WHY Einstein was a pure genius who changed the game of physics Anatomy of a genius Albert Einstein was a pure genius, an epic scientist, an innovator, and a visionary, like a few others in the history of mankind. He left an inestimable heritage, a deep footprint not only in the physics of his time. Still nowadays, in fact, a century later, his ideas are inspiring scientists all over the world. Einstein’s work is an example of extraordinary creativity, elegance, fantasy. Real Pindaric flights of a free, creative, unconventional, brilliant thought. Some people believe it was an alien, Kardec would say a perispirit of some higher entity coming to Earth from the future, to reveal new truth to advance our civilization for centuries. Typically, scientific progress is the result of collaborations of several scientists. each giving their own contribution in a gradual advancement, and every scientist is the bearer of a single great intuition or at most a couple. Einstein is unique in the history of physics because, maybe even more than Isaac Newton, he changed the game in almost any field and worked mainly alone. There are many stories about him and also some wrong beliefs, such as the one according to which, in the beginning, he was not good in math, because he only took the second attempt at the entrance exam at the Polytechnic University of Zurich. For the record, Einstein was rejected the first time but he was only 17 years old and failed only because of the French test. His IQ was in fact greater than 150, a very high coefficient for us ordinary mortals. However, there are and there have been human beings with superior qi who nevertheless did not make such vast and profound contributions to science. What really makes Einstein unique is his boundless fantasy and imagination: the ability to visualize things forbidden to ordinary mortals. He could imagine very rich and detailed abstract processes and represent them with great precision. After giving birth to general relativity, he declared that he already had all the theory clear in his mind but lacked the “words” to express it. Many people, overlook the fact that he was, first of all, a physicist, not a mathematician, that is different. Physicists use math as a language to express their ideas and give them coherence, and Einstein found the “words” he was looking for, thanks to mathematicians of the time such as Bernard Riemann, Ricci Curbastro, Henri Poincarè, Hermann Minkowski. These men had developed in their work the tools that Einstein used afterwards to write the theory of relativity. The German mathematician Bernhard Riemann had developed a non-euclidean elliptical differential geometry that Einstein and Minkowski employed to draw the “landscape” of space-time, the background on which the physical phenomena of general relativity occur. Whereas the Italian mathematician Ricci Curbastro had developed the absolute tensorial calculus, a generalization of the vectors in n dimensions that Einstein used to express the laws that regulate the phenomena within space-time. When Einstein was a student at the Zurich Polytechnic, Hermann Minkowski was his professor. At the beginning Minkowski considered Einstein a slacker because the young Albert did not attend his lectures. Einstein probably got bored going to class. He preferred to study independently on his course mate’s notes Marcell Grossmann. He certainly didn’t want to deprive himself of the pleasure of learning by himself, without the help of the professor in a boring frontal lesson! Einstein is celebrated mainly for the theory of general relativity, a masterpiece of creativity and imagination published in 1915, that still today proves to be at least a century ahead of its time. However, many people ignore that Einstein never took the Nobel prize for relativity: he was honored by the Nobel prize for his work on the photoelectric effect. For this discovery, he can be fully-fledged considered one of the fathers of quantum mechanics. In 1905, with a work of such great importance, 1905, Einstein could already be said to be satisfied, but in the same year, he released three other works equally revolutionary and shocking. 1905 EINSTEIN’S ANNUS MIRABILIS 1905 is remembered as Einstein’s “annus mirabilis”. Within a few months, in fact, on “Annals of Physics”, one of the main scientific journals of the time, four papers were published. Those will be fundamental for modern physics. They deeply changed the concepts of space, time, mass, and energy. 1-On June 9 an article named “On a Heuristic Viewpoint Concerning the Production and Transformation of Light” was published. It was precisely this paper that will go to posterity as the discovery of the photoelectric effect and will let Einstein win the Nobel Prize in 1921. This is considered a fundamental contribution to quantum theory. It was a work of paramount importance because it confirmed the intuition that Planck had in 1900, in an attempt to explain the problem of radiation of the black body, that electromagnetic radiation, up to that time considered an exclusively wave phenomenon, could in some cases also act as a stream of particles, corpuscles, afterwards called photons. This idea was later confirmed by Arthur Compton a few years later when he discovered the effect that bears his name that definitively certified the accuracy of this insight. 2-On July 18, a second article was published: ”On the Motion of Small Particles Suspended in a Stationary Liquid, as Required by the Molecular Kinetic Theory of Heat” This is today known as “the Brownian motion” and it was very important because provided strong empirical evidence to the idea that matter is made of atoms. Nowadays we take it for granted, but at the time it was still a controversial issue. 3- On September 26, “The Electrodynamics of Moving Bodies” was released Today we call it special relativity. What is often overlooked is that to formulate special relativity Einstein had to reform all physics starting from the classical mechanics of Galileo: In fact, he fixed some inconsistencies that had arisen with the development of Maxwell’s electromagnetism and then replaced the concept of ether, which had created so many problems for physicists for so many centuries, with that of Space-Time. 4- On November 21, Einstein published the last paper named “Does the Inertia of a Body Depend Upon Its Energy Content?” Here Einstein introduced la magic formula E =MC^2, considered the most elegant formula ever in physics. Its deep implications go far beyond special relativity. First, it clarifies that c is not only the speed of light but is also a universal constant that regulates the energy and mass of bodies in the universe. Then introduces the idea that mass is a form of energy and mass and energy can convert to each other. This gave a fundamental contribution to the development of nuclear physics, studied simultaneously by other scientists as Thompson, Curie and later it will lead to the comprehension of nuclear fission, discovered in 1939 by Lise Meitner and Otto Hahn. In 1939, Einstein, who had already become the most famous scientist in the world, realized the scope of his discovery and as a man with an iron ethic, along with the Hungarian physicists Leó Szilárd, Edward Teller, and Eugene Wigner, wrote down a letter to the American President Roosevelt, to warn that Nazi Germany could shortly use fission to create atomic bombs, and suggested the United States to begin conducting research in this regard. All these 4 wonderful works of theoretical physics were signed by a 26-year-old boy with no official role in the scientific life of the time, who worked 8 hours a day for 6 days a week, who kept a family and wrote scientific articles in his spare time. And this was only the beginning because in the following years Einstein with the help of Minkowski will complete the mathematics of space-time and will finish the work signing the general relativity. Special relativity, however revolutionary, was in the air long ago, someone else could have discoveried it in a short time. Maybe Lorentz, Poincarè or Minkowski, would have definitely got there. General relativity, instead, is a flashing light that comes from the future, a theory that was certainly not daughter of its time. If it wasn’t for Albert Einstein it would have come out after decades and decades. General relativity has clarified what universe is and how space-time and gravity work on a cosmic scale. It completes and replaces Newton’s universal gravitation. It was published in 1915 and still nowadays, a century later, is our theory of the gravitation: it has been tested by several accurate experiments and works beautifully. 1915 is also considered the year of birth of modern cosmology: all theories about the birth and evolution of the universe in fact are inspired and developed within the framework of general relativity. The Big Bang theory itself is a direct daughter. Furthermore, hidden within Einstein’s field equations, there was another stunning prediction: gravitational waves. (We talked about it in a dedicated video, if you missed it, go see it now!) The first gravitational wave was experimentally revealed in 2015, exactly a century later. EINSTEIN’S MISTAKES Einstein was great even in making mistakes! Few people know that he made huge mistakes. As we’ve shown in our video dedicated to the dark energy (again, if you’ve missed it, go watch it now!) when in 1915 Einstein published general relativity, he believed the universe was a steady system as all the observations suggested. By contrast, the field equations admitted no static solutions: they led to a dynamic and unstable universe. Therefore Einstein added a new term, corresponding to a repulsive force to counterbalance gravity and make the universe stable and steady: he named it “cosmological constant”. However, in 1929 when Hubble first and then Lemaitre showed that the universe wasn’t static at all, but it was even expanding, Einstein considered the introduction of the cosmological constant as the biggest mistake of his life! However, even in the mistake, Einstein proves himself too far ahead for his time. In fact, in 1997 dark energy was discovered: it turned out that the expansion of the universe was even accelerating: and this was not at all expected by Einstein’s equations unless you don’t add a repulsive term… which is precisely a cosmological constant! The term that Einstein had introduced to ensure the stability of the universe and that he had threw out of the door, came back from the window. Einstein’s other big mistake was in the calculation of the deflection of the light because of the curvature of space-time. In fact, general relativity describes gravity as a geometric property of space-time that, by bending like a sheet because of the presence of masses, shows to mass how to move. Light, like mass itself, travels on the space-time “sheet” and is also subject to this curvature. In 1912 Einstein had calculated the gravitational deflection by making a serious mistake: his prediction was half of what was actually. In 1914, an eclipse of the sun would have occurred, and an expedition was planned to measure the light of the sun and see if it could have been deflected. Unfortunately the expedition was aborted because of the outbreak of the war. A dramatic event like the First World War was almost providential because it allowed Einstein to have a few more years to correct the error and refine his theory. Otherwise, he could have even abandoned his theory. Nevertheless, 1919 was the right year: Einstein became famous all over the world. Sir Arthur Eddington, during an eclipse of the sun, experimentally observed a deflection of the light compatible with Einstein’s equation. He thus verified the curvature of light providing a first overwhelming proof in favor of general relativity.