The "World Year of Physics 2005" will be celebrated this year. It will mark the 100th anniversary of three of Albert Einstein's remarkable insights into how our world and our universe work.In the six short chapters below we describe, in simple language, one of these accomplishments.
This is a very short book. Nevertheless, it may take you a while to read it. (I know because it took me a while to write it.) If you persevere you will be rewarded by understanding one of the World's greatest intellectual achievements: Albert Einstein's theory of, what we now call, Special Relativity.
In 1900, when he was 21, Einstein graduated from ETH, a "technical high school" in Zurich, Switzerland. He had a degree that allowed him to teach mathematics and physics, but he couldn’t find a job. In 1902, with a little pull from a friend, he landed a temporary job at a patent office in Bern. His title was “technical expert third class”, hardly a portent of things to come. During the next three years he must have had a fair amount of spare time because, in 1905, he wrote three landmark papers in physics. (Apparently he didn’t foul up any patent applications during those three intervening years because, also in 1905, he got promoted to “technical expert second class”.) He also got a doctorate from the University of Zurich in 1905. It was a busy year.
The three papers Einstein wrote in 1905 were on different subjects; each worthy of a Nobel Prize. For one of them he did receive the Nobel Prize in 1921. In that one he hypothesized that light waves could, under certain conditions, act like particles. This allowed a simple explanation of puzzling results from experiments in which light ejected electrons from metals. The paper became an early foundation for the theories of quantum mechanics developed twenty years later by W. Heisenberg and E. Schrödinger.
Important as his other two papers were, Einstein’s paper that developed Special Relativity was, to my mind, the greater intellectual achievement. It required some very bold leaps of imagination: what we call nowadays “thinking outside the box”. As you read the book I think you will agree that Einstein’s thoughts were, indeed, outside the box –way outside.
One of the most intriguing things about Special Relativity is that, with a little work, anyone can understand it. Of course, like every important achievement, it can have various levels of understanding. (Think of Darwin’s theory of evolution.) To comprehend all the full-blown implications of Special Relativity takes a lot of mathematics and requires thinking about motion in four dimensions. However, one can get the essential import of the theory by thinking about only one-dimensional motion and by using just a little simple algebra.
That defines our purpose in this book. We want to understand, and marvel at, what Einstein did back there in Bern 100 years ago. I’ve tried to make it as easy as possible by drawing a lot of pictures and keeping the mathematics to an absolute minimum. Discussions of Special Relativity are usually replete with vectors, Greek letters, and square roots. There are only two square root signs in this text. I do need to make frequent use of a little formula that you learned in high school (or grade school?): Velocity = Distance divided by Time. You may see it in its different forms: V=D/T, D=VT, T=V/D
If you are already familiar with Special Relativity you should be able to breeze through quite rapidly. In that case, just do it, and then pass the book on to your friends. If you come here with very little prior knowledge you will need to go more slowly and think a little harder, but I can almost guarantee that you will come away understanding what Einstein did back in 1905 to change our view of the world.
Now click on the buttons below to read the chapters of this little book.
(The format is in PDF.
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