Einstein: A Hundred Years of Relativity

Andrew Robinson’s compendium on all things Einstein is a lavishly illustrated treat which I read with great pleasure in one sitting. It consists of contributions from Robinson himself as well as from a variety of writers, scientists and philosophers on various aspects of Einstein’s life, work and the times he lived in. There are scores of photos of Einstein with everyone from Niels Bohr to Charlie Chaplain to Rabindranath Tagore. Robinson himself is a measured and very engaging guide to Einstein’s life, treading methodically and evenly over all major events in his life. The book consists of introductory essays by Robinson followed by chapters on specific topics. All the chapters on Einstein’s work are drawn from past writings on Einstein by leading thinkers and scientists; Stephen Hawking, Steven Weinberg, Freeman Dyson, Max Jammer, Philip Anderson and Philip Glass. It is especially illuminating to read Glass’s essay in which Glass talks about how Einstein inspired his opera, “Einstein on the Beach”. Each of these writers talks about a particular triumph and folly of Einstein’s, or how he influenced their own work. The volume also contains a reprint of a revealing interview with Einstein by Bernard Cohen, conducted only two weeks before his death.

Although Einstein is known for relativity – and both general and special relativity receive an extended treatment here - he contributed to many other important parts of physics. He was one of the fathers of quantum theory, a fact of perpetual irony given his vociferous later opposition to the meaning of the theory. In 1905 which is regarded as his annus mirabilis, he published papers on the sizes of atoms, on diffusion through different media and of course, on special relativity. Even after putting the finishing touches on relativity in 1915, Einstein made at least two major contributions to science. One was his work with Satyendranath Bose predicting what are called Bose-Einstein condensates; it took until the 1990s for these novel forms of matter to be created in the laboratory. The other was his contribution in explaining the process of stimulated emission which led to the laser. Another of Einstein’s lesser-known works was a practical one – the Einstein-Szilard refrigerator which he invented as a safe refrigerator with his friend Leo Szilard, the same Szilard who encouraged him to write the famous letter to president Roosevelt warning of the discovery of fission.

The book is roughly chronological; starting with Einstein’s rebellious days as a student and trailblazer at the Swiss patent office, as deep thinker and revolutionary when he was a professor in Berlin, as pacifist during World War 1, as one of the most famous men in the world after World War 2, as target of anti-Semitic propaganda, as world-famous émigré in Princeton and as pacifist, tongue-wagging celebrity-sage again after World War 2. One of the themes that constantly emerges through these different periods of Einstein’s life is that of stubbornness and rebellion combined with an unusual tolerance for unorthodox thinking and unconventional people. One of the significant myths about Einstein that the volume demolishes is that of an introverted, lonely, deep thinker. Throughout his life Einstein was surrounded by close friends who he kept in touch with either in person or through letters; his personal and professional correspondence with famous as well as common folk number in the thousands. During his young days he was a lusty, vivacious and joyful man filled with dry humor and cheekiness, and these qualities endured late into his life.

Robinson’s volume is also very good at exploring the paradoxes of Einstein’s life. Einstein was a wise, avuncular figure to strangers and the world at large, but he was often terribly cruel and indifferent to his family; he was an adulterer who womanized regularly even after being married twice, and he was estranged from both of his sons. Much of this revelation was hidden from the public and only became apparent with the discovery of Einstein’s letters to his wife in the 1990s. As with most other people, Einstein had trouble being consistent in his morality. His pacifism was perhaps one of the most consistent qualities in him, although he wisely cast it off once Hitler came to power.

Scientifically Einstein’s life presents even more interesting paradoxes. Freeman Dyson opens the volume with an essay talking about what was perhaps Einstein’s biggest scientific failure; his inability to imagine a universe without black holes. As I described in a post, both Einstein and Oppenheimer played foundational roles in the discovery of black holes; they were a logical result of Einstein’s field equations of general relativity. Yet both men essentially abandoned their scientific creations, staying utterly indifferent to them for the rest of their lives. Einstein even wrote a paper in 1939 that supposedly refuted black holes, but it was fatally flawed in its assumptions of static spacetime around these inherently dynamic objects. Today black holes are recognized as the engines which fuel the birth and death of the universe. Einstein also made a mistake when he inserted a cosmological constant in his equations to keep the universe from expanding or contracting. However to his credit, he immediately got rid of this constant once he learnt of Edwin Hubble’s discovery of the expanding universe. Ironically, as the expansion of the universe was found to be accelerating, the cosmological constant was resurrected.

Einstein’s reliance on beauty and mathematics was also paradoxical. As the physicist Philip Anderson describes, many still think of Einstein as primarily a mathematical physicist. But all his early advances in relativity were fueled not by abstract mathematics but by practical thought experiments in physics. He always stayed close to experiment and let the data guide his thinking. His time in the patent office in Bern had given him a real taste for mechanical contraptions. However, as described by Steven Weinberg, when developing general relativity, Einstein did have to take advantage of the novel field of Riemannian geometry which he learnt from his friend Marcel Grossmann. Weinberg speculates that perhaps Einstein got so enamored with mathematics during this time that it led to his isolation from the mainstream of physics during the last few decades of his life when he kept on trying to develop a unified field theory without paying attention to real advances in physics. Sadly, Weinberg finds that almost everything that Einstein did after 1925 was irrelevant in terms of real contributions to physics. The one exception was the debate with Niels Bohr and others about quantum entanglement which he sparked in 1935, and even in that debate he finally ended up on the losing side.

Einstein remains of great interest to a new generation, not because he was a genius but because – as this volume illustrates - he was human. Ultimately when we strip away the trappings of myth and fame from his scientific contributions, what remains is a human being in all his honest clarity. That is what makes him a topic of enduring interest.