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EINSTEINâS LIFE
If my theory of relativity is proven successful, Germany will claim me as a German and France will declare that I am a citizen of the world. Should my theory prove untrue, France will say that I am a German and Germany will declare that I am a Jew.
Albert Einstein, 1922
If the dismissal of Jewish scientists means the annihilation of contemporary German science, then we shall do without science for a few years!
Adolf Hitler to Max Planck, 1933
Albert Einstein was born on March 15, 1879 in the town of Ulm, and no, he didnât flunk high school math. The town is now part of Germany, but had only joined the newly created German empire in 1871, having been part of the Kingdom of Wurttemburg before that. His parents, Hermann and Pauline, were what would be called today members of the upper middle class. His father was involved in manufacturing, a partner in a firm that produced feather beds at the time of Albertâs birth.
The family were assimilated Jews, as is evidenced by the fact that they did not give their son a biblical name. Thus, Albert grew up in a liberal atmosphere as far as religion was concerned (although he did go through an adolescent period of hyper-religiosity). He apparently had a happy childhood. His father, an easy-going man, frequently read to the family and his mother was an accomplished pianist. In addition, Albert became very close to his younger sister Maria (he called her Maja) whose 1924 memoir remains our main source of information about his early life.
He apparently was slow to start speaking. Later on he would write that at the age of two or three he decided that he wanted to speak in complete sentences, which may explain the delay. (There is an old joke to the effect that his first words, at the age of three, were âFather, there is something terribly wrong with the state of thermodynamics.â)
Unfortunately, the feather-bed business did not prosper, and in 1880 the family moved to Munich where Hermann, in partnership with his younger brother, set up a business manufacturing electrical equipment. It was in Munich that, at the age of six, Albert started his formal schooling. Contrary to popular legend, he was a good studentâthere is a letter from his mother to his grandmother bragging that he was first in his class, for example. It was during this period that he began the study of the violin, a pastime that would play an important role in his public image later in life. In 1888 he moved on to a Gymnasium, where he would remain until he was 15. Again, contrary to the popular legend, he always received high marks in mathematics.
Although he was generally a good student, he was not particularly happy with the rigid, authoritarian teaching style that was the norm in Germany at the time. He also made few friends, showing an early inclination to become what his biographer Abraham Pais termed âa man apartâ. His most important educational experience, as he recounted later in life, was reading a book on Euclidean geometry and finding there an order and logical consistency that opened his mind. (I should point out that Euclid has played that same role in the lives of many boys who went on to become theoretical physicists, the author included.)
In 1894, the family business began to fail, and, leaving 16-year-old Albert behind to finish Gymnasium, the family moved to Italy, eventually settling in Pavia. Alone, depressed, and worried about compulsory military service, the young man left school and joined his family in Italy, planning to study on his own for the entrance exam to the EidgenĹssiche Technische Hochshule (ETH) in Zurich, then as now one of the worldâs most prestigious technical universities. Although he did well in physics and math, he did not pass the exam, which included subjects like literary history and drawing. Consequently he took an alternate path to admission, enrolling at a school in Aarau to obtain a Matura (essentially a high school diploma). In 1896 he enrolled at the ETH and renounced his German citizenship (he became a Swiss citizen in 1901 and an American citizen in 1940).
At the ETH he made friends with fellow student Marcel Grossman, who would be important in his later life. Unfortunately, he apparently rubbed his professor, Heinrich Weber, the wrong way. Weber felt that Einstein, though bright, was too reluctant to take advice from othersânot an uncommon failing in college students. In any case, when Einstein graduated in 1900 he was not offered a position as a teaching assistant at the ETH.
The next few years were difficult ones. Between periods of unemployment he had a couple of temporary teaching positions at what were essentially private high schools. This drought ended when Marcel Grossmanâs father brought him to the attention of the head of the Swiss patent office, with the result that in 1902 he was appointed as a patent examiner third class, his first permanent position and one that has lived on in the folklore of science. Shortly thereafter he married Mileva Maric, a woman who had been a fellow student in Zurich, and their first son was born in 1904.
Throughout this period Einstein found time to write a steady stream of physics papers, mostly about statistical mechanics. It was in 1905, however, a year often referred to as the annus mirabilis (year of wonders) in physics that he really came into his own. In that year he published four papers, any one of which could have earned him the Nobel Prize. Two of them, dealing with special relativity and massâenergy equivalence, will be discussed in later chapters. It is, I think, worthwhile to take a short detour to discuss the other two.
The photoelectric effect is a phenomenon that occurs when light (usually ultraviolet) is shone on a metal. As soon as the light is turned on, electrons start being ejected from the metal, and the energy of the electrons depends on the frequency (color) of the lightâthe higher the frequency the more energetic the electrons.
According to classical electrodynamics, there is no reason why electrons shouldnât be ejected because of the action of the light. Light, after all, consists partly of an electric field which can exert a force on electrons. The problem is that in the classical picture the effect should be analogous to surf washing a piece of driftwood ashoreâit should happen slowly and should not depend on the frequency of the light.
Building on Max Planckâs introduction of the idea of quantization, which will be discussed in the next chapter, Einstein suggested that light actually came in quanta as wellâwe now call these bundles of light âphotonsâ. (Planck had been unwilling to be so radical, and had only suggested that atoms absorbed and emitted light at specific frequencies while remaining agnostic as to the nature of light itself.) In this picture, the interaction between light and electrons is more like the collision between two billiard balls than surf washing driftwood ashore. In addition, the rules of quantization required that the higher the frequency of the light, the more energy the photon has and the more energy it can transmit to the electron. Thus, the introduction of the photon explained what is observed in the photoelectric effect.
This paper was one of the foundations of the developing field of quantum mechanics. In addition, it was the basis for the awarding of the Nobel Prize to Einstein in 1921âapparently relativity was still considered a bit too far out for the award at that time.
The other paper concerned a phenomenon known as Brownian motion. In 1827 the British botanist Robert Brown noticed that when a small particle like a pollen grain was suspended in a liquid and observed under a microscope, it jiggled around in an erratic kind of motion. Einstein realized that this obscure effect might be the solution to a long-standing debate about the nature of atoms. Throughout the nineteenth century, a debate had gone back and forth on the question of whether atoms were real, physical objects or whether matter just behaved as if it were made of atoms. In the latter case, of course, atoms would simply be mental constructs.
Einstein realized that if atoms were real, when one bounced off a pollen grain it would exert a tiny forceâif the atom bounced to the right the grain would recoil to the left, for example. On average, as many atoms will hit on the left as on the right, so these forces would cancel out over time. Einstein noted, however, that at any given moment there could be more atoms hitting on one side of the grain than the other. Thus, the pollen grain would be subject to shifting forces, producing just the kind of erratic motion Brown had observed. Since mental constructs canât exert physical forces, this result was crucial in resolving the old debate.
In 1905, as well, Einstein completed his thesis (on molecular sizes) and was awarded a PhD at the University of Zurich. Not a bad output for a single year!
His reputation growing, Einstein started to move into academe. In 1908 he was appointed as a privatdocent at the University of Bern. This position allowed him to teach, but paid so little that he had to keep his day job at the patent office. It wasnât until 1909 that he obtained his first real faculty positionâan associate professorship in theoretical physics at the University of Zurich. (We have records of faculty debates in which his future colleagues argue, in effect, that he was such a good scientist that the fact that he was Jewish should be ignored.) The position, of course, allowed him to resign from the patent office. Shortly thereafter, in 1910, his second son was born.
At Zurich, Einstein continued to publish papers in theoretical physics (11 papers in two yearsâan impressive output) and dabbled in experimental physics. Then, in a move that still puzzles his biographers, in 1911 he accepted a professorship at Karl Ferdinand University, a German language institution in Prague. He stayed there only a little over a year, and in 1912 he was back in Zurich, this time with a senior appointment at the ETH. It is clear that by this time Einstein had developed a growing reputation in the world of physics, and he received numerous inquiries from universities throughout Europe, garnering enthusiastic letters of support from luminaries like Max Planck and Marie Curie. Throughout this period, Einstein was also slowly working his way through the concepts that would result in the theory of general relativity, which we will discuss in Chapter 9.
This rapid hopping around between institutions was somewhat atypical of career paths in European universities at the time. It was much more common for people to enter a university as an undergraduate and remain at the same place, holding positions in graduate school, the junior faculty, and, eventually, the senior faculty. Today, however, Einsteinâs career track wouldnât look unusual at all. Physics students are routinely encouraged to apply for graduate training away from their undergraduate institutions and then, as often as not, will do post-doctoral fellowships at several other places before finally settling down. This kind of varied experience makes sense in a world in which all branches of science are becoming increasingly international.
In any case, after just three semesters in Zurich, Einstein left to take up a prestigious appointment in Berlin. The details of that appointment illustrate what a hot prospect the young theorist had become. His primary appointment was as a member of the Prussian Academy, but he was also made a professor at the University of Berlin, where he could teach if he wanted to, and promised the directorship of a new research lab. In fact, the promised new physics institute was created in the Kaiser Wilhelm Gessellschaft, a major research institute, in 1917. Even today, an appointment like this would be quite a plum. Einstein wrote to a friend âI could not resist the temptation to accept a position which frees me of all obligations so that I can devote myself freely to thinkingâ.
Einstein would stay in Berlin until 1932. Unfortunately, soon after his arrival there he and Mileva separated, and she returned to Zurich with the boys. His professional life flourished, however. In 1915 he presented the field equations that make up the heart of general relativity to the Prussian Academy (the paper was published in 1916). Throughout the war years he continued to publish important papers. He also became involved with pacifist, and, to a lesser extent, Zionist organizationsâpolitical activities that would remain important throughout the rest of his life. Also, in 1919 he divorced Mileva (the divorce agreement stipulated that she would receive his Nobel Prize money, should it be awarded). He then married his distant cousin, Elsa Einstein Lowenthal, whom he had known since childhood.
During this period he also began what would be a lifelong project to present the results of his theories to the general public. In 1917, the publishers Vieweg in Braunschweig, Germany, published his popular book On the Special and General Theories of Relativity, a book that was to go through multiple expansions as time went on. The book was translated into English by Methuen publishers in London in 1920, and later brought out by Holt (now Holt, Rinehart, and Winston) in the United States. In 1993, Routledge brought the book out in its classic series, and this companion volume will be part of that long history.
The early Berlin years were full of what can only be described as professional administrative duties. In 1916 Einstein succeeded Max Planck as president of the German Physical Society (Deutsche Physikalische Gessellschaft), the society of professional physicists. He also served on boards of various scientific institutions in Germany and Holland. Then as now, these are the sorts of things you would expect for a man who was nearing the top of his profession. But as the war wound down, events were in motion that would change Einsteinâs life forever.
As we shall discuss in Chapter 13, general relativity makes predictions that can be verified experimentally. Einstein showed that the theory could explain a small but troubling anomaly in the orbit of Mercury, but, more importantly, he predicted that light passing near a massive body like the sun would be bent by a specified amount. The bending itself wasnât newâNewton had made a similar predictionâbut the amount of predicted bending was (basically, relativity predicted twice as much deflection as did Newton). In those days, the only way this prediction could be verified was to observe stars near the sun during an eclipse. The war prevented several eclipse expeditions from being undertaken, but in 1919 the British astronomer (later Sir) Arthur Eddington was able to mount one. The details will be discussed in Chapter 13, but the result was stunning. Einsteinâs predictions were verified.
Itâs hard to overstate the effect this turn of events had on the life of someone the New York Times called âthe suddenly famous Dr Einsteinâ. Headlines blared âRevolution in Science: Newton Overthrownâ, and Einstein became a household name all around the world. Historians have speculated about why this unusual âcanonizationâ occurred. Coming as it did at the end of World War I, the news broke on a populace that was weary, searching for a sign of hope. To people who had seen an entire generation of young men slaughtered senselessly in the trenches, the sudden appearance of a man who seemed to paint a new picture of the universe must have seemed little short of miraculous.
In addition, there seemed to be something almost magical about relativityâthe legend that only a dozen men in the world understood it was born about this time. Given the outpouring of theoretical papers after 1919, that legend certainly wasnât true then, and it certainly isnât true today. Special relativity is routinely taught to tens of thousands of undergraduates every year, and the general theory to hundreds of graduate students. Human beings always need to sense a distance between themselves and their heroes, and the mathematical difficulty of general relativity seemed to provide just that sort of separation. Einsteinâs accomplishments seemed otherwordly, clouded in mystery. Popular descriptions of the man pictured him almost as a priest rather than a scientist. One biographer suggested that he was seen as a ânew Mosesâ, bringing the word of God to humanity. In our modern world we can see a bit of this sort of attitude in the treatment of cosmologist Stephen Hawking.
Einstein was not only admired, but loved. A good illustration of this is an essay written by humorist Robert Benchley in 1936. Titled âTaking up Cudgelsâ, it can be found in his book My Ten Years in a Quandary. It is a hilarious âdefenseâ of general relativity against a competing theory, and concludes with these words addressed to the author of that theory:
Who asked you to butt in on this? We were getting along very nicely with Prof. Einstein, who has proven himself to be an extremely pleasant gentleman⌠He also plays the violin. What do you play?
This veneration of Einstein culminated in 1999 when Time Magazine named him the âperson of the centuryâ, calling him âthe embodiment of pure intellectâ.
In any case, Einstein enjoyed, but was not overwhelmed by, his newfound fame. Throughout the 1920s and early 1930s he traveled extensively, visiting the United States, South America, and Japan, among other places. As we shall see in Chapter 4, the visit to Japan has come to play a part in a minor scholarly debate about the genesis of special relativity. It was while he was en route to Japan, in fact, that he was notified that he would be awarded the Nobel Prize.
As we mentioned above, the Prize was not given for relativity, his most important contribution to science, but for his explanation of the photoelectric effect, one of the founding documents of the new field of quantum mechanics. This new science grew in stages. In 1913 the Danish physicist Niels Bohr (1885â1962) explained the behavior of the hydrogen atoms in quantum terms, and in the years that followed what is now known as the âoldâ quantum theory was developed. We donât have the space to go into this in detail, but the central point was that it described the world inside the atom as a place where everything came in little bundles (quanta), but in which things like electrons could be thought of as something like miniature billiard balls in comforting analogy to the Newtonian world view. In 1925, however, the young German physicist Werner Heisenberg (1901â1976), joined later by the Austrian physicist Erwin Schrodinger (1887â1961), developed the modern version of quantum mechanics. The central differences between this new way of describing the world and the old, comfortable classical physics, we...
