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      Because I had progressed rapidly in my private studies, I began feeling that surely, with my newly discovered aptitude, I could do something more interesting than the odd jobs that provided me with a meagre wage. I decided to push things further. I made an appointment with the director of the astronomical observatory in Copenhagen. I explained to him that I was interested in becoming a physicist, and was studying physics, astronomy and cosmology by myself. He sent me to the Copenhagen University Geophysics Institute, where the kindly director took an interest in me, and gave me a job solving least squares calculations of gravitational measurements. These calculations went into large published tables of gravitational measurement data and were used in geological surveys as well as in searches for minerals and other resources in Greenland, which was part of Denmark.

      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.