He called it “optical molasses.” The beams bombard target atoms with a steady stream of photons, whose wavelengths are carefully selected so that they will only be absorbed if they collide head-on with atoms. In the mid-1980s, Stanford University physicist Steven Chu demonstrated laser cooling by weaving a “web” out of infrared laser beams. In August of this year (see Members in the Media), a student at Leiden University’s Lorentz Institute for Theoretical Physics uncovered Einstein’s manuscript for the paper, while reviewing documents in the archive for his thesis on Paul Ehrenfest.īut the technology didn’t yet exist to create such a new state of matter in the laboratory. If the temperature gets low enough (billionths of a degree above absolute zero) and the atoms are densely packed enough, the different matter waves will be able to “sense” one another and coordinate themselves as if they were one big “monoatom.”Įinstein published a paper on the topic, entitled “ Quantum Theory of the Monatomic Ideal Gas,” in the proceedings of the Prussian Academy of Sciences in Berlin, Germany, in January 1925. Lowering the temperature reduces the atoms’ speed. They surmised that the wavelike nature of atoms might allow them to spread out and even overlap, if they are packed closely enough together. Many physicists regard this work as Einstein’s last major contribution to physics.Įinstein and Bose used their new method to predict the possibility of a new form of matter, dubbed a Bose-Einstein condensate (BEC). The result was the creation of Bose-Einstein statistics. Einstein promptly forwarded the paper for publication, and applied the same reasoning as Bose used to a gas of indistinguishable atoms. That omission was remedied in 1924, when he received a paper from a colleague, Satyendra Nath Bose, that successfully derived Planck’s law by treating photons as indistinguishable particles, rather than individual quanta. However, he didn’t immediately work out the statistical mechanics of those particles–an omission that has surprised several science historians, since he based his 1905 paper on the energy quantization of radiation on a study of the entropy of thermal radiation. And it also provided the underpinnings for a theoretical new state of matter.Įinstein’s theory of radiation provided a complete characterization of the light quantum’s specific particle properties. Einstein’s 1917 paper detailing a quantum theory of radiation sowed the seeds for quantum electrodynamics and quantum optics, cavity quantum electrodynamics, and the processes of spontaneous and stimulated emission – the last of which led, later on, to the invention of masers and lasers by other physicists. Scientifically, however, he was still going strong. That same year he married Elsa, and settled in with her and her two grown daughters by a previous marriage. Mileva and Albert separated in 1914, after bitter arguments, and divorced in 1919. His wife, Mileva, complained that he had no time for her in the midst of his fame, adding, "I am very starved for love." For his part, Einstein felt increasingly suffocated in his marriage and embarked on a love affair with his cousin, Elsa Löwenthal. Einstein Lays Theoretical Foundation for BECsĮinstein had achieved worldwide fame with his theory of general relativity, although his personal life was far from idyllic.
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