Tuesday, November 23, 2010
Albert Einstein
Albert Einstein (March 14, 1879 – April 18, 1955) was a German-born theoretical physicist who is widely considered to have been one of the greatest physicists of all time. While best known for the theory of relativity (and specifically mass-energy equivalence, E=mc²), he was awarded the 1921 Nobel Prize in Physics for his work on the photoelectric effect. Read more
Saturday, March 10, 2007
Albert Einstein
Albert Einstein (March 14, 1879 – April 18, 1955) was a German-born theoretical physicist who is widely considered to have been one of the greatest physicists of all time. While best known for the theory of relativity (and specifically mass-energy equivalence, E=mc²), he was awarded the 1921 Nobel Prize in Physics for his work on the photoelectric effect.[2]
Einstein's many contributions to physics include his special theory of relativity, which reconciled mechanics with electromagnetism, and his general theory of relativity which extended the principle of relativity to nonuniform motion, creating a new theory of gravitation. His other contributions include relativistic cosmology, capillary action, critical opalescence, classical problems of statistical mechanics and their application to quantum theory, an explanation of the Brownian movement of molecules, atomic transition probabilities, the quantum theory of a monatomic gas, thermal properties of light with low radiation density (which laid the foundation for the photon theory), a theory of radiation including stimulated emission, the conception of a unified field theory, and the geometrization of physics.
In 1999 Einstein was named Time magazine's "Person of the Century". In popular culture the name "Einstein" has become synonymous with genius.
Albert Einstein Tie
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Thursday, March 1, 2007
General relativity
In 1906, the patent office promoted Einstein to Technical Examiner Second Class, but he was not giving up on academia. In 1908, he became a Privatdozent. In the interval he wrote a paper on critical opalescence that described the cumulative effect of light scattered by individual molecules in the atmosphere, i.e. why the sky is blue.[19]
During 1909, Einstein published "Über die Entwicklung unserer Anschauungen über das Wesen und die Konstitution der Strahlung" ("The Development of Our Views on the Composition and Essence of Radiation"), on the quantization of light. In this and in an earlier 1909 paper, Einstein showed that Max Planck's energy quanta must have a well-defined momentum and act in some respects as independent, point-like particles. This paper is the introduction of the "photon" concept (although the term itself was introduced by Gilbert N. Lewis in 1926). Even more importantly, Einstein showed that light must be simultaneously a wave and a particle.
In 1911, Einstein became an associate professor at the Universität Zürich, however shortly afterward he accepted a full professorship at the Univerzita Karlova in Prague, Czechloslovakia. While in Prague, Einstein published a paper challenging astronomers to test a prediction of his nascent theory of relativity: that gravity affected even light, producing a "redshift" that should be measurable during a solar eclipse. German astronomer Erwin Freundlich publicized Einstein's challenge to scientists around the world.[20]
In 1912, Einstein returned to Switzerland to accept a professorship at his alma mater, the ETH. There he met mathematician Marcel Grossmann who introduced him to Riemannian geometry, and at the recommendation of Italian mathematician Tullio Levi-Civita, Einstein began exploring the usefulness of general covariance (essentially the use of tensors) for his gravitational theory. It was at this time that Einstein began to refer to time as the fourth dimension, as H.G. Wells had done in his 1895 novel The Time Machine.
After so many relocations, Mileva established a permanent home with the children in Zurich in 1914, just before the start of World War I. Einstein continued on alone to Germany, accepting a professorship at the Universität unter den Linden in Berlin, where he reapplied for German citizenship. In Berlin he became a member of the Preußische Akademie der Wissenschaften and from 1914 to 1933 he was also the director of the Kaiser-Wilhelm-Gesellschaft for physics.
During World War I the speeches and writings of Central Powers scientists were only available to Central Powers academics for national security reasons. Some of Einstein's work did reach the UK and the USA through the efforts of the Austrian Paul Ehrenfest and physicists in the Netherlands, especially 1902 Nobel Prize-winner Hendrik Lorentz, and Willem de Sitter of the Universiteit Leiden. After the war ended Einstein maintained his relationship with the Universiteit Leiden, accepting a contract as a "buitengewoon hoogleraar"; he travelled to Holland regularly to lecture there between 1920 and 1946.
In 1917, Einstein published an article in Physkalische Zeitschrift that proposed the possibility of stimulated emission, the physical technique that makes possible the laser.[21] He also published a paper that described a cosmological constant, applying the general theory of relativity to the behavior of the entire universe.
1917 was the year astronomers began taking Einstein up on his 1911 challenge from Prague. The Mount Wilson Observatory in California, USA, published a solar spectroscopic analysis that showed no gravitational redshift.[22] In 1918 the Lick Observatory, also in California, announced that they too had disproven Einstein's prediction, although their findings were not published.[23]
However, in May of 1919, a team led by British astronomer Arthur Eddington claimed to have confirmed Einstein's prediction of gravitational deflection of starlight by the Sun while photographing a solar eclipse in Brazil and Principe,[24] and Eddington brought it to the attention of the popular press. On November 7, 1919, leading British newspaper The Times printed a banner headline that read: "Revolution in Science – New Theory of the Universe – Newtonian Ideas Overthrown". In an interview Nobel laureate Max Born praised general relativity as the "greatest feat of human thinking about nature"; fellow laureate Paul Dirac was quoted saying it was "probably the greatest scientific discovery ever made".[25]
In their excitement, the world media made Albert Einstein world-famous. Ironically, later examination of the photographs taken on the Eddington expedition showed that the experimental uncertainty was about the same magnitude as the effect Eddington claimed to have demonstrated. The deflection of light during an eclipse has, however, been more accurately measured (and confirmed) by a number of later observations. There was some resentment toward the newcomer Einstein's fame in the scientific community, notably among German physicists who would later start the Deutsche Physik anti-Einstein movement.[26][27]
Having lived apart for five years, Einstein and Mileva divorced on February 14, 1919. On June 2 of that year Einstein married Elsa Löwenthal, who had nursed him through an illness. Elsa was Albert's first cousin (maternally) and his second cousin (paternally). Together the Einsteins raised Margot and Ilse, Elsa's daughters from her first marriage.
During 1909, Einstein published "Über die Entwicklung unserer Anschauungen über das Wesen und die Konstitution der Strahlung" ("The Development of Our Views on the Composition and Essence of Radiation"), on the quantization of light. In this and in an earlier 1909 paper, Einstein showed that Max Planck's energy quanta must have a well-defined momentum and act in some respects as independent, point-like particles. This paper is the introduction of the "photon" concept (although the term itself was introduced by Gilbert N. Lewis in 1926). Even more importantly, Einstein showed that light must be simultaneously a wave and a particle.
In 1911, Einstein became an associate professor at the Universität Zürich, however shortly afterward he accepted a full professorship at the Univerzita Karlova in Prague, Czechloslovakia. While in Prague, Einstein published a paper challenging astronomers to test a prediction of his nascent theory of relativity: that gravity affected even light, producing a "redshift" that should be measurable during a solar eclipse. German astronomer Erwin Freundlich publicized Einstein's challenge to scientists around the world.[20]
In 1912, Einstein returned to Switzerland to accept a professorship at his alma mater, the ETH. There he met mathematician Marcel Grossmann who introduced him to Riemannian geometry, and at the recommendation of Italian mathematician Tullio Levi-Civita, Einstein began exploring the usefulness of general covariance (essentially the use of tensors) for his gravitational theory. It was at this time that Einstein began to refer to time as the fourth dimension, as H.G. Wells had done in his 1895 novel The Time Machine.
After so many relocations, Mileva established a permanent home with the children in Zurich in 1914, just before the start of World War I. Einstein continued on alone to Germany, accepting a professorship at the Universität unter den Linden in Berlin, where he reapplied for German citizenship. In Berlin he became a member of the Preußische Akademie der Wissenschaften and from 1914 to 1933 he was also the director of the Kaiser-Wilhelm-Gesellschaft for physics.
During World War I the speeches and writings of Central Powers scientists were only available to Central Powers academics for national security reasons. Some of Einstein's work did reach the UK and the USA through the efforts of the Austrian Paul Ehrenfest and physicists in the Netherlands, especially 1902 Nobel Prize-winner Hendrik Lorentz, and Willem de Sitter of the Universiteit Leiden. After the war ended Einstein maintained his relationship with the Universiteit Leiden, accepting a contract as a "buitengewoon hoogleraar"; he travelled to Holland regularly to lecture there between 1920 and 1946.
In 1917, Einstein published an article in Physkalische Zeitschrift that proposed the possibility of stimulated emission, the physical technique that makes possible the laser.[21] He also published a paper that described a cosmological constant, applying the general theory of relativity to the behavior of the entire universe.
1917 was the year astronomers began taking Einstein up on his 1911 challenge from Prague. The Mount Wilson Observatory in California, USA, published a solar spectroscopic analysis that showed no gravitational redshift.[22] In 1918 the Lick Observatory, also in California, announced that they too had disproven Einstein's prediction, although their findings were not published.[23]
However, in May of 1919, a team led by British astronomer Arthur Eddington claimed to have confirmed Einstein's prediction of gravitational deflection of starlight by the Sun while photographing a solar eclipse in Brazil and Principe,[24] and Eddington brought it to the attention of the popular press. On November 7, 1919, leading British newspaper The Times printed a banner headline that read: "Revolution in Science – New Theory of the Universe – Newtonian Ideas Overthrown". In an interview Nobel laureate Max Born praised general relativity as the "greatest feat of human thinking about nature"; fellow laureate Paul Dirac was quoted saying it was "probably the greatest scientific discovery ever made".[25]
In their excitement, the world media made Albert Einstein world-famous. Ironically, later examination of the photographs taken on the Eddington expedition showed that the experimental uncertainty was about the same magnitude as the effect Eddington claimed to have demonstrated. The deflection of light during an eclipse has, however, been more accurately measured (and confirmed) by a number of later observations. There was some resentment toward the newcomer Einstein's fame in the scientific community, notably among German physicists who would later start the Deutsche Physik anti-Einstein movement.[26][27]
Having lived apart for five years, Einstein and Mileva divorced on February 14, 1919. On June 2 of that year Einstein married Elsa Löwenthal, who had nursed him through an illness. Elsa was Albert's first cousin (maternally) and his second cousin (paternally). Together the Einsteins raised Margot and Ilse, Elsa's daughters from her first marriage.
Monday, January 2, 2006
The Annus Mirabilis
Main article: Annus Mirabilis Papers
In 1905, while working in the patent office, Einstein published four times in the Annalen der Physik. These are the papers that history has come to call the "Annus Mirabilis Papers":
"On a Heuristic Viewpoint Concerning the Production and Transformation of Light" on the photoelectric effect (completed March 17)
"On the Motion Required by the Molecular Kinetic Theory of Heat of Small Particles Suspended in a Stationary Liquid" on Brownian motion (received by Annalen der Physik May 11)
"On the Electrodynamics of Moving Bodies" on special relativity (received by Annalen der Physik June 30)
"Does the Inertia of a Body Depend Upon Its Energy Content?" on equivalence of matter and energy (received by Annalen der Physik September 27, 1905)[17]
At the age of 26, having studied under Alfred Kleiner, Professor of Experimental Physics, Einstein was awarded a PhD by the University of Zurich. His dissertation was entitled "Eine neue Bestimmung der Moleküldimensionen" ("A new determination of molecular dimensions"); it was completed April 30, 1905 and accepted in July.[18]
In 1905, while working in the patent office, Einstein published four times in the Annalen der Physik. These are the papers that history has come to call the "Annus Mirabilis Papers":
"On a Heuristic Viewpoint Concerning the Production and Transformation of Light" on the photoelectric effect (completed March 17)
"On the Motion Required by the Molecular Kinetic Theory of Heat of Small Particles Suspended in a Stationary Liquid" on Brownian motion (received by Annalen der Physik May 11)
"On the Electrodynamics of Moving Bodies" on special relativity (received by Annalen der Physik June 30)
"Does the Inertia of a Body Depend Upon Its Energy Content?" on equivalence of matter and energy (received by Annalen der Physik September 27, 1905)[17]
At the age of 26, having studied under Alfred Kleiner, Professor of Experimental Physics, Einstein was awarded a PhD by the University of Zurich. His dissertation was entitled "Eine neue Bestimmung der Moleküldimensionen" ("A new determination of molecular dimensions"); it was completed April 30, 1905 and accepted in July.[18]
Sunday, January 1, 2006
Youth and schooling
His parents worried about his intellectual development because of initial language delay and speech difficulties until the age of nine, although he was a top student in elementary school.[4] Thomas Sowell used Einstein's name for a book on such children.[5]
In 1880, the family moved to Munich where his father and his uncle founded a company, Elektrotechnische Fabrik J. Einstein & Cie, that manufactured electrical equipment, providing the first lighting for the Oktoberfest and cabling for the Munich suburb of Schwabing. The Einstein family was not strictly observant, and Albert attended a Catholic elementary school. At his mother's insistence he took violin lessons, and although he disliked them and eventually quit he would later take great pleasure in Mozart's violin sonatas.
When Albert was five, his father showed him a pocket compass. Albert saw that something in empty space was moving the needle and later described the experience as one of the most revelatory of his life. As he grew Albert built models and mechanical devices for fun, and began to show a talent for mathematics.
In 1889, a family friend named Max Talmud, a medical student,[6] introduced the ten-year-old Albert to key science and philosophy texts, including Kant's Critique of Pure Reason and Euclid's Elements (Einstein called it the "holy little geometry book").[6] From Euclid Albert began to understand deductive reasoning (integral to theoretical physics), and at the age of twelve he learned Euclidean geometry from a school booklet. He soon began to investigate calculus.
In his early teens Albert attended the new and progressive Luitpold Gymnasium. His father intended for him to pursue electrical engineering but Albert clashed with authorities and resented the school regimen. He later wrote that the spirit of learning and creative thought were lost in strict rote learning.
In 1894, when Einstein was fifteen, his father's business failed and the Einstein family moved to Italy, first to Milan and then after a few months to Pavia. During this time Albert wrote his first "scientific work", "The Investigation of the State of Aether in Magnetic Fields".[7] Albert had been left behind in Munich to finish high school but in the spring of 1895 he withdrew, convincing the school to let him go by using a doctor's note, to join his family in Pavia.
Rather than completing high school Albert decided to apply directly to the Eidgenössische Technische Hochschule Zürich (ETH), the Federal Polytechnic Institute in Zurich, Switzerland. Without a school certificate he was required to take an entrance examination. He did not pass. Einstein wrote that it was in that same year, at age 16, that he first performed his famous thought experiment, visualizing travelling alongside a beam of light.
The Einsteins sent Albert to Aarau, Switzerland to finish secondary school. While lodging with the family of Professor Jost Winteler, he fell in love with the family's daughter, Sofia Marie-Jeanne Amanda Winteler, called "Marie". (Albert's sister, Maja, his confidant, later married Paul Winteler.)[8] In Aarau Albert studied Maxwell's electromagnetic theory. In 1896 he graduated at age 17, renounced German citizenship to avoid military service (with his father's approval), and finally enrolled in the mathematics program at ETH. On February 21, 1901, he gained Swiss citizenship, which he never revoked. [9] Marie moved to Olsberg, Switzerland for a teaching post.
In 1896, Mileva Marić also enrolled at ETH, the only woman studying Mathematics. During the next few years Einstein and Marić's friendship developed into romance. Einstein's mother objected because she thought Marić too old, not Jewish and "physically defective".[10] Einstein and Marić had a daughter, Lieserl Einstein, born in January 1902. Her fate is unknown.
In 1900, Einstein's friend Michele Besso introduced him to the work of Ernst Mach. That year Einstein published a paper in the prestigious Annalen der Physik entitled "Folgerungen aus den Capillaritätserscheinungen" ("Consequences of the observations of capillarity phenomena"), on the capillary forces of a straw [11]. He graduated from ETH with a teaching diploma.
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