Einstein, Albert (1879-1955), was the most important physicist of the 1900's and one of the greatest and most famous scientists of all time. He was a theoretical physicist, a scientist who creates and develops theories of matter and energy. Einstein's greatness arose from the fact that his theories solved fundamental problems and presented new ideas. Much of his fame came from the fact that several of those ideas were strange and hard to understand-but proved true.
Some of Einstein's most famous ideas make up parts of his special theory of relativity and his general theory of relativity. For example, the special theory describes an entity known as space-time. This entity is a combination of the dimension of time and the three dimensions of space-length, width, and height. Thus, space-time is four-dimensional. In the general theory, matter and energy distort (change the shape of) space-time; the distortion is experienced as gravity.
Einstein also became known for his support of political and social causes. Those included pacifism, a general opposition to warfare; Zionism, a movement to establish a Jewish homeland in Palestine; and socialism, a political system in which the means of production would be owned by society and production would be planned to match the needs of the community.
Einstein was born on March 14, 1879, in Ulm, in southern Germany, the son of Hermann Einstein and Pauline Koch Einstein. The next year, Hermann moved the family about 70 miles (110 kilometers) to Munich. Albert Einstein's younger sister, Maria-whom he called Maja -recalled that Einstein was slow to learn to speak. But even as a young child, he displayed the powers of concentration for which he became famous.
Einstein recalled seeing the seemingly miraculous behavior of a magnetic compass when he was about 5 years old. The fact that invisible forces acted on the compass needle made a deep impression on the boy. A booklet on Euclidean geometry made a comparable impression on Einstein when he was around 12 years old. Euclidean geometry is based on a small number of simple, self-evident (obviously true) statements about geometric figures. Mathematicians use those statements to deduce (develop by reasoning) other statements, many of which are complex and far from self-evident. Einstein was impressed that geometric statements that are not self-evident could be proved clearly and with certainty.
Einstein began to take violin lessons when he was 6 years old. He eventually became an accomplished violinist, and he played the instrument throughout his life. At the age of 9, Einstein entered the Luitpold Gymnasium, a distinguished secondary school in Munich. He enjoyed some of his classes and performed well, but he disliked the strict discipline. As a result, he dropped out at the age of 15 to follow his parents to Pavia, Italy, near Milan.
Einstein finished high school in 1896, in Aarau, Switzerland. He then entered a school in Zurich, Switzerland, that ranked as one of Europe's finest institutions of higher learning in science. The school is known as the Swiss Federal Institute of Technology Zurich or the ETH Zurich, from the initials for Federal Institute of Technology in German. While at the ETH, Einstein met and fell in love with Mileva Maric. Mileva was a physics student from Novi Sad, in what is now Serbia.
Einstein often skipped class, relying on the notes of others. He spent his free time in the library reading the latest books and physics journals. Einstein's behavior annoyed Heinrich F. Weber, the professor who supervised his course work. Although professors customarily helped their students obtain university positions, when Einstein neared graduation, Weber did not help him get a university post. Instead, a friend helped him find a job as a clerk in the Swiss Federal Patent Office in Bern. He became a Swiss citizen in 1901.
First marriage. Meanwhile, Mileva had become pregnant. Albert and Mileva's child, a daughter they named Lieserl, was born in January 1902 at the home of Mileva's parents. In January 1903, Albert and Mileva married. They had two more children, Hans Albert in 1904 and Eduard in 1910. However, Lieserl never joined them in Bern, and her fate remains a mystery.
Famous theories. Einstein worked at the patent office from 1902 to 1909. Those years were among Einstein's most productive. The job of reviewing patent applications left him with much time for physics. In 1905, he obtained a Ph.D. degree in physics by submitting a dissertation (a long, formal paper) to the University of Zurich. He had already completed all the necessary classwork at the ETH.
The year 1905 is known as Einstein's annus mirabilis-Latin for year of marvels. In that year, the German scientific periodical the Annalen der Physik (Annals of Physics) published three of his papers that were among the most revolutionary in the history of science. The photoelectric effect. The first paper, published in March 1905, deals with the photoelectric effect. By means of that effect, a beam of light can cause metal atoms to release subatomic particles called electrons. In a photoelectric device, these freed electrons flow as electric current, so the device produces a current when light shines on it.
Einstein explained that the photoelectric effect occurs because light comes in "chunks" of energy called quanta. The singular of quanta is quantum. A quantum of light is now known as a photon. An atom can absorb a photon. If the photon has enough energy, an electron will leave its atom. Einstein received the 1921 Nobel Prize in physics for his paper on the photoelectric effect. The principle that light comes in quanta is a part of an area of physics known as quantum mechanics. Quantum mechanics is one of the "foundation blocks" of modern physics; Einstein's relativity theories are two others.
Brownian motion. In the second paper, published in May 1905, Einstein explained Brownian motion, an irregular movement of microscopic particles suspended in a liquid or a gas. Such motion was named for the Scottish botanist Robert Brown, who first observed it in 1827. Einstein's analysis stimulated research on Brownian motion that produced the first experimental proof that atoms exist.
The special theory of relativity. The third paper, published in June, presented the special theory of relativity. In that paper, titled "On the Electrodynamics of Moving Bodies," Einstein made a remarkable statement about light. He said that constant motion does not affect the velocity (speed in a particular direction) of light.
Imagine, for example, that you are on a railroad car traveling on a straight track at a constant speed of one-third the speed of light. You flash a light from the back of the car to the front of the car. You precisely measure the speed of the light. You find that the speed is 186,282 miles (299,792 kilometers) per second-represented by the letter c in scientific equations. A friend standing on the ground also measures the speed of the light.
You might expect your friend's result to be c + 1 1/3 c. That would be a "common-sense" result consistent with ordinary experience with the velocities of material objects. For example, a ball thrown forward inside a railroad car would have a velocity-as measured by an observer on the ground-equal to the velocity of the car plus the velocity of the ball as measured in the car. But, strangely, in the case of the light beam, your friend's answer turns out to be the same as yours: c.
The strange fact that the velocity of light is constant has even stranger results. For example, a clock can appear to one observer to be running at a given rate, yet seem to another observer to run at a different rate. Two observers can measure the length of the same rod correctly but obtain different results. Einstein also said that c is a universal "speed limit." No physical process can spread through space at a velocity higher than c. No material body can reach a velocity of c. Interchangeability of mass and energy. In a fourth paper, published in September 1905, Einstein discussed a result of the special theory of relativity-that energy and mass are interchangeable.
Mass is a measure of an object's inertia, its resistance to a change in its motion. An object at rest tends to remain at rest due to inertia. A moving object tends to maintain its velocity. In addition, an object's weight is proportional to its mass; more massive objects weigh more. Einstein's paper contains an equation that has become famous: E = mc2. The equation says that a body's energy, E, equals the body's mass, m, times the speed of light, c, squared (multiplied by itself). The speed of light is so high that the conversion of a tiny quantity of mass releases a tremendous amount of energy. The conversion of mass creates energy in the sun and other stars. It also produces the heat energy that is converted to electric energy in nuclear power plants. In addition, mass-to-energy conversion is responsible for the tremendous destructive force of nuclear weapons. Next >>>
Contributor: Don Howard, Ph.D., Professor, Department of Philosophy, University of Notre Dame.
World Book 2005
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