Now at least I had an occupation in a scientific field! I couldn’t help thinking about Einstein’s somewhat similar position as a Swiss civil servant in the patent office in Bern, where in the miraculous year of 1905 he published five papers in his “spare time,” including one on the special theory of relativity, which revolutionized physics.
After my first intense learning period, I began concentrating on relativity theory and advanced through Einstein’s special relativity and general relativity theories to his most recent work on unified field theory, which was his attempt to unify gravity and electromagnetism within a geometrical spacetime structure. Einstein had the brilliant idea that the force of gravity, as first envisioned by Isaac Newton, was not actually a force of attraction between two massive bodies. Rather, it was the effect of one massive body distorting or curving the spacetime geometry around it, which in turn affects another body nearby. Einstein’s idea that spacetime geometry is curved in the presence of matter was the basic tenet of his general theory of relativity.
In Einstein’s special theory of relativity, he envisioned velocity as “relative.” That is, an observer moving in a non-accelerating frame of reference cannot tell whether he is at rest or moving, or how fast he is moving, in relation to an object in another non-accelerating frame. This concept was easy for me to grasp, thinking of the momentary confusion of sitting in one moving train and watching another that is also moving.
In his general theory of relativity, Einstein envisioned acceleration— or changing velocity—as also “relative.” In fact, he proposed the startling idea that gravity and acceleration are equivalent. Picture a skydiver falling before she opens her parachute. With her eyes closed, she would not be able to tell whether she was falling due to the pull of the earth’s gravity or to a force exerting an acceleration upon her.
Relativity was an idea that was in the air at the beginning of the twentieth century. Others besides Einstein, such as the mathematical physicists Hendrik Lorentz and Henri Poincaré, had formulated theories of relativity beyond those already envisioned by Galileo in the sixteenth century. However, they could not free themselves from the concept of the “ether,” the supposed substance that permeated all of space and allowed electromagnetic waves to travel through it, which virtually all scientists believed in at the time. It took the genius of Einstein to ignore the concept of the undetected ether, to make special relativity a universal property of space and time, and to develop a classical mechanics that was compatible with special relativity.
Relativity, however, constituted only half of Einstein’s effort to create a unified theory. There is also the concept of “fields.” In the nineteenth century, James Clerk Maxwell’s equations unified the electric and magnetic fields. These fields were first conceived by Michael Faraday, who pictured them as lines of force originating from electrically charged particles or magnets. These fields can be observed in the regular lines formed by pieces of metal filings on a sheet of paper when it is held above a magnet. In Maxwell’s theory, the electromagnetic fields exist in four-dimensional spacetime, which acts like an arena in which the fields themselves and electrically charged particles move like hockey players in an ice rink. Einstein wanted to unify his geometrical theory of gravity with Maxwell’s equations for the electromagnetic fields into one unified theory. In 1918, the famous German mathematical physicist Hermann Weyl had proposed a way of unifying Maxwell’s theory and Einstein’s gravity theory that was not successful. In his later years, Einstein continued, also unsuccessfully, to try to find better ways of unifying gravity and electromagnetism.
I quickly became caught up in this quest for a unified field theory, and studied Einstein’s papers closely. I had been checking through the basic calculations underlying Einstein’s latest unified field theory, and I discovered that one of its basic assumptions had what I considered a flaw. I composed my first physics paper on this subject.*
After composing this paper, feeling intense excitement as I wrote it and calm satisfaction when I reviewed it, I began to dare to think that yes, possibly I could have a career as a physicist, and began considering steps that I could take to achieve this. At age nineteen, I should have been in my second year at university, but I hoped to somehow find another route to this new goal.
My father had made the acquaintance of an American chemist who was conducting research in the laboratory of the Carlsberg brewery in Valby, not far from my parents’ apartment. This gentleman expressed an interest in meeting me, as he thought he might be able to help me achieve my goal. He was acquainted with John Page, an assistant to the British consulate in Copenhagen.
My father agreed with his friend that I should go through the British consulate for help because I was still a British citizen. Although I had been born in Copenhagen, I was not considered a Danish citizen because my father was British. With my father’s help, I composed a letter to Mr. Page, and explained that I was a nineteen-year-old student who had, through private studies at the university library, achieved enough knowledge of mathematics and physics to study Einstein’s work on unified field theory, and had written a manuscript on his theory. I was now hoping to somehow enter the academic world and pursue physics studies, possibly in England. My father added a note explaining that he had been a major in the British army and had been stationed in Flensburg, Germany, at the end of the war as the district station commander. He thought that perhaps this would help establish our family’s credibility.
About a week later we received a letter from Mr. Page showing much interest in my situation. He said that he had contacted the Niels Bohr Institute in Copenhagen and had spoken with Niels Bohr himself. Bohr, he wrote, wished to speak with me. The following week, I received a letter from Bohr’s secretary setting up an appointment.
Within one extraordinary year in my young life, I had left the path of Serge Poliakoff and my aspirations to become an abstract painter, and was now starting down a completely different road, towards a door being opened to me by the greatest living Danish physicist, Niels Bohr.
*In technical terms, I was questioning the need for Einstein’s action principle based on a nonsymmetric metric field to satisfy a real Hermitian symmetry. He had been hunting for the most satisfactory action principle that was the basis for the derivation of his unified field theory equations.
ON THE MORNING of my appointment with Niels Bohr, I took a tram to Blegdamsvej 17 in Copenhagen, carrying my manuscripts in a large brown envelope. By this time, I had written a second manuscript about unified field theory. I paused for a few moments outside the three-storey building with its red-tiled roof and little courtyard facing the street, and gazed at the tarnished brass letters spelling out “Niels Bohr Institutet 1920.” I suddenly felt my heart palpitating. What was I going to say? How should I address Niels Bohr? Could he really help me?
Bohr had mapped out the structure of the atom in 1913, and later in the 1920s had helped to develop the quantum revolution. After Ernest Rutherford discovered that there was a hard core in the centre of atoms, consisting of a positively charged nucleus, Bohr produced a model of the atom in which the energy associated with the spectral line radiation* was quantized, or occurred in discrete quantum units. This followed the important discovery by Max Planck in 1900 that radiation emitted by a hot body was not continuous, as had been assumed in classical physics, but came in discrete parcels of energy. In effect, Bohr succeeded in making the atom stable. Previously, the classical model of the atom could not prevent the orbiting electron from spiralling in towards the nucleus. Bohr pictured his atom as a mini-solar system, with the positively charged nucleus playing the role of the sun and the electrons swirling in stable, planet-like orbits around it. However, Bohr’s young assistants, Werner Heisenberg and Wolfgang Pauli, were not able to apply his model of the atom to more complicated spectral