“The most important human endeavor is the striving for morality in our actions.”
Albert Einstein was a German-born American physicist whose name is synonymous with genius. During a single year, 1905, he produced three papers that revolutionized science. These three masterpieces dealt with Brownian motion, the photoelectric effect, and the special theory of relativity. In 1921, he was awarded the Nobel Prize in physics for his explanation of the photoelectric effect. Einstein extended his special theory of relativity into the more general theory of relativity, which he formulated into the well-known equation E=mc2.
In addition to being one of the world's greatest scientists, Einstein was also a public figure. He gave generously of his time and energy to causes he supported, enduring harsh criticism and even risking death as a result of the stands he took on some of the major issues of his day. He opposed World War I (1914-18), and after the nuclear attack by the United States on Japan in World War II (1939-45), he became an ardent supporter of nuclear disarmament (getting rid of or reducing a nation's nuclear weapons). Despite his fame, Einstein was a solitary man who spent most of his time in isolation; although he was extremely popular, he did not seek the admiration of others.
Einstein was born March 14, 1879, the son of Pauline Koch Einstein and Hermann Einstein, owner of a company that made and sold electrical equipment. No one in the family was particularly gifted in science or math, and for some time it appeared that the young Einstein shared this trait--in fact, as a child he did not show much aptitude for anything. He did not talk until he was three, and for a number of years after that he still had trouble speaking fluently. In elementary school, his performance was dismal at best, leading some people (including his parents) to suspect that he was retarded. From the time he was a small child, however, Einstein preferred to learn on his own, and in his early teens he taught himself advanced mathematics and science. He followed this pattern of independent study throughout his life.
Graduating from the Swiss Federal Polytechnic School in Zurich in 1900 with a degree in physics, Einstein worked at a series of temporary jobs before he secured a permanent position in 1902 as a technical expert with the Swiss Patent Office. For the next seven years he evaluated proposed inventions by day and conducted his own research in the evenings and in his spare time. Einstein applied his work toward a doctorate at the University of Zurich. He also married a former classmate at the Polytechnic, Mileva Maric, and together they had a daughter and two sons. The couple divorced in 1919; Einstein was later remarried to his cousin Elsa.
Publishes paper on Brownian motion
In 1905, Einstein published a series of papers, any one of which would have assured his fame in history. "On the Movement of Small Particles Suspended in a Stationary Liquid Demanded by the Molecular-Kinetic Theory of Heat" addressed a phenomenon first observed by the Scottish botanist Robert Brown in 1827. Brown had reported that tiny particles, such as specks of dust, move about with a rapid and random zigzag motion when suspended in a liquid.
Einstein hypothesized that the visible motion of particles was caused by the random movement of molecules (the smallest particles of an element or compound) that make up the liquid. He derived a mathematical formula that predicted the distance traveled by the particles and their relative speed. This formula was confirmed experimentally by the French physicist Jean Baptiste Perrin in 1908. Einstein's work on Brownian motion is generally regarded as the first direct experimental evidence of the existence of molecules.
Studies photoelectric effect
In his 1905 study titled "On a Heuristic Viewpoint Concerning the Production and Transformation of Light," Einstein tackled another puzzle in physics, the photoelectric effect. First observed by Heinrich Hertz in 1888, the photoelectric effect involves the release of electrons (negatively charged particles that orbit the nucleus of an atom) from a metal that occurs when light is shined on the metal. The puzzling aspect of the photoelectric effect was that the number of electrons released is not a function of the light's intensity, but of the color (that is, the wavelength) of the light.
To solve this problem, Einstein made use of the quantum hypothesis, a concept developed only a few years earlier, in 1900, by the German physicist Max Planck. Einstein assumed that light travels in tiny discrete bundles (quanta) of energy. The energy of any given light quantum (later renamed the photon), Einstein said, is determined by its wavelength. Thus, when light falls on a metal, electrons in the metal absorb specific quanta of energy, giving them enough energy to escape from the surface of the metal. The number of electrons released will depend not on the number of quanta (that is, the intensity of the light), but on the light's energy (or wavelength). Einstein's hypothesis was confirmed by several experiments and laid the foundation for the fields of quantitative photoelectric chemistry and quantum mechanics (the branch of physics that studies the energy levels in atoms). In recognition of this work, Einstein was awarded the 1921 Nobel Prize in physics.
Formulates special theory of relativity
A third paper Einstein wrote in 1905, for which he became best known, details his special theory of relativity. In essence, "On the Electrodynamics of Moving Bodies" discusses the relationship between measurements made by observers in two separate systems moving at constant velocity (speed) with respect to each other.
Einstein's work on relativity was by no means the first in the field. The French physicist Jules Henri Poincare, the Irish physicist George Francis Fitzgerald, and the Dutch physicist Hendrik Lorentz had already analyzed in some detail the problem attacked by Einstein in his 1905 paper. Each had developed mathematical formulas that described the effect of motion on various types of measurement. Still, there is little question that Einstein provided the most complete analysis of the subject. He began by making two assumptions. First, he said that the laws of physics are the same in all frames of reference. Second, he declared that the velocity of light is always the same, regardless of the conditions under which it is measured.
Using only these two assumptions, Einstein proceeded to uncover an unexpectedly extensive description of the properties of bodies that are in uniform motion. For example, he showed that the length and mass of an object are dependent upon their movement relative to an observer. He derived a mathematical relationship between the length of an object and its velocity that had previously been suggested by both Fitzgerald and Lorentz. Einstein's theory was revolutionary, for previously scientists had believed that basic measurable entities such as time, mass, and length remain the same in all frames of reference. Einstein's work established the opposite--that measurable properties will differ depending on the relative motion of the observer.
Special theory explains perception problems
Although Einstein's special theory of relativity seems abstract and complicated, it has two simple main ideas. The first is that measurements of time, space, and motion are relative. To illustrate this idea, pretend that you have just fired a gun. The bullet goes speeding off into the distance at, say, 500 miles per hour. Imagine also that an airplane has swooped down just as you fired the gun, and it, too, is going 500 miles per hour in the same direction. The pilot ends up flying along right next to the bullet. To him, the bullet looks like it is standing still. And it is--relative to him. Einstein believed that perceptions of time and space were also relative to the person perceiving them.
The second concept underlying special relativity is that the first idea involves a major exception--the nonrelative element in any situation is the speed of light. According to Einstein, the speed of light is constant (approximately 186,282 miles per second; a light-year measures the distance light travels in a year, roughly six trillion miles). Thus the speed of light is the same no matter who is measuring that speed. To examine a situation involving relativity and the speed of light, imagine what would happen if a train were traveling at the speed of light and the engineer turned on the headlights. According to Einstein, nothing would happen. In order for the headlights to shine--or rather, for our eyes to perceive the light shining from them--the light coming out of the lamps would have to move even faster than the train. This is impossible because the speed of light is constant. The theory of relativity, in part, was the answer to these questions.
Devises formula E=mc2
In addition to his studies on the photoelectric effect, Brownian movement, and relativity, Einstein wrote two other papers in 1905. "Does the Inertia of a Body Depend on Its Energy Content?" was an extension of his earlier work on relativity. He came to the conclusion that the energy and mass of a body are closely interrelated. Two years later he stated that relationship in a formula, E = mc2 (energy equals mass times the speed of light squared). Einstein submitted the final paper, "A New Determination of Molecular Dimensions," as his doctoral dissertation. He earned a Ph.D. from the University of Zurich in 1905.
Fame did not come to Einstein immediately. Indeed, when he submitted his paper on relativity to the University of Bern in support of his application to become a privatdozent, (lecturer or teacher) the paper and the application were rejected. His work was too important to be ignored for long, however, and a second application three years later was accepted. Einstein spent only a year at Bern before taking a job as a professor of physics at the University of Zurich in 1909. He then went to the German University of Prague for a year and a half before returning to Zurich in 1912. A year later Einstein was made director of scientific research at the Kaiser Wilhelm Institute for Physics in Berlin, a post he held until 1933.
Formulates general theory of relativity
Upon the outbreak of World War I, Einstein returned to Zurich. The war years marked the culmination of Einstein's attempt to extend his theory of relativity to a broader context. The general theory of relativity applied to motions that are not uniform and relative velocities that are not constant. Einstein was able to write mathematical expressions that describe the relationships between measurements made in any two systems in motion relative to each other, even if the motion is accelerated (changing) in one or both. A fundamental feature of the general theory is the concept of a space-time continuum in which space is curved. That concept means that a body affects the shape of the space that surrounds it so that a second body moving near the first body will travel in a curved path.
Proves his theory
Einstein's new theory was too radical to be immediately accepted because the mathematics behind it were extremely complex and it would replace Isaac Newton's theory of gravitation that had been accepted for two centuries. Einstein therefore offered three testable proofs of general relativity. First, he predicted that relativity would cause Mercury's perihelion (a point of orbit closest to the Sun) to advance slightly more than was predicted by Newton's laws. Second, he predicted that light from a star will be bent by gravity as it passes close to a massive body, such as the Sun. Finally, Einstein suggested that relativity would also affect light by changing its wavelength, a phenomenon known as the redshift effect. Observations of the planet Mercury soon bore out Einstein's hypothesis and calculations, but astronomers and physicists had yet to test the other two proofs.
Einstein had calculated that the light passing by the Sun is bent by 1.7 seconds of an arc, a small but detectable change. In 1919, during a solar eclipse, English astronomer Arthur Eddington measured the deflection of starlight as it passed by the Sun and found it to be 1.61 seconds of an arc, well within experimental error. The publication of this proof made Einstein an instant celebrity and made "relativity" a household word, although it was not until 1924 that Eddington proved the final hypothesis concerning redshift with the spectral analysis of the star Sirius B.
To understand the redshift of light, consider sound waves. When an automobile drives by, sounding its horn, a noticeable change in pitch is heard because the car's velocity stretches the sound waves out. Einstein predicted that gravity would stretch out light waves as they travel through space. As the waves were lengthened, a shift in color, toward the low (red) end of the spectrum, would be observed. This phenomenon, that light would be shifted to a longer wavelength in the presence of a strong gravitational field, became known as the "Einstein shift."
Since the outbreak of World War I, Einstein had been opposed to war, and during the 1920s and 1930s he traveled extensively, presenting lectures on his views. With the rise of National Socialism (the Nazi Party) in Germany in the early 1930s, Einstein's position became difficult. Although he was not in Germany when Nazi leader Adolf Hitler assumed power, he had renewed his German citizenship. Nevertheless, he was under suspicion as both a Jew and a pacifist. (The German Nazis systematically persecuted Jews.) Fortunately, by 1930 Einstein had become internationally famous, and a number of institutions were eager to appoint him to their faculties.
Comes to America
In early 1933, Einstein decided not to return to Germany. Instead he accepted an appointment at the Institute for Advanced Studies in Princeton, New Jersey, where he spent the rest of his life. In addition to his continued work on unified field theory (a single theory that would explain all physical phenomena, particularly gravitation electromagnetism), Einstein was in demand as a speaker and wrote extensively on many topics, especially peace. The growing fascism and anti-Semitism of Hitler's regime, however, convinced him in 1939 to sign his name to a letter written by American physicist Leo Szilard informing President Franklin D. Roosevelt of the possibility that an atomic bomb could be developed. This letter led to the formation of the Manhattan Project for the construction of the world's first nuclear weapons. Einstein's work on relativity, particularly his formulation of the equation E = mc2, was essential to the development of the atomic bomb, but Einstein himself did not participate in the project. He was considered a security risk, although he had renounced his German citizenship and had become a U.S. citizen in 1940.
Receives awards and honors
After World War II, in which the United States dropped two atomic bombs on Japan, Einstein became an ardent supporter of nuclear disarmament. He also lent his support to efforts to establish a world government and to the Zionist movement to establish a Jewish state. In 1952, after the death of Israel's first president, Chaim Weizmann, Einstein was invited to succeed him as president; he declined the offer. Among the many other honors accorded Einstein were the Barnard Medal of Columbia University in 1920, the Copley Medal of the Royal Society in 1925, the Gold Medal of the Royal Astronomical Society in 1926, the Max Planck Medal of the German Physical Society in 1929, and the Franklin Medal of the Franklin Institute in 1935. Einstein died at his home in Princeton on April 18, 1955, after suffering an aortic aneurysm.
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