
Near the
beginning of his career, Einstein thought that Newtonian mechanics was no
longer enough to reconcile the laws of classical mechanics with the laws of the
electromagnetic field. This led to the development of his special theory of
relativity. He realized, however, that the principle of relativity could also
be extended to gravitational fields, and with his subsequent theory of
gravitation in 1916, he published a paper on the general theory of relativity.
He continued to deal with problems of statistical mechanics and quantum theory,
which led to his explanations of particle theory and the motion of molecules.
He also investigated the thermal properties of light which laid the foundation
of the photon theory of light. In 1917, Einstein applied the general theory of
relativity to model the structure of the universe as a whole.
He was visiting
the United States when Adolf Hitler came to power in 1933, and did not go back
to Germany, where he had been a professor at the Berlin Academy of Sciences. He
settled in the U.S., becoming a citizen in 1940. On the eve of World War II, he
helped alert President Franklin D. Roosevelt that Germany might be developing
an atomic weapon, and recommended that the U.S. begin similar research; this
eventually led to what would become the Manhattan Project. Einstein was in
support of defending the Allied forces, but largely denounced using the new
discovery of nuclear fission as a weapon. Later, together with Bertrand
Russell, Einstein signed the Russell–Einstein Manifesto, which highlighted the
danger of nuclear weapons. Einstein was affiliated with the Institute for
Advanced Study in Princeton, New Jersey, until his death in 1955.
Einstein
published more than 300 scientific papers along with over 150 non-scientific
works. His great intelligence and originality have made the word
"Einstein" synonymous with genius.
Biography
Early life and
education
Einstein at the
age of three in 1882
Albert Einstein
in 1893 (age 14)
Einstein's
matriculation certificate at the age of 17, showing his final grades from the
Aargau Kantonsschule (on a scale of 1-6).
Albert Einstein
was born in Ulm, in the Kingdom of Württemberg in the German Empire on 14 March
1879. His father was Hermann Einstein, a salesman and engineer. His mother was
Pauline Einstein (née Koch). In 1880, the family moved to Munich, where his
father and his uncle founded Elektrotechnische Fabrik J. Einstein & Cie, a
company that manufactured electrical equipment based on direct current.
The Einsteins
were non-observant Jews. Albert attended a Catholic elementary school from the
age of five for three years. Later, at the age of eight, Einstein was
transferred to the Luitpold Gymnasium where he received advanced primary and
secondary school education until he left Germany seven years later. Although it
has been thought that Einstein had early speech difficulties, this is disputed
by the Albert Einstein Archives, and he excelled at the first school that he
attended.
His father once
showed him a pocket compass; Einstein realized that there must be something
causing the needle to move, despite the apparent "empty space". As he
grew, Einstein built models and mechanical devices for fun and began to show a
talent for mathematics. When Einstein was ten years old Max Talmud (later changed
to Max Talmey), a poor Jewish medical student from Poland, was introduced to
the Einstein family by his brother, and during weekly visits over the next five
years he gave the boy popular books on science, mathematical texts and
philosophical writings. These included Immanuel Kant's Critique of Pure Reason
and Euclid's Elements (which Einstein called the "holy little geometry
book").
In 1894, his
father's company failed: direct current (DC) lost the War of Currents to
alternating current (AC). In search of business, the Einstein family moved to
Italy, first to Milan and then, a few months later, to Pavia. When the family
moved to Pavia, Einstein stayed in Munich to finish his studies at the Luitpold
Gymnasium. His father intended for him to pursue electrical engineering, but
Einstein clashed with authorities and resented the school's regimen and
teaching method. He later wrote that the spirit of learning and creative
thought were lost in strict rote learning. At the end of December 1894 he
travelled to Italy to join his family in Pavia, convincing the school to let
him go by using a doctor's note. It was during his time in Italy that he wrote
a short essay with the title "On the Investigation of the State of the
Ether in a Magnetic Field."
In late summer
1895, at the age of sixteen, Einstein sat the entrance examinations for the
Swiss Federal Polytechnic in Zurich (later the Eidgenössische Polytechnische
Schule). He failed to reach the required standard in several subjects, but
obtained exceptional grades in physics and mathematics. On the advice of the
Principal of the Polytechnic, he attended the Aargau Cantonal School in Aarau,
Switzerland, in 1895-96 to complete his secondary schooling. While lodging with
the family of Professor Jost Winteler, he fell in love with Winteler's
daughter, Marie. (His sister Maja later married the Wintelers' son, Paul.) In
January 1896, with his father's approval, he renounced his citizenship in the
German Kingdom of Württemberg to avoid military service. In September 1896 he
passed the Swiss Matura with mostly good grades (gaining maximum grade 6 in
physics and mathematical subjects, on a scale 1-6), and though still only
seventeen he enrolled in the four year mathematics and physics teaching diploma
program at the Zurich Polytechnic. Marie Winteler moved to Olsberg, Switzerland
for a teaching post.
Einstein's future
wife, Mileva Marić, also enrolled at the Polytechnic that same year, the only
woman among the six students in the mathematics and physics section of the
teaching diploma course. Over the next few years, Einstein and Marić's
friendship developed into romance, and they read books together on
extra-curricular physics in which Einstein was taking an increasing interest.
In 1900 Einstein was awarded the Zurich Polytechnic teaching diploma, but Marić
failed the examination with a poor grade in the mathematics component, theory
of functions. There have been claims that Marić collaborated with Einstein on
his celebrated 1905 papers, but historians of physics who have studied the
issue find no evidence that she made any substantive contributions.
Marriages and
children
Main article:
Einstein family
In early 1902,
Einstein and Mileva Marić (Милева Марић) had a daughter they named Lieserl in
their correspondence, who was born in Novi Sad where Marić's parents lived. Her
full name is not known, and her fate is uncertain after 1903.
Einstein and
Marić married in January 1903. In May 1904, the couple's first son, Hans Albert
Einstein, was born in Bern, Switzerland. Their second son, Eduard, was born in
Zurich in July 1910. In 1914, Einstein moved to Berlin, while his wife remained
in Zurich with their sons. Marić and Einstein divorced on 14 February 1919,
having lived apart for five years.
Einstein married
Elsa Löwenthal (née Einstein) on 2 June 1919, after having had a relationship
with her since 1912. She was his first cousin maternally and his second cousin
paternally. In 1933, they emigrated permanently to the United States. In 1935,
Elsa Einstein was diagnosed with heart and kidney problems and died in December
1936.
After graduating,
Einstein spent almost two frustrating years searching for a teaching post, but
a former classmate's father helped him secure a job in Bern, at the Federal
Office for Intellectual Property, the patent office, as an assistant examiner.
He evaluated patent applications for electromagnetic devices. In 1903,
Einstein's position at the Swiss Patent Office became permanent, although he
was passed over for promotion until he "fully mastered machine
technology".
Much of his work
at the patent office related to questions about transmission of electric
signals and electrical-mechanical synchronization of time, two technical
problems that show up conspicuously in the thought experiments that eventually
led Einstein to his radical conclusions about the nature of light and the
fundamental connection between space and time.
With a few
friends he met in Bern, Einstein started a small discussion group,
self-mockingly named "The Olympia Academy", which met regularly to
discuss science and philosophy. Their readings included the works of Henri
Poincaré, Ernst Mach, and David Hume, which influenced his scientific and
philosophical outlook.
Einstein's
official 1921 portrait after receiving the Nobel Prize in Physics.
During 1901, the
paper "Folgerungen aus den Kapillarität Erscheinungen"
("Conclusions from the Capillarity Phenomena") was published in the
prestigious Annalen der Physik. On 30 April 1905, Einstein completed his
thesis, with Alfred Kleiner, Professor of Experimental Physics, serving as
pro-forma advisor. Einstein was awarded a PhD by the University of Zurich. His
dissertation was entitled "A New Determination of Molecular
Dimensions". That same year, which has been called Einstein's annus
mirabilis (miracle year), he published four groundbreaking papers, on the
photoelectric effect, Brownian motion, special relativity, and the equivalence
of matter and energy, which were to bring him to the notice of the academic
world.
By 1908, he was
recognized as a leading scientist, and he was appointed lecturer at the
University of Bern. The following year, he quit the patent office and the
lectureship to take the position of physics docent at the University of Zurich.
He became a full professor at Karl-Ferdinand University in Prague in 1911. In
1914, he returned to Germany after being appointed director of the Kaiser
Wilhelm Institute for Physics (1914–1932) and a professor at the Humboldt
University of Berlin, with a special clause in his contract that freed him from
most teaching obligations. He became a member of the Prussian Academy of
Sciences. In 1916, Einstein was appointed president of the German Physical
Society (1916–1918).
During 1911, he
had calculated that, based on his new theory of general relativity, light from
another star would be bent by the Sun's gravity. That prediction was claimed
confirmed by observations made by a British expedition led by Sir Arthur
Eddington during the solar eclipse of 29 May 1919. International media reports
of this made Einstein world famous. On 7 November 1919, the leading British
newspaper The Times printed a banner headline that read: "Revolution in
Science – New Theory of the Universe – Newtonian Ideas Overthrown". (Much
later, questions were raised whether the measurements had been accurate enough
to support Einstein's theory).
In 1921, Einstein
was awarded the Nobel Prize in Physics for his explanation of the photoelectric
effect, as relativity was considered still somewhat controversial. He also received
the Copley Medal from the Royal Society in 1925.
Travels abroad
Einstein visited
New York City for the first time on 2 April 1921, where he received an official
welcome by the Mayor, followed by three weeks of lectures and receptions. He
went on to deliver several lectures at Columbia University and Princeton
University, and in Washington he accompanied representatives of the National
Academy of Science on a visit to the White House. On his return to Europe he
was the guest of the British statesman and philosopher Viscount Haldane in
London, where he met several renowned scientific, intellectual and political
figures, and delivered a lecture at Kings College.
In 1922, he
traveled throughout Asia and later to Palestine, as part of a six-month
excursion and speaking tour. His travels included Singapore, Ceylon, and Japan,
where he gave a series of lectures to thousands of Japanese. His first lecture
in Tokyo lasted four hours, after which he met the emperor and empress at the
Imperial Palace where thousands came to watch. Einstein later gave his
impressions of the Japanese in a letter to his sons: "Of all the people I
have met, I like the Japanese most, as they are modest, intelligent,
considerate, and have a feel for art."
On his return
voyage, he also visited Palestine for 12 days in what would become his only
visit to that region. "He was greeted with great British pomp, as if he
were a head of state rather than a theoretical physicist", writes
Isaacson. This included a cannon salute upon his arrival at the residence of
the British high commissioner, Sir Herbert Samuel. During one reception given
to him, the building was "stormed by throngs who wanted to hear him".
In Einstein's talk to the audience, he expressed his happiness over the event:
I consider this
the greatest day of my life. Before, I have always found something to regret in
the Jewish soul, and that is the forgetfulness of its own people. Today, I have
been made happy by the sight of the Jewish people learning to recognize
themselves and to make themselves recognized as a force in the world..
Love of music
Einstein
developed an appreciation of music at an early age. His mother played the piano
reasonably well and wanted her son to learn the violin, not only to instill in
him a love of music but also to help him assimilate within German culture.
According to conductor Leon Botstein, Einstein is said to have begun playing
when he was five, but didn't enjoy trying to learn it at that age.
When he turned
thirteen, however, he discovered the violin sonatas of Mozart. "Einstein
fell in love" with Mozart's music, notes Botstein, and learned to play
music more willingly. According to Einstein, he taught himself to play by
"ever practicing systematically," adding that "Love is a better
teacher than a sense of duty." At age seventeen, he was heard by a school
examiner in Aarau as he played Beethoven's violin sonatas, the examiner stating
afterward that his playing was "remarkable and revealing of 'great
insight.'" What struck the examiner, writes Botstein, was that Einstein
"displayed a deep love of the music, a quality that was and remains in
short supply. Music possessed an unusual meaning for this student."
Botstein notes
that music assumed a pivotal and permanent role in Einstein's life from that
period on. Although the idea of becoming a professional was not on his mind at
any time, he did play chamber music with others, and performed for private
audiences and friends. Chamber music also became a regular part of his social
life while living in Bern, Zurich, and Berlin, where he played with Max Planck
and his son, among others. Near the end of his life, while living in Princeton,
the young Juilliard Quartet visited him and he joined them playing his violin,
although they slowed the tempo to accommodate his lesser abilities. However,
notes Botstein, the quartet was "impressed by Einstein's level of
coordination and intonation."
Emigration
Cartoon of
Einstein, who has shed his "Pacifism" wings, standing next to a
pillar labeled "World Peace." He is rolling up his sleeves and
holding a sword labeled "Preparedness" (circa 1933).
In 1933, Einstein
decided to emigrate to the United States due to the rise to power of the Nazis
under Germany's new chancellor, Adolf Hitler. While visiting American
universities in April, 1933, he learned that the new German government had
passed a law barring Jews from holding any official positions, including
teaching at universities. A month later, the Nazi book burnings occurred, with
Einstein's works being among those burnt, and Nazi propaganda minister Joseph
Goebbels proclaimed, "Jewish intellectualism is dead." Einstein also
learned that his name was on a list of assassination targets, with a
"$5,000 bounty on his head." One German magazine included him in a
list of enemies of the German regime with the phrase, "not yet
hanged".
Einstein was
undertaking his third two-month visiting professorship at the California
Institute of Technology when Hitler came to power in Germany. On his return to
Europe in March 1933 he resided in Belgium for some months, before temporarily
moving to England.
He took up a
position at the Institute for Advanced Study at Princeton, New Jersey, an
affiliation that lasted until his death in 1955. He was one of the four first
selected (two of the others being John von Neumann and Kurt Gödel). At the
institute, he soon developed a close friendship with Gödel. The two would take
long walks together discussing their work. His last assistant was Bruria
Kaufman, who later became a renowned physicist. During this period, Einstein
tried to develop a unified field theory and to refute the accepted
interpretation of quantum physics, both unsuccessfully.
Other scientists
also fled to America. Among them were Nobel laureates and professors of
theoretical physics. With so many other Jewish scientists now forced by
circumstances to live in America, often working side by side, Einstein wrote to
a friend, "For me the most beautiful thing is to be in contact with a few
fine Jews—a few millennia of a civilized past do mean something after
all." In another letter he writes, "In my whole life I have never
felt so Jewish as now."
World War II and
the Manhattan Project
In 1939, a group
of Hungarian scientists that included emigre physicist Leó Szilárd attempted to
alert Washington of ongoing Nazi atomic bomb research. The group's warnings were
discounted. Einstein and Szilárd, along with other refugees such as Edward
Teller and Eugene Wigner, "regarded it as their responsibility to alert
Americans to the possibility that German scientists might win the race to build
an atomic bomb, and to warn that Hitler would be more than willing to resort to
such a weapon." In the summer of 1939, a few months before the beginning
of World War II in Europe, Einstein was persuaded to lend his prestige by
writing a letter with Szilárd to President Franklin D. Roosevelt to alert him
of the possibility. The letter also recommended that the U.S. government pay
attention to and become directly involved in uranium research and associated
chain reaction research.
The letter is
believed to be "arguably the key stimulus for the U.S. adoption of serious
investigations into nuclear weapons on the eve of the U.S. entry into World War
II". President Roosevelt could not take the risk of allowing Hitler to
possess atomic bombs first. As a result of Einstein's letter and his meetings
with Roosevelt, the U.S. entered the "race" to develop the bomb,
drawing on its "immense material, financial, and scientific
resources" to initiate the Manhattan Project. It became the only country
to successfully develop an atomic bomb during World War II.
For Einstein,
"war was a disease . . . [and] he called for resistance to war." But
in 1933, after Hitler assumed full power in Germany, "he renounced
pacifism altogether . . . In fact, he urged the Western powers to prepare
themselves against another German onslaught." In 1954, a year before his
death, Einstein said to his old friend, Linus Pauling, "I made one great
mistake in my life — when I signed the letter to President Roosevelt
recommending that atom bombs be made; but there was some justification — the
danger that the Germans would make them..."
Einstein became
an American citizen in 1940. Not long after settling into his career at
Princeton, he expressed his appreciation of the "meritocracy" in American
culture when compared to Europe. According to Isaacson, he recognized the
"right of individuals to say and think what they pleased", without
social barriers, and as result, the individual was "encouraged" to be
more creative, a trait he valued from his own early education. Einstein writes:
What makes the
new arrival devoted to this country is the democratic trait among the people.
No one humbles himself before another person or class. . . American youth has
the good fortune not to have its outlook troubled by outworn traditions.
As a member of
the National Association for the Advancement of Colored People (NAACP) at
Princeton who campaigned for the civil rights of African Americans, Einstein
corresponded with civil rights activist W. E. B. Du Bois, and in 1946 Einstein
called racism America's "worst disease". He later stated, "Race
prejudice has unfortunately become an American tradition which is uncritically
handed down from one generation to the next. The only remedies are enlightenment
and education".
After the death
of Israel's first president, Chaim Weizmann, in November 1952, Prime Minister
David Ben-Gurion offered Einstein the position of President of Israel, a mostly
ceremonial post. The offer was presented by Israel's ambassador in Washington,
Abba Eban, who explained that the offer "embodies the deepest respect
which the Jewish people can repose in any of its sons". However, Einstein
declined, and wrote in his response that he was "deeply moved", and
"at once saddened and ashamed" that he could not accept it:
All my life I
have dealt with objective matters, hence I lack both the natural aptitude and
the experience to deal properly with people and to exercise official function.
I am the more distressed over these circumstances because my relationship with
the Jewish people became my strongest human tie once I achieved complete
clarity about our precarious position among the nations of the world.
The New York
World-Telegram announces Einstein's death on 18 April 1955.
On 17 April 1955,
Albert Einstein experienced internal bleeding caused by the rupture of an
abdominal aortic aneurysm, which had previously been reinforced surgically by
Dr. Rudolph Nissen in 1948. He took the draft of a speech he was preparing for
a television appearance commemorating the State of Israel's seventh anniversary
with him to the hospital, but he did not live long enough to complete it.
Einstein refused surgery, saying: "I want to go when I want. It is
tasteless to prolong life artificially. I have done my share, it is time to go.
I will do it elegantly." He died in Princeton Hospital early the next
morning at the age of 76, having continued to work until near the end.
During the
autopsy, the pathologist of Princeton Hospital, Thomas Stoltz Harvey, removed
Einstein's brain for preservation without the permission of his family, in the
hope that the neuroscience of the future would be able to discover what made
Einstein so intelligent. Einstein's remains were cremated and his ashes were
scattered at an undisclosed location.
In his lecture at
Einstein's memorial, nuclear physicist Robert Oppenheimer summarized his
impression of him as a person: "He was almost wholly without
sophistication and wholly without worldliness . . . There was always with him a
wonderful purity at once childlike and profoundly stubborn."
The photoelectric
effect. Incoming photons on the left strike a metal plate (bottom), and eject
electrons, depicted as flying off to the right.
Throughout his
life, Einstein published hundreds of books and articles. In addition to the
work he did by himself he also collaborated with other scientists on additional
projects including the Bose–Einstein statistics, the Einstein refrigerator and
others.
1905 - Annus
Mirabilis papers
Main articles:
Annus Mirabilis papers, Photoelectric effect, Special theory of relativity, and
Mass–energy equivalence
The Annus
Mirabilis papers are four articles pertaining to the photoelectric effect
(which gave rise to quantum theory), Brownian motion, the special theory of
relativity, and E = mc that Albert Einstein published in the Annalen der Physik
scientific journal in 1905. These four works contributed substantially to the
foundation of modern physics and changed views on space, time, and matter. The
four papers are:
Title
(translated) Area of focus Received Published Significance
On a Heuristic
Viewpoint Concerning the Production and Transformation of Light Photoelectric effect 18 March 9 June Resolved an unsolved puzzle by
suggesting that energy is exchanged only in discrete amounts (quanta). This
idea was pivotal to the early development of quantum theory.
On the Motion of
Small Particles Suspended in a Stationary Liquid, as Required by the Molecular
Kinetic Theory of Heat Brownian
motion 11 May 18 July Explained
empirical evidence for the atomic theory, supporting the application of
statistical physics.
On the
Electrodynamics of Moving Bodies Special
relativity 30 June 26 Sept Reconciled Maxwell's equations for electricity and
magnetism with the laws of mechanics by introducing major changes to mechanics
close to the speed of light, resulting from analysis based on empirical
evidence that the speed of light is independent of the motion of the observer.
Discredited the concept of an "luminiferous ether."
Does the Inertia
of a Body Depend Upon Its Energy Content? Matter–energy
equivalence 27 Sept 21 Nov Equivalence
of matter and energy, E = mc (and by implication, the ability of gravity to
"bend" light), the existence of "rest energy", and the
basis of nuclear energy.
Thermodynamic
fluctuations and statistical physics
Main articles:
Statistical mechanics, thermal fluctuations, and statistical physics
Albert Einstein's
first paper submitted in 1900 to Annalen der Physik was on capillary
attraction. It was published in 1901 with the title "Folgerungen aus den
Kapillarität Erscheinungen," which translates as "Conclusions from
the capillarity phenomena". Two papers he published in 1902–1903
(thermodynamics) attempted to interpret atomic phenomena from a statistical
point of view. These papers were the foundation for the 1905 paper on Brownian
motion, which showed that Brownian movement can be construed as firm evidence
that molecules exist. His research in 1903 and 1904 was mainly concerned with
the effect of finite atomic size on diffusion phenomena.
General
principles
He articulated
the principle of relativity. This was understood by Hermann Minkowski to be a
generalization of rotational invariance from space to space-time. Other
principles postulated by Einstein and later vindicated are the principle of
equivalence and the principle of adiabatic invariance of the quantum number.
Theory of
relativity and
Main article:
History of special relativity
Einstein's
"Zur Elektrodynamik bewegter Körper" ("On the Electrodynamics of
Moving Bodies") was received on 30 June 1905 and published 26 September of
that same year. It reconciles Maxwell's equations for electricity and magnetism
with the laws of mechanics, by introducing major changes to mechanics close to
the speed of light. This later became known as Einstein's special theory of
relativity.
Consequences of
this include the time-space frame of a moving body appearing to slow down and
contract (in the direction of motion) when measured in the frame of the
observer. This paper also argued that the idea of a luminiferous aether – one
of the leading theoretical entities in physics at the time – was superfluous.
In his paper on
mass–energy equivalence Einstein produced E = mc from his special relativity
equations. Einstein's 1905 work on relativity remained controversial for many
years, but was accepted by leading physicists, starting with Max Planck.
Photons and
energy quanta
Main articles:
Photon and Quantum
In a 1905 paper,
Einstein postulated that light itself consists of localized particles (quanta).
Einstein's light quanta were nearly universally rejected by all physicists,
including Max Planck and Niels Bohr. This idea only became universally accepted
in 1919, with Robert Millikan's detailed experiments on the photoelectric
effect, and with the measurement of Compton scattering.
Einstein
concluded that each wave of frequency f is associated with a collection of
photons with energy hf each, where h is Planck's constant. He does not say much
more, because he is not sure how the particles are related to the wave. But he
does suggest that this idea would explain certain experimental results, notably
the photoelectric effect.
Quantized atomic
vibrations
Main article:
Einstein solid
In 1907 Einstein
proposed a model of matter where each atom in a lattice structure is an
independent harmonic oscillator. In the Einstein model, each atom oscillates
independently – a series of equally spaced quantized states for each
oscillator. Einstein was aware that getting the frequency of the actual
oscillations would be different, but he nevertheless proposed this theory
because it was a particularly clear demonstration that quantum mechanics could
solve the specific heat problem in classical mechanics. Peter Debye refined
this model.
Adiabatic
principle and action-angle variables
Main article: Old
quantum theory
Throughout the
1910s, quantum mechanics expanded in scope to cover many different systems.
After Ernest Rutherford discovered the nucleus and proposed that electrons
orbit like planets, Niels Bohr was able to show that the same quantum
mechanical postulates introduced by Planck and developed by Einstein would
explain the discrete motion of electrons in atoms, and the periodic table of
the elements.
Einstein
contributed to these developments by linking them with the 1898 arguments
Wilhelm Wien had made. Wien had shown that the hypothesis of adiabatic
invariance of a thermal equilibrium state allows all the blackbody curves at
different temperature to be derived from one another by a simple shifting
process. Einstein noted in 1911 that the same adiabatic principle shows that
the quantity which is quantized in any mechanical motion must be an adiabatic
invariant. Arnold Sommerfeld identified this adiabatic invariant as the action
variable of classical mechanics. The law that the action variable is quantized
was a basic principle of the quantum theory as it was known between 1900 and
1925.
Wave–particle
duality
Einstein at the
Solvay Conference in 1911
Main article:
Wave–particle duality
Although the
patent office promoted Einstein to Technical Examiner Second Class in 1906, he
had not given up on academia. In 1908, he became a privatdozent at the
University of Bern. In "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, and in an earlier 1909 paper, Einstein showed that Max Planck's
energy quanta must have well-defined momenta and act in some respects as
independent, point-like particles. This paper introduced the photon concept
(although the name photon was introduced later by Gilbert N. Lewis in 1926) and
inspired the notion of wave–particle duality in quantum mechanics.
Theory of
critical opalescence
Main article:
Critical opalescence
Einstein returned
to the problem of thermodynamic fluctuations, giving a treatment of the density
variations in a fluid at its critical point. Ordinarily the density
fluctuations are controlled by the second derivative of the free energy with
respect to the density. At the critical point, this derivative is zero, leading
to large fluctuations. The effect of density fluctuations is that light of all
wavelengths is scattered, making the fluid look milky white. Einstein relates
this to Raleigh scattering, which is what happens when the fluctuation size is
much smaller than the wavelength, and which explains why the sky is blue.
Einstein quantitatively derived critical opalescence from a treatment of
density fluctuations, and demonstrated how both the effect and Rayleigh
scattering originate from the atomistic constitution of matter.
Zero-point energy
Main article:
Zero-point energy
Einstein's
physical intuition led him to note that Planck's oscillator energies had an
incorrect zero point. He modified Planck's hypothesis by stating that the
lowest energy state of an oscillator is equal to ⁄2hf, to half the energy
spacing between levels. This argument, which was made in 1913 in collaboration
with Otto Stern, was based on the thermodynamics of a diatomic molecule which
can split apart into two free atoms.
General
relativity and the Equivalence Principle
Main article:
History of general relativity
See also:
Principle of equivalence, Theory of relativity, and Einstein field equations
Eddington’s
photograph of a solar eclipse.
General
relativity (GR) is a theory of gravitation that was developed by Albert
Einstein between 1907 and 1915. According to general relativity, the observed
gravitational attraction between masses results from the warping of space and
time by those masses. General relativity has developed into an essential tool
in modern astrophysics. It provides the foundation for the current understanding
of black holes, regions of space where gravitational attraction is so strong
that not even light can escape.
As Albert
Einstein later said, the reason for the development of general relativity was
that the preference of inertial motions within special relativity was
unsatisfactory, while a theory which from the outset prefers no state of motion
(even accelerated ones) should appear more satisfactory. So in 1908 he
published an article on acceleration under special relativity. In that article,
he argued that free fall is really inertial motion, and that for a freefalling
observer the rules of special relativity must apply. This argument is called
the Equivalence principle. In the same article, Einstein also predicted the
phenomenon of gravitational time dilation. In 1911, Einstein published another
article expanding on the 1907 article, in which additional effects such as the
deflection of light by massive bodies were predicted.
Hole argument and
Entwurf theory
Main article:
Hole argument
While developing
general relativity, Einstein became confused about the gauge invariance in the
theory. He formulated an argument that led him to conclude that a general
relativistic field theory is impossible. He gave up looking for fully generally
covariant tensor equations, and searched for equations that would be invariant
under general linear transformations only.
In June, 1913 the
Entwurf ("draft") theory was the result of these investigations. As
its name suggests, it was a sketch of a theory, with the equations of motion
supplemented by additional gauge fixing conditions. Simultaneously less elegant
and more difficult than general relativity, after more than two years of
intensive work Einstein abandoned the theory in November, 1915 after realizing
that the hole argument was mistaken.
Cosmology
Main article:
Cosmology
In 1917, Einstein
applied the General theory of relativity to model the structure of the universe
as a whole. He wanted the universe to be eternal and unchanging, but this type
of universe is not consistent with relativity. To fix this, Einstein modified
the general theory by introducing a new notion, the cosmological constant. With
a positive cosmological constant, the universe could be an eternal static
sphere.
Einstein in his
office at the University of Berlin.
Einstein believed
a spherical static universe is philosophically preferred, because it would obey
Mach's principle. He had shown that general relativity incorporates Mach's
principle to a certain extent in frame dragging by gravitomagnetic fields, but
he knew that Mach's idea would not work if space goes on forever. In a closed
universe, he believed that Mach's principle would hold. Mach's principle has
generated much controversy over the years.
Modern quantum
theory
Main article:
Schrödinger equation
Einstein was
displeased with quantum theory and mechanics, despite its acceptance by other
physicists, stating "God doesn't play with dice." As Einstein passed
away at the age of 76 he still would not accept quantum theory. In 1917, at the
height of his work on relativity, Einstein published an article in
Physikalische Zeitschrift that proposed the possibility of stimulated emission,
the physical process that makes possible the maser and the laser. This article
showed that the statistics of absorption and emission of light would only be
consistent with Planck's distribution law if the emission of light into a mode
with n photons would be enhanced statistically compared to the emission of
light into an empty mode. This paper was enormously influential in the later
development of quantum mechanics, because it was the first paper to show that
the statistics of atomic transitions had simple laws. Einstein discovered Louis
de Broglie's work, and supported his ideas, which were received skeptically at
first. In another major paper from this era, Einstein gave a wave equation for
de Broglie waves, which Einstein suggested was the Hamilton–Jacobi equation of
mechanics. This paper would inspire Schrödinger's work of 1926.
Bose–Einstein
statistics
Main article:
Bose–Einstein condensation
In 1924, Einstein
received a description of a statistical model from Indian physicist Satyendra
Nath Bose, based on a counting method that assumed that light could be
understood as a gas of indistinguishable particles. Einstein noted that Bose's
statistics applied to some atoms as well as to the proposed light particles,
and submitted his translation of Bose's paper to the Zeitschrift für Physik.
Einstein also published his own articles describing the model and its implications,
among them the Bose–Einstein condensate phenomenon that some particulates
should appear at very low temperatures. It was not until 1995 that the first
such condensate was produced experimentally by Eric Allin Cornell and Carl
Wieman using ultra-cooling equipment built at the NIST–JILA laboratory at the
University of Colorado at Boulder.Bose–Einstein statistics are now used to
describe the behaviors of any assembly of bosons. Einstein's sketches for this
project may be seen in the Einstein Archive in the library of the Leiden
University.
Energy momentum
pseudotensor
Main article:
Stress-energy-momentum pseudotensor
General
relativity includes a dynamical spacetime, so it is difficult to see how to
identify the conserved energy and momentum. Noether's theorem allows these
quantities to be determined from a Lagrangian with translation invariance, but
general covariance makes translation invariance into something of a gauge
symmetry. The energy and momentum derived within general relativity by
Noether's presecriptions do not make a real tensor for this reason.
Einstein argued
that this is true for fundamental reasons, because the gravitational field
could be made to vanish by a choice of coordinates. He maintained that the
non-covariant energy momentum pseudotensor was in fact the best description of
the energy momentum distribution in a gravitational field. This approach has
been echoed by Lev Landau and Evgeny Lifshitz, and others, and has become
standard.
The use of
non-covariant objects like pseudotensors was heavily criticized in 1917 by
Erwin Schrödinger and others.
Unified field
theory
Main article:
Classical unified field theories
Following his
research on general relativity, Einstein entered into a series of attempts to
generalize his geometric theory of gravitation to include electromagnetism as
another aspect of a single entity. In 1950, he described his "unified
field theory" in a Scientific American article entitled "On the
Generalized Theory of Gravitation". Although he continued to be lauded for
his work, Einstein became increasingly isolated in his research, and his
efforts were ultimately unsuccessful. In his pursuit of a unification of the
fundamental forces, Einstein ignored some mainstream developments in physics,
most notably the strong and weak nuclear forces, which were not well understood
until many years after his death. Mainstream physics, in turn, largely ignored
Einstein's approaches to unification. Einstein's dream of unifying other laws
of physics with gravity motivates modern quests for a theory of everything and
in particular string theory, where geometrical fields emerge in a unified quantum-mechanical
setting.
Wormholes
Main article:
Wormhole
Einstein
collaborated with others to produce a model of a wormhole. His motivation was
to model elementary particles with charge as a solution of gravitational field
equations, in line with the program outlined in the paper "Do
Gravitational Fields play an Important Role in the Constitution of the
Elementary Particles?". These solutions cut and pasted Schwarzschild black
holes to make a bridge between two patches.
If one end of a
wormhole was positively charged, the other end would be negatively charged.
These properties led Einstein to believe that pairs of particles and
antiparticles could be described in this way.
Einstein–Cartan
theory
Main article:
Einstein–Cartan theory
In order to
incorporate spinning point particles into general relativity, the affine
connection needed to be generalized to include an antisymmetric part, called
the torsion. This modification was made by Einstein and Cartan in the 1920s.
Equations of
motion
Main article:
Einstein–Infeld–Hoffmann equations
The theory of
general relativity has a fundamental law
– the Einstein equations which describe how space curves, the geodesic
equation which describes how particles move may be derived from the Einstein
equations.
Since the equations
of general relativity are non-linear, a lump of energy made out of pure
gravitational fields, like a black hole, would move on a trajectory which is
determined by the Einstein equations themselves, not by a new law. So Einstein
proposed that the path of a singular solution, like a black hole, would be
determined to be a geodesic from general relativity itself.
This was
established by Einstein, Infeld, and Hoffmann for pointlike objects without
angular momentum, and by Roy Kerr for spinning objects.
Other
investigations
Main article:
Einstein's unsuccessful investigations
Einstein
conducted other investigations that were unsuccessful and abandoned. These
pertain to force, superconductivity, gravitational waves, and other research.
Please see the main article for details.
Collaboration
with other scientists
The 1927 Solvay
Conference in Brussels, a gathering of the world's top physicists. Einstein in
the center.
In addition to
long time collaborators Leopold Infeld, Nathan Rosen, Peter Bergmann and others,
Einstein also had some one-shot collaborations with various scientists.
Einstein–de Haas
experiment
Main article:
Einstein–de Haas effect
Einstein and De
Haas demonstrated that magnetization is due to the motion of electrons,
nowadays known to be the spin. In order to show this, they reversed the
magnetization in an iron bar suspended on a torsion pendulum. They confirmed
that this leads the bar to rotate, because the electron's angular momentum
changes as the magnetization changes. This experiment needed to be sensitive,
because the angular momentum associated with electrons is small, but it
definitively established that electron motion of some kind is responsible for
magnetization.
Schrödinger gas
model
Einstein
suggested to Erwin Schrödinger that he might be able to reproduce the
statistics of a Bose–Einstein gas by considering a box. Then to each possible
quantum motion of a particle in a box associate an independent harmonic
oscillator. Quantizing these oscillators, each level will have an integer
occupation number, which will be the number of particles in it.
This formulation
is a form of second quantization, but it predates modern quantum mechanics.
Erwin Schrödinger applied this to derive the thermodynamic properties of a
semiclassical ideal gas. Schrödinger urged Einstein to add his name as
co-author, although Einstein declined the invitation.
Einstein
refrigerator
Main article:
Einstein refrigerator
In 1926, Einstein
and his former student Leó Szilárd co-invented (and in 1930, patented) the
Einstein refrigerator. This absorption refrigerator was then revolutionary for
having no moving parts and using only heat as an input. On 11 November 1930,
U.S. Patent 1,781,541 was awarded to Albert Einstein and Leó Szilárd for the
refrigerator. Their invention was not immediately put into commercial
production, as the most promising of their patents were quickly bought up by
the Swedish company Electrolux to protect its refrigeration technology from
competition.
Bohr versus
Einstein
Main article:
Bohr–Einstein debates
Einstein and
Niels Bohr, 1925
The Bohr–Einstein
debates were a series of public disputes about quantum mechanics between Albert
Einstein and Niels Bohr who were two of its founders. Their debates are
remembered because of their importance to the philosophy of science.
Einstein–Podolsky–Rosen
paradox
Main article: EPR
paradox
In 1935, Einstein
returned to the question of quantum mechanics. He considered how a measurement
on one of two entangled particles would affect the other. He noted, along with
his collaborators, that by performing different measurements on the distant particle,
either of position or momentum, different properties of the entangled partner
could be discovered without disturbing it in any way.
He then used a
hypothesis of local realism to conclude that the other particle had these
properties already determined. The principle he proposed is that if it is
possible to determine what the answer to a position or momentum measurement
would be, without in any way disturbing the particle, then the particle
actually has values of position or momentum.
This principle distilled
the essence of Einstein's objection to quantum mechanics. As a physical
principle, it was shown to be incorrect when the Aspect experiment of 1982
confirmed Bell's theorem, which had been promulgated in 1964.
Political and
religious views
Main articles:
Albert Einstein's political views and Albert Einstein's religious views
Albert Einstein,
seen here with his wife Elsa Einstein and Zionist leaders, including future
President of Israel Chaim Weizmann, his wife Dr. Vera Weizmann, Menahem
Ussishkin, and Ben-Zion Mossinson on arrival in New York City in 1921.
Albert Einstein's
political views emerged publicly in the middle of the 20th century due to his
fame and reputation for genius. Einstein offered to and was called on to give
judgments and opinions on matters often unrelated to theoretical physics or
mathematics (see main article).
Einstein's views
about religious belief have been collected from interviews and original
writings. These views covered Judaism, theological determinism, agnosticism, and
humanism. He also wrote much about ethical culture, opting for Spinoza's god
over belief in a personal god.
Non-scientific
legacy
While travelling,
Einstein wrote daily to his wife Elsa and adopted stepdaughters Margot and
Ilse. The letters were included in the papers bequeathed to The Hebrew
University. Margot Einstein permitted the personal letters to be made available
to the public, but requested that it not be done until twenty years after her
death (she died in 1986). Barbara Wolff, of The Hebrew University's Albert
Einstein Archives, told the BBC that there are about 3,500 pages of private
correspondence written between 1912 and 1955.
Einstein
bequeathed the royalties from use of his image to The Hebrew University of
Jerusalem. Corbis, successor to The Roger Richman Agency, licenses the use of
his name and associated imagery, as agent for the university.
In popular
culture
Main article:
Albert Einstein in popular culture
In the period
before World War II, Einstein was so well known in America that he would be
stopped on the street by people wanting him to explain "that theory".
He finally figured out a way to handle the incessant inquiries. He told his
inquirers "Pardon me, sorry! Always I am mistaken for Professor Einstein."
Einstein has been
the subject of or inspiration for many novels, films, plays, and works of
music. He is a favorite model for depictions of mad scientists and
absent-minded professors; his expressive face and distinctive hairstyle have
been widely copied and exaggerated. Time magazine's Frederic Golden wrote that
Einstein was "a cartoonist's dream come true".
Awards and honors
Main article:
Einstein's awards and honors
Einstein received
numerous awards and honors, including the Nobel Prize in Physics.
simply one can explain by this formulae
ReplyDeleteE=MC2
but we know E=Mas
if you combine this two
you can explain elementary level
swarnalatha ganesan
ReplyDeleteExcellent information. it will be useful for the students to know about Einstein. Hats off to you.
all of u must see this message
ReplyDelete