Albert Einstein (1879-1955)

CONTENTS

Einstein: An Overview

His Life and Works

Special Relativity

General Relativity

His Legacy

Links to Einstein' Writings and More Information

EINSTEIN: AN OVERVIEW

Einstein wanted to unify all branches of physics around a cohesive set of simple laws, ones that described physical behavior in all possible settings.

He was initially troubled by the inherent contradictions between the classic understanding of the relativity of the laws of mechanics (Galileo and Newton) and the newer view of the absolute character of the laws of electromagnetism (Maxwell). With his theory of special relativity (1905) he demonstrated mathematically that electromagnetism functions with the same relativity of classic mechanics--because of the elasticity of space and time! This theory seemed counter-intuitive at the time, though experiments over the next quarter of a century gave clear demonstration of the correctness of his theory.

A major difficulty with his theory of special relativity was that it applied only to "special" situations (thus its name), that is, situations where light was being measured by an observer whose momentum was constant. Einstein knew that situations of perfectly constant momentum (unchanging speed and direction) are rare. Normally our movements are in constant flux, accelerating, decelerating, turning, etc. as we encounter varying forces acting externally upon our movements. Einstein thus set out to define a more comprehensive theory of mechanical and electromagnetic physics, one he called general relativity.

In this quest for a general theory of relativity it was the issue of gravity that received his greatest attention. Through a number of mental "games," he came up with the notion that gravity is not really a separate force but merely a result of the structuring of the movement of objects through what he called spacetime. This too was counter-intuitive, in the sense that he was attempting to describe a dimension of physical existence that had no exact parallels in what we humans have ever been able to perceive directly. So he used analogies. One of these was the analogy of the curve that is always described on the surface of a globe when something attempts to move along the globe's surface in a straight line. Gravity is really only such a curvature in spacetime.

Another analogy was a rubber membrane with a heavy iron ball nestled in the center of it--and the effect this would have if we tried to roll a much smaller ball across the membrane and past the iron ball in an attempt to reach the other side of the membrane. Depending on how close the smaller ball came to the larger ball, it might be led around and past the larger ball by the curvature of the membrane around the ball--or if it came too close, the smaller ball might be drawn in a circular path around the larger ball and finally into collision with it. Einstein asserted that there was no gravitational "force" that drew the the smaller ball into the orbit of the larger ball--only the curvature (of spacetime) around the larger ball. Thus gravity was explained as being (sort of) merely a curve in the flow of spacetime--a curve created by the presence of concentrated matter/energy. And thus we could calculate the effect of gravity without having to resort to the notion of gravity itself, thus eliminating an unnecessary concept in physics and thus further simplifying physics.

Thus with general relativity Einstein saw himself moving the discipline of physics closer to a cohesive body of laws, laws uniformly applicable in a variety of different physical settings. By eliminating gravity as a separate concept he had certainly moved physics closer to that goal.

But with the development of the field of quantum mechanics Einstein felt that the move toward conceptual unity was headed in the opposite direction. For the longest time he debated the quantum theorists (Bohr, for instance)--until he had to admit that their theoretical world worked--though in apparent contradiction to his own world of relativity.

For the rest of his life he tried to close the gap within physics created by the quantum revolution--though seemingly without further success.

HIS LIFE AND WORKS

Albert Einstein was born in Ulm, Germany, in early 1879. The following year his family moved to Munich where his father, Hermann, and uncle, Jacob Einstein, established a small electical engineering operation.

Early Life

Einstein showed no particular aptitude for formal schooling and was thought by his teachers to be a slow learner. But he had a strong curiosity about the doings of his father's engineering works--and his uncle Jacob was careful to teach young Albert some of the mathematical principles involved in the workings of the electrical dynamos. At the same time a maternal uncle, Caesar Koch, taught him basic principles of science.

Problems in his father's company forced the family to leave Germany--to settle in Milan, Italy. Albert was sent back to school, this time in Switzerland. Eventually he found his stride and in 1900 successfully completed a four-year course of study at the Federal Polytechnique Academy in Zurich. Soon thereafter he became a Swiss citizen and took a position in the Swiss Patent Office in Bern.

In 1903 he married a classmate from the Academy, Mileva Maric.

Special Relativity: 1905

In 1905 Einstein entered for publication in the monthly journal, Annalen der Physik, a number of articles relating molecular action to heat, light, and body mass. These were the foundational pieces for his Special Theory of Relativity. Immediately the genius in these works was recognized, and University of Zurich awarded him the Ph.D. for his work.

Einstein left his work at the Patent Office and took up teaching, eventually becoming a full professor at the University of Prague. Then in 1912 he returned to Switzerland to a teaching position at the Federal Polytechnique in Zurich.

World War One: Family Turmoil

The years leading up to World War One (1914) were a time of great contentment for Einstein, his wife and his two sons, Hans Albert and Edward.

But World War One intervened to upset this serene picture. In the spring of 1914 the family moved to Berlin where Einstein had accepted a position at the University of Berlin. That summer his wife and sons left on vacation for Switzerland, but when the war broke out in September, they were unable to return to Berlin. The physical separation eventually evolved into an emotional separation--and Einstein and his wife divorced.

The growing tragedy of the war led Einstein to an ever more vocal pacifist position--which put Einstein quite out of step with his very nationalistic, even militaristic, professorial colleagues. Einstein was appalled by the ability of the supposedly highly civilized European nations to rationalize the massive murderousness of the war effort.

General Relativity: 1916

Nonetheless Einstein's work on a pet project of his had been making headway and in 1916 he published an article in Annalen der Physik entitled "The Foundation of the General Theory of Relativity." Here he laid out the basic principles for a theory that united a number of his special laws of relativity into a single General Theory of Relativity.

In late 1918, with the end of the "Great War," as World War One was then called, Einstein looked forward to the rule of peace and reason within the West, and in Germany in particular.

In 1919, with a solar eclipse that validated his theories about the action of light as it passed close to a massive body, Einstein's fame became truly international in its extent.

A Growing Personal and Social Life

In that same year, 1919, he remarried--taking for his wife his own widowed second cousin, Elsa, and fashioning a new home with her and her two daughters.

Berlin in those days was a scene of emotional-political turmoil, vented on the Communists and Jews who, according to German ultra-nationalists, were supposedly conspiring to take over the German nation. This was the beginning of very hard times for Jews in Germany. It was at this time that Einstein, though a religious agnostic, began to focus more on his own cultural Jewishness--by taking up the Zionist cause. He even came to the United States in 1921 to raise money for the Palestine Foundation Fund, used to resettle Jews in British-controlled Palestine (modern-day Israel).

Needless to say, he was much sought-after as a lecturer on his new theories of physics and he found himself travelling much over the next years, lecturing in Europe, America, and Asia. In 1921 he was awarded the Nobel Prize for Physics.

His Quest for a Theory of Everything

Einstein was now focusing his thoughts on the matter of how a simple principle stood behind the workings of the whole universe. He was looking for a unified field theory--a theory of "everything."

Unfortunately, the discovery of quantum physicists (Bohr, Heisenberg and others) that there was a built-in indeterminacy or uncertainty about the behavior of the fundamental particles of matter (quanta) made Einstein's study of "everything" problematic at its its very heart. Einstein himself refused to accept the uncertainty principle as a final statement about the behavior of the universe's fundamental material--and continued to look for a theory that could side-step this uncertainty.

He Leaves Germany for America

In the meantime the very hard times of the late 1920s and early 1930s touched even Einstein. The Zionist program to resettle Jews in Palestine was getting unyielding oppostion from the British authorities in Palestine--and violent opposition from the Arabs living there. And in Germany, Hitler's Nazis were gaining popularity by bashing Jews as national demons (along with international capitalists, Communists, Socialists, Gypsies, homosexuals and a few other categories of "undesireables"). Einstein's hope was also sinking quickly that a new international legal order, embodied in the League of Nations, would bring peace to the world. Increasingly the League was proving itself unable to deal with the growing number of diplomatic crises afflicting the world. Einstein grew bitter in his disappointment over this failure.

In 1933, with Hitler's appointment as Chancellor of Germany, Einstein renounced his German citizenship and left the country. His mood now changed from one of pacifism to adamant opposition to the Nazi regime, even calling on Europe to arm itself against Hitler.

He soon thereafter (October 1933) came to Princeton, New Jersey, to become part of the faculty of the new graduate Institute for Advanced Study. Here he lived quietly and routinely with his wife (until her death in 1936)--rarely leaving Princeton over the years. Eventually he became an American citizen.

World War Two and the Bomb

As war clouds gathered in Europe (1939) Einstein was informed by his friend Niels Bohr that in accordance with Einstein's theories, the uranium atom had been split, giving off a small amount of its mass in the form of energy. This pointed to the thought that this process could be--and most probably would be--controlled to produce a bomb of catastrophic proportions. The question was--who would be the first to achieve this goal: Germany or its enemies? Einstein himself decided to write President Roosevelt to make him aware of the critical challenge that nuclear power posed--and the need to develop atomic weaponry before the Germans did. Thus was born the idea of the Manhattan Project.

Einstein himself was not part of the Manhattan Project in Los Alamos, New Mexico, where America's atomic bombs were developed during the war years. Nonetheless his own hand in developing the theoretical foundations underpinning the nuclear age was quite evident to everyone. However, at war's end, the pacifist in Einstein now reasserted himself, and Einstein's thoughts now ran to the question of securing a world free from the terror of nuclear arms--rather than to the challenge of staying ahead in the nuclear arms race.

Einstein Moves to the Sidelines

In his later years he remained focused on the quest for a unified field theory. In 1950 Einstein published a paper on the subject. But most physicists remained unconvinced that his theories, though carefully worked out mathematically, were valid.

And this growing sense of separation from the mainstream of physics and mathematics remained with Einstein all the way to his death in Princeton in April of 1955.

SPECIAL RELATIVITY

The Impossibility of a Moving Observer Achieving the Speed of Light

In his earliest studies (1905), Einstein focused himself on the question of what one would see if he could speed himself up to a light wave so that the wave and the observer were travelling at the same speed (186,000 miles per second) along parallel courses. This would be quite fast of course! What would the observer see in the light wave? Absolutely nothing--because the very quality of light as a wave would be contradicted. From the point of view of an observer moving at the speed of light a light wave would no longer be a wave--moving up/down or back/forth. The wave would be frozen in movement, stilled of any apparent action. From the point of view of the observer, the wave would no longer be a wave, and the light would simply cease to be light. This would be a contradiction to the law of physics which states that there is no place or point in the universe at which the laws of physics would not pertain. Thus the very idea of an observer ever attaining the speed of light and thus causing its extinction is a logical impossibility.

Just as logically impossible was the idea of an observer even moving up toward the speed of light. Experiments had demonstrated that the speed of light reaching an observer remained constant (always 186,000 miles per second)--no matter what the speed or direction of the observer. As the observer speeded up, something in the relationship between light and the observer shifted in such a way that light continued to reach him from the surrounding world at exactly the same speed--irrespective of his own motion. From whatever point of reference that a person observed the illuminated world around him, the speed of light reaching him would always be the same. Thus we should say that there was always an invariance in the speed of light reaching an observer, no matter what his particular situation, no matter what his particular frame of reference.

In other words, unlike sound waves which are speeded up or slowed down as the sound source is pushed toward us or or drawn away from us--light waves are sent out from their source always at the same speed (186,000 miles or 300,000 kilometres per second) irrespective of the momentum of the light source.

What Was It Then That Was Variable?

But some kind of variance must surely occur as an observer's frames of reference varied. The variance could not be in the speed of light--for that was a constant. Rather, the variance would have to be in the nature of the frames of reference themselves, frames of reference built on our understanding of space and time. It was our notions of space and time, not light, that were the true variables.

The Relativity of Simultaneity

For instance, how would this principle of invariance then work on two observers, each watching a particular event from a different vantage point of speed and direction--each simultaneously observing the event from different frames of reference?

Einstein, in another thought experiment, posited a train station example. Two bolts of lightning strike a train as it is passing through a train station, one bolt hitting the front of the train and one hitting the very rear of the train, each bolt leaving a burn mark on the station platform showing exactly where the train was when it took the two hits. To an observer on the platform both bolts of lightining appear to have hit at exactly the same time. The observer confirms this view by measuring off the distance between his point of observation and the two burn marks, noting that the distance is the same in each case. The observer was standing exactly in the center of the two events and saw them take place at exactly the same moment.

But a person standing in the very middle of the train, saw the flash of light coming from the front of the train just slightly before observing the flash coming from the rear of the train. He confirms this observation that the two events did not take place simultaneously by noting through careful measurement that he had been standing in exactly the middle of the train.

Now, which of these two observers was correct? The person on the platform or the person on the train? Einstein said both were correct!

But we might be inclined to answer: yes, but the person of the platform was standing at a stationary position, which would logically seem to be the truer position. The person on the moving train was moving toward the bolt that hit the front of the train thus would naturally perceive that event first (the difference of course being very small--in terms of the speed of light).

But Einstein argued that both observers had an equal claim on the laws of physics from their respective frames of reference. The laws of physics do not favor one frame of reference over another.

Time Dilation

If we on earth were able to see a clock in a rocket moving away from us at a very rapid rate, it would seem to be lagging in comparison to our clocks on earth. With each second of the rocket's rapid movement away from us it would take longer for sight of the clock to reach us--thus the clock's seconds would appear to be slower than our earth seconds.

But guess what? From the frame of reference on the rocket ship, from the point of view of an observer able to see a clock on earth, the earth clock would likewise appear to be just as slow, for with each second of increasing distance between the rocket and earth, it would take longer for a second on the earth to reach the observer rocket.

Thus for both observers, the clocks on the other frames of reference would both slower slower than their own as they move away from each other. Einstein called this time dilation.

Length Contraction

By the same token, an attempt of an earth observer to measure the length of the rocket as it rapidly moves away from him will result in a shorter measurement than that which an observer on the rocket itself would come up with (for him the rocket was a stationary object, not moving toward or away from him).

This is all because of the invariance in the speed of light. Variance occurs instead with time and space. This has been verified in a number of experiments involving Einstein's theories of special relativity.

Dilation and Contraction Increased Geometrically
as One Approaches of the Speed of Light

Of course these variations are largely undetectible until the speeds involved are very great--until they begin to approach the speed of light itself. For the rocket to contract in the eyes of an outside observer to two-thirds its original length, it would have to be travelling at two-thirds the speed of light (that would be about 124,000 miles per second).

The actual capacity of modern rockets is a thousand times less than the speed of light--and thus the actual measurements of dilation and contraction of Einstein's rocket examples are very miniscule. But they have been measured in the context of the movement of atoms within the giant accelerators, which can bring atomic speeds up very close to the speed of light.

The Relationship Between Mass and Energy of a Body: E = mc²

All of this relationship between time, speed, and the invariance of light began to suggest how other basic elements of physics are interrelated. The energy of motion and momentum come into question. For instance, we know momentum to be the mass of an object times its velocity. As velocity involves both distance (space) and time, this brings momentum under the influence of relativity theory--which in turn raises questions even about mass.

As he contemplated these matters, Einstein began to realize that all these basic elements or aspects of physical reality that we had long supposed to be independent of each other are in fact highly interconnected--including, even to his own surprise, mass and energy.

The well-understood heat that was given off in a chemical process was long supposed to be a product of "energy" somehow stored in the atoms of the elements involved. But Einstein became suspicious that the very mass of the atoms themselves were somehow the source of the heat--that heat (as energy) was the result of a transformation of a small amount of mass itself into energy form. In fact, mass was itself merely stored energy.

He thus hypothesized that the amount of energy given off in a chemical reaction was measurable in terms of loss of mass in the elements involved. In the end, he came up with the well-known theory that energy (E) contained in something was equatable to the product of the mass (M) of that same something and the speed of light times itself (c²) or E = mc².

The Bomb

That's a lot of energy! Eventually it would occurr to scientists (including Einstein) that the converstion of mass into such enormous energy could be used to produce a bomb of incredibly powerful proportions. All that was needed was a material whose mass was not terribly steady (given easily to breakdown into energy).

GENERAL RELATIVITY

Wave or Field Theory

Special Relativity hypothesized about a body whose momentum was a constant. Einstein then began to think about how his theories would work in describing a body whose momentum varied over time and space.

A conceptual analogy presented itself in the form of a line ploted across a graph whose two axes represented time and distance (space). If that line represented constant momentum, it would be plotted as a straight line, moving from the "0" position upward and to the right as the plotted object moved along at a steady rate.

But if the momentum that was charted varied, the line would be wavy, with curves that represented a slowing down or a speeding up of the line's movement over time and distance.

This is a "representation" of reality--of space and time. Of course we know that reality does not "look" like this graph. It looks like the images that form in our minds through our power of sight, touch, hearing, smell, and taste.

Or does it?

In the 20th century we have begun to realize that what our mind portrays as reality is also only a "representation" of reality. Our sense of depth, color, temperature, shock or impact, sweetness, fragrance, etc. are perhaps "translations" of wave-like information into what our minds recognize as "solid reality." But in fact, the "solid reality" might only be the waves, energy waves, themselves and not our translations of those waves into human realities.

Einstein was inclined to go to the source of reality in his thinking about it: reality as waves of energy--and how they were configured in order to produce the physical realities of velocity, momentum, mass.

The Principle of Equivalence: Acceleration and Gravity

Einstein's Elevator Riddle
Acceleration as Curvature
Acceleration as Curvature in the Space-Time Dimension
Inertial Frames of Reference and Accelerating or Changing Frames of Reference

EINSTEIN'S WRITINGS

Einstein's major works or writings:

"A New Determination of Molecular Dimensions," Annalen der Physik (1905)
"On the Motion Required by the Molecular Kinetic Theory of Heat of Small
        Particles Suspended in a Stationary Liquid," Annalen der Physik (1905)
"On a Heuristic Viewpoint Concerning the Production and Transformation of
        Light," Annalen der Physik (1905)
"On the Electrodynamics of Moving Bodies" Annalen der Physik (1905)
"Does the Inertia of a Body Depend Upon Its Energy Content?" Annalen der
        Physik (1905)
Relativity: The Special and General Theory (1916)
"What Is Relativity?" (1919)
The Principle of Relativity (1923)
"The World As I See It" (1949)
Ideas and Opinions(1954)

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