New Delhi: April 19, 2022 is the 67th death anniversary of renowned physicist Albert Einstein, famous for his discoveries and the development of the special and general theories of relativity.
Throughout his life, Einstein conducted research on various fields including quantum mechanics and gravity. Considered one of the most influential physicists of the 20th century, Einstein published several groundbreaking papers, and toured the world to give speeches about his discoveries.
Einstein was awarded the Nobel Prize for Physics in 1921 "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect."
Two "Wonders" Which Deeply Affected Einstein During His Childhood
Einstein had written that two "wonders" deeply affected his early years, according to Britannica. When he encountered a compass at the age of five, he was spellbound by the fact that invisible forces could deflect the needle. This is how he became fascinated with invisible forces.
When Einstein was 12 years of age, he came across the second "wonder". He discovered a book of geometry, and called it his "sacred little geometry book."
At age 12, Einstein became deeply religious, and composed several songs to praise God.
A young medical student, Max Talmud, was an important influence on Einstein, and became an informal tutor, introducing Einstein to higher mathematics and philosophy.
When Einstein was 16 years of age, Talmud introduced him to a children's science series by German author Aaron Bernstein. In this series, the author imagined riding alongside electricity that was travelling inside a telegraph wire, which is a wire that carries telegraph and telephone signals. Einstein then asked himself a question: what would a light beam look like if one could run alongside it. If light were a wave, and one could run alongside it, the light beam should appear stationary, like a frozen wave, he thought.
Despite being a child, Einstein knew that stationary light waves had never been seen, creating a paradox. At that time, Einstein also wrote his first "scientific paper", which was based on magnetic fields.
Einstein's father, Hermann Einstein, was facing financial troubles due to repeated failures at business. Hermann moved to Milan to work with a relative, and left Einstein at a boarding house in Munich.
However, Einstein ran away six months later, and went to his parents.
Einstein's Early Years Of Education
Though Einstein's prospects did not look promising, he could apply directly to an institute in Zürich, which was renamed the Swiss Federal Institute of Technology in 1911, without the equivalent of a high school diploma if he passed its entrance examinations. Einstein excelled in mathematics and physics, but failed at French, chemistry, and biology.
His exceptional mathematics scores gained him admission into the polytechnic on the condition that he first complete his formal schooling.
Einstein went to a special high school in Switzerland, and graduated in 1896.
Einstein considered his years in Zürich some of the happiest years of his life. He met Marcel Grossmann, a mathematician, and Besso, with whom he had conversations about space and time.
Einstein's "Miracle Year" Of Scientific Theories
Einstein faced one of the greatest crises in life after graduation in 1900. He often missed his classes because he studied advanced subjects on his own. This angered some of his professors, especially Heinrich Weber, whom Einstein had asked for a letter of recommendation.
Einstein applied for several academic positions, but was turned down for each of them.
According to Britannica, Einstein wrote, "I would have found [a job] long ago if Weber had not played a dishonest game with me."
Einstein reached the lowest point in his life in 1902. He was unemployed, and his father's business went bankrupt. Later that year, came the turning point in Einstein's life, when the father of Marcel Grossmann recommended Einstein for a position as a clerk in the Swiss patent office in Bern.
His job at the patent office was a blessing, because he would quickly finish analysing patent applications, which left him time to think about various aspects of physics.
How Einstein Formulated The Principle Of Relativity
When Einstein was at polytechnic school, he had studied Maxwell's equations, which describe the nature of light.
Einstein discovered that the speed of light remains the same no matter how fast one moves, a fact unknown to James Clerk Maxwell himself.
Since there is no absolute velocity in Isaac Newton's theory, the fact discovered by Einstein violates Newton's laws of motion.
This is how Einstein formulated the principle of relativity: "the speed of light is a constant in any inertial frame (constantly moving frame)."
The year 1905 is often called Einstein's "miracle year", during which he published four papers in the Annalen der Physik. Each of these papers went on to alter the course of modern physics.
How Einstein Explained The Photoelectric Effect Through Quantum Theory
In one of his papers, Einstein described how he applied quantum theory to light in order to explain the photoelectric effect. According to the photoelectric effect, electrons can be ejected from the surface of a material (generally metal) when electromagnetic radiation hits the material.
In another paper, Einstein offered the first experimental proof of the existence of atoms.
The Special Theory Of Relativity
Einstein laid out the mathematical theory of special relativity in one of his papers. Special relativity is a scientific theory which explains how speed affects mass, time, and space. The theory of special relativity revealed that the speed of light can be approached but not reached by any material object.
Special relativity is the origin of the famous equation, E = mc², which defines the relationship between energy and matter. It expresses the fact that mass and energy can be interchanged.
The equation also provided the first mechanism to explain the energy source of the Sun and other stars.
Scientists such as Henri Poincaré and Hendrik Lorentz had pieces of the theory of special relativity, but Einstein was the first to assemble the whole theory together. He was also the first one to realise that the theory of special relativity was a universal law of nature.
Newton's laws of motion and Maxwell's theory of light were the two pillars of physics in the 19th century. Einstein realised that these pillars were in contradiction, and that one of them had to fall.
How Einstein Developed The General Theory Of Relativity
At first, the physics community ignored Einstein's 1905 papers. However, this changed when Einstein received the attention of the most influential physicist of his time, Max Planck, who was the founder of quantum theory.
Einstein rapidly rose in the academic world, after experiments gradually confirmed his theories, and he was invited to lecture at international meetings such as the Solvay Conferences.
Einstein was offered a series of positions at prestigious institutions including the University of Zürich, the University of Prague, the Swiss Federal Institute of Technology, and the University of Berlin.
He served as director of the Kaiser Wilhelm Institute for Physics at the University of Berlin, from 1913 to 1933.
From 1905 to 1915, Einstein thought of a crucial flaw in his own theory: it made no mention of gravitation or acceleration.
Einstein, for the next 10 years, was absorbed in formulating a theory of gravity in terms of the curvature of space-time. He considered Newton's gravitational force to be a by-product of a deeper reality, which was the bending of the fabric of space and time.
Einstein completed the general theory of relativity in November 1915, which he considered to be his masterpiece.
What Is The General Theory Of Relativity?
The general theory of relativity, a major building block of modern physics, associates the force of gravity with the changing geometry of space-time. Also known as Einstein's theory of gravity, the theory is the physicist's understanding of how gravity affects the fabric of space-time.
The general theory of relativity expanded the special theory of relativity which Einstein had published 10 years earlier.
Special relativity shows that space and time were interwoven as a single structure which Einstein dubbed space-time. Over the next decade, the physicist worked to incorporate gravity into the picture.
According to NASA, Einstein realised that the traditional gravitational field can be understood as the motion of stars, planets, and light on the stretched and curved surface of space-time. General relativity is a way to describe gravity by attributing it to the curvature of space-time that occurs in the presence of massive bodies, which cause space-time to stretch.
Einstein gave six two-hour lectures at the University of Gottingen in the summer of 1915. He explained an incomplete version of general relativity which lacked a few necessary mathematical details. Mathematician David Hilbert, who had organised the lectures, completed these details and submitted a paper on general relativity in November, just five days before Einstein, and presented the theory as if it were his own. However, Einstein and Hilbert resolved their differences and remained friends.
Physicists refer to the action from which the equations are derived as the Einstein-Hilbert action. However, the general theory of relativity is attributed solely to Einstein.
What Did Einstein’s Theory Of Gravity Predict?
Since general relativity accurately predicted the precession of the perihelion of Mercury's orbit around the Sun, Einstein was convinced that his theory was correct. Precession refers to the gravity-induced, slow and continuous change in an astronomical object's rotational axis or orbital path, while perihelion is the point in the orbit of a planet, asteroid or comet that is nearest to the Sun.
General relativity also predicted a measurable deflection of light around the Sun.
How Einstein Became A World-Renowned Physicist
World War I interrupted the work of Einstein, who was only one of four intellectuals in Germany to sign a manifesto opposing Germany's entry into war.
After World War I ended, two expeditions were sent to test Einstein's prediction of deflected starlight near the Sun. One of the expeditions set sail for the island of Principe, off the coast of West Africa, and the other to Sobral in northern Brazil to observe the solar eclipse of May 29, 1919. The results were announced in London on November 6, 1919, at a joint meeting of the Royal Society and the Royal Astronomical Society.
Nobel laureate J J Thompson, president of the Royal Society, stated that "this is the most important result obtained in connection with the theory of gravitation since Newton's day, and it is fitting that it should be announced at a meeting of the Society so closely connected with him."
In this way, Einstein became a world-renowned physicist, the successor to Isaac Newton.
In 1921, Einstein travelled around the world, to give speeches about his discoveries.
What Is The Photoelectric Effect?
The same year, he was awarded the Nobel Prize in Physics for his discovery of the law of the photoelectric effect.
The photoelectric effect is a phenomenon in which electrically charged particles are ejected from or within a material when it absorbs electromagnetic radiation. It is also defined as the ejection of electrons from a metal plate when light shines on it.
The phenomenon is also known as photoemission, and the electrons ejected are referred to as photoelectrons.
For the photoelectric effect to occur, the light waves must be above a certain frequency. The photoelectric effect played an important role in the development of modern physics because it raised some questions about the nature of light, which Einstein resolved in 1905. One of the questions raised was the dual nature of light, which means that light can behave both as a wave and as a particle. Einstein said that light is a particle containing energy corresponding to its wavelength.
Einstein’s “Greatest Blunder”
The physicist also launched the new science of cosmology. His equations predicted that the universe is dynamic, which means it is expanding or contracting. However, this contradicted the prevailing view that the universe was static, because of which Einstein introduced a "cosmological term" to stabilise his model of the universe.
Astronomer Edwin Hubble found in 1929 that the universe is indeed expanding. This confirmed Einstein's earlier work.
In 1930, Einstein visited the Mount Wilson Observatory near Los Angeles. He met with Hubble and declared the cosmological constant to be his "greatest blunder."
However, recent satellite data have shown that the cosmological constant is probably not zero, but dominates the matter-energy content of the entire universe.
Einstein Continued To Work Until His Death
On April 17, 1955, Einstein experienced internal bleeding due to the rupture of an abdominal aortic aneurysm, which is an enlargement of the aorta, the main blood vessel that supplies blood to the abdomen, pelvis, and legs. It was previously reinforced surgically by Rudolph Nissen, a surgeon, in 1948.
However, in 1955, Einstein refused surgery, saying that "it is tasteless to prolong life artificially."
Einstein breathed his last on April 18, 1955, in the University Medical Center of Princeton at Plainsboro, United States, having continued to work until his death.