Georges Henri Joseph Édouard Lemaître, RAS Associate (French: [ʒɔʁʒᵊ ləmɛ:tʁᵊ] (listen); 17 July 1894 – 20 June 1966) was a Belgian Roman Catholic priest, mathematician, astronomer, and professor of physics at the Catholic University of Louvain. He was the first to identify that the recession of nearby galaxies can be explained by a theory of an expanding universe, 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 "Big Bang theory" of the creation of the universe, originally calling it the "hypothesis of the primeval atom".
Portrait of Lemaître
|Born||17 July 1894|
|Died||20 June 1966 (aged 71)|
|Alma mater||Catholic University of Louvain|
St Edmund's House, Cambridge
Massachusetts Institute of Technology
|Known for||Theory of the expansion of the universe|
Big Bang theory
|Awards||Francqui Prize (1934)|
Eddington Medal (1953)
|Institutions||Catholic University of Leuven|
|Doctoral advisor||Charles Jean de la Vallée-Poussin (Leuven)|
Arthur Eddington (Cambridge)
Harlow Shapley (MIT)
|Doctoral students||Louis Philippe Bouckaert, Rene van der Borght|
After a classical education at a Jesuit secondary school, the Collège du Sacré-Coeur, in Charleroi, Lemaître began studying civil engineering at the Catholic University of Louvain at the age of 17. In 1914, he interrupted his studies to serve as an artillery officer in the Belgian army for the duration of World War I. At the end of hostilities, he received the Belgian War Cross with palms.
After the war, he studied physics and mathematics, and began to prepare for the diocesan priesthood, not for the Jesuits. He obtained his doctorate in 1920 with a thesis entitled l'Approximation des fonctions de plusieurs variables réelles (Approximation of functions of several real variables), written under the direction of Charles de la Vallée-Poussin. He was ordained a priest on 22 September 1923 by the Cardinal Mercier.
In 1923, he became a research associate in astronomy at Cambridge UK, spending a year at St Edmund's House (now St Edmund's College, University of Cambridge). He worked with Arthur Eddington, who introduced him to modern cosmology, stellar astronomy, and numerical analysis. He spent the next year at Harvard College Observatory in Cambridge, Massachusetts, with Harlow Shapley, who had just gained renown for his work on nebulae, and at the Massachusetts Institute of Technology (MIT), where he registered for the doctoral program in sciences.
On his return to Belgium in 1925, he became a part-time lecturer at the Catholic University of Louvain. He began the report which brought him international fame when it was published in 1927 in the Annales de la Société Scientifique de Bruxelles (Annals of the Scientific Society of Brussels) under the title "Un Univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extragalactiques" ("A homogeneous Universe of constant mass and growing radius accounting for the radial velocity of extragalactic nebulae"). In this report, he presented his new idea that the universe is expanding, which he derived from General Relativity; this later became known as Hubble's law, even though Lemaître was the first to provide an observational estimate of the Hubble constant. The initial state he proposed was taken to be Einstein's own model of a finitely sized static universe. The paper had little impact because the journal in which it was published was not widely read by astronomers outside Belgium; Arthur Eddington reportedly helped translate the article into English in 1931, but the part of it pertaining to the estimation of the "Hubble constant" was not included in the translation for reasons that remained unknown for a long time. This issue was clarified in 2011 by Mario Livio; Lemaître omitted the paragraphs written by himself upon initially translating the paper for the Royal Astronomical Society, in favour of reports of new work on the subject, since by that time Hubble's calculations had already improved on his earlier ones.
At this time, Einstein, while not taking exception to the mathematics of Lemaître's theory, refused to accept that the universe was expanding; Lemaître recalled his commenting "Vos calculs sont corrects, mais votre physique est abominable" ("Your calculations are correct, but your physics is atrocious"). In the same year, Lemaître returned to MIT to present his doctoral thesis on The gravitational field in a fluid sphere of uniform invariant density according to the theory of relativity. Upon obtaining his Ph.D., he was named ordinary professor at the Catholic University of Louvain.
In 1931, Arthur Eddington published in the Monthly Notices of the Royal Astronomical Society a long commentary on Lemaître's 1927 article, in which he described the latter as a "brilliant solution" to the outstanding problems of cosmology. The original paper was published in an abbreviated English translation later on in 1931, along with a sequel by Lemaître responding to Eddington's comments. Lemaître was then invited to London to participate in a meeting of the British Association on the relation between the physical universe and spirituality. There he proposed that the universe expanded from an initial point, which he called the "Primeval Atom". He developed this idea in a report published in Nature. Lemaitre's theory appeared for the first time in an article for the general reader on science and technology subjects in the December 1932 issue of Popular Science. Lemaître's theory became better known as the "Big Bang theory," a picturesque term playfully coined during a 1949 BBC radio broadcast by the astronomer Fred Hoyle, who was then still a proponent of the steady state universe and remained so until his death in 2001.
Lemaître's proposal met with skepticism from his fellow scientists. Eddington found Lemaître's notion unpleasant. Einstein thought it unjustifiable from a physical point of view, although he encouraged Lemaître to look into the possibility of models of non-isotropic expansion, so it is clear he was not altogether dismissive of the concept. Einstein also appreciated Lemaître's argument that Einstein's model of a static universe could not be sustained into the infinite past.
With Manuel Sandoval Vallarta, Lemaitre discovered that the intensity of cosmic rays varied with latitude because these charged particles are interacting with the Earth's magnetic field. In their calculations, Lemaître and Vallarta made use of MIT's differential analyzer computer developed by Vannevar Bush. They also worked on a theory of primary cosmic radiation and applied it to their investigations of the sun's magnetic field and the effects of the galaxy's rotation.
Lemaître and Einstein met on four occasions: in 1927 in Brussels, at the time of a Solvay Conference; in 1932 in Belgium, at the time of a cycle of conferences in Brussels; in California in January 1933; and in 1935 at Princeton. In 1933 at the California Institute of Technology, after Lemaître detailed his theory, Einstein stood up, applauded, and is supposed to have said, "This is the most beautiful and satisfactory explanation of creation to which I have ever listened." However, there is disagreement over the reporting of this quote in the newspapers of the time, and it may be that Einstein was not referring to the theory as a whole, but only to Lemaître's proposal that cosmic rays may be the leftover artifacts of the initial "explosion".
In 1933, when he resumed his theory of the expanding universe and published a more detailed version in the Annals of the Scientific Society of Brussels, Lemaître achieved his greatest public recognition. Newspapers around the world called him a famous Belgian scientist and described him as the leader of the new cosmological physics.
In 1941, he was elected a member of the Royal Academy of Sciences and Arts of Belgium. In 1946, he published his book on L'Hypothèse de l'Atome Primitif (The Primeval Atom Hypothesis). It was translated into Spanish in the same year and into English in 1950.
By 1951, Pope Pius XII declared that Lemaître's theory provided a scientific validation for Catholicism. However, Lemaître resented the Pope's proclamation, stating that the theory was neutral and there was neither a connection nor a contradiction between his religion and his theory. Lemaître and Daniel O'Connell, the Pope's scientific advisor, persuaded the Pope not to mention Creationism publicly, and to stop making proclamations about cosmology. While a devout Roman Catholic, he opposed mixing science with religion, although he held that the two fields were not in conflict.
During the 1950s, he gradually gave up part of his teaching workload, ending it completely when he took emeritus status in 1964. In 1962, strongly opposed to the expulsion of French speakers from the Catholic University of Louvain, he created the ACAPSUL movement together with Gérard Garitte to fight against the split.
During the Second Vatican Council of 1962–65 he was asked by Pope John XXIII to serve on the 4th session of the Pontifical Commission on Birth Control. However, since his health made it impossible for him to travel to Rome – he suffered a heart attack in December 1964 – Lemaître demurred, expressing surprise that he was chosen. He told a Dominican colleague, Père Henri de Riedmatten, that he thought it was dangerous for a mathematician to venture outside of his area of expertise. He was also named Dometisc prelate (Monsignor) in 1960 by Pope John XXIII.
At the end of his life, he was increasingly devoted to problems of numerical calculation. He was a remarkable algebraicist and arithmetical calculator. Since 1930, he had used the most powerful calculating machines of the time, the Mercedes-Euklid. In 1958 he was introduced to the University's Burroughs E 101, its first electronic computer. Lemaître maintained a strong interest in the development of computers and, even more, in the problems of language and computer programming.
Lemaître was a pioneer in applying Albert Einstein's theory of general relativity to cosmology. In a 1927 article, which preceded Edwin Hubble's landmark article by two years, Lemaître derived what became known as Hubble's law and proposed it as a generic phenomenon in relativistic cosmology. Lemaître was also the first to estimate the numerical value of the Hubble constant.
Einstein was skeptical of this paper. When Lemaître approached Einstein at the 1927 Solvay Conference, the latter pointed out that Alexander Friedmann had proposed a similar solution to Einstein's equations in 1922, implying that the radius of the universe increased over time. (Einstein had also criticized Friedmann's calculations, but withdrew his comments.) In 1931, his annus mirabilis, Lemaître published an article in Nature setting out his theory of the "primeval atom."
Friedmann was handicapped by living and working in the USSR, and died in 1925, soon after inventing the Friedmann–Lemaître–Robertson–Walker metric. Because Lemaître spent his entire career in Europe, his scientific work is not as well known in the United States as that of Hubble or Einstein, both well known in the U.S. by virtue of residing there. Nevertheless, Lemaître's theory changed the course of cosmology. This was because Lemaître:
Both Friedmann and Lemaître proposed relativistic cosmologies featuring an expanding universe. However, Lemaître was the first to propose that the expansion explains the redshift of galaxies. He further concluded that an initial "creation-like" event must have occurred. In the 1980s, Alan Guth and Andrei Linde modified this theory by adding to it a period of inflation.
Einstein at first dismissed Friedmann, and then (privately) Lemaître, out of hand, saying that not all mathematics lead to correct theories. After Hubble's discovery was published, Einstein quickly and publicly endorsed Lemaître's theory, helping both the theory and its proposer get fast recognition.
Lemaître was also an early adopter of computers for cosmological calculations. He introduced the first computer to his university (a Burroughs E 101) in 1958 and was one of the inventors of the Fast Fourier transform algorithm.
In 1931, 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 he recalled the Erlangen program in geometry while developing the metric geometry of elliptic space. H. S. M. Coxeter, another contributor to elliptic geometry, summarized Lemaître's work for Mathematical Reviews.
Lemaître was the first theoretical cosmologist ever nominated in 1954 for the Nobel Prize in physics for his prediction of the expanding universe. Remarkably, he was also nominated for the 1956 Nobel prize in chemistry for his primeval-atom theory.
On 17 March 1934, Lemaître received the Francqui Prize, the highest Belgian scientific distinction, from King Leopold III. His proposers were Albert Einstein, Charles de la Vallée-Poussin and Alexandre de Hemptinne. The members of the international jury were Eddington, Langevin, Théophile de Donder and Marcel Dehalu. The same year he received the Mendel Medal of the Villanova University.
Another distinction that the Belgian government reserves for exceptional scientists was allotted to him in 1950: the decennial prize for applied sciences for the period 1933–1942.
In 2005, Lemaître was voted to the 61st place of De Grootste Belg ("The Greatest Belgian"), a Flemish television program on the VRT. In the same year he was voted to the 78th place by the audience of the Les plus grands Belges ("The Greatest Belgians"), a television show of the RTBF.
The International Astronomical Union recommends that the law should now be known as the Hubble–Lemaître law, to pay tribute to the Belgian priest and astronomer Georges Lemaître, who derived the speed–distance relationship two years earlier than did US astronomer Edwin Hubble.
Indeed the attempt in 1951 by Pope Pius XII to look forward to a time when creation would be established by science was resented by several physicists, notably by George Gamow and even George Lemaitre, a member of the Pontifical Academy.
It is tempting to think that Lemaître's deeply-held religious beliefs might have led him to the notion of a beginning of time. After all, the Judeo-Christian tradition had propagated a similar idea for millennia. Yet Lemaître clearly insisted that there was neither a connection nor a conflict between his religion and his science. Rather he kept them entirely separate, treating them as different, parallel interpretations of the world, both of which he believed with personal conviction. Indeed, when Pope Pius XII referred to the new theory of the origin of the universe as a scientific validation of the Catholic faith, Lemaître was rather alarmed.CS1 maint: Uses authors parameter (link)
Lemaître was determined to discourage the Pope from making proclamations about cosmology, partly to halt the embarrassment that was being caused to supporters of the Big Bang, but also to avoid any potential difficulties for the Church. ...Lemaître contacted Daniel O'Connell, director of the Vatican Observatory and the Pope's science advisor, and suggested that together they try to persuade the Pope to keep quiet on cosmology. The Pope was surprisingly compliant and agreed to the request–the Big Bang would no longer be a matter suitable for Papal addresses.
It was Lemaître's firm belief that scientific endeavour should stand isolated from the religious realm. With specific regard to his Big Bang theory, he commented: 'As far as I can see, such a theory remains entirely outside any metaphysical or religious question.' Lemaître had always been careful to keep his parallel careers in cosmology and theology on separate tracks, in the belief that one led him to a clearer comprehension of the material world, while the other led to a greater understanding of the spiritual realm.... Not surprisingly, he was frustrated and annoyed by the Pope's deliberate mixing of theology and cosmology. One student who saw Lemaître upon his return from hearing the Pope's address to the Academy recalled him 'storming into class...his usual jocularity entirely missing'.
1565 Lemaître, provisional designation 1948 WA, is a highly eccentric Phocaea asteroid and sizable Mars-crosser from the inner regions of the asteroid belt, approximately 8 kilometers in diameter. It was discovered on 25 November 1948, by Belgian astronomer Sylvain Arend at the Royal Observatory of Belgium in Uccle, Belgium. It was named after cosmologist and priest Georges Lemaître.Albert Lemaître
Albert Lemaître (c. 1864 – in or after 1906), (aka Georges Lemaître), was a French sporting motorist and early racing driver. He was the first petrol powered finisher in what is described as 'the world's first competitive motoring event' when he drove his Peugeot Type 7 from Paris to Rouen at 19 km/h (12 mph) in 1894. The Comte de Dion had finished first but his steam powered vehicle was ineligible for the main prize which was shared between the manufacturers Peugeot and Panhard.Throughout the 1890s he competed in a range of events and races driving Peugeots, but after their withdrawal from competition in the early 1900s he was contracted to drive Mercedes.
In 1906 in Paris he murdered his wife in a domestic argument after she had filed for divorce. He then fired the third gunshot into his own head, but survived. In September 1906 he was acquitted of a crime of passion.Automated Transfer Vehicle
The Automated Transfer Vehicle, originally Ariane Transfer Vehicle or ATV, was an expendable cargo spacecraft developed by the European Space Agency (ESA) 1995–2007, used for space cargo transport in 2008–2014. The ATV design was launched to orbit five times, exclusively by the Ariane 5 heavy-lift launch vehicle. It functioned much like the Russian Progress cargo spacecraft for carrying upmass to a single destination—the International Space Station (ISS)—but with three times the capacity.
The five ATVs were Jules Verne, Johannes Kepler, Edoardo Amaldi, Albert Einstein, and Georges Lemaître. Following several delays to the programme, the first of these was launched in March 2008. These ATVs performed supply missions to the ISS, transporting various payloads such as propellant, water, air, food, and scientific research equipment; ATVs also reboosted the station into a higher orbit while docked. It was an uncrewed platform that operated with a high level of automation, such as its docking sequence; at no point was it used for transporting passengers.
Further use of the ATV was proposed in 2008. Various further developments, including crewed versions of the ATV as well as opportunities to reuse sections or elements of its technology, were studied by both the ESA and Airbus Defence and Space, the principal manufacturer of the vehicle.
However, on 2 April 2012, the ESA announced that the ATV program would be terminated following the launch of the fifth ATV in 2014.In 2012, ESA member states decided that the ATV design might be adapted to serve as the service module of the NASA Orion spacecraft.
In January 2013, the ESA and NASA announced that they would proceed with a combined Orion and ATV derived service module, which would serve as a major component for the in-development Orion crewed spacecraft.Big Bang
The Big Bang theory is the prevailing cosmological model for the observable universe from the earliest known periods through its subsequent large-scale evolution. The model describes how the universe expanded from a very high-density and high-temperature state, and offers a comprehensive explanation for a broad range of phenomena, including the abundance of light elements, the cosmic microwave background (CMB), large scale structure and Hubble's law (the farther away galaxies are, the faster they are moving away from Earth). If the observed conditions are extrapolated backwards in time using the known laws of physics, the prediction is that just before a period of very high density there was a singularity which is typically associated with the Big Bang. Physicists are undecided whether this means the universe began from a singularity, or that current knowledge is insufficient to describe the universe at that time. Detailed measurements of the expansion rate of the universe place the Big Bang at around 13.8 billion years ago, which is thus considered the age of the universe. After its initial expansion, the universe cooled sufficiently to allow the formation of subatomic particles, and later simple atoms. Giant clouds of these primordial elements (mostly hydrogen, with some helium and lithium) later coalesced through gravity, eventually forming early stars and galaxies, the descendants of which are visible today. Astronomers also observe the gravitational effects of dark matter surrounding galaxies. Though most of the mass in the universe seems to be in the form of dark matter, Big Bang theory and various observations seem to indicate that it is not made out of conventional baryonic matter (protons, neutrons, and electrons) but it is unclear exactly what it is made out of.
Since Georges Lemaître first noted in 1927 that an expanding universe could be traced back in time to an originating single point, scientists have built on his idea of cosmic expansion. The scientific community was once divided between supporters of two different theories, the Big Bang and the Steady State theory, but a wide range of empirical evidence has strongly favored the Big Bang which is now universally accepted. In 1929, from analysis of galactic redshifts, Edwin Hubble concluded that galaxies are drifting apart; this is important observational evidence consistent with the hypothesis of an expanding universe. In 1964, the cosmic microwave background radiation was discovered, which was crucial evidence in favor of the Big Bang model, since that theory predicted the existence of background radiation throughout the universe before it was discovered. More recently, measurements of the redshifts of supernovae indicate that the expansion of the universe is accelerating, an observation attributed to dark energy's existence. The known physical laws of nature can be used to calculate the characteristics of the universe in detail back in time to an initial state of extreme density and temperature.Cold Big Bang
Cold Big Bang is a designation used in cosmology to denote an absolute zero temperature at the beginning of the Universe, instead of a (hot) Big Bang.
In an attempt to understand the origin of atoms, Georges Lemaître proposed (by 1927) that before the expansion of the universe started all the matter in the universe, it formed a gigantic ball of nuclear liquid at very low temperature. This low temperature was required to provide an adequate cohesion within the Lemaître's primeval atom. In 1966, David Layzer proposed a variant on Lemaître's cosmology in which the initial state of the universe was near absolute zero. Layzer argued that, rather than in an initial high entropy state, the primordial universe was in a very low entropy state near absolute zero.
The mainstream version of the Cold Big Bang model predicted an absence of acoustic peaks in the cosmic microwave background radiation and was eventually explicitly ruled out by WMAP observations.Cosmon
Cosmon or Cosmonium is a hypothetical form of matter where the Universe would have been in a dense form of matter as a particle named Cosmon. The idea was originally proposed by Georges Lemaître who suggested the idea of a 'primeval atom’ (L'Hypothèse de l'Atome Primitif) 1946. He illustrated the idea by imagining an object 30 times larger than the volume of the sun containing all the matter of the Universe. Its density would be around . In his view this exploded somewhere between 20–60 billion years ago.
The idea of a primeval “super-atom” lived on and was developed forward by Maurice Goldhaber in 1956. In his proposal there would have been a point, which had been called a Universon, that would have collapsed into a Cosmon and an Anticosmon pair. Goldhaber was wondering about why is there any matter if equal amount of matter and antimatter was formed in the beginning of the big bang. One explanation for this is the asymmetry of matter meaning that there could have been slightly more matter than antimatter, for instance 1001 matter particles to every 1000 antimatter. In Goldhabers model cosmon and anticosmon would have flown apart and therefore explaining issue without asymmetry.
In 1989 Hans Dehmelt attempted to modernize the idea of the primeval atom. In this hypothesis, Cosmonium would have been the heaviest form of matter at the beginning of the big bang.Edwin Hubble
Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology and is regarded as one of the most important astronomers of all time.Hubble discovered that many objects previously thought to be clouds of dust and gas and classified as "nebulae" were actually galaxies beyond the Milky Way. He used the strong direct relationship between a classical Cepheid variable's luminosity and pulsation period (discovered in 1908 by Henrietta Swan Leavitt) for scaling galactic and extragalactic distances.Hubble provided evidence that the recessional velocity of a galaxy increases with its distance from the Earth, a property now known as "Hubble's law", despite the fact that it had been both proposed and demonstrated observationally two years earlier by Georges Lemaître. Hubble-Lemaître's Law implies that the universe is expanding. A decade before, the American astronomer Vesto Slipher had provided the first evidence that the light from many of these nebulae was strongly red-shifted, indicative of high recession velocities.Hubble's name is most widely recognized for the Hubble Space Telescope which was named in his honor, with a model prominently displayed in his hometown of Marshfield, Missouri.Georges Lemaître ATV
The Georges Lemaître ATV, or Automated Transfer Vehicle 5 (ATV-5), was a European unmanned cargo resupply spacecraft, named after the Belgian astronomer Georges Lemaître. The spacecraft was launched during the night of 29 July 2014 (23:44 GMT, 20:44 local time, 30 July 01:44 CEST), on a mission to supply the International Space Station (ISS) with propellant, water, air, and dry cargo. It was the fifth and final ATV to be built and launched. Georges Lemaître was constructed in Turin, Italy, and Bremen, Germany. Cargo loading was completed in Guiana Space Center on 23 July 2014.Georges Lemaître was launched on an Ariane 5ES rocket from the Guiana Space Centre in Kourou, French Guiana. The launch was conducted by Arianespace on behalf of the European Space Agency.
Artist Katie Paterson sent artwork to the International Space Station aboard ATV-5.Gérard Garitte
Gérard Garitte (1914–1992) was a Belgian historian and scientist at the Catholic University of Leuven and later the French-speaking University of Louvain in Louvain-la-Neuve, Belgium. He raised the study of Georgian ecclesiastical literature to a high level. In 1959, he was awarded the Francqui Prize on Human Sciences ("Orientalisme chrétien - Philologie classique"). In 1962, strongly opposed to the expulsion of French speakers from the Catholic University of Louvain, he created the ACAPSUL movement together with Georges Lemaître to fight against the split of the university.Hubble's law
Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that:
Hubble's law is considered the first observational basis for the expansion of the universe and today serves as one of the pieces of evidence most often cited in support of the Big Bang model. The motion of astronomical objects due solely to this expansion is known as the Hubble flow.
Although widely attributed to Edwin Hubble, the notion of the universe expanding at a calculable rate was first derived from the general relativity equations in 1922 by Alexander Friedmann. Friedmann published a set of equations, now known as the Friedmann equations, showing that the universe might expand, and presenting the expansion speed if this was the case. Then Georges Lemaître, in a 1927 article, independently derived that the universe might be expanding, observed the proportionality between recessional velocity of and distance to distant bodies, and suggested an estimated value of the proportionality constant, which when corrected by Hubble became known as the Hubble constant. Though the Hubble constant is roughly constant in the velocity-distance space at any given moment in time, the Hubble parameter , which the Hubble constant is the current value of, varies with time, so the term 'constant' is sometimes thought of as somewhat of a misnomer. Moreover, two years later Edwin Hubble confirmed the existence of cosmic expansion, and determined a more accurate value for the constant that now bears his name. Hubble inferred the recession velocity of the objects from their redshifts, many of which were earlier measured and related to velocity by Vesto Slipher in 1917.
The law is often expressed by the equation v = H0D, with H0 the constant of proportionality—Hubble constant—between the "proper distance" D to a galaxy, which can change over time, unlike the comoving distance, and its velocity v, i.e. the derivative of proper distance with respect to cosmological time coordinate. (See uses of the proper distance for some discussion of the subtleties of this definition of 'velocity'.) Also, the SI unit of H0 is s−1, but it is most frequently quoted in (km/s)/Mpc, thus giving the speed in km/s of a galaxy 1 megaparsec (3.09×1019 km) away. The Hubble constant is about 70 (km/s)/Mpc. The reciprocal of H0 is the Hubble time.Jean-Pierre Luminet
Jean-Pierre Luminet (born 3 June 1951) is a French astrophysicist, writer and poet, world-known specialist of black holes and cosmology. He works as research director for the CNRS (Centre national de la recherche scientifique), and is a member of the Laboratoire d’Astrophysique de Marseille (LAM), of the Laboratoire Univers et Théories (LUTH) of the Paris-Meudon Observatory and a visiting scientist at the Centre de Physique Théorique (CPT) in Marseilles.
He has published many articles in the most prestigious journals and reviews in these areas. He has been awarded several prizes for his work in pure science and in science communication, such as the International Georges Lemaître Prize 1999 and the European Prize 2007 for Science Communication. He also serves on the editorial boards of The Astronomical Review and Inference : The International Review of Science.
The asteroid 5523 Luminet, discovered in 1991 at Mt Palomar Observatory, was named after him.Indeed one of Luminet’s greatest efforts has been to make his research work understandable to the non-scientific community. Luminet is also a prominent figure in art and literature. He has produced fifteen popular science books, seven historical novels, TV documentaries, multimedia productions, and six collections of poetry. He is also an artist, an engraver, a sculptor and a musician. He has collaborated with celebrated composers such as Gérard Grisey and Hèctor Parra.
Luminet’s literary work has been translated into a dozen of languages.Jonathan Lunine
Jonathan I. Lunine (born June 26, 1959) is an American planetary scientist and physicist. Lunine teaches at Cornell University, where he is the David C. Duncan Professor in the Physical Sciences and Director of the Center for Radiophysics and Space Research. Having published more than 300 research papers, Lunine is at the forefront of research into planet formation, evolution, and habitability. His work includes analysis of brown dwarfs, gas giants, and planetary satellites. Within the Solar System, bodies with potential organic chemistry and prebiotic conditions, particularly Saturn's moon Titan, have been the focus of Lunine's research.Lunine is the David Baltimore Distinguished Visiting Scientist at NASA's Jet Propulsion Laboratory. He is an interdisciplinary scientist on the Cassini mission to Saturn, and on the James Webb Space Telescope, as well as co-investigator on the Juno mission launched in 2011 to Jupiter. He is the Principal Investigator of a proposed astrobiology mission to Enceladus called Enceladus Life Finder.Lunine is a member of the U.S. National Academy of Sciences, a fellow of the American Association for the Advancement of Science and the American Geophysical Union, and a member of the International Academy of Astronautics, which gave him its Basic Science Award in 2009. In 2015 he was awarded the Jean Dominique Cassini medal of the European Geosciences Union. He earned a B.S. in Physics and Astronomy from the University of Rochester in 1980, followed by M.S. (1983) and Ph.D. (1985) degrees in Planetary Science from the California Institute of Technology.Lunine was raised Jewish, but is a convert to Catholicism who helped found the Society of Catholic Scientists. He also delivered a lecture on Georges Lemaître.Lemaître
Lemaître or Lemaitre is a French surname meaning "the master" – derived from the Latin word "magister". Notable people with the surname include:
Frédérick Lemaître (1800–1876), French actor and playwright
Georges Lemaître (1894–1966), Belgian Roman Catholic priest and astronomer.
Named for Georges Lemaître:
Lemaître (crater), an impact crater on the Moon
1565 Lemaître, a minor planet
the Friedmann–Lemaître–Robertson–Walker metric
the Lemaître metric
the Lemaître–Tolman metric
Lemaitre (band), Norwegian indie electronic band
Georges Lemaître ATV, an unmanned spacecraft
Jules Lemaître (1853–1914), French critic and dramatist
Maurice Lemaître (1928-2018), French painter
Maurice Lemaître (mechanical engineer) (1898-1974), Belgian mechanical engineer, who developed a steam locomotive exhaustLemaitre:
Christophe Lemaitre (born 1990), French sprinter
Pierre Lemaitre (born 1951), a French author and a screenwriter
Rafael Lemaitre, French carcinologistMusic
Lemaitre (band), a Norwegian indie electronic bandLemaître coordinates
Lemaître coordinates are a particular set of coordinates for the Schwarzschild metric—a spherically symmetric solution to the Einstein field equations in a vacuum—introduced by Georges Lemaître in 1932. Changing from Schwarzschild to Lemaître coordinates removes the coordinate singularity at the Schwarzschild radius.Lemaître–Tolman metric
In mathematical physics, the Lemaître–Tolman metric is the spherically symmetric dust solution of Einstein's field equations. It was first found by Georges Lemaître in 1933 and Richard Tolman in 1934 and later investigated by Hermann Bondi in 1947. This solution describes a spherical cloud of dust (finite or infinite) that is expanding or collapsing under gravity. It is also known as the Lemaître–Tolman–Bondi metric or the Tolman metric.Observational cosmology
Observational cosmology is the study of the structure, the evolution and the origin of the universe through observation, using instruments such as telescopes and cosmic ray detectors.St Edmund's College, Cambridge
St Edmund's College is a constituent college of the University of Cambridge in England. It is the second-oldest of the four Cambridge colleges oriented to mature students, which only accept students reading for either masters or doctorate degrees, or undergraduate degrees if they are aged 21 or older.
Named after St Edmund of Abingdon (1175–1240), who was the first known Oxford Master of Arts and the Archbishop of Canterbury from 1234 to 1240, the college has traditionally Catholic roots. Its founders were Henry Fitzalan Howard, the 15th Duke of Norfolk, then the most prominent Catholic in England, and Baron Anatole von Hügel, the first Catholic to take a Cambridge degree since the revolution of 1688. In recognition of this Catholic connection, the College Visitor is the Archbishop of Westminster (at present Cardinal Vincent Nichols).The college is located on Mount Pleasant, northwest of the centre of Cambridge, beside Lucy Cavendish College, Murray Edwards College and Fitzwilliam College. Its campus consists of a garden setting on the edge of what was Roman Cambridge, with housing for over 350 students.
Members of St Edmund's include the former Archbishop of Amagh, Eamon Martin, cosmologist and Big Bang theorist Georges Lemaître, the Bishop of Menevia, John Petit, and the Leader of the House of Commons, Norman St John-Stevas, Lord St John of Fawsley. Historically, St Edmund's was also the residential college of the university's first Catholic students in two hundred years - most of whom were studying for the Priesthood - after the lifting of the papal prohibition on attendance at the Universities of Oxford and Cambridge in 1895 at the urging of a delegation to Pope Leo XIII led by Baron von Hügel.Static universe
A static universe, also referred to as a "stationary" or "infinite" or "static infinite" universe, is a cosmological model in which the universe is both spatially infinite and temporally infinite, and space is neither expanding nor contracting. Such a universe does not have so-called spatial curvature; that is to say that it is 'flat' or Euclidean. A static infinite universe was first proposed by Thomas Digges (1546 .. 1595) .In contrast to this model, Albert Einstein proposed a temporally infinite but spatially finite model as his preferred cosmology during 1917, in his paper Cosmological Considerations in the General Theory of Relativity.
After the discovery of the redshift–distance relationship (deduced by the inverse correlation of galactic brightness to redshift) by Vesto Slipher and Edwin Hubble, the astrophysicist and Roman Catholic priest Georges Lemaître interpreted the redshift as proof of universal expansion and thus a Big Bang, whereas Fritz Zwicky proposed that the redshift was caused by the photons losing energy as they passed through the matter and/or forces in intergalactic space. Zwicky's proposal would come to be termed 'tired light'- a term invented by the major Big Bang proponent Richard Tolman.Stigler's law of eponymy
Stigler's law of eponymy, proposed by University of Chicago statistics professor Stephen Stigler in his 1980 publication "Stigler’s law of eponymy", states that no scientific discovery is named after its original discoverer. Examples include Hubble's law which was derived by Georges Lemaître two years before Edwin Hubble, the Pythagorean theorem although it was known to Babylonian mathematicians before the Pythagoreans, and Halley's comet which was observed by astronomers since at least 240 BC. Stigler himself named the sociologist Robert K. Merton as the discoverer of "Stigler's law" to show that it follows its own decree, though the phenomenon had previously been noted by others.