ALBERT EINSTEIN WAS DIFFERENT. He was aloof; in the popular image, he was the definition of a dweller in the Ivory Tower. He was socially and politically concerned, but only occasionally became involved. He was not a seeker of companions, personal or scientific, yet his writings show deep insights into the psychology of other people; his technical communications, both papers and personal letters, were voluminous. There might be room for a reasonable person to disagree with his social and political opinions, but they cannot be dismissed as naive or shallow.
Einstein's physics was different, too. It may not always seem so because his work is woven into just about all of modern physics, but there is a thread of the truly different running through his many and varied technical contributions. Einstein never followed the crowd, and the crowd, even while incorporating many of his results directly into the main stream, never really followed him.
This paper explores one of the reasons for the unique quality of Einstein's contributions to physics. I will try to show that he had a unique take on fundamental problems, and that this unique approach resulted in answers that, time and again, were so profound as to be the final word on the topic, at least for the last 100 years or so. Einstein had an ability to focus on problems that were sometimes simple but always profound. He could identify and hold to elementary governing principles that, when applied, drove the answers to contain an uncommon degree of universality.
Albert Einstein approached many of his key problems as if he had seen the underlying situation in a dream, with all of a dream's vibrant reality and stark simplicity. I do not maintain that he always had such dreams but rather that the dream metaphor is a useful way of describing this element of his unique approach to physics. What I will discuss are particularly vibrant examples of Einstein's gedankenexperiments, or thought-experiments, a technique that permeated much of his work. Most of Einstein's thought-experiments were emphatically not dreamlike; these were always intricate and usually required long and hard effort to devise. Many of his attempts at formulating counter-examples to quantum mechanics were in this category. (1) Although the two images I will focus on are certainly examples of gedankenexperiments Einstein reported them both to have arisen as dreams, or at least as daydreams.
In each of these dreams of Albert Einstein, some central part of the problem was depicted in a simple and elegant way. These images made it profoundly obvious that there were assertions that must be true for any solution to the problem. In the cases I will describe, Einstein held to his dream throughout the process of finding the answer, bringing the dream image into reality as a piece of physical theory while maintaining the truth of the associated assertions.
My two shining examples of Einstein's dreams concern the Special Theory of Relativity, completed in 1905, and the General Theory of Relativity, which reached final form in 1915. I will also discuss his search for a unified theory of the gravitational and electromagnetic fields, a search that is notable for its lack of a keynote dream, and one in which he was unsuccessful.
Special Relativity and Einstein's Annus Mirabilis. Einstein's physics career had a rocky start. He completed his formal training in 1900, but in spite of great academic accomplishment, he left a universally bad impression on his professors. For that reason, Einstein was unable to obtain the references and other support needed to obtain an entry-level university appointment. He made do with temporary work and freelance tutoring until he obtained a position in the Swiss patent office in 1902. He began his physics research in this period, focusing on statistical mechanics and publishing several papers.
His independent researches intensified once he had settled in at the patent office. …