In 1643, a premature baby born was told he could fit in a quart mug. He barely survived. By his mid-20s, he had already invented calculus. In 1895, a 16 year-old imagined himself chasing a beam of light. This thought eventually changed the world forever. Those 2 scientists are Sir Isaac Newton (1643-1727) and Albert Einstein (1879-1955) who are acknowledged to be two of the greatest and most influential physicists of all time. Both Einstein and Newton came up with ideas that changed the way we view the world. Isaac Newton discovered the laws of gravity and motion and invented calculus. Albert Einstein devised his theory of relativity which revolutionized our understanding of space, time, gravity, and the universe.
Isaac Newton spent most of his childhood with grandparents since his mother left him to remarry after the death of her husband 3 months before Isaac’s birth. He went to school and when his mother came back after the death of her second husband, the school’s principle convinced her to let Isaac stay to finish his education. After finishing school and getting the proper education to get him to college, Isaac went to the Trinity College in Cambridge in 1661. He graduated and got a degree in mathematics and philosophy. He wrote in Latin: “Amicus Plato- amicus Aristotle- magis amica veritas” meaning “Plato is my friend. Aristotle is my friend. But my best friend is truth.” This showed Newton’s will and passion for discovering and questioning concepts and principles that were yet unknown and mysterious until the 17th century. Upon his death in 1727, a single sentence was written on the slab of his grave: “Here lies that which was mortal of Isaac Newton.” To be able to create laws that are still recognized in our daily lives in the 21st century supports the writing on his slab and confirms the claim that Isaac Newton is a “mad scientist.” Alexander Pope an English poet wrote an epitaph about Isaac saying: “Nature and Nature’s laws lay hid in night; God said “Let Newton Be” and all was light.”
Albert Einstein lived in Munich right after the birth of his younger sister. When he was 5 years old, his father gave him a compass. Einstein was fascinated that the needle always pointed at the magnetic north no matter which way he turned the compass. He said: “I can still remember- or at least I believe I can remember- that this experience made a deep and lasting impression on me. Something deeply hidden had to be behind things.” His family traveled to Italy and left him behind so he could finish school. When he moved to Switzerland, he tried applying to the Swiss Federal Institute of Technology. However, he only passed the Math and Physics section. He failed in language, politics, and zoology (mainly because the exam was in French). When he took the exam a second time, he passed and was enrolled in the university where he studied math and physics. In 1905, he developed his most famous theory: the theory of special relativity. In 1955, he checked himself to Princeton hospital after his abdominal aortic aneurysm burst. He didn’t agree on doing surgery, for he said it is useless to prolong life and that it was time to go. He died the next day. After his death, scientists took permission from his family to study his brain to know why he was so intelligent. It turns out that his brain was missing a bordering region called the lateral sulcus which may have lead neurons to communicate better in this part of his brain.
In the 17th century, the bubonic plague (an infection that killed 1 in every 4 people) ravaged Europe. This forced Isaac Newton to stay isolated at home for 2 whole years that lead to his most amazing breakthroughs. There, he used a prism to discover that white light was made up of the colors of the rainbow. He also stuck a sew needle in his eye socket to check if changing the shape of his eye would make him see colors differently. But most importantly, the plague that compelled Newton to stay at home lead to his most famous discovery: Gravity.
It is said that outside Newton’s house exists a tree, the famous apple tree. That one day, when he was sitting under it, an apple fell which made him question gravity. He then asked a question that eventually helped us understand the universe: “If the apple falls, does the moon also fall?” He reasoned that gravity is a force generated by the mass of an object causing it to attract other objects. This is why we stand on the ground of earth (we are attracted to its center), why the Earth revolves around the Sun, and why the moon doesn’t fall. Now if the Sun disappeared, all planets would lose their orbits, for there is no gravitational pull that’s pulling them to the center. This is why up until the 20th century, Physics was mostly explained in terms of Newton’s laws. It was mostly explained in Newton’s laws up until Einstein, the genius that had a different explanation to gravity than Newton thought. He asked: “if the Sun disappeared, how could the Earth go off its orbit before we Earthlings stopped seeing sunlight?” So gravity is no longer a force of attraction between objects, but an effect of the space-time curvature on bodies. The key difference between Newton and Einstein is that Newton describes gravity as a pull, a force expressed between objects in relation to their masses while Einstein describes it as a push, a curvature in a 4-dimensional space-time. Shakespeare has written in ‘As You Like It’ that “All the world’s a stage / And all men and women are merely players.” This is the kind of picture of metaphor that Isaac Newton had in mind throughout his greatest work: “The Principia”. He claimed that all the actions in the world (like planets moving, apples moving...) take place on a perfectly rigid unchanging stage that is space and time. Space and time to him were absolutely “absolute”, meaning they flow without compromise, nothing that happens on that stage is going to affect the stage itself. Space and time are “not actors in the drama.” Newton declared time universal. It’s the same for everyone no matter where we are or what we’re doing and that it ticks at a constant rate for everyone.
Space-time has now become an actor in the play. So the other actors in the play like the Sun (a massive object) could affect the shape of space and the flow of time in its vicinity. He thought space and time were intertwined in an infinite fabric (like a blanket). Massive objects like the Sun bend the space-time fabric with their gravity. This means light no longer travels in a straight path as it passes by the Sun (a theory of General Relativity which he published later in 1915). Einstein also stated that “time is but a stubborn illusion.” He asked his students in his lecture: “What is time? A deceptively simple question, yet it is the key to understanding relativity.” He told his friend to imagine himself standing in front of a bus moving at a very high speed. Then to imagine two lightning bolts 100 meters apart striking simultaneously. Now he asks him to stand in the middle of the train during the exact same scenario. Would the lightning bolts be simultaneous? The answer is NO! This was because he was moving towards one and away from the other. To Einstein, standing still, they were simultaneous. He asked himself: “How could the two of us experience the same event differently?” This is where he came up with the conclusion that time is NOT absolute. The explanation to the above experiment is that closer one gets to the speed of light, the slower time gets (and vice versa).
Einstein is best known for developing the theory of special relativity. He developed this theory in 1905. The theory is mostly applicable when discussing huge energies like astronomical distances all with the absence of gravity. He later on added gravity to the theory in 1915 with the publication of his paper on general relativity. But before understanding Einstein’s theory, let’s take a step back and ask: What was Physics like before Relativity? The answer is simple: the universe was understood in the terms of Newton’s 3 laws of motion (Einstein’s theory of relativity is usually understood as a repudiation of these laws). But there are some things that could not be explained by Newton’s laws like light. In the 1880s, scientists supposed that light must travel through some medium which they called the “luminiferous ether”. Then the scientists found out that light travels at a constant speed, no matter what happens to Earth’s motion. So they concluded that there might not even be an ether to begin with, that light traveled in vacuum. When Einstein was 16 years old, he imagined himself catching a light beam. He imagined himself traveling at the speed of light. Now if a person could theoretically catch up to the speed of light, then that beam of light would appear motionless or frozen to him. When that thought was introduced, scientists raised this question: “Would Physics as a whole have to change depending on a person’s speed, and their vantage point?” This is when Einstein hunted a unified theory that would make the rules of Physics the same for everyone. Taking the example of the two lightning bolts mentioned previously, where one lightning bolt struck before the other when the person was standing in the middle of the train, Einstein deduced that it is not light speed that changes, but that time itself is relative (Simultaneity is not absolute). So now time differs to people at motion than those at rest, but light is always the same. The principle of relativity requires that mass be a direct measure of the energy contained in a body. In short, light carries mass. The theory includes a way for the speed of light to define the relationship between mass and energy. It
is defined by the most famous equation in the world: E= mc .
Einstein explains this relation by saying “it followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing. A somewhat unfamiliar conception for the average mind. Furthermore, the equation E= mc2 in which energy is put equal to mass multiplied with the square of the velocity of light showed that a very small amount of mass may be converted into a very large amount of energy, and vice versa. The mass and energy were in fact equivalent, according to the formula mentioned before.” Even though mass and energy are but different forms of the same thing, they are not easily exchangeable. Since the speed of light is already a humongous number and the equation requires that it be multiplied by itself, then a very small amount of mass contains a large amount of energy. If we turn every atom of a paper clip into energy, without leaving any mass in it, the paper clip could yield an amount of energy equivalent to 18 kilotons of TNT, which is roughly the size of the bomb that destroyed Hiroshima in 1945.
350 years ago, Isaac Newton, a true polymath whose brilliance could never be surpassed, was the first to question why or how things fall. Why an apple moves downwards and not sideways or upwards. 100 years ago, Albert Einstein had the revolutionary insight that gravity was NOT what people believed it was for 3 centuries. These 2 geniuses laid the foundation for Physics, showed keener interest in their passions, and deepened our understanding of the universe. To say these 2 physicists changed the world is an understatement. What they both came up with, the discoveries they made, and the theories they created, not only show how brilliant they are, but also how brave and daring they were to think of concepts not any average mind could comprehend. What they both hid in their work is the secret message that imagination is more important than knowledge. Both started with a single imaginary thought that later on helped them develop what were later known as the most important papers ever published in the field of Physics. What made both Newton and Einstein special is their tendency to always ask questions. It is with no doubt that both physicists will always remain two of the most influential people in the field of Physics and Mathematics. Some scientists operate at the edge of light where the dark is present, but a very small number of scientists- like Newton and Einstein- jump right into the dark and create their own light.