Albert Einstein was a German-American physicist and probably the most well-known scientist of the 20th century. He is famous for his theory of relativity, a pillar of modern physics that describes the dynamics of light and extremely massive entities, as well as his work in quantum mechanics, which focuses on the subatomic realm.
Contrary to popular belief, Einstein was a good student. "Yesterday Albert received his grades, he was again number one, and his report card was brilliant," his mother once wrote to her sister, according to a German website dedicated to Einstein's legacy. But when he later switched to the Luitpold grammar school, young Einstein chafed under the school's authoritarian attitude, and his teacher once said of him, "never will he get anywhere."
In 1896, at age 17, Einstein entered the Swiss Federal Polytechnic School in Zurich to be trained as a teacher in physics and mathematics. A few years later, he gained his diploma and acquired Swiss citizenship but was unable to find a teaching post. So he accepted a position as a technical assistant in the Swiss patent office.
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Einstein divorced Maric in 1919 and soon married his cousin Elsa Löwenthal, with whom he had been in a relationship since 1912.
The first incorporated the idea that light could come in discrete particles called photons. This theory describes the photoelectric effect, the concept that underpins modern solar power. The second explained Brownian motion, or the random motion of particles or molecules. Einstein looked at the case of a dust mote moving randomly on the surface of water and suggested that water is made up of tiny, vibrating molecules that kick the dust back and forth.
The final two papers outlined his theory of special relativity, which showed how observers moving at different speeds would agree about the speed of light, which was a constant. These papers also introduced the equation E = mc^2, showing the equivalence between mass and energy. That finding is perhaps the most widely known aspect of Einstein's work. (In this infamous equation, E stands for energy, m represents mass and c is the constant speed of light).
In 1915, Einstein published four papers outlining his theory of general relativity, which updated Isaac Newton's laws of gravity by explaining that the force of gravity arose because massive objects warp the fabric of space-time. The theory was validated in 1919, when British astronomer Arthur Eddington observed stars at the edge of the sun during a solar eclipse and was able to show that their light was bent by the sun's gravitational well, causing shifts in their perceived positions.
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In 1921, he won the Nobel Prize in physics for his work on the photoelectric effect, though the committee members also mentioned his "services to Theoretical Physics" when presenting their award. The decision to give Einstein the award was controversial because the brilliant physicist was a Jew and a pacifist. Anti-Semitism was on the rise and relativity was not yet seen as a proven theory, according to an article from The Guardian.
Einstein was a professor at the University of Berlin for a time but fled Germany with Löwenthal in 1933, during the rise of Adolf Hitler. He renounced his German citizenship and moved to the United States to become a professor of theoretical physics at Princeton, becoming a U.S. citizen in 1940.
During this era, other researchers were creating a revolution by reformulating the rules of the smallest known entities in existence. The laws of quantum mechanics had been worked out by a group led by the Danish physicist Niels Bohr, and Einstein was intimately involved with their efforts.
Bohr and Einstein famously clashed over quantum mechanics. Bohr and his cohorts proposed that quantum particles behaved according to probabilistic laws, which Einstein found unacceptable, quipping that "God does not play dice with the universe." Bohr's views eventually came to dominate much of contemporary thinking about quantum mechanics.
This autographed photo of Albert Einstein with his tongue out was sold at auction for $125,000. (Image credit: Arthur Sasse/Nate D. Sanders Auctions)
Einstein's body was cremated and his ashes were spread in an undisclosed location, according to the American Museum of Natural History. But a doctor performed an unauthorized craniotomy before this and removed and saved Einstein's brain.
The brain has been the subject of many tests over the decades, which suggested that it had extra folding in the gray matter, the site of conscious thinking. In particular, there were more folds in the frontal lobes, which have been tied to abstract thought and planning. However, drawing any conclusions about intelligence based on a single specimen is problematic.
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Einstein's theories concerning relativity have so far held up spectacularly as a predictive models. Astronomers have found that, as the legendary physicist anticipated, the light of distant objects is lensed by massive, closer entities, a phenomenon known as gravitational lensing, which has helped our understanding of the universe's evolution. The James Webb Space Telescope, launched in Dec. 2021, has utilized gravitational lensing on numerous occasions to detect light emitted near the dawn of time, dating to just a few hundred million years after the Big Bang.
In 2016, the Advanced Laser Interferometer Gravitational-Wave Observatory also announced the first-ever direct detection of gravitational waves, created when massive neutron stars and black holes merge and generate ripples in the fabric of space-time. Further research published in 2023 found that the entire universe may be rippling with a faint "gravitational wave background," emitted by ancient, colliding black holes.
This article was last updated on March 11, 2024 by Live Science editor Brandon Specktor to include new information about how Einstein's theories have been validated by modern experiments.