Best Known As: Other

Gist:  Albert Einstein (; ; 14 March 1879 ? 18 April 1955) was a theoretical physicist. He is best known for his theories of special relativity and general relativity. Einstein received the 1921 Nobel Prize in Physics "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect."{{cite web | url = Nobel Prize in Physics 1921 | accessdate = 2007-03-06 | publisher =Nobel Foundation|archiveurl=

Einstein's many contributions to physics include:

* The special theory of relativity, which reconciled mechanics with electromagnetism

* The general theory of relativity, a new theory of gravitation obeying the equivalence principle

* The founding of relativistic cosmology with a cosmological constant

* The first post-Newtonian expansion, explaining the perihelion advance of Mercury

* Prediction of the deflection of light by gravity and gravitational lensing

* The first fluctuation dissipation theorem which explained the Brownian movement of molecules

* The theory of density fluctuations in gasses and liquids, giving a criterion for critical opalescence

* The photon theory and wave-particle duality derived from the thermodynamic properties of light

* The quantum theory of atomic motion in solids

* Zero-point energy concept

* The semiclassical version of the Schrödinger equation

* Relations for atomic transition probabilities which predicted stimulated emission

* The quantum theory of a monatomic gas which predicted Bose-Einstein condensation

* The EPR paradox

* A program for a unified field theory

* The geometrization of fundamental physics

Einstein published more than 300 scientific works and more than 150 non-scientific works. He is often regarded as the father of Modern Physics and the greatest scientist of the 20th Century. In 1999 Time magazine named him the Person of the Century, beating contenders like Mahatma Gandhi and Franklin Roosevelt, and in the words of a biographer, "to the scientifically literate and the public at large, Einstein is synonymous with genius."

Life Facts:  Albert Einstein was born in Ulm, in the Kingdom of Württemberg in the German Empire on March 14, 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.

|year = 1979}} ]]

The Einsteins, although of Jewish ancestry, did not observe Jewish religious practices, and their son attended a Catholic elementary school. Although Einstein had early speech difficulties, he was a top student in elementary school. As he grew, Einstein built models and mechanical devices for fun, and began to show a talent for mathematics.

, Einstein began to understand deductive reasoning, and by the age of twelve, he had learned Euclidean geometry. Soon after he began to investigate infinitesimal calculus. At age 16, he performed the first of his famous thought experiments in which he visualized traveling alongside a beam of light.]]

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. In the spring of 1895, he withdrew to join his family in Pavia, convincing the school to let him go by using a doctor's note. During this time, Einstein wrote his first scientific work, "The Investigation of the State of Aether in Magnetic Fields".



Einstein applied directly to the Eidgenössische Polytechnische Schule (later Eidgenössische Technische Hochschule (ETH)) in Zürich, Switzerland. Lacking the requisite gymnasium certificate, he took an entrance examination, which he failed, although he got exceptional marks in mathematics and physics.

The Einsteins sent Albert to Aarau, in northern Switzerland to finish secondary school. In Aarau, Einstein studied Maxwell's electromagnetic theory. At age 17, he graduated, and, with his father's approval, renounced his citizenship in the German Kingdom of Württemberg to avoid military service, and enrolled in 1896 in the mathematics and physics program at the Polytechnic in Zurich. Marie Winteler moved to Olsberg, Switzerland for a teaching post.

In the same year, Einstein's future wife, Mileva Mari?, also entered the Polytechnic to study mathematics and physics, the only woman in the academic cohort. Over the next few years, Einstein and Mari?'s friendship developed into romance. In a letter to her, Einstein called Mari? "a creature who is my equal and who is as strong and independent as I am." Einstein graduated in 1900 from the Polytechnic with a diploma in mathematics and physics; Although historians have debated whether Mari? influenced Einstein's work, the overwhelming consensus amongst academic historians of science is that she did not.



Einstein's early papers all come from attempts to demonstrate that atoms exist and have a finite nonzero size. At the time of his first paper in 1902, it was not yet completely accepted by physicists that atoms were real, even though chemists had good evidence ever since Antoine Lavoisier's work a century earlier. The reason physicists were skeptical was because no 19th century theory could fully explain the properties of matter from the properties of atoms.

Ludwig Boltzmann was a leading 19th century atomist physicist, who had struggled for years to gain acceptance for atoms. Boltzmann had given an interpretation of the laws of thermodynamics, suggesting that the law of entropy increase is statistical. In Boltzmann's way of thinking, the entropy is the logarithm of the number of ways a system could be configured inside. The reason the entropy goes up is only because it is more likely for a system to go from a special state with only a few possible internal configurations to a more generic state with many. While Boltzmann's statistical interpretation of entropy is universally accepted today, and Einstein believed it, at the turn of the 20th century it was a minority position.

The statistical idea was most successful in explaining the properties of gases. James Clerk Maxwell, another leading atomist, had found the distribution of velocities of atoms in a gas, and derived the surprising result that the viscosity of a gas should be independent of density. Intuitively, the friction in a gas would seem to go to zero as the density goes to zero, but this is not so, because the mean free path of atoms becomes large at low densities. A subsequent experiment by Maxwell and his wife confirmed this surprising prediction. Other experiments on gases and vacuum, using a rotating slitted drum, showed that atoms in a gas had velocities distributed according to Maxwell's distribution law.

In addition to these successes, there were also inconsistencies. Maxwell noted that at cold temperatures, atomic theory predicted specific heats that are too large. In classical statistical mechanics, every spring-like motion has thermal energy k_BT on average at temperature T, so that the specific heat of every spring is Boltzmann's constant k_B. A monatomic solid with N atoms can be thought of as N little balls representing N atoms attached to each other in a box grid with 3N springs, so the specific heat of every solid is 3Nk_B, a result which became known as the Dulong?Petit law. This law is true at room temperature, but not for colder temperatures. At temperatures near zero, the specific heat goes to zero.

Similarly, a gas made up of two atoms can be thought of as two balls on a spring. This spring has energy k_BT at high temperatures, and should contribute an extra k_B to the specific heat. It does at room temperature, but at low temperature, this contribution disappears. At zero temperature, all other contributions to the specific heat from rotations and vibrations also disappear. This behavior was inconsistent with classical physics.

The most glaring inconsistency was in the theory of light waves. Continuous waves in a box can be thought of as infinitely many spring-like motions, one for each possible standing wave. Each standing wave has a specific heat of k_B, so the total specific heat of a continuous wave like light should be infinite in classical mechanics. This is obviously wrong, because it would mean that all energy in the universe would be instantly sucked up into light waves, and everything would slow down and stop.

These inconsistencies led some people to say that atoms were not physical, but mathematical. Notable among the skeptics was Ernst Mach, whose logical positivist philosophy led him to demand that if atoms are real, it should be possible to see them directly. Mach believed that atoms were a useful fiction, that in reality they could be assumed to be infinitesimally small, that Avogadro's number was infinite, or so large that it might as well be infinite, and k_B was infinitesimally small. Certain experiments could then be explained by atomic theory, but other experiments could not, and this is the way it will always be.

Einstein opposed this position. Throughout his career, he was a realist. He believed that a single consistent theory should explain all observation, and that this theory would be a description what was really going on, underneath it all. So he set out to show that the atomic point of view was correct. This led him first to thermodynamics, then to statistical physics, and to the theory of specific heats of solids.

In 1905, while he was working in the patent office, the leading German language physics journal Annalen der Physik published four of Einstein's papers. The four papers eventually were recognized as revolutionary, and 1905 became known as Einstein's "Miracle Year", and the papers, as the Annus Mirabilis Papers.

, 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. ]]

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's paper on the light particles was almost entirely motivated by thermodynamic considerations. He was not at all motivated by the detailed experiments on the photoelectric effect, which did not confirm his theory until fifteen years later.

Einstein considers the entropy of light at temperature T, and decomposes it into a low-frequency part and a high-frequency part. The high-frequency part, where the light is described by Wien's law, has an entropy which looks exactly the same as the entropy of a gas of classical particles.

Since the entropy is the logarithm of the number of possible states, Einstein concludes that the number of states of short wavelength light waves in a box with volume V is equal to the number of states of a group of localizable particles in the same box. Since (unlike others) he was comfortable with the statistical interpretation, he confidently postulates that the light itself is made up of localized particles, as this is the only reasonable interpretation of the entropy.

This leads him to conclude 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.

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.

at the University of Zurich and shortly afterward, he accepted a full professorship at the German Charles-Ferdinand University in Prague.]]

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, was awarded to Albert Einstein and Leó Szilárd for the refrigerator. Although the refrigerator was not immediately put into commercial production, the most promising of their patents being quickly bought up by the Swedish company Electrolux to protect its refrigeration technology from competition.

Rabindranath Tagore during their widely publicized 14 July 1930 conversation]]

With increasing public demands, his involvement in political, humanitarian, and academic projects in various countries, and his new acquaintances with scholars and political figures from around the world, Einstein was less able to achieve the productive isolation that he needed in order to work.

In the period before World War II, Albert 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."

Albert Einstein has been the subject of or inspiration for many novels, films, and plays. Einstein 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."

Einstein's association with great intelligence has made the name Einstein synonymous with genius, often used in ironic expressions such as "Nice job, Einstein!".

Career Facts:  Throughout his life, Einstein published hundreds of books and articles. Most were about physics, but a few expressed leftist political opinions about pacifism, socialism, and zionism.