"Einstein–de Sitter universe The Einstein–de Sitter universe is a model of the universe proposed by Albert Einstein and Willem de Sitter in 1932. On first learning of Edwin Hubble's discovery of a linear relation between the redshift of the galaxies and their distance, Einstein set the cosmological constant to zero in the Friedmann equations, resulting in a model of the expanding universe known as the Friedmann–Einstein universe. In 1932, Einstein and de Sitter proposed an even simpler cosmic model by assuming a vanishing spatial curvature as well as a vanishing cosmological constant. In modern parlance, the Einstein–de Sitter universe can"
"Georges Lemaître Georges Henri Joseph Édouard Lemaître, RAS Associate (; 17 July 1894 – 20 June 1966) was a Belgian Roman Catholic priest, astronomer, and professor of physics at the Catholic University of Leuven. He proposed on theoretical grounds that the universe is expanding, which was observationally confirmed soon afterwards by Edwin Hubble. He was the first to derive what is now known as Hubble's law, or the Hubble-Lemaître law, and made the first estimation of what is now called the Hubble constant, which he published in 1927, two years before Hubble's article. Lemaître also proposed what became known as"
"The mathematician and physicist Alexander Friedmann pioneered the theory that universe was expanding governed by a set of equations he developed now known as the Friedmann equations. Arno Allan Penzias, the physicist and radio astronomer co-discoverer of the cosmic microwave background radiation, which helped establish the Big Bang theory, the scientists Robert Herman and Ralph Alpher had also worked on that field. In quantum mechanics Jewish role was significant as well and many of most influential figures and pioneers of the theory were Jewish: Niels Bohr and his work on the atom structure, Max Born (Schrödinger equation), Wolfgang Pauli, Richard"
"majority of cosmologists, astrophysicists and astronomers, as the observational evidence points to a hot Big Bang cosmology with a finite age of the universe, which the steady state model does not predict. In the 13th century, Siger of Brabant authored the thesis ""The Eternity of the World"", which argued that there was no first man, and no first specimen of any particular: the physical universe is thus without any first beginning, and therefore eternal. Siger's views were condemned by the Pope in 1277. Cosmological expansion was originally discovered through observations by Edwin Hubble. Theoretical calculations also showed that the static"
"David Layzer David Raymond Layzer (born December 31, 1925) is an American astrophysicist, cosmologist, and the Donald H. Menzel Professor Emeritus of Astronomy at Harvard University. He is known for his cosmological theory of the expansion of the universe, which postulates that its order and information are increasing despite the second law of thermodynamics. He is also known for being one of the most notable researchers who advocated for a Cold Big Bang theory. When he proposed this theory in 1966, he suggested it would solve Olbers' paradox, which holds that the night sky on Earth should be much brighter"
"Alexander Friedmann Alexander Alexandrovich Friedmann (also spelled Friedman or Fridman ; ) (June 16 [O.S. 4], 1888 – September 16, 1925) was a Russian and Soviet physicist and mathematician. He is best known for his pioneering theory that the universe was expanding, governed by a set of equations he developed now known as the Friedmann equations. Alexander Friedmann was born to the composer and ballet dancer Alexander Friedmann (who was a son of a baptized Jewish cantonist) and the pianist Ludmila Ignatievna Voyachek. Friedmann was baptized into the Russian Orthodox Church as an infant, and lived much of his life"
"in the universe expanding or contracting. In 1929, Edwin Hubble found evidence for the idea that the universe is expanding. This resulted in Einstein dropping the cosmological constant, referring to it as ""the biggest blunder in my career"". At the time, it was an ad hoc hypothesis to add in the cosmological constant, as it was only intended to justify one result (a static universe). Progress in solving the field equations and understanding the solutions has been ongoing. The solution for a spherically symmetric charged object was discovered by Reissner and later rediscovered by Nordström, and is called the Reissner–Nordström"
"the meeting is to promote contacts between scientists working in the field of Relativity, Gravitation and Cosmology and related fields. The First Alexander Friedmann International Seminar on Gravitation and Cosmology devoted to the centenary of his birth took place in 1988. Alexander Friedmann Alexander Alexandrovich Friedmann (also spelled Friedman or Fridman ; ) (June 16 [O.S. 4], 1888 – September 16, 1925) was a Russian and Soviet physicist and mathematician. He is best known for his pioneering theory that the universe was expanding, governed by a set of equations he developed now known as the Friedmann equations. Alexander Friedmann was"
"Einstein brushed him off with """" (“Your math is correct, but your physics is abominable”). In 1929, Edwin Hubble (1889–1953) announced his discovery of the expanding universe. The current generally accepted cosmological model, the Lambda-CDM model, has a positive cosmological constant and thus not only an expanding universe but an accelerating expanding universe. If the universe were expanding, then it must have been much smaller and therefore hotter and denser in the past. George Gamow (1904–1968) hypothesized that the abundance of the elements in the Periodic Table of the Elements, might be accounted for by nuclear reactions in a hot"
"stars throughout endless space."" ""By grafting endless space onto the Copernican system and scattering the stars throughout this endless space, Digges pioneered... the idea of an unlimited universe filled with the mingling rays of countless stars."" An illustration of the Copernican universe can be seen at right. The outer inscription on the map reads: Thomas Digges Thomas Digges (; c. 1546 – 24 August 1595) was an English mathematician and astronomer. He was the first to expound the Copernican system in English but discarded the notion of a fixed shell of immoveable stars to postulate infinitely many stars at varying"
"fact, and indeed at the time it was highly controversial whether or not these nebulae were ""island universes"" outside our Milky Way. Ten years later, Alexander Friedmann, a Russian cosmologist and mathematician, derived the Friedmann equations from Albert Einstein's equations of general relativity, showing that the universe might be expanding in contrast to the static universe model advocated by Einstein at that time. In 1924 Edwin Hubble's measurement of the great distance to the nearest spiral nebulae showed that these systems were indeed other galaxies. Independently deriving Friedmann's equations in 1927, Georges Lemaître, a Belgian physicist, proposed that the inferred"
"nebulae well beyond the edge of the Milky Way. Subsequent modelling of the universe explored the possibility that the cosmological constant, introduced by Einstein in his 1917 paper, may result in an expanding universe, depending on its value. Thus the Big Bang model was proposed by the Belgian priest Georges Lemaître in 1927 which was subsequently corroborated by Edwin Hubble's discovery of the red shift in 1929 and later by the discovery of the cosmic microwave background radiation by Arno Penzias and Robert Woodrow Wilson in 1964. These findings were a first step to rule out some of many alternative"
"Edward Robert Harrison Edward R. ""Ted"" Harrison (8 January 1919 – 29 January 2007) was a British astronomer and cosmologist, noted for his work about the increase of fluctuations in the expanding universe, for his explanation of Olbers' Paradox, and for his books on cosmology for lay readers. He spent much of his career at the University of Massachusetts, Amherst and University of Arizona, USA. Harrison's education at Sir John Cass Technical Institute was interrupted by World War II, during which he served for six years with the British Army in various military campaigns, eventually serving as Radar Adviser to"
"Giordano Bruno Giordano Bruno (; ; ; born Filippo Bruno, 1548 – 17 February 1600) was an Italian Dominican friar, philosopher, mathematician, poet, and cosmological theorist. He is known for his cosmological theories, which conceptually extended the then-novel Copernican model. He proposed that the stars were distant suns surrounded by their own planets, and he raised the possibility that these planets might foster life of their own, a philosophical position known as cosmic pluralism. He also insisted that the universe is infinite and could have no ""center"". Starting in 1593, Bruno was tried for heresy by the Roman Inquisition on"
"of the world's most highly cited scientists. Idit Zehavi Idit Zehavi () (born 1969) is an Israeli astrophysicist and researcher who discovered an anomaly in the mapping of the cosmos, which offered insight into how the universe is expanding. She is part of the team completing the Sloan Digital Sky Survey and is one of the world's most highly cited scientists according to the list published annually by Thomson Reuters. Idit Zehavi was born in Israel in 1969 and completed her education in Jerusalem, earning a PhD from the Racah Institute of Physics at the Hebrew University of Jerusalem in"
"The first published proposal that the universe is infinite came from Thomas Digges in 1576. Eight years later, in 1584, the Italian philosopher and astronomer Giordano Bruno proposed an unbounded universe in ""On the Infinite Universe and Worlds"": ""Innumerable suns exist; innumerable earths revolve around these suns in a manner similar to the way the seven planets revolve around our sun. Living beings inhabit these worlds."" Cosmologists have long sought to discover whether infinity exists in our physical universe: Are there an infinite number of stars? Does the universe have infinite volume? Does space ""go on forever""? This is an"
"Arthur Eddington. From the early 1930s, Milne's interests focused increasingly on relativity theory and cosmology. From 1932 he worked on the problem of the ""expanding universe"" and in ""Relativity, Gravitation, and World-Structure"" (1935), proposed an alternative to Albert Einstein's general relativity theory. With McCrea (1934) he also showed that the 3 models which form the foundations of modern cosmology first proposed by Friedmann (1922) using the general theory of relativity, can also be derived using only Newtonian mechanics. The main difference between the Milne model of an expanding universe, and the current (Einstein's) model of an expanding universe was that"
"astronomers. The Big Bang itself had been proposed in 1931, long before this period, by Georges Lemaître, a Belgian physicist, who suggested that the evident expansion of the Universe in time required that the Universe, if contracted backwards in time, would continue to do so until it could contract no further. This would bring all the mass of the Universe to a single point, a ""primeval atom"", to a state before which time and space did not exist. Hoyle later gave Lemaître's model the derisive term of Big Bang, not realizing that Lemaître's model was needed to explain the existence"
"a huge number of external galaxies beyond our own Milky Way; then, work by Vesto Slipher and others showed that the universe is expanding. These advances made it possible to speculate about the origin of the universe, and allowed the establishment of the Big Bang Theory, by Georges Lemaître, as the leading cosmological model. A few researchers still advocate a handful of alternative cosmologies; however, most cosmologists agree that the Big Bang theory explains the observations better. Dramatic advances in observational cosmology since the 1990s, including the cosmic microwave background, distant supernovae and galaxy redshift surveys, have led to the"
"Friedmann–Einstein universe The Friedmann–Einstein universe is a model of the universe published by Albert Einstein in 1931. The model is of historic significance as the first scientific publication in which Einstein embraced the possibility of a cosmos of time-varying radius. Interpreting Edwin Hubble's discovery of a linear relation between the redshifts of the galaxies and their radial distance as evidence for an expanding universe, Einstein abandoned his earlier static model of the universe and embraced the dynamic cosmology of Alexander Friedmann. Removing the cosmological constant term from the Friedmann equations on the grounds that it was both unsatisfactory and unnecessary,"
"is uniformly expanding everywhere. This universal expansion was predicted from general relativity by Alexander Friedmann in 1922 and Georges Lemaître in 1927, well before Hubble made his 1929 analysis and observations, and it remains the cornerstone of the Big Bang theory as developed by Friedmann, Lemaître, Robertson, and Walker. The theory requires the relation formula_9 to hold at all times, where formula_7 is the comoving distance, ""v"" is the recessional velocity, and formula_6, formula_12, and formula_7 vary as the universe expands (hence we write formula_8 to denote the present-day Hubble ""constant""). For distances much smaller than the size of the"
"Lemaitre was the first scientist to propose the expansion of the universe was actually accelerating which was confirmed observationally in the 1990s through observations of very distant Type IA supernova with the Hubble Space Telescope which led to the 2011 Nobel Prize in Physics. In 1948 Lemaître published a polished mathematical essay ""Quaternions et espace elliptique"" which clarified an obscure space. William Kingdon Clifford had cryptically described elliptic space in 1873 at a time when versors were too common to mention. Lemaître developed the theory of quaternions from first principles so that his essay can stand on its own, but"
"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, however, the work of Hubble and others had shown that our universe is expanding. This is readily 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"
"of the Big Bang theory, the book tells the personal stories of the people who played a part in advancing it, both by hypothesis and by experiment. These include Einstein, for his General Relativity, Friedmann for first discovering that this theory led to an expanding universe, Lemaître who concluded independently of Friedman discovered an expanding universe, and then that the theory must lead to an initial event of creation, which is the Big Bang theory we know today, Hubble for observing that the universe expanded, thereby confirming Friedman and Lemaître, Gamow, Alpher, Herman, Ryle, Penzias and Wilson, among many others."
"than it actually is. He also published several articles critiquing hereditarian views on human intelligence, such as those of Richard Herrnstein and Arthur Jensen. He has been a member of the American Academy of Arts and Sciences since 1963, and is also a member of Divisions B and J of the International Astronomical Union. David Layzer David Raymond Layzer (born December 31, 1925) is an American astrophysicist, cosmologist, and the Donald H. Menzel Professor Emeritus of Astronomy at Harvard University. He is known for his cosmological theory of the expansion of the universe, which postulates that its order and information"
"in Saint Petersburg. Friedmann obtained his degree from St. Petersburg State University in 1910, and became a lecturer at Saint Petersburg Mining Institute. From his school days, Friedmann found an inseparable companion in Jacob Tamarkin, who at the end of his career was one of Brown University's most distinguished mathematicians. Friedmann fought in World War I on behalf of Imperial Russia, as an army aviator, an instructor and eventually, under the revolutionary regime, as the head of an airplane factory. Friedmann in 1922 introduced the idea of an expanding universe that contained moving matter; Belgian astronomer Georges Lemaître would later"
"luminosity of galaxies due to galaxy evolution. Earlier, in 1917, Albert Einstein had found that his newly developed theory of general relativity indicated that the universe must be either expanding or contracting. Unable to believe what his own equations were telling him, Einstein introduced a cosmological constant (a """") to the equations to avoid this ""problem"". When Einstein learned of Hubble's redshifts, he immediately realized that the expansion predicted by general relativity must be real, and in later life he said that changing his equations was ""the biggest blunder of [his] life."" In fact, Einstein apparently once visited Hubble and"
"and Arthur Eddington to explore its astronomical ramifications, which enhanced the ability of astronomers to study very distant objects. Physicists began changing the assumption that the Universe was static and unchanging. In 1922 Alexander Friedmann introduced the idea of an expanding universe that contained moving matter. Around the same time (1917 to 1922) 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"
"showing that the universe might expand, and presenting the expansion speed if this was the case. Then Georges Lemaître, in a 1927 article, proposed the expansion of the universe and suggested an estimated value of the rate of expansion, which when corrected by Hubble became known as the Hubble constant. However, though the Hubble constant formula_1 is roughly constant in the velocity-distance space at this moment in time, the Hubble parameter formula_2, which the Hubble constant is the current value of, changes with time, so the term 'constant' is sometimes thought of as somewhat of a misnomer. Moreover, two years"
"In 1915 Albert Einstein published the theory of general relativity and in 1917 constructed the first cosmological model based on his theory. In order to remain consistent with a steady state universe, Einstein added what was later called a cosmological constant to his equations. However, already in 1922, also using Einstein's theory, Alexander Friedmann, and independently five years later Georges Lemaître, showed that the universe cannot be static and must be either expanding or contracting. Einstein's model of a static universe was in addition proved unstable by Arthur Eddington. The first direct observational hint that the universe has a finite"
"universe. His final book, ""Masks of the Universe"" (2nd ed., 2003), questions current perceptions of reality, asking whether present cosmology, with ordinary matter, dark matter, plus dark energy, is yet only another ""mask"" obscuring a Universe which will remain perforce forever unknown to humans. Edward Robert Harrison Edward R. ""Ted"" Harrison (8 January 1919 – 29 January 2007) was a British astronomer and cosmologist, noted for his work about the increase of fluctuations in the expanding universe, for his explanation of Olbers' Paradox, and for his books on cosmology for lay readers. He spent much of his career at the"
"represented the entire Universe or was merely one of numerous galaxies in the Universe. In 1929, Hubble and Milton L. Humason formulated what is now known as Hubble's Law by combining Cepheid distances to several galaxies with Vesto Slipher's measurements of the speed at which those galaxies recede from us. They discovered that the Universe is expanding (see the expansion of the Universe). However, the expansion of the Universe was posited several years before by Georges Lemaître. In the mid 20th century, significant problems with the astronomical distance scale were resolved by dividing the Cepheids into different classes with very"
"by Europeans in 1568 called mercator projection that could make a cylindrical map flat by copying projections of constellations onto a transparent globe. Chinese astronomical theories further developed as early as the 4th century. Chinese philosopher Ge Hong (Ko Hung, 283-342), who compiled doctrines from various schools of thought, theorized of a universe that is infinite “having no bounds.” The most sophisticated xuan ye theory was adopted by the neo-Confucian orthodoxy, and widely accepted by Chinese astronomers long before re-opened communications by Europe with a new corridor into China in 1514. Bala then writes how these Chinese astronomical theories along"