Albert Einstein

Albert Einstein was a German-born theoretical physicist, one of the most influential scientists of all time. He developed the theory of relativity and made fundamental contributions to quantum theory, and his work transformed the understanding of space, time, and gravitation.

Life

Einstein was born in Ulm, Germany, in 1879. He studied in Zurich and worked in the patent office in Bern, where he published the papers of 1905 that transformed physics.

He held professorships in Switzerland, Prague, and Berlin, and he won the Nobel Prize in Physics in 1921 for his work on the photoelectric effect. He emigrated to the United States in 1933 and worked at the Institute for Advanced Study in Princeton.

He died in 1955. He was celebrated in his lifetime as a symbol of genius and of the power of science.

Special Relativity

The special theory of relativity, published in 1905, holds that the laws of physics are the same for all observers in uniform motion, and that the speed of light is constant. The theory implies that time and space are not absolute but depend on the observer.

The theory led to the famous equation E = mc2, which expresses the equivalence of mass and energy. It also implies that simultaneity is relative and that moving clocks run slow.

General Relativity

The general theory of relativity, published in 1915, extends the theory to accelerating observers and to gravitation. It holds that gravitation is not a force but a consequence of the curvature of space-time caused by mass and energy.

The theory predicted the bending of light by gravity and the expansion of the universe, and it has been confirmed by many observations. It remains the basis of modern cosmology.

Quantum Theory

Einstein made important contributions to quantum theory, including the explanation of the photoelectric effect and the concept of the photon. He was, however, critical of the interpretation of quantum mechanics, and his debates with Niels Bohr are among the most famous in the history of science.

His objections, including the argument that quantum mechanics is incomplete, stimulated the development of the field. The experiments that tested his ideas confirmed the predictions of quantum mechanics.

Legacy

Einstein's work transformed physics and influenced philosophy and culture. His theories are central to modern physics, and his name is synonymous with genius.

His contributions to relativity and to quantum theory, and his role in the public understanding of science, make him one of the most influential figures of the twentieth century.

The Miracle Year

In 1905, while working in the patent office in Bern, Einstein published four papers that transformed physics. They dealt with the photoelectric effect, with Brownian motion, with special relativity, and with the equivalence of mass and energy.

The paper on the photoelectric effect introduced the concept of the photon and contributed to the development of quantum theory. The paper on Brownian motion provided evidence for the existence of atoms. The papers on relativity transformed the understanding of space and time.

The year is often described as the miracle year, and the papers are among the most influential in the history of science.

General Relativity and Cosmology

The general theory of relativity, published in 1915, extended the theory to gravitation. It holds that mass and energy curve space-time, and that the curvature determines the motion of bodies.

The theory predicted the bending of light by the sun, which was confirmed by the eclipse expedition of 1919, and the existence of gravitational waves, which were detected in 2015. It also provided the framework for the modern theory of cosmology, including the expanding universe and the big bang.

The Quantum Debates

Einstein was one of the founders of quantum theory, but he was critical of its interpretation. His debates with Niels Bohr over the completeness of quantum mechanics are among the most famous in the history of science.

His argument, presented in the paper with Podolsky and Rosen, sought to show that quantum mechanics is incomplete. The argument stimulated the development of the field, and the experiments that tested it confirmed the predictions of quantum mechanics.

Politics and Public Life

Einstein was active in public life and spoke on political and social issues. He supported pacifism and Zionism, and he renounced his German citizenship in response to the rise of the Nazi party.

He urged the United States to develop the atomic bomb, fearing that Germany would do so first, and he later regretted the decision and campaigned for nuclear disarmament. He was offered the presidency of Israel, which he declined.

Summary

Einstein's work transformed physics and influenced philosophy and culture. His theories of relativity and his contributions to quantum theory made him one of the most influential scientists of all time, and his public role shaped the popular conception of science.

See also

• Isaac Newton
• Niels Bohr
• Theory of relativity