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Ralph Asher Alpher
Ralph Asher Alpher (1921–2007)
|Born||February 3, 1921|
Washington, D.C., U.S.
|Died||August 12, 2007 86) (aged|
|Alma mater||George Washington University|
|Known for||First modern physical theory of nucleosynthesis and prediction of the Cosmic Microwave Background Radiation in 1948.|
|Awards|| Magellanic Premium (1975)|
Henry Draper Medal (1993)
National Medal of Science (2005)
|Fields||Cosmology, Theoretical Physics and Astrophysics|
|Institutions||Johns Hopkins University Applied Physics Laboratory, General Electric Research and Development Center, Union College, Dudley Observatory|
|Doctoral advisor||Georg Antonovich Gamow|
|Part of a series on|
Ralph Asher Alpher (February 3, 1921 – August 12, 2007)was an American cosmologist, who carried out pioneering work in the early 1950s on the Big Bang model, including Big Bang nucleosynthesis and predictions of the cosmic microwave background radiation.
Alpher was the son of a Belarusian Jewish immigrant, Samuel Alpher (born Ilfirovich), from Vitebsk, Belarus. His mother, Rose Maleson, died of stomach cancer in 1938, and his father later remarried. Alpher graduated at age 15 from Theodore Roosevelt High School in Washington, D.C., and held the ranks of Major and Commander of his school's Cadet program. He worked in the high school theater as stage manager for two years, supplementing his family's Depression-era income. He also learned Gregg shorthand, and in 1937 began working for the Director of the American Geophysical Union as a stenographer. In 1940 he was hired by the Department of Terrestrial Magnetism of the Carnegie Foundation, where he worked with Dr. Scott Forbush under contract for the U.S. Navy to develop ship degaussing techniques during World War II. He contributed to the development of the Mark 32 and Mark 45 detonators, torpedoes, Naval gun control, Magnetic Airborne Detection (of submarines), and other top-secret ordnance work (including the Manhattan Project), and he was recognized at the end of the War with the Naval Ordnance Development Award (December 10, 1945—with Symbol), and another Naval Ordnance Development award in 1946. Alpher's war time work been somewhat obscured by security classification.[ citation needed ] From 1944 through 1955, he was employed at the Johns Hopkins University Applied Physics Laboratory. During the daytime he was involved in the development of ballistic missiles, guidance systems, supersonics, and related subjects. In 1948 he earned his Ph.D. in Physics with a theory of nucleosynthesis called neutron-capture, and from 1948 onward collaborated with Dr. Robert C. Herman (Ph.D. in Physics, 1940, Princeton University, under E. Condon), also at APL, on predictions of the Cosmic Microwave Background Radiation (now widely referred to by the acronym CMB). Alpher was somewhat ambivalent about the nature of his ordnance work. having dedicated much of his early career to this in order to obtain his doctorate.[ citation needed ]
At age 16, he was offered a full scholarship to the Massachusetts Institute of Technology (MIT), but it may have been withdrawn after Alpher had required meeting with an alumnus in Washington, D.C., with little explanation or clarification.[ citation needed ] Instead, he earned his bachelor's degree and advanced graduate degrees in physics from George Washington University, all the while working as a physicist on contract to the Navy, and eventually for the Johns Hopkins University Applied Physics Laboratory. He met Russian-Ukrainian physicist George Gamow at the University, who subsequently took him on as his doctoral student. This was somewhat of a coup, as Gamow was a prominent Soviet defector and one of the luminaries on the GWU faculty. His first physics course was taught by Edward Teller, brought onto the GWU faculty in 1935 to give Gamow a peer on the faculty. Alpher provided much needed mathematical ability to support Gamow's theorizing. Gamow often gave talks across the world on "The Origin of the Elements", which was Alpher's original dissertation. Gamow continues to be credited with Alpher's work on nucleosynthesis. Alpher followed his dissertation immediately with the first prediction of the existence of "fossil" radiation from a hypothetical singularity—the Cosmic Microwave Background Radiation. This was observationally confirmed by Arno Allan Penzias and Robert Wilson at Bell Labs using a horn radiotelescope. Further research has shown other observations made, but not interpreted cosmologically. They were awarded the Nobel Prize in Physics for the observation in 1978. Ironically a group at Princeton was given credit for making a cosmological interpretation in an inflationary universe (Big Bang) in a companion publication in 1965 to Penzias and Wilson, which is incorrect.
While attending GWU, Alpher met Louise Ellen Simons, who was majoring in psychology at night school and working as a day secretary with the State Department. Nearly two months after the attack on Pearl Harbor, Alpher and Louise were married. At this time he had already done classified work for the U.S. Navy through the Carnegie Institution for nearly one and a half years. During a hiatus in his scientific work in early 1944, he did apply to the Navy for a commission, for which he was eligible. By this time he had done so much classified and secret work he was no longer subject to the draft (along with about 7,000 others), and prohibited from enlistment. That summer, he signed on to the Johns Hopkins University Applied Physics Laboratory to work on another classified project—a new magnetic-influence torpedo exploder. This was badly needed since the Mark 14 torpedo, which had a poorly tested exploder that had its magnetic component turned off by order of the Chief of Naval Operations in late 1943, was badly in need of replacement (V.S. Alpher, The Submarine Review, October, 2009).
Alpher's dissertation in 1948 dealt with a subject that came to be known as Big Bang nucleosynthesis. The Big Bang is a term coined initially in derision by Fred Hoyle on BBC Radio in 1950 to describe the cosmological model of the universe as expanding into its current state from a primordial condition of enormous density and temperature. Nucleosynthesis is the explanation of how more complex elements are created out of simple elements in the moments following the Big Bang. Right after the Big Bang, when the temperature was extremely high, if any nuclear particles, such as neutrons and protons, became bound together (being held together by the attractive nuclear force) they would be immediately broken apart by the high energy photons (quanta of light) present in high density. In other words, at this extremely high temperature, the photons' kinetic energy would overwhelm the binding energy of the strong nuclear force. For example, if a proton and a neutron became bound together (forming deuterium), it would be immediately broken apart by a high energy photon. However, as time progressed, the universe expanded and cooled and the average energy of the photons decreased. At some point, roughly one second after the Big Bang, the attractive force of nuclear attraction would begin to win out over the lower energy photons and neutrons and protons would begin to form stable deuterium nuclei. As the universe continued to expand and cool, additional nuclear particles would bind with these light nuclei, building up heavier elements such as helium, etc.
Alpher argued that the Big Bang would create hydrogen, helium and heavier elements in the correct proportions to explain their abundance in the early universe. Alpher and Gamow's theory originally proposed that all atomic nuclei are produced by the successive capture of neutrons, one mass unit at a time. However, later studies challenged the universality of the successive capture theory, since no element was found to have a stable isotope with an atomic mass of five or eight, hindering the production of elements beyond helium. It was eventually recognized that most of the heavy elements observed in the present universe are the result of stellar nucleosynthesis in stars, a theory largely developed by Hans Bethe, William Fowler and Subrahmanyan Chandrasekhar. Bethe had been a last minute addition to Alpher's dissertation examining committee.
Since Alpher's dissertation was perceived to be ground-breaking, over 300 people attended the dissertation defense, including the press, and articles about his predictions and a Herblock cartoon appeared in major newspapers. This was quite unusual for a doctoral dissertation.
Later the same year, collaborating with Robert Herman, Alpher predicted the temperature of the residual radiation known as cosmic microwave background radiation resulting from the hypothesized Big Bang.However, Alpher's predictions concerning the cosmic background radiation were more or less forgotten until they were rediscovered by Robert Dicke and Yakov Zel'dovich in the early 1960s. The existence of the cosmic background radiation and its temperature were measured experimentally in 1964 by two physicists working for Bell Laboratories in New Jersey, Arno Penzias and Robert Wilson, who were awarded the Nobel prize in physics for this work in 1978.
Elements of Alpher's independent dissertation were first published on April 1, 1948 in the Physical Review with three authors: Alpher, Hans Bethe and Gamow.Although his name appears on the paper, Bethe had no direct part in the development of the theory, although he later worked on related topics; Gamow added his name to make the author list Alpher, Bethe, Gamow, a pun on alpha, beta, gamma (α, β, γ), the first three letters of the Greek alphabet. Gamow joked that "There was, however, a rumor that later, when the alpha, beta, gamma theory went temporarily on the rocks, Bethe seriously considered changing his name to Zacharias". When referring to Robert Herman he wrote: "R. C. Herman, who stubbornly refuses to change his name to Delter." Alpher worried that the humor engendered by Gamow may have obscured his own critical role in developing the theory. With the award of the 2005 National Medal of Science, Alpher's original work on nucleosynthesis and the cosmic microwave background radiation prediction was recognised. Neil deGrasse Tyson was instrumental in a NSF committee recommendation (personal communication to Dr. Victor S. Alpher, July 26, 2007).
Alpher and Robert Herman were awarded the Henry Draper Medal from the National Academy of Sciences in 1993.They were also awarded the Magellanic Premium of the American Philosophical Society in 1975, the Georges Vanderlinden Physics prize of the Belgian Academy of Sciences, as well as significant awards of the New York Academy of Sciences and the Franklin Institute of Philadelphia. Two Nobel Prizes in physics have been awarded for empirical work related to the cosmic background radiation — in 1978 to Arno Penzias and Robert Wilson and in 2006 to John Mather and George Smoot. Alpher and Herman (the latter, posthumously) published their own account of their work in cosmology in 2001, Genesis of the Big Bang (Oxford University Press). Published as a trade book, it received little promotion or sales in the first edition.
He was elected a Fellow of the American Academy of Arts and Sciences in 1986.In 2005 Alpher was awarded the National Medal of Science. The citation for the award reads "For his unprecedented work in the areas of nucleosynthesis, for the prediction that universe expansion leaves behind background radiation, and for providing the model for the Big Bang theory." The medal was presented to his son, Dr. Victor S. Alpher, on July 27, 2007 by President George W. Bush, as his father could not travel to receive the award. Ralph Alpher died following an extended illness on August 12, 2007. He had been in failing health since falling and breaking his hip in February 2007.
In 1955 Alpher moved to a position with the General Electric Company's Research and Development Center. His primary role in his early years there was working on problems of vehicle re-entry from space. During the late 1940s at the Applied Physics Laboratory at Johns Hopkins University, he worked as a member of John van Allen's work group, studying cosmic rays with high altitude balloons. In 1955, both Alpher and Herman applied for positions at Iowa, where van Allen was now department chair, however, the salaries in academia were simply too low to support families. Alpher also continued to collaborate with Robert Herman, who had moved to the General Motors Research Laboratory, on problems in cosmology. The Cosmic Microwave Background Radiation was finally confirmed in 1964, although in retrospect many other astronomers and radio astronomers probably observed it without recognizing the cosmological significance.
From 1987 to 2004 he served as distinguished research professor of physics and astronomy at Union College in Schenectady, New York, during which time he was able to return to research and teaching. During all this time he continued to publish major peer-reviewed scientific papers and was active in community service for Public Broadcasting. Alpher was also (1987–2004) director of The Dudley Observatory.
In 1986 he was recognized with the Distinguished Alumnus Achievement Award of the George Washington University. All of his degrees were achieved by studying at night whilst working for the navy and Johns Hopkins Applied Physics Laboratory during the daytime. In 2004 he joined the emeritus faculty at Union and was emeritus director of Dudley. He also received honorary Doctor of Science degrees from Union College and the Rensselaer Polytechnic Institute. From 2005 until his death, he remained emeritus director of the Dudley Observatory and emeritus distinguished professor of physics and astronomy at Union College.
Alpher told Joseph D'Agnese in his interview for Discover Magazine, "There are two reasons you do science. One is the altruistic feeling that maybe you can contribute to mankind's store of knowledge about the world. The other and more personal thing is you want the approbation of your peers. Pure and simple."
Ralph Alpher told his son Victor in 1980, when considering advanced education, that approbation of anyone was not the reason to pursue graduate study or a career requiring advanced intensive study. Rather, he said to Victor, "you must enjoy and find satisfaction in the work you do every day, because you will not receive frequent rewards or pats on the back." Up to that time, he had received only three awards for his work in cosmology, from the American Philosophical Society, the Belgian Academy of Science, and the Franklin Institute—all occurring after he turned 50.[ citation needed ]
Despite being raised in a Jewish family, he later on became an agnostic and considered himself to be a humanist.
The Big Bang theory is a cosmological model of the observable universe from the earliest known periods through its subsequent large-scale evolution. The model describes how the universe expanded from an initial state of very high density and high temperature, and offers a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the cosmic microwave background (CMB) radiation, 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. Current knowledge is insufficient to determine if anything existed prior to the singularity.
Physical cosmology is a branch of cosmology concerned with the studies of the largest-scale structures and dynamics of the universe and with fundamental questions about its origin, structure, evolution, and ultimate fate. Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed those physical laws to be understood. Physical cosmology, as it is now understood, began with the development in 1915 of Albert Einstein's general theory of relativity, followed by major observational discoveries in the 1920s: first, Edwin Hubble discovered that the universe contains a huge number of external galaxies beyond the 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 best explains the observations.
The cosmic microwave background, in Big Bang cosmology, is electromagnetic radiation as a remnant from an early stage of the universe, also known as "relic radiation". The CMB is faint cosmic background radiation filling all space. It is an important source of data on the early universe because it is the oldest electromagnetic radiation in the universe, dating to the epoch of recombination. With a traditional optical telescope, the space between stars and galaxies is completely dark. However, a sufficiently sensitive radio telescope shows a faint background noise, or glow, almost isotropic, that is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the radio spectrum. The accidental discovery of the CMB in 1964 by American radio astronomers Arno Penzias and Robert Wilson was the culmination of work initiated in the 1940s, and earned the discoverers the 1978 Nobel Prize in Physics.
In physical cosmology, Big Bang nucleosynthesis is the production of nuclei other than those of the lightest isotope of hydrogen during the early phases of the Universe. Primordial nucleosynthesis is believed by most cosmologists to have taken place in the interval from roughly 10 seconds to 20 minutes after the Big Bang, and is calculated to be responsible for the formation of most of the universe's helium as the isotope helium-4 (4He), along with small amounts of the hydrogen isotope deuterium, the helium isotope helium-3 (3He), and a very small amount of the lithium isotope lithium-7 (7Li). In addition to these stable nuclei, two unstable or radioactive isotopes were also produced: the heavy hydrogen isotope tritium ; and the beryllium isotope beryllium-7 (7Be); but these unstable isotopes later decayed into 3He and 7Li, as above.
This timeline of cosmological theories and discoveries is a chronological record of the development of humanity's understanding of the cosmos over the last two-plus millennia. Modern cosmological ideas follow the development of the scientific discipline of physical cosmology.
George Gamow, born Georgiy Antonovich Gamov, was a Soviet-American theoretical physicist and cosmologist. He was an early advocate and developer of Lemaître's Big Bang theory. He discovered a theoretical explanation of alpha decay by quantum tunneling, invented the liquid drop model and the first mathematical model of the atomic nucleus, and worked on radioactive decay, star formation, stellar nucleosynthesis and Big Bang nucleosynthesis, and molecular genetics.
Arno Allan Penzias is an American physicist, radio astronomer and Nobel laureate in physics who is co-discoverer of the cosmic microwave background radiation along with Robert Woodrow Wilson, which helped establish the Big Bang theory of cosmology.
Ylem is a term that was used by George Gamow, his student Ralph Alpher, and their associates in the late 1940s for a hypothetical original substance or condensed state of matter, which became subatomic particles and elements as we understand them today. The term ylem was actually resuscitated by Ralph Alpher.
The discovery of cosmic microwave background radiation constitutes a major development in modern physical cosmology. The cosmic background radiation (CMB) was measured by Andrew McKellar in 1941 at an effective temperature of 2.3 K using CN stellar absorption lines observed by W. S. Adams. Theoretical work around 1950 showed the need for a CMB for consistency with the simplest relativistic universe models. In 1964, US physicist Arno Penzias and radio-astronomer Robert Woodrow Wilson rediscovered the CMB, estimating its temperature as 3.5 K, as they experimented with the Holmdel Horn Antenna. The new measurements were accepted as important evidence for a hot early Universe and as evidence against the rival steady state theory. In 1978, Penzias and Wilson were awarded the Nobel Prize for Physics for their joint measurement.
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.
Phillip James Edwin Peebles is a Canadian-American astrophysicist, astronomer, and theoretical cosmologist who is currently the Albert Einstein Professor Emeritus of Science at Princeton University. He is widely regarded as one of the world's leading theoretical cosmologists in the period since 1970, with major theoretical contributions to primordial nucleosynthesis, dark matter, the cosmic microwave background, and structure formation.
Robert Herman was a United States scientist, best known for his work with Ralph Alpher in 1948-50, on estimating the temperature of cosmic microwave background radiation from the Big Bang explosion.
The cosmic neutrino background is the universe's background particle radiation composed of neutrinos. They are sometimes known as relic neutrinos.
In physical cosmology, the Alpher–Bethe–Gamow paper, or αβγ paper, was created by Ralph Alpher, then a physics PhD student, and his advisor George Gamow. The work, which would become the subject of Alpher's PhD dissertation, argued that the Big Bang would create hydrogen, helium and heavier elements in the correct proportions to explain their abundance in the early universe. While the original theory neglected a number of processes important to the formation of heavy elements, subsequent developments showed that Big Bang nucleosynthesis is consistent with the observed constraints on all primordial elements.
Nuclear astrophysics is an interdisciplinary part of both nuclear physics and astrophysics, involving close collaboration among researchers in various subfields of each of these fields. This includes, notably, nuclear reactions and their rates as they occur in cosmic environments, and modeling of astrophysical objects where these nuclear reactions may occur, but also considerations of cosmic evolution of isotopic and elemental composition. Constraints from observations involve multiple messengers, all across the electromagnetic spectrum, as well as isotopic measurements of solar-system materials such as meteorites and their stardust inclusions, cosmic rays, material deposits on Earth and Moon). Nuclear physics experiments address stability for atomic nuclei well beyond the regime of stable isotopes into the realm of radioactive/unstable nuclei, and under high density, and high temperature plasma temperatures up to GK). Theories and simulations are essential parts herein, as cosmic nuclear reaction environments cannot be realized, but at best partially approximated by experiments. In general terms, nuclear astrophysics aims to understand the origin of the chemical elements and isotopes, and the role of nuclear energy generation, in cosmic sources such as stars, supernovae, novae, violent binary-star interactions.
The B2FH paper was a landmark scientific paper on the origin of the chemical elements. The paper's title is "Synthesis of the Elements in Stars", but it became known as B2FH from the initials of its authors: Margaret Burbidge, Geoffrey Burbidge, William A. Fowler, and Fred Hoyle. It was written from 1955-56 at the University of Cambridge and Caltech, then published in Reviews of Modern Physics in 1957.
In Big Bang cosmology, neutrino decoupling refers to the epoch at which neutrinos ceased interacting with other types of matter, and thereby ceased influencing the dynamics of the universe at early times. Prior to decoupling, neutrinos were in thermal equilibrium with protons, neutrons and electrons, which was maintained through the weak interaction. Decoupling occurred approximately at the time when the rate of those weak interactions was slower than the rate of expansion of the universe. Alternatively, it was the time when the time scale for weak interactions became greater than the age of the universe at that time. Neutrino decoupling took place approximately one second after the Big Bang, when the temperature of the universe was approximately 10 billion kelvins, or 1 MeV.
Cosmic background radiation is electromagnetic radiation from the Big Bang. The origin of this radiation depends on the region of the spectrum that is observed. One component is the cosmic microwave background. This component is redshifted photons that have freely streamed from an epoch when the Universe became transparent for the first time to radiation. Its discovery and detailed observations of its properties are considered one of the major confirmations of the Big Bang. The discovery of the cosmic background radiation suggests that the early universe was dominated by a radiation field, a field of extremely high temperature and pressure.
The Hans A. Bethe Prize, is presented annually by the American Physical Society. The prize honors outstanding work in theory, experiment or observation in the areas of astrophysics, nuclear physics, nuclear astrophysics, or closely related fields. The prize consists of $10,000 and a certificate citing the contributions made by the recipient.
This leads inevitably to my identifying philosophically as an agnostic and a humanist, and explains my temerity in sharing my views with you.