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Topic: Fermi Principle


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In the News (Thu 12 Nov 09)

  
  Enrico Fermi - MSN Encarta
Fermi studied with German physicist Max Born in Göttingen, Germany, from 1922 to 1924.
Fermi became a professor at Columbia University in New York in 1939, and in 1941 moved to Chicago, Illinois, for a professorship at the University of Chicago.
The method that Fermi developed became known as Fermi statistics, and the particles that obey the Pauli exclusion principle became known as fermions.
encarta.msn.com /encyclopedia_761578253/Enrico_Fermi.html   (1194 words)

  
 Fermi Paradox - Crystalinks
The Fermi Paradox is a physical paradox in which high estimates of the probability of the existence of extraterrestrial life are contrasted with a lack of evidence.
The belief that the lack of evidence conclusively demonstrates the non-existence of extraterrestrial civilizations is known as the Fermi principle.
The Fermi paradox is a conflict between an argument of scale and probability, and a lack of evidence.
www.crystalinks.com /fermiparadox.html   (1282 words)

  
 The Istituto Fisico on Via Panisperna: the new Museo Storico della Fisica e Centro Studi e Ricerche 'Enrico Fermi' di ...
Fermi adopted the nuclear model with protons and neutrons only, and, because he did not want to renounce the conservation of energy, accepted Pauli's proposal, of the existence of a new particle, the neutrino, with no electrical charge and with a mass as high as the electron mass or less.
That morning Fermi, before putting the wedge between the neutron source and the silver sample to be activated, "suddenly" decided to test the effect of a light element and put in a piece of paraffin 4 cm thick (19).
Fermi was conscious that to maintain the level of excellence of neutron physics acquired, it was necessary to build a particle accelerator to replace traditional radon-beryllium sources; targets made from weak elements and irradiated by accelerated deuterons or protons could in fact produce a neutron source, stronger than traditional ones.
library.cern.ch /HEPLW/7/papers/3   (4467 words)

  
 Fermi paradox - Wikipedia, the free encyclopedia
However Fermi principle adherents believe that, due to a lack of evidence to the contrary, in all probability, humans (as a technologically advanced species) are effectively alone in at least our part of the Milky Way.
Critics argue that the anthropic principle is essentially a tautology; life as we know it may not exist if things were different, but a different sort of life might exist in its place, for whatever reason, depending on which side of the anthropic fence you sit on (so to speak).
Some adherents to the Fermi principle state that it is highly unlikely that all advanced civilizations would not eventually take full advantage of the power source of their home star, and in doing so change the electromagnetic signature of their sun.
en.wikipedia.org /wiki/Fermi_paradox   (5872 words)

  
 Fermi, Enrico - Hutchinson encyclopedia article about Fermi, Enrico   (Site not responding. Last check: )
Fermi built the first nuclear reactor in 1942 at Chicago University and later took part in the Manhattan Project to construct an atom bomb.
Fermi's experimental work on beta decay in radioactive materials provided further evidence for the existence of the neutrino, predicted by Austrian physicist Wolfgang Pauli.
Fermi was born in Rome and studied at Pisa; Göttingen, Germany; and Leiden, the Netherlands.
encyclopedia.farlex.com /Fermi,+Enrico   (598 words)

  
 Talk:Fermi paradox - Wikipedia, the free encyclopedia
Fermi and Drake generally deal with the possibility of civilizations within our galaxy, with the assumption that intergalactic distances are too far for civilizations to spread.
Proposed by physicist Enrico Fermi, the Fermi Paradox attempts to answer one of the most profound questions of all time: 'Are we the only technologically advanced civilization in the Universe?'.
The Fermi Paradox was in reply to speculation about extraterrestrial life, and it has been used a a counter argument to the Drake equation, but it was NOT and could NOT have been "formulated in response to the Drake equation".
en.wikipedia.org /wiki/Talk:Fermi_paradox   (3806 words)

  
 Enrico Fermi: Fine Young Scientist
The Italian government granted Fermi scholarships and fellowships which permitted advanced studies with two specialists in quantum mechanics: Professor Max Born, the Physics Nobelist, at the University of Gottingen and Dr. Paul Ehrenfest at the University of Leiden.
Laura Capon, a chemistry student, and Enrico Fermi were married in 1928 and their children, Nella and Giulio were born in 1931 and in 1936.
Fermi first visited the United States in 1930 to address a summer symposium on quantum theory; he returned in the summers of 1933 and 1935 through 1937.
www.fi.edu /learn/case-files/fermi/scientist.html   (282 words)

  
 Fermi, Enrico
Fermi was the youngest of the three children of Alberto Fermi, a railroad employee, and Ida de Gattis.
Fermi did not make this claim, for he was not certain what had occurred; indeed, he was unaware that he was on the edge of a world-shaking discovery.
At the Metallurgical Laboratory of the University of Chicago, Fermi continued his studies of the basic properties of nuclear particles, with particular emphasis on mesons, which are the quantized form of the force that holds the nucleus together.
www.crownedanarchist.com /emc2/enrico_fermi.htm   (2414 words)

  
 Malaspina Great Books - Enrico Fermi (1901-1954)
The son of a railroad official, Fermi studied at the University of Pisa from 1918 to 1922 and later at the universities of Leyden and Gottingen.
Fermi's accomplishments were in both theoretical and experimental physics, a unique feat in an age in which scientific endeavors have tended to specialize on one aspect or the other.
Fermi and his family used the opportunity offered by his trip to Sweden for the awards ceremonies to leave permanently because of their increasing concern about living under the Italian Fascist regime.
www.malaspina.org /home.asp?topic=./search/details&lastpage=./search/results&ID=376   (803 words)

  
 ScienceMaster - JumpStart - Enrico Fermi Biography
Fermi's accomplishments were in both theoretical and experimental physics, a unique feat in an age in which scientific endeavors have tended to specialize on one aspect or the other.
Fermi moved to the University of Chicago to be in charge of the first major step in making feasible the building of a bomb.
Fermi is recognized among physicists as one of the great scientists of the 20th century.
www.sciencemaster.com /jump/physical/fermi_07.php   (734 words)

  
 Pioneers: Enrico Fermi
After a short visit in Rome, Fermi left for Germany with a fellowship from the Italian Ministry of Public Instruction to study at the University of Gottingen under the physicist Max Born, whose contributions to quantum mechanics were part of the knowledge prerequisite to Fermi's later work.
Fermi's colleagues were inclined to believe that he had actually made a new, "transuranic" element of atomic number 93; that is, during bombardment, the nucleus of uranium had captured a neutron, thus increasing its atomic weight.
Late in 1938 Fermi was named a Nobel laureate in physics "for his identification of new radioactive elements produced by neutron bombardment and for his discovery of nuclear reaction effected by slow neutrons." He was given permission by the Fascist government of Mussolini to travel to Sweden to receive the award.
www.radiochemistry.org /nuclearmedicine/pioneers/fermi_e.shtml   (1283 words)

  
 Enrico Fermi - Biography
Enrico Fermi was born in Rome on 29th September, 1901, the son of Alberto Fermi, a Chief Inspector of the Ministry of Communications, and Ida de Gattis.
In 1944, Fermi became American citizen, and at the end of the war (1946) he accepted a professorship at the Institute for Nuclear Studies of the University of Chicago, a position which he held until his untimely death in 1954.
Fermi was member of several academies and learned societies in Italy and abroad (he was early in his career, in 1929, chosen among the first 30 members of the Royal Academy of Italy).
nobelprize.org /nobel_prizes/physics/laureates/1938/fermi-bio.html   (975 words)

  
 National High Magnetic Field Laboratory - Pioneers in Electricity and Magnetism: Enrico Fermi
He went on to incorporate the neutral particle (lightheartedly hailed by Fermi as the neutrino, or “little neutral one”) hypothesized by Wolfgang Pauli into a quantitative theory of beta decay, as well as to demonstrate that bombardment of elements with neutrons can generate artificial radioactivity and that slow neutrons produce much stronger nuclear reactions.
Fermi carried out his statistical work at the University of Florence, where he had joined the faculty as a lecturer of mathematics.
The prize stemmed from Fermi’s work on neutron irradiation that led to the discovery of new radioactive elements and his related research on the nuclear reactions facilitated by slow neutrons.
www.magnet.fsu.edu /education/tutorials/pioneers/fermi.html   (930 words)

  
 Enrico Fermi Biography
Fermi worked out a detailed theory of beta decay based on the idea that a neutron (a particle with no electric charge) in the nucleus "decays," or changes, into three particles: a proton, an electron (beta particle), and a neutrino.
Fermi and his team then found that the level of radioactivity created in a substance was increased if a filter made of paraffin (a waxy substance) was placed in the path of the neutrons bombarding the substance.
Fermi's idea was that in passing through the paraffin (a compound containing a large amount of hydrogen), the speed of the neutrons was reduced by contact with the hydrogen atoms, and these very slow neutrons caused a much higher radioactivity in substances than fast neutrons did.
www.notablebiographies.com /Du-Fi/Fermi-Enrico.html   (1183 words)

  
 Fermi level and Fermi function
In doped semiconductors, p-type and n-type, the Fermi level is shifted by the impurities, illustrated by their band gaps.
The Fermi energy also plays an important role in understanding the mystery of why electrons do not contribute significantly to the specific heat of solids at ordinary temperatures, while they are dominant contributors to thermal conductivity and electrical conductivity.
The Fermi function gives the probability of occupying an available energy state, but this must be factored by the number of available energy states to determine how many electrons would reach the conduction band.This density of states is the electron density of states, but there are differences in its implications for conductors and semiconductors.
hyperphysics.phy-astr.gsu.edu /hbase/solids/fermi.html   (934 words)

  
 Centenario della nascita di E. Fermi
Fermi was teaching mechanics and mathematics in Florence, as incaricato, a position carrying no tenure or pension privileges.
Fermi and Rasetti were going to let their captured geckos loose in the dining hall for the simple pleasure of scaring the peasant girls who waited on tables.
From subconscious depths came the missing factor Fermi had long sought: no two atoms of a gas can move with exactly the same velocity or, as physicists say, there can be only on atom in each of the quantum states possible for the atoms of a perfect monoatomic gas.
www.fi.infn.it /fermi   (620 words)

  
 Pauli's Exclusion Principle - Cambridge University Press
Since the exclusion principle was born as a phenomenological rule in a period of crisis for the old quantum theory, we need to explain how it could be accredited as an important scientific principle of the new quantum theory (after 1925).
Pauli’s principle was introduced as a tentative rule on mainly phenomenological grounds, within the semi-empirical discipline of spectroscopy, and in a context of revolutionary transition characterized by the waning fortunes of the old quantum theory.
The discovery of some prima facie negative evidence against quarks obeying Pauli’s principle gave rise to two rival research programmes: the parastatistics programme that revoked the strict validity of the exclusion principle for quarks; and quantum chromodynamics that on the contrary reconciled the negative evidence by introducing a further degree of freedom (‘colour’) for quarks.
www.cambridge.org /catalogue/catalogue.asp?isbn=9780521839112&ss=exc   (2990 words)

  
 Enrico Fermi
The book is organized into three parts: three biographical overviews by close colleagues, replete with personal insights; fourteen analyses of Fermi's impact by specialists in their fields, spanning physics, chemistry, mathematics, and engineering; and a year-by-year chronology of Fermi’s scientific endeavors.
Written for a general scientific audience, Enrico Fermi: His Work and Legacy offers a highly readable source on the life of one of the 20th century's most distinguished scientists and a must for everybody interested in the history of modern science.
Fermi was a fine skier and occasionally chastised his Los Alamos colleagues to ski better.
lycos.cs.cmu.edu /info/enrico-fermi.html   (640 words)

  
 PlanetPhysics: Fermion
Since fermions have half-integer spin they obey Fermi-Dirac statistics, which in turn constitues a Pauli Exclusion principle which states that no two fermions can occupy a same quantum mechanical state at the same time in a given quantum mechanical system.
This phenomenon is the sole reason behind fermions being a building block of the "real" world and also for the stability of electron shells in atoms.
This is version 1 of Fermion, born on 2006-06-06.
planetphysics.org /encyclopedia/Fermion.html   (319 words)

  
 A Fermi gas of atoms - physicsworld.com
Once the Fermi gas had reached the quantum regime, we obtained information about it by turning the magnetic trap off, allowing the gas to expand and measuring the shadow of the gas cast by a laser.
The lack of collisions in a single-component Fermi gas of atoms could be exploited for precision measurements of these atoms, while recent experiments on two-component Fermi gases have begun to study the interplay of interactions and quantum statistics in determining behaviour.
Even before Fermi gases of atoms were created in the laboratory, this notion had been explored by theorists such as Marianne Houbiers and Henk Stoof from the University of Utrecht in the Netherlands.
physicsweb.org /articles/world/15/4/7/1   (2962 words)

  
 Exobiology - The origins of life.
Some of those who subscribe to the Fermi principle state that given enough time to develop, the radio transmissions of any sufficiently advanced civilization will begin to outshine their parent star in the radio part of the spectrum.
Some adherents to the Fermi principle state that it is highly unlikely that all advanced civilizations would not eventually take full advantage of the power source of their home star, and in doing so changing the electromagnetic signature of their sun.
This conflict is often called the Fermi paradox, after Enrico Fermi who first publicised the subject, and suggests that our understanding of what is a "conservative" value for some of the parameters may be overly optimistic or that some other factor is involved to suppress the development of intelligent space-faring life.
www.freewebs.com /exobiology   (6750 words)

  
 PhysicsCentral: Energetic Degenerates
At a crucial stage in the cooling, the more energetic atoms are allowed to escape, and collisions among the remaining atoms ordinarily would redistribute their energy to bring the system back into thermal equilibrium at a lower temperature.
In a degenerate Fermi gas, however, the low-energy states are already filled, so if two atoms collide, there are no lower-energy states available for the atoms to go to after the collision and they must stay in the original ones.
A system of identical Fermions is called a “Fermi gas.” If the temperature is low enough, the Fermi gas is “degenerate,” which means the low-lying states are filled up to a well-defined maximum energy, as shown in the diagram.
www.physicscentral.com /explore/action/gas-1.cfm   (512 words)

  
 Nat' Academies Press, Nuclear Physics (1986)
A fundamental symmetry principle governing the nature of physical laws when the spatial coordinates of the system are totally reflected.
The parity principle is obeyed (i.e., nature exhibits no spatial preference) in the strong and electromagnetic interactions, but it appears always to be violated in weak interactions, such as beta decay.
A fundamental symmetry principle gov- erning the nature of physical laws when the direction of the flow of time is considered to be reversed.
www.nap.edu /books/0309035473/html/203.html   (3577 words)

  
 Enrico Fermi
He discovered neutron-induced radioactivity.In 1938, Fermi was awarded Nobel Prize in physics “for his identification of new radioactive elements produced by neutron bombardment and for his discovery of nuclear reaction effected by slow neutrons.” In 1942 Fermi constructed the first nuclear reactor.
Fermi was a great teacher and through the influence of his eminent students, in Italy and the US, Fermi effectively revolutionized the training of physicists.
Fermi was the first to apply Pauli exclusion principle to systems of multiple electrons not attached to atoms.The result was the so-called Fermi-Dirac Statistics, as Dirac also obtained the same conclusion.
www.vigyanprasar.gov.in /scientists/EFermi.htm   (2270 words)

  
 Fermi-Dirac statistics – FREE Fermi-Dirac statistics Information | Encyclopedia.com: Facts, Pictures, Information!
Dependence of electron density on Fermi energy in n-type gallium antimonide.
Experimenting with 40 trillion electron-volts: it takes hundred of physicists several years to design experimental detectors for the Superconducting Super Collider.
In 1940 Fermi produced the first synthetic transuranic element, neptunium.
www.encyclopedia.com /doc/1E1-FermiDir.html   (769 words)

  
 Fermi level and Fermi function
The Fermi energy is the maximum energy occupied by an electron at 0K.
By the Pauli exclusion principle, we know that the electrons will fill all available energy levels, and the top of that "Fermi sea" of electrons is called the Fermi energy or Fermi level.
One of the remarkable things about the Fermi energy is how large it is compared to the energies which electrons could gain by ordinary physical interactions with their environment.
hyperphysics.phy-astr.gsu.edu /hbase/solids/fermi2.html   (575 words)

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