology. In line with contemporary thinking, he assumed a static universe, adding a new parameter to his original field equations—the cosmological constant—to match that observational presumption. By 1929, the work of Hubble and others had shown that our universe is expanding; this is described by the expanding cosmological solutions found by Friedmann in 1922, which do not require a cosmological constant.
Lemaître used these solutions to formulate the earliest version of the Big Bang models, in which our universe has evolved from an hot and dense earlier state. Einstein declared the cosmological constant the biggest blunder of his life. During that period, general relativity remained something of a curiosity among physical theories, it was superior to Newtonian gravity, being consistent with special relativity and accounting for several effects unexplained by the Newtonian theory. Einstein himself had shown in 1915 how his theory explained the anomalous perihelion advance of the planet Mercury without any arbitrary parameters. A 1919 expedition led by Eddington confirmed general relativity's prediction for the deflection of starlight by the Sun during the total solar eclipse of May 29, 1919, making Einstein famous, yet the theory entered the mainstream of theoretical physics and astrophysics only with the developments between 1960 and 1975, now known as the golden age of general relativity. Physicists began to understand the concept of a black hole, to identify quasars as one of these objects' astrophysical manifestations.
More precise solar system tests confirmed the theory's predictive power, relativistic cosmology, became amenable to direct observational tests. Over the years, general relativity has acqui
Astrophysics is the branch of astronomy that employs the principles of physics and chemistry "to ascertain the nature of the astronomical objects, rather than their positions or motions in space". Among the objects studied are the Sun, other stars, extrasolar planets, the interstellar medium and the cosmic microwave background. Emissions from these objects are examined across all parts of the electromagnetic spectrum, the properties examined include luminosity, density and chemical composition; because astrophysics is a broad subject, astrophysicists apply concepts and methods from many disciplines of physics, including mechanics, statistical mechanics, quantum mechanics, relativity and particle physics, atomic and molecular physics. In practice, modern astronomical research involves a substantial amount of work in the realms of theoretical and observational physics; some areas of study for astrophysicists include their attempts to determine the properties of dark matter, dark energy, black holes.
Topics studied by theoretical astrophysicists include Solar System formation and evolution. Astronomy is an ancient science, long separated from the study of terrestrial physics. In the Aristotelian worldview, bodies in the sky appeared to be unchanging spheres whose only motion was uniform motion in a circle, while the earthly world was the realm which underwent growth and decay and in which natural motion was in a straight line and ended when the moving object reached its goal, it was held that the celestial region was made of a fundamentally different kind of matter from that found in the terrestrial sphere. During the 17th century, natural philosophers such as Galileo and Newton began to maintain that the celestial and terrestrial regions were made of similar kinds of material and were subject to the same natural laws, their challenge was. For much of the nineteenth century, astronomical research was focused on the routine work of measuring the positions and computing the motions of astronomical objects.
A new astronomy, soon to be called astrophysics, began to emerge when William Hyde Wollaston and Joseph von Fraunhofer independently discovered that, when decomposing the light from the Sun, a multitude of dark lines were observed in the spectrum. By 1860 the physicist, Gustav Kirchhoff, the chemist, Robert Bunsen, had demonstrated that the dark lines in the solar spectrum corresponded to bright lines in the spectra of known gases, specific lines corresponding to unique chemical elements. Kirchhoff deduced that the dark lines in the solar spectrum are caused by absorption by chemical elements in the Solar atmosphere. In this way it was proved that the chemical elements found in the Sun and stars were found on Earth. Among those who extended the study of solar and stellar spectra was Norman Lockyer, who in 1868 detected bright, as well as dark, lines in solar spectra. Working with the chemist, Edward Frankland, to investigate the spectra of elements at various temperatures and pressures, he could not associate a yellow line in the solar spectrum with any known elements.
He thus claimed the line represented a new element, called helium, after the Greek Helios, the Sun personified. In 1885, Edward C. Pickering undertook an ambitious program of stellar spectral classification at Harvard College Observatory, in which a team of woman computers, notably Williamina Fleming, Antonia Maury, Annie Jump Cannon, classified the spectra recorded on photographic plates. By 1890, a catalog of over 10,000 stars had been prepared that grouped them into thirteen spectral types. Following Pickering's vision, by 1924 Cannon expanded the catalog to nine volumes and over a quarter of a million stars, developing the Harvard Classification Scheme, accepted for worldwide use in 1922. In 1895, George Ellery Hale and James E. Keeler, along with a group of ten associate editors from Europe and the United States, established The Astrophysical Journal: An International Review of Spectroscopy and Astronomical Physics, it was intended that the journal would fill the gap between journals in astronomy and physics, providing a venue for publication of articles on astronomical applications of the spectroscope.
Around 1920, following the discovery of the Hertsprung-Russell diagram still used as the basis for classifying stars and their evolution, Arthur Eddington anticipated the discovery and mechanism of nuclear fusion processes in stars, in his paper The Internal Constitution of the Stars. At that time, the source of stellar energy was a complete mystery; this was a remarkable development since at that time fusion and thermonuclear energy, that stars are composed of hydrogen, had not yet been discovered. In 1
International Astronomical Union
The International Astronomical Union is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy. Among other activities, it acts as the internationally recognized authority for assigning designations and names to celestial bodies and any surface features on them; the IAU is a member of the International Council for Science. Its main objective is to promote and safeguard the science of astronomy in all its aspects through international cooperation; the IAU maintains friendly relations with organizations that include amateur astronomers in their membership. The IAU has its head office on the second floor of the Institut d'Astrophysique de Paris in the 14th arrondissement of Paris. Working groups include the Working Group for Planetary System Nomenclature, which maintains the astronomical naming conventions and planetary nomenclature for planetary bodies, the Working Group on Star Names, which catalogs and standardizes proper names for stars.
The IAU is responsible for the system of astronomical telegrams which are produced and distributed on its behalf by the Central Bureau for Astronomical Telegrams. The Minor Planet Center operates under the IAU, is a "clearinghouse" for all non-planetary or non-moon bodies in the Solar System; the Working Group for Meteor Shower Nomenclature and the Meteor Data Center coordinate the nomenclature of meteor showers. The IAU was founded on 28 July 1919, at the Constitutive Assembly of the International Research Council held in Brussels, Belgium. Two subsidiaries of the IAU were created at this assembly: the International Time Commission seated at the International Time Bureau in Paris and the International Central Bureau of Astronomical Telegrams seated in Copenhagen, Denmark; the 7 initial member states were Belgium, France, Great Britain, Greece and the United States, soon to be followed by Italy and Mexico. The first executive committee consisted of Benjamin Baillaud, Alfred Fowler, four vice presidents: William Campbell, Frank Dyson, Georges Lecointe, Annibale Riccò.
Thirty-two Commissions were appointed at the Brussels meeting and focused on topics ranging from relativity to minor planets. The reports of these 32 Commissions formed the main substance of the first General Assembly, which took place in Rome, Italy, 2–10 May 1922. By the end of the first General Assembly, ten additional nations had joined the Union, bringing the total membership to 19 countries. Although the Union was formed eight months after the end of World War I, international collaboration in astronomy had been strong in the pre-war era; the first 50 years of the Union's history are well documented. Subsequent history is recorded in the form of reminiscences of past IAU Presidents and General Secretaries. Twelve of the fourteen past General Secretaries in the period 1964-2006 contributed their recollections of the Union's history in IAU Information Bulletin No. 100. Six past IAU Presidents in the period 1976–2003 contributed their recollections in IAU Information Bulletin No. 104. The IAU includes a total of 12,664 individual members who are professional astronomers from 96 countries worldwide.
83% of all individual members are male, while 17% are female, among them the union's former president, Mexican astronomer Silvia Torres-Peimbert. Membership includes 79 national members, professional astronomical communities representing their country's affiliation with the IAU. National members include the Australian Academy of Science, the Chinese Astronomical Society, the French Academy of Sciences, the Indian National Science Academy, the National Academies, the National Research Foundation of South Africa, the National Scientific and Technical Research Council, KACST, the Council of German Observatories, the Royal Astronomical Society, the Royal Astronomical Society of New Zealand, the Royal Swedish Academy of Sciences, the Russian Academy of Sciences, the Science Council of Japan, among many others; the sovereign body of the IAU is its General Assembly. The Assembly determines IAU policy, approves the Statutes and By-Laws of the Union and elects various committees; the right to vote on matters brought before the Assembly varies according to the type of business under discussion.
The Statutes consider such business to be divided into two categories: issues of a "primarily scientific nature", upon which voting is restricted to individual members, all other matters, upon which voting is restricted to the representatives of national members. On budget matters, votes are weighted according to the relative subscription levels of the national members. A second category vote requires a turnout of at least two-thirds of national members in order to be valid. An absolute majority is sufficient for approval in any vote, except for Statute revision which requires a two-thirds majority. An equality of votes is resolved by the vote of the President of the Union. Since 1922, the IAU General Assembly meets every three years, with the ex
Jean Zay was a French politician and freemason. He served as Minister of National Education and Fine Arts from 1936 until 1939, he was imprisoned by the Vichy government from August 1940 until he was murdered in 1944. Zay was born in the départment of Loiret, about 130 kilometres south of Paris, his father, Leon Zay, descended from a Jewish family from Metz, but was born and died in Orléans, where he was the director of a radical socialist regional newspaper, Le Progrès du Loiret. His mother Alice Chartres was a teacher. Zay was educated at the Lycée Pothier in Orléans, became a lawyer in 1928, he was politically active from his early days, joining the Radical Party aged 21. With his wife, he had two daughters, Catherine Martin-Zay, Hélène Mouchard-Zay. In May 1932 he was elected to the French parliament as député to represent Loiret, for the Radical Socialist Party, he defeated the incumbent representative of Maurice Berger. He became one of the Jeunes Turcs who wanted to renew the Radical Party, was instrumental in the party joining the Popular Front in 1935.
After the 1936 election, he was the Minister of National Education and Fine Arts from June 1936. While serving in his position, he extended the school leaving age and introduced a common curriculum in elementary schools. In 1938, Jean Zay proposed the creation of an international film event in France, planned to debut in Cannes in 1939. Due to the outbreak of the Second World War, the inauguration of the Cannes Film Festival was postponed until 1946, he resigned as minister in 1939 to join the French Army on the outbreak of the Second World War, serving as a second lieutenant attached to the headquarters of the Fourth Army. He remained a député until 1942, he was given leave to attend the last session of the French Parliament, held in Bordeaux in June 1940. After the invasion of France by Nazi Germany in 1940, he was one of the passengers aboard the vessel Le Massilia that left from Bordeaux bound for Casablanca on 21 June 1940, with the intention of forming a resistance government in North Africa.
He was arrested in August 1940, for desertion, returned to France where he was held at the military prison in Clermont-Ferrand. A press campaign, organised by Philippe Henriot, the minister of information in the Vichy government, called for his execution for being "jewish and member of the Radical Party", pointing to his anti-war poem of March 1924, Le Drapeau, as evidence of his lack of patriotism, he was convicted of desertion by a military tribunal in October 1940, sentenced to loss of military rank and deportation for life. Held in Marseille, his sentence was commuted to one of internment in France, he was held in the prison in Riom, sharing a cell with Rabbi Edward Gourévitch, he was allowed to communicate with friends and family, did not attempt to escape. He was removed from the prison by three miliciens on 20 June 1944, Henri Millou, Charles Develle and Pierre Cordier, purportedly so he could be transferred to Melun, they murdered him in a wood near an abandoned quarry, at a place called Les Malavaux in the faille du Puits du diable, at Molles in Allier.
Zay's conviction was posthumously annulled by the appeal court in Riom in July 1945. His body was found with those of two others under a pile of stones; the three were reburied together in Cusset, but Zay's body was exhumed in 1947 and identified through his dental records. The surviving milicien Charles Develle was convicted of Zay's murder in February 1953, sentenced to forced labour for life, but released in 1955. Zay was buried in Orléans in 1948. A memorial was erected near the site of his death in Molles, a plaque at his high school in Orléans. A French literary prize, the Prix Jean-Zay, was created and named in his honour in 2005. In March 2014 French President François Hollande announced his intention to recognize Jean Zay at the Pantheon in Paris as a leading figure in the Resistance, along with Pierre Brossolette, Germaine Tillion, Geneviève de Gaulle-Anthonioz.. The official ceremony was held on May 27, 2015, National Day of Resistance
France the French Republic, is a country whose territory consists of metropolitan France in Western Europe and several overseas regions and territories. The metropolitan area of France extends from the Mediterranean Sea to the English Channel and the North Sea, from the Rhine to the Atlantic Ocean, it is bordered by Belgium and Germany to the northeast and Italy to the east, Andorra and Spain to the south. The overseas territories include French Guiana in South America and several islands in the Atlantic and Indian oceans; the country's 18 integral regions span a combined area of 643,801 square kilometres and a total population of 67.3 million. France, a sovereign state, is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre. Other major urban areas include Lyon, Toulouse, Bordeaux and Nice. During the Iron Age, what is now metropolitan France was inhabited by a Celtic people. Rome annexed the area in 51 BC, holding it until the arrival of Germanic Franks in 476, who formed the Kingdom of Francia.
The Treaty of Verdun of 843 partitioned Francia into Middle Francia and West Francia. West Francia which became the Kingdom of France in 987 emerged as a major European power in the Late Middle Ages following its victory in the Hundred Years' War. During the Renaissance, French culture flourished and a global colonial empire was established, which by the 20th century would become the second largest in the world; the 16th century was dominated by religious civil wars between Protestants. France became Europe's dominant cultural and military power in the 17th century under Louis XIV. In the late 18th century, the French Revolution overthrew the absolute monarchy, established one of modern history's earliest republics, saw the drafting of the Declaration of the Rights of Man and of the Citizen, which expresses the nation's ideals to this day. In the 19th century, Napoleon established the First French Empire, his subsequent Napoleonic Wars shaped the course of continental Europe. Following the collapse of the Empire, France endured a tumultuous succession of governments culminating with the establishment of the French Third Republic in 1870.
France was a major participant in World War I, from which it emerged victorious, was one of the Allies in World War II, but came under occupation by the Axis powers in 1940. Following liberation in 1944, a Fourth Republic was established and dissolved in the course of the Algerian War; the Fifth Republic, led by Charles de Gaulle, remains today. Algeria and nearly all the other colonies became independent in the 1960s and retained close economic and military connections with France. France has long been a global centre of art and philosophy, it hosts the world's fourth-largest number of UNESCO World Heritage Sites and is the leading tourist destination, receiving around 83 million foreign visitors annually. France is a developed country with the world's sixth-largest economy by nominal GDP, tenth-largest by purchasing power parity. In terms of aggregate household wealth, it ranks fourth in the world. France performs well in international rankings of education, health care, life expectancy, human development.
France is considered a great power in global affairs, being one of the five permanent members of the United Nations Security Council with the power to veto and an official nuclear-weapon state. It is a leading member state of the European Union and the Eurozone, a member of the Group of 7, North Atlantic Treaty Organization, Organisation for Economic Co-operation and Development, the World Trade Organization, La Francophonie. Applied to the whole Frankish Empire, the name "France" comes from the Latin "Francia", or "country of the Franks". Modern France is still named today "Francia" in Italian and Spanish, "Frankreich" in German and "Frankrijk" in Dutch, all of which have more or less the same historical meaning. There are various theories as to the origin of the name Frank. Following the precedents of Edward Gibbon and Jacob Grimm, the name of the Franks has been linked with the word frank in English, it has been suggested that the meaning of "free" was adopted because, after the conquest of Gaul, only Franks were free of taxation.
Another theory is that it is derived from the Proto-Germanic word frankon, which translates as javelin or lance as the throwing axe of the Franks was known as a francisca. However, it has been determined that these weapons were named because of their use by the Franks, not the other way around; the oldest traces of human life in what is now France date from 1.8 million years ago. Over the ensuing millennia, Humans were confronted by a harsh and variable climate, marked by several glacial eras. Early hominids led a nomadic hunter-gatherer life. France has a large number of decorated caves from the upper Palaeolithic era, including one of the most famous and best preserved, Lascaux. At the end of the last glacial period, the climate became milder. After strong demographic and agricultural development between the 4th and 3rd millennia, metallurgy appeared at the end of the 3rd millennium working gold and bronze, iron. France has numerous megalithic sites from the Neolithic period, including the exceptiona
Jean-Claude Pecker is a French astronomer and author, member of the Académie des Sciences and former director of the Nice Observatory. He served as the secretary-general of the International Astronomical Union from 1964 to 1967. Pecker was the President of the Société astronomique de France, the French amateur astronomical society, from 1973-1976, he was awarded the Prix Jules Janssen by the French Astronomical Society in 1967. A minor planet is named after him. Pecker is a vocal opponent of astrology and pseudo-science and was the president of the Association française pour l'information scientifique, a skeptical organisation which promotes scientific enquiry in the face of quackery and obscurantism. Jean-Claude Pecker was born 10 May 1923, in Reims, to Victor-Noel Pecker and Nelly Catherine née Hermann, in the department of Marne, France; the grandson of Joseph Hermann, rabbi of Valenciennes and Reims, Pecker was born in his maternal grandparents' house, moving to Bordeaux. In the summer of 1941 they moved to the Hermann house in Paris because of anti-jewish restrictions placed on his parents during the Vichy regime.
In May 1944 both his parents were transported to Auschwitz where they died, while his grandmother, absent during the raid, was hidden by neighbour Ida Barrett, designated by the state of Israel as one of the Righteous Among the Nations for her actions to conceal the old lady until the liberation of Paris. Pecker was interested in astronomy from a young age, he studied at the Lycée Michel de Montaigne de Bordeaux but was forced to go into hiding during the second world war. After the Liberation of France he attended the École Normale Supérieure in Paris. In October 1946 he joined the Institut d'astrophysique de Paris and studied for the agrégation of physics and chemistry, where he studied under, had his doctoral thesis judged by Nobel Prize winning physicist Alfred Kastler, he earned his doctorate in May 1950. At the Institut d’Astrophysique he got to know and shared an office with Évry Schatzman with whom he collaborated for many years. From 1952 to 1955 Pecker was associate professor of astronomy and astrophysics at the University of Clermont-Ferrand.
From early in his career he held many international appointments including fellow of the High Altitude Observatory in Colorado, USA. In 1955 he became astronomer for the Paris Observatory followed by director of the Nice Observatory in 1961. In 1963 Pecker became professor of theoretical astrophysics at the Collège de France in Paris, a position he held until 1988 when he became honorary professor, he was director of the French National Centre for Scientific Research Institute of Astrophysics from 1972-1978. His main fields of work within astrophysics have been solar and stellar atmospheres and sun-earth interactions, he is known for questioning the standard big bang theory, positing "alternative but partial solutions" and was signatory, with 33 other scientists, to an open letter to the scientific community expressing concern over the dominance of the big bang and expansion of the Universe theories. They complained that the tired light theory in particular was discounted or ignored by most cosmologists at the time of writing.
1952-1955 Professor at the Faculty of Science, University of Clermont-Ferrand 1955-1962 Astronomer of the Paris Observatory 1962-1969 Director of the Nice Observatory 1963-1988 Professor of theoretical astrophysics at the Collège de France and honorary professor thereafter 1964-1967 General secretary of the Société astronomique de France and President thereafter until 1976 1972-1979 Director of the French National Centre for Scientific Research Institute of Astrophysics 1978 President of the French association for the advancement of science 1983-1985 President of the Comité d'Orientation du Musée de la Villette 1986-1988 President of the Comité National de culture scientifique et technique 1988 Vice-chair of the Scientific committee of the Musées de France 1989-1992 Vice-President of the Academia Europaea 1990-1996 Vice-President of the French UNESCO committee and thereafter permanent representative to UNESCO of the International Humanist and Ethical Union 1999-2001 President of the Association française pour l'information scientifiqueIn the 1950s Pecker spent a year as associate fellow of the High Altitude Observatory at Boulder, Colorado.
Pecker is associate member of the Royal Society of Science, associate of the Royal Astronomical Society, member of the National Academy of Bordeaux, the Royal Academies for Science and the Arts of Belgium, the European Academy of Sciences and Arts and honorary associate of Rationalist International, member of the Academia Europaea and sits on the international advisory board of the Institute for Science and Human Values. Pecker is a member of the International Astronomical Union. Pecker has written and co-written many books and over 700 academic papers on subjects such as cosmology, astrophysics, human rights, pseudo-science and art, he has presented paintings at exhibitions in France. He writes popular science articles and books for the general public, some of which have been translated into other languages, his books include: The Sky Astrophysique Générale The Orion Book of the Sky Contribution to the spectral type theory: iv Formation of lines in stellar spectra Experimental Astronomy Space Observatories Papa, dis-moi, qu'est-ce que c'est que l'Astronomie Stellar Paths: Photographic Astrometry with Long-Focus Instruments Clefs pour l'