Eddington experiment

The Knowledge Machine: How Irrationality Created Modern Science

by Michael Strevens  · 12 Oct 2020

end, “freedom is more important than equality.” Figure 1.1. Police attempt to contain communist demonstrators in Vienna, June 1919. In the same year, Popper heard Einstein lecture on his new theory of relativity: “I remember only that I was dazed. This thing was quite beyond my understanding.” But he was struck by

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Popper recalled his youthful bedazzlement by Einstein in 1919—is evidence against a theory. “If the redshift of spectral lines due to the gravitational potential should not exist,” Einstein wrote of a certain phenomenon predicted by his ideas, “then [my] general theory of relativity will be untenable.” As Einstein saw, we can know for

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every species was created separately by God. And shortly after the beginning of the twentieth century, Newton’s physics was replaced in turn by Einstein’s theory of relativity and by quantum physics. How does this happen? How do paradigms end? A scientist working within a paradigm is not seeking to undermine

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who grew up with the old paradigm—such as adherents of Ptolemy when the Copernican revolution crested in the seventeenth century, or of Newton as Einstein precipitated the twentieth-century revolution in gravitational theory. They know that something has gone badly wrong. Their paradigm has ceased to bestow scientific blessings.

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University, which undertook to launch a satellite into orbit around the earth that would measure the “geodetic” and “frame-dragging” effects implied by Einstein’s general theory of relativity. The project was initiated in 1964 and made its final report to NASA—after overcoming extraordinary setbacks and technical problems and creating, as

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THE MOON’S DISK CREPT across the face of the sun on May 29, 1919, a new science of gravity hung in the balance. Just a few years earlier, Albert Einstein had formulated his theory of general relativity, a conceptually radical replacement for the gravitational theory that made Isaac Newton famous at

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light of that number at most one theory could survive—either Einstein’s or Newton’s—or, if both predictions turned out to be wrong, neither. Six months after the eclipse, the expedition leader Arthur Eddington announced the results: Newton was dethroned and Einstein was declared the new emperor of gravitation. The Great War was

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finally over, and Einstein’s esoteric German physics had been confirmed by Eddington’s exacting British experiment, a scientific triumph that was

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those telescopes said two different things. One instrument, the “4-inch” telescope, showed a shift in the positions of the stars roughly in accordance with Einstein’s prediction. But the other, the “astrographic” telescope (especially designed for photographing stars), showed a shift that was almost exactly Newtonian. Figure 2.1.

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Another cloudy day on Príncipe. How did Eddington and his collaborators reach the conclusion, then, that it was Einstein’s predictions that came true? They had three sets of data at their fingertips. First, there were 2 photographs from

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gave a value for gravitational bending that was considerably greater than that predicted by Einstein, to a degree that they could be considered to support Einstein’s theory only if that telescope, too, was assumed to be systematically biased. Eddington appeared to be engaged in some rather special pleading, then: he assumed

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as to reach the conclusion that the results they delivered were quite consistent with Einstein’s theory of relativity. As W. W. Campbell, an American astronomer and director of the Lick Observatory in San Jose, California, wrote about Eddington’s analysis in 1923: “the logic of the situation does not seem entirely

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Príncipe telescope to decide the issue conclusively against Newton and in favor of Einstein’s theory of relativity. Figure 2.3. The orderly presentation of scientific data: tables summarizing results from the Brazilian astrographic telescope in Eddington’s eclipse expedition of 1919. In the methodist’s dream of science, the bodies of data from

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to educated guesswork, and that makes scientific reasoning irreducibly, unavoidably, essentially subjective. CAST YOUR MIND BACK to 1919, the year of Eddington’s eclipse. The rationale for the expedition to observe the eclipse was straightforward. If Einstein was right, then the light of stars close to the sun would be bent by twice as much

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we know that something was systematically off kilter in the 4-inch telescope as well, since it indicated a bending angle rather larger than Einstein’s theory allowed. Eddington had to make a choice. Discount the astrographic data? Overlook the 4-inch discrepancy? Declare the experiment to be inconclusive? He did not

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created at the CERN research facility in Switzerland were clocked traveling faster than the speed of light—an athletic feat forbidden by Einstein’s theory of relativity. Rather than discard relativity, the great majority of physicists supposed instead that something had gone wrong with the measurement apparatus. The matter did not rest

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observed following this advice—but again, it is not always feasible. Solar eclipses are rare enough; what made Eddington’s 1919 eclipse rarer still was the sun’s position, at the time of totality, in the center of a field of relatively bright stars. As Eddington pointed out when touting the experiment, this happy alignment “would not

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round of stellar photography, but he could not—so he found other ways to press his case against the Brazilian astrographic and in favor of Einstein. Eddington’s course of action was unconstrained not because he disdained the rules of scientific thought but because the complexities and difficulties of empirical investigation—of

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think that the Brazilian astrographic telescope was working perfectly, you will count its measurements of the bending angle of light as powerful evidence against Einstein’s theory of relativity. If you find it quite plausible that something went systematically wrong in those measurements—if you suspect that this particular link in the

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respect to the ether. For a time, there was contention and confusion about both ether and the experimental setup. It was cured by Einstein, whose special theory of relativity dispensed with the ether and explained exactly what Michelson and Morley had unwittingly observed: that the velocity of incoming light is the same

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dead. That is the difference made by 0.00001 of an inch. As you have already seen, Einstein’s treatment of gravity was tested a few years later by scrutinizing similarly tiny details: Eddington’s eclipse experiment measured a shift in the apparent positions of stars equal to about one-third of the

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or the pre-Newtonian seventeenth century, competing philosophies meant competing sciences. But quantum mechanics did not split into philosophical schools. Rather, even as Bohr, Einstein, and many other key figures at the Solvay Conference in 1927 philosophized furiously, the theory remained a unified set of ideas that “developed rapidly, disseminated

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its interpretation, it provided a clear and well-defined system for providing shallow explanations that had no serious rivals. Had Newton rather than Bohr debated Einstein at the Solvay conferences, he would perhaps have proclaimed: I have not as yet been able to deduce from phenomena the nature of quantum

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go back to a quintessential case of subjectivity, embarking one last time with Eddington on his expedition to test Einstein’s theory of general relativity by observing the 1919 total eclipse of the sun. THREE TELESCOPES, you will recall, were trained on the eclipse. The instrument on the African island of Príncipe barely saw the sun

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through the clouds. The two telescopes in Brazil gave conflicting testimony: one, the 4-inch telescope, saw light bent roughly as Einstein

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the murk. He then convinced various British scientific luminaries to endorse his conclusion that the observation of the eclipse was a spectacular confirmation of Einstein’s new theory. The astrographic anomaly was largely forgotten. Eddington’s behavior was not fraudulent, but his reasoning was partial and self-regarding. Enchanted by the elegance of

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the probability of a systematic Brazilian astrographic breakdown—were twisted by his hopes and expectations for what that truth might be. Figure 7.2. Albert Einstein and Arthur Eddington enjoy a quiet moment together at the University of Cambridge Observatory in 1930. All this is, of course, just to repeat and to underscore

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objective. In Figure 7.4, for example, the names and positions of the brighter stars surrounding the eclipsed sun are listed, along with Einstein’s predictions for the apparent shift in the stars’ positions. Even Eddington’s fiercest critics will grant the accuracy and the impartiality of the information thereby presented. Those were

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light takes place in the neighborhood of the sun and that it is of the amount demanded by Einstein’s generalized theory of relativity. The subjectivity in the paper must manifest itself, then, in Eddington’s argument that the Brazilian astrographic was functioning so badly that its measurements should in effect be ignored

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use to build their own arguments. To the eclipse paper, for example, add a high plausibility ranking for the assumption that the Brazilian astrographic suffered a change of scale, underreporting the bending angle, and you have a powerful argument for Einstein’s theory of relativity. Add, by contrast, a high plausibility ranking

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experiment was likely “due to minor features . . . that will get cleared up with further developments.” Beauty is the beacon; truth is what it marks. Einstein, according to the physicist Eugene Wigner, thought along the same lines: “The only physical theories which we are willing to accept are the beautiful ones

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allowed by the iron rule and follow their own tastes and inclinations wherever they lead. Among them you might encounter “philosopher-scientists,” such as Albert Einstein and the eighteenth-century physicist, mathematician, and social thinker Émilie du Châtelet (who translated Newton’s Principia into French), or thinkers as familiar with

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relies to a not inconsiderable extent on this furtive openness, which has allowed thinkers such as Murray Gell-Mann, D’Arcy Thompson, and Albert Einstein to use their aesthetic and philosophical senses in the search for extraordinary theories. These great scientists were exceptional in more than one way. Not only

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theory”) has for decades been proffered as a promising “theory of everything,” providing a unified framework to explain both gravitation, currently handled by Einstein’s general theory of relativity, and the other fundamental forces, currently handled by the Standard Model of particle physics. String theory has many seductive features, but it is

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Matthew Stanley’s “An Expedition to Heal the Wounds of War” is also largely sympathetic to Eddington’s treatment of the data and provides much fascinating historical background. Stanley gives a broader perspective in his book Einstein’s War. 45 “the pursuit of truth”: Quoted by Matthew Stanley, “Expedition to Heal the

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Wounds of War,” 64. Stanley argues that Eddington saw the eclipse expedition as a “religious calling” (p. 59). 45 “the most influential figure in British astronomy”: Earman and Glymour, “Relativity and Eclipses,” 71. 46 According

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.” 145 “Bohr from out of philosophical smoke clouds”: Quoted in Kragh, Quantum Generations, 213. 145 “Quantum mechanics is certainly imposing”: In Born and Einstein, The Born-Einstein Letters, 91. 146 “met almost no resistance”: According to Kragh, Quantum Generations, 169. On the marginalization of the philosophical aspects of quantum theory in

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479–84. Boas, M. Robert Boyle and Seventeenth-Century Chemistry. Cambridge, UK: Cambridge University Press, 1958. Born, M., H. Born, and A. Einstein. The Born-Einstein Letters: Correspondence between Albert Einstein and Max and Hedwig Born from 1916 to 1955 with Commentaries by Max Born. Translated by I. Born. London: Macmillan, 1971. Boyle

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the Improving of Natural Knowledge. London: T. R., 1667. Stanley, M. Einstein’s War: How Relativity Triumphed Amid the Vicious Nationalism of World War I. New York: Dutton, 2019. Stanley, M. “An Expedition to Heal the Wounds of War: The 1919 Eclipse and Eddington as Quaker Adventurer.” Isis 94 (2003): 57–89. Stephen, L. “William

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Solvay Institute) 7.1 Retinal neurons drawn by Cajal (Dr. Juan A. de Carlos, Cajal Legacy, Instituto Cajal [CSIC]) 7.2 Einstein and Eddington (Royal Astronomical Society / Science Photo Library / Science Source) 7.3 First page of Eddington’s eclipse paper (From Dyson et al., “A Determination of the Deflection of Light”) 7.4

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Einstein’s predictions for eclipsed stars (From Dyson et al., “A Determination of the Deflection of Light”) 7.5 Snowflakes drawn by Hooke and

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45 earth age of, 74–81, 75 rotation of, 27 Eccles, John, 20 eclipse expedition (Eddington), 42–50, 43, 44, 68–73, 155–61 École normale supérieure (ENS) (Paris), 50 Eddington, Arthur, 156 and auxiliary assumptions, 81 expedition to test Einstein’s gravitation theory, 42–50, 43, 44, 68–73, 155–61 and importance of

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theoretical cohorts, 139 wording of eclipse report, 167 education, See science education educational reform, 175 Ehrenfest, Paul, 145, 150 eightfold way, 230–32, 235, 236 Einstein, Albert, 145, 156 aesthetic/philosophical senses, 273 on beauty, 227 and Eddington expedition, 42–50, 156 gravity theory, see general theory of relativity as philosopher-scientist, 265 photoelectric

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effect, 144 Popper and, 15, 18 and quantum mechanics, 145–46 See also relativity theory electromagnetic radiation, 92 electrons, 144

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iron rule vs., 268 liberalism, 252 lieutenants of the Scientific Revolution, 192–94 life, history of, 175 light in Cartesian physics, 133 and Eddington’s expedition to test Einstein’s gravitation theory, 42–50, 43, 44, 68–73, 155–61 and ether, 143 Galileo and, 290 Michelson–Morley experiment, 112–14 speed

Einstein's Dice and Schrödinger's Cat: How Two Great Minds Battled Quantum Randomness to Create a Unified Theory of Physics

by Paul Halpern  · 13 Apr 2015  · 282pp  · 89,436 words

the Nazis. During the war, Einstein had little chance to test his hypothesis about the gravitational bending of starlight by the Sun. Finlay-Freundlich’s inability to complete his expedition was a great disappointment to him. Einstein quietly began to correspond with a British astronomer, Arthur Eddington, who was keenly interested in verifying

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Einstein’s theory. According to several widely reported stories, Eddington was known at the time as one of the few people who truly understood general relativity.14 A Quaker and a pacifist, Eddington, like Einstein, was opposed to the war and

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in favor of international scientific cooperation. Naturally, during the bloody conflict, open cooperation between British and German scientists was close to impossible. The armistice opened up a grand opportunity for Eddington to help test Einstein’s

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theory and thus rekindle the trust between scientists of their respective nations. Eddington and Frank Watson Dyson, Astronomer Royal of Britain, realized that an ideal opportunity to measure gravitational light bending would arise on May 29, 1919. On that day, a solar eclipse would occur over

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part of the Southern Hemisphere just when the Sun was passing in front of the Hyades star cluster, a particularly bright formation. Dyson appointed Eddington to be the organizer of a project to 66

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The Crucible of Gravity observe the eclipse, a move that helped

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save the latter from internment as a conscientious objector.15 In January 1919, to set a baseline for the observation, Eddington carefully measured the unaltered positions of the Hyades stars. Then he organized two

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As he began to explore the ramifications of various unified approaches, Einstein used the electron dilemma as a touchstone. Eddington fully agreed with Einstein on the importance of the electron problem. Using Weyl’s theory as a starting point, Eddington 73 Einstein’s Dice and Schrödinger’s Cat proposed an alternative unified theory based

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the present generalisation succeeds in providing the material for its solution.”25 Embarking on the road to unification, the question for Einstein became how to choose between Weyl, Kaluza, and Eddington’s theories. Although he found none of the theories satisfactory, he would borrow from them to construct his own models.

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at least give her a chance for basic comforts. After his divorce was final, Albert married Elsa on June 2. Months later, following Eddington’s eclipse announcement, she realized that she had exchanged vows with the most famous scientist in the world. Elsa relished standing by her husband’s side

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example? Stimulated by the unification proposals of Weyl, Kaluza, and later Eddington, by the early 1920s Einstein had started to contemplate ways of explaining electron behavior through an extension of general relativity that included electromagnetism as well as gravity. The jumps, Einstein thought, must be mathematical artifacts of an otherwise deterministic continuous theory.

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to be taken lightly. There needed to be clear justification—if not through physical principles, then through mathematical reasoning. Einstein had dabbled with variations of Kaluza’s, Weyl’s, and Eddington’s ideas, but was not happy with the results. Try as he might, he couldn’t find physically realistic

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of the neck, something we had already discussed so much in Berlin,” he said.7 However, as philosophers of science Arthur Fine and Don Howard each have pointed out, Einstein was careful to distinguish his personal views from the arguments expressed in the EPR paper. Surprisingly enough for such an established

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of that year. Once again he tried to ignore politics, focusing on his research. He had become intrigued by recent proposals by Arthur Eddington for uniting quantum physics with general relativity and explaining uncertainty through cosmological arguments. Thus in the midst of Austria’s turmoil, his gaze was fixed on his equations.

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The Quantum and the Cosmos Eddington’s role in the late 1910s and early 1920s as a leading defender, interpreter, and tester of general relativity had won him much respect in the physics community. However, starting in the mid- to

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Herbert Dingle referred to his work (along with other speculative theories) as the “pseudoscience of invertebrate cosmythology.”20 On the other hand, Einstein and Schrödinger greatly respected Eddington’s independent-minded thinking. Like them, he was certainly not one of the herd. While they did not agree with his prescriptions,

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test drive, found to be a clunker, and then traded in for another. Eddington was similarly intrigued by Dirac’s equation and tantalized by its bridge between quantum physics and the four-dimensional realm of special relativity. Along with Heisenberg’s uncertainty principle, which appeared the previous year, it motivated

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propositions, such that the universe is curved and finite—similar to Einstein’s original model of the universe with a cosmological constant—and that all physical quantities are relative. To measure a physical quantity such as position or momentum, Eddington suggested, a researcher must compare it to the values for other

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but the result of human inability to measure everything in the universe with absolute precision. Regarding wavefunctions as composites rather than fundamental, Eddington used general relativity, modified by his idea of relative physical quantities, to map out distributions of positions, momenta, and other quantities for collections of particles. Then he combined this

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laws of spacetime, when viewed through the foggy lens of human limitations in ascertaining positions and momenta, led to equations resembling those of quantum mechanics. Eddington developed an estimate for Planck’s constant, based on the number of particles in the universe, the curvature of the universe, and other quantities.

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blackbody, he calculated the energy available for each of its constituents, and thereby attempted to match Planck’s figure. 147 Einstein’s Dice and Schrödinger’s Cat While Eddington could be clear and engaging in his writings, his calculations pertaining to his fundamental theory, as he would call his connection

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June 1937, Schrödinger wrote to him for clarification about his calculation of Planck’s constant. Eddington responded, but still not to Schrödinger’s satisfaction. Italy was closely allied with Austria at the time, so it was relatively easy to travel there. In the course of 1937, Schrödinger journeyed there several times.

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work out his own theory of unification. Like Einstein and Eddington, he began to see merit in explaining the troubling aspects of quantum mechanics, such as indeterminacy, jumps between states, entanglement, and so forth, through a greater theory based on modifying general relativity. In Another Dimension with Unifying Intention While Schrödinger

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was wrestling with the nuances of Eddington’s fundamental theory, Einstein returned to the higher-dimensional realm of Kaluza and Klein. Coming full circle, he decided to

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try again to make use of the extra space provided by a fifth dimension to extend general relativity to include the laws of electromagnetism

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? When the institute opened in its Merrion Square headquarters, no one, save perhaps Dev, could be happier. 158 CHAPTER SIX Luck of the Irish [Einstein and Eddington’s theory] did not work, they gave it up. Why should it work now? Is it the Irish climate? Well, yes, or perhaps the

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never again mention the institute in his column. Schrödinger had not been O’Nolan’s only scientific target. After Eddington gave a July 1942 colloquium at DIAS about unification, explaining that relativity was truly understood by few people, O’Nolan proposed in his column that the subject should be taught in

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an impasse, Schrödinger started to become an enthusiast. Inspired by three of the theorists he admired most—Einstein, Eddington, and Weyl—he decided to try his luck too. He perused some of their early papers on general relativity and unified field theory and began to devise his own approach. Because they were

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Schrödinger), or relaxing the symmetry requirements and making the affine connections fundamental. 172 Luck of the Irish Following a path taken by Eddington and briefly considered by Einstein in 1923, Schrödinger elected to drop the symmetry requirements and focus on the affine connections. He called his approach the general unitary theory

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His paper would be published about five months later in the academy’s proceedings. He explained in the talk how he had picked up where Eddington and Einstein had left off. In a year honoring Hamilton, Schrödinger was happy to make use of the Irish mathematician’s methods, offering further tribute to

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headlines danced in their heads. They hoped they could somehow get the math straight enough to convey its importance to readers. Schrödinger explained how Einstein and Eddington had almost stumbled on the correct Lagrangian, the square root of the negative of the determinant of the Ricci tensor, but he was the

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his own efforts. His chronicle seemed to imply that he would be the logical successor to the Greeks and Einstein. After describing the essence of his theory, he reiterated how Einstein and Eddington would have come up with the same thing in the 1920s had they been more open-minded. He mentioned

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, he certainly hasn’t been the only one to try to fill Einstein’s shoes. Since 1919, when the public first tasted the theory of relativity through the announcement of the solar eclipse measurements, it has had an insatiable appetite for news about Einstein and possible successors. While he was alive, as we’ve seen,

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fields? Those are among the many open questions in particle physics today. Dreams of Geometry, Symmetry, and Unity In recent decades the dream of Einstein, Schrödinger, Eddington, Hilbert, and others to explain everything in the cosmos through pure geometry has undergone a marked revival. It seems that every time science veers

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Unified Theory of Nature (New York: Simon and Schuster, 1984). Einstein, Albert, Autobiographical Notes, translated and edited by Paul Arthur Schilpp (La Salle, IL: Open Court, 1979). ———, Ideas and Opinions, translated by Sonja Bargmann (New York: Bonanza Books, 1954). ———, The Meaning of Relativity (Princeton: Princeton University Press, 1956). ———, Out of My Later

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a Daughter, the Meaning of Nothing, and the Beginning of Everything (New York: Bantam, 2014). Goenner, Hubert, “Unified Field Theories: From Eddington and Einstein up to Now,” in Proceedings of the Sir Arthur Eddington Centenary Symposium, edited by V. de Sabbata and T. M. Karade, 1:176–196 (Singapore: World Scientific, 1984). Greene, Brian

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. 12. Peter Freund, A Passion for Discovery (Hackensack, NJ: World Scientific, 2007), 5–6. CHAPTER ONE: THE CLOCKWORK UNIVERSE 1. Albert Einstein, Autobiographical Notes, trans. and ed. Paul Arthur Schilpp (La Salle, IL: Open Court, 1979), 9. 2. John Casey, The First Six Books of the Elements of Euclid (Dublin: Hodges

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The Berlin Years: Writings, 1918–1921 (Princeton: Princeton University Press, 2002), doc. 3. 13. Harvey, “How Einstein Discovered Dark Energy.” 14. Ben Almassi, “Trust in Expert Testimony: Eddington’s 1919 Eclipse Expedition and the British Response to General Relativity,” Studies in History and Philosophy of Science Part B 40, no. 1 (2009): 57–67. 15

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. Ibid. 16. “Eclipse Showed Gravity Variation,” New York Times, November 8, 1919, 6. 17. Ibid. 18. “Revolution in Science . . .

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, Der Erfinder der 5. Dimension, Theodor Kaluza (Göttingen: Termessos, 2007), 66. 24. Theodor Kaluza Jr., interviewed in NOVA: What Einstein Never Knew, PBS, originally broadcast October 22, 1985. 25. Arthur S. Eddington, “A Generalisation of Weyl’s theory of the Electromagnetic and Gravitational Fields,” Proceedings of the Royal Society of London, Ser

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Bay for a Week,” New York Times, January 19, 1929. 11. Albert Einstein, quoted in “News and Views,” Nature, February 2, 1929, reprinted in Hubert Goenner, “On the History of Unified Field Theories,” in Proceedings of the Sir Arthur Eddington Centenary Symposium, edited by V. de Sabbata and T. M. Karade, 1

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:176–196 (Singapore: World Scientific, 1984). 12. H. H. Sheldon, quoted in “Einstein Reduces All Physics to 1 Law,” New York Times, January 25, 1929.

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22-052. 16. Erwin Schrödinger, “Die Gegenwärtigen Situation in der Quantenmechanik,” Die Naturwissenschaften 23 (1935): 807–812, 824–828, quoted and translated in Arthur Fine, The Shaky Game: Einstein, Realism and the Quantum Theory (Chicago: University of Chicago Press, 1986), 65. 17. Erwin Schrödinger, “Indeterminism and Free Will,” Nature, July 4,

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thought experiment, 209–210 Bohr, Margrethe, 102 Bohr, Niels, 1, 110, 215 atomic model, 35, 46–48, 73, 81, 82, 84–85 Eddington’s theory and, 148 Einstein and, 137, 168, 200 EPR paper and, 138 escape from Denmark, 179 uncertainty principle and, 106 “Bohr Festival,” 82, 84–85 Bohr’s

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, 74, 220 Naturforscherversammlung and, 91 new theory and reissue of The Meaning of Relativity, 203–206 Dukas, Helen, 122, 132, 149, 208, 212, 213, 220 Dunsink Observatory, 154 Duso, Don, 133 Dvali, Gia, 232 Dyson, Frank Watson, 66–67 Eddington, Arthur, 66–67, 73–74, 81, 112, 164, 166, 173, 191 estimate

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for Planck’s constant, 145, 147–148 Ehrenfest, Paul, 23, 32, 59, 69, 126 Ehrenfest, Wassik, 126 Eigenstates, 97, 99–100, 105–106, 138–139, 146, 210 Einstein, Albert, 24, 29, 30, 73,

E=mc2: A Biography of the World's Most Famous Equation

by David Bodanis  · 25 May 2009  · 349pp  · 27,507 words

not because they’re poorly written, but because they take on too much. Instead of writing yet another account of all of relativity, let alone another biography of Einstein—those are interesting topics, but have been done to death—I could simply write about E=mc 2. That’s possible, for

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just suppose— that light did take some time to travel the great distance from Jupiter. What would that mean? Roemer imagined he was straddling the solar system, watching the first flicker of Io’s light burst out from behind the planet Jupiter, and rush all the way to Earth. In the

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could have 41 a n c e s t o r s o f e = m c2 swung around to the other side of the solar system. It would take a lot longer for Io’s signal to reach us. Roemer went through Cassini’s stacked years of observations, and by

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its way, since it had to travel that extra distance. Even at 5:30 or 5:35 it wouldn’t have made it across the solar system. Only at 5:37 precisely would anyone be able to get their first sighting on November 9. There are many ways to make astronomers

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keep on leapfrogging over each other in tiny, fast jumps—a “mutual embrace,” in Maxwell’s words. The light Roemer had seen hurtling across the solar system, and which Maxwell saw bouncing off the stone towers at Cambridge, was merely a sequence of these quick, leapfrogging jumps. 47 a n c

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own. We can date to within a month or so the moment when he first saw that E would equal mc 2. Einstein finished writing his initial paper on relativity by late June 1905, and had the addendum with the equation ready for printing in September, so he probably first realized it

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.) At the fair, Poincaré had actually given a lecture on what he’d labeled a “theory of relativity,” but that name is misleading for it only skirted around the edges of what Einstein would soon achieve. Possibly if Poincaré had been younger he could have pushed it through to come up

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where instead of the uppermost speed limit being the speed of light at 670 million, it is instead an easy 30 mph. What does Einstein’s 1905 relativity paper say we’ll see? The first striking thing we would see if we entered that world follows from the space shuttle example. Cars

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banks use to synchronize payments, are programmed to correct for 83 the early years this—in exact accord with the equations Einstein worked out in 1905. Einstein never especially liked the label relativity for what he’d created. He thought it gave the wrong impression, suggesting that anything goes: that no exact results

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political attitude of the scientists involved. The P.S., it was understood, meant that Heisenberg could use Einstein’s results on relativity and E=mc 2, but he had to show he disavowed Einstein himself, and gave no support to the sort of liberal or internationalist views—such as supporting the League

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an atom. Most of the neutrons released by the first explosions would speed right past the nucleus, like an alien space probe hurtling through our solar system. The twist Fermi had found—that there was a great power in using slowed neutrons—could help solve this problem, and get a reaction

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out there asking questions.’ ” But she wasn’t put off, and a few weeks later she described another such incident: “I bicycled up to the Solar Physics Observatory with a question in my mind. I found a young man, his fair hair tumbling over his eyes, sitting astride the roof of

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retired from her professorship at Harvard, she remembered the rows of braying young men, nervously trying to do what their teacher expected of them. But Arthur Eddington, a quiet Quaker, was also at the university, and he was happy to take her on as a tutorial student. Although his reserve never lifted

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from a middle-aged bachelor’s fear of a young woman turning to him with emotion. Her friend from her student days at the Cambridge Solar Physics Observatory, the young fair-haired Edward Milne, was by now an established astronomer, and did try to help, but he didn’t have

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Lifts His Eyes Unto the Sky E=mc 16 Even though the sun is vast, it can’t keep on burning forever. Heating the entire solar system takes immense amounts of fuel, even for a furnace that pumps material directly across the equals sign of E=mc 2. The sun’s

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already been absorbed by the expanding sun, then—after 11 billion years of steady orbit—the sun’s grip will let the planets go. The solar system breaks up, and Earth flies away. One of the key insights into what happens next—and within which E=mc 2 is once again

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already on track to collide with the Andromeda galaxy, and in several billion years, about the time of Earth’s escape or immolation in the solar system, the great collision should finally happen. The spaces between stars are so great that most of the dimmed suns will just slowly pass between

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But it’s probably pretty close. Freundlich was going to make his career, he decided, by shepherding the great general relativity equations forward, and performing the observations that would prove Professor Einstein’s predictions were 207 till the end of time right. He was very generous about this—in the way that

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newspaper, back in Berlin. He hadn’t been invited along. In fact, it was a cool Englishman we’ve already met who led the team. Arthur Eddington wore small metalrimmed glasses, was medium height and barely medium weight, and spoke in sentences that tapered off whenever he had to pause for thought

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sun is positioned in front of an exceptionally dense group of bright stars—the Hyades cluster. That wouldn’t usually help anyone, for without a solar eclipse occurring on that particular 209 till the end of time date, there would be no chance to see how that rich field of stars gets

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their light bent around the sun. The glare from the daytime sun would overwhelm that small effect. But in 1919 there was going to be an eclipse, precisely on May 29. As Eddington innocently noted: “Attention was called to this remarkable opportunity by the Astronomer Royal [Frank Dyson] in March 1917; and

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send him to one of the prisons. What Else Einstein Did Arthur Eddington aip emilio segrè visual archives This is the point at which the Astronomer Royal, Frank Dyson, called attention to the remarkable eclipse opportunity. If Dyson could get Eddington to arrange the expedition, could Eddington still be deferred, despite that postscript? Dyson’s work

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media celebrity on the planet. Headlines in the New York Times for November 10, 1919, announced: What Else Einstein Did “Light All Askew in the Heavens: Men of Science More or Less Agog Over Results of Eclipse Observations.” and “Einstein Theory Triumphs: Stars Not Where They Seemed or Were Calculated to Be, but

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of mental institutions his whole life. She died in Zurich in 1948, increasingly depressed and alone. michele besso, Einstein’s closest friend from his Bern years, with whom the ideas of special relativity were first talked over, had a rich home life, and a successful career as a mechanical engineer. Even

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cannot say she truly mastered it.” Cecilia Payne had the pleasure of seeing that daughter become an astronomer—and publishing several papers with her. arthur stanle y eddington became increasingly resistant to the main trends of modern astronomy. One of his final works, published in 1939, had a chapter beginning “I 

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Cambridge, and Chicago included—in its mission, and it is called the chandr a x-r ay observatory. Although erwin freundlich missed out on the 1919 eclipse expedition, his spirits recovered when industrialists in the new Weimar Republic donated large funds to build a great astronomical tower in Potsdam. This would allow

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further tests of general relativity’s predictions, even in periods when there was no eclipse. Zeiss supplied the equipment, and Mendelsohn, the great expressionist architect, designed the building—it’s the famous Einstein Tower featured in many books on 1920s German architecture. appendix Through

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that Faraday never said, “Well, Prime Minister, someday you can tax it”; and even why Einstein never liked calling his work the theory of relativity. Preface viii “Einstein explained his theory to me every day . . .”: Carl Seelig, Albert Einstein: A Documentary Biography (London: Staples Press, 1956), pp. 80-81. ix George Marshall saw

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amount of mass in the process. The full understanding that the reverse happens only came later. During World War II, when Einstein wrote out a copy of his main 1905 relativity paper to be auctioned for war bonds, he turned at one point to his secretary, Helen Dukas, as he was

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missed the point in his powerful satire Candide, but it became a fundamental principle in physics. In a variant form, it became central to Einstein’s general relativity, where—as we’ll see in the epilogue—planets and stars move in optimal paths within the curved spacetime of the universe. 255 notes

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or another, have wrapped their hands around devices that contain miniaturized transpositions of the logical sequences that once occurred in Einstein’s brain. 84 . . . the label relativity . . . : Einstein never used the phrase theory of relativity in his original 1905 paper; this was only suggested by Planck and others a year later. The name he

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the case of Picasso’s painting. . . . This new artistic “language” has nothing in common with the Theory of Relativity. The quote is in Paul LaPorte, “Cubism and Relativity, with a Letter of Albert Einstein,” Art Journal, 25, no. 3 (1966), 2 61 notes p. 246; quoted in Gerald Holton’s The Advancement

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such isolation, the one thing that travels intact is yourself. 86 . . . different views about personal responsibility . . . : What type of theory is the theory of relativity that Einstein created? It’s not like detailed laws such as the ones found in engineering texts, which might say that air resistance goes up as a

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for they’re much more deeply embedded in the nature of an analytic system. Their application in such systems is, in principle, unlimited. Einstein’s special theory of relativity is different yet again. It’s not a particular result, which simply happens to go beyond Newton or Maxwell’s work. Rather, it

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his Manchester results to seem to fit—but it also meant that for years students were taught that the atom really was like a miniature solar system. That doesn’t make sense, however: there’s no reason the electrons wouldn’t crash inward after emitting radiation in their fast orbits;

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nor is there any physical analogue to the stability of the actual solar system, guaranteed by Newtonian inverse-square gravity. But such is the power of assumption-loaded mathematics (and also, who had a better idea?) that

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although the solar system model was 267 notes eventually overthrown, what began with the mathematical weakness of Ernest Rutherford has carried on in popular mythology to become the

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can one possibly work out such things? The hottest noon heat in Death Valley is due to 2 91 notes about one thousand watts of solar radiation hitting a square yard of the Earth’s atmosphere directly overhead; if extended to cover the whole planet, that means the total amount of

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5 billion years, the . . . fuel will be gone: Once again, this is the domain of E=mc2; it allows us to foresee how long our solar system will last. The sun’s mass can be symbolized as Mº. Only 10 percent of that is hydrogen in a form available for burning

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, or flung loose. In slightly more wieldy units, 3.21017 seconds is about 10 billion years. Since we’re about halfway along in the solar process, that’s the reason we can assert there are about 5 billion years left. 196 “Some say the world will end in fire . . . :

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happiest thought of my life”: From an unpublished manuscript Einstein wrote for Nature in 1920. 205 “Do not worry . . .”: Albert Einstein, the Human Side, Helen Dukas and Banesh Hoffmann (Princeton, N.J.: Princeton University Press, 1979), p. 8. notes 210 “Attention was called . . .”: Arthur Eddington, Space, Time and Gravitation (Cambridge: Cambridge University Press,

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and Rebel (New York: Viking, 1972) is the ideal introductory mix of biography and scientific background. For the early years, The Young Einstein: The Advent of Relativity, by Lewis Pyenson (Boston: Adam Hilger, 1985) shows what thoughtful academic work can achieve, as with Pyen- guide to further reading son’s hunting

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verifying the signals from two independent clocks—a key part, once the issue is pondered over, of the reasoning behind special relativity. Another ingenious probing is in Robert Schulmann’s “Einstein at the Patent Office: Exile, Salvation or Tactical Retreat”; in a special edition of Science in Context, vol. 6, number

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s dated though highly readable The Birth and Death of the Sun: Stellar Evolution and Subatomic Energy (London: Macmillan, 1941) gives a useful impression of solar physics in Payne’s time. Hoyle and Earth Fred Hoyle is the best writer of any high-level scientist I’m aware of: his autobiography

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it is vivid, and Thorne, as much as Wald and Geroch, has been a leader in the field of general relativity for decades. For a thoughtful account of the 1919 eclipse expeditions—and Eddington’s true motivations—don’t miss Chapter 6 of Chandrasekhar’s Truth and Beauty: Aesthetics and Motivations in Science. Acknowledgments

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homes on Jermyn Street; when I finally settled for lunch I was right across 321 acknowledgments from the great hall where the news confirming Einstein’s general relativity predictions was released. Most of the actual writing was done when my wife, Karen, was making a transition from being a distinguished historian,

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c2, 69, 77, 99, 112–13, 166, 183, 194 bridge connecting energy and mass, 111 C-14, 194 Calculus, 84 Cambridge, 175, 176, 197 Cambridge Solar Physics Observatory, 175, 181 Cancer, 76 Candide (Voltaire), 64 Carbon, 109, 184, 188, 189, 190–91 unstable varieties of, 193–94 Carbon dating, 194 Casimir

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–2 hydrogen atoms, 182 material substances interconnected on, 27, 35 movement of, 41–42 Eclipse, 207, 208, 209 expeditions, 208, 209–12 Eddington, Arthur, 176–77, 181, 187, 200, 201, 209–14, 211f Egyptian symbols, 24 327 index Ehrenfest, 212 Einstein, Albert, 3–8, 6f, 15, 36, 37, 91f, 103, 108, 119f, 120,

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as student, 5, 21, 22, 48, 178 theory of, confirmed, 213–14, 215, 217 theory of relativity, 7–8 Einstein, Hans Albert, 74 Einstein, Hermann, 4 Einstein, Maja, 6, 87, 218 Einstein, Mileva, 4, 5–6, 89–90, 91f Einstein family, 86, 87, 88, 159 Eisenhower, Dwight D., 152, 161 Electric engine, 16 Electricity, 12, 45

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63 Segrè, Emilio, 143–44 Serber, Charlotte, 151 index Sexism, 178–79 Shapley, Harlow, 177 Silicon, 184, 188, 190 Simultaneity, 85 Smoke detectors, ix, 193 Solar system, 41–42, 47, 201 breakup of, 197 sun heating, 195 Sonic boom, 196–97 Sörlie, Rolf, 155 Space distortion of, 200 fabric of, 205

Coming of Age in the Milky Way

by Timothy Ferris  · 30 Jun 1988  · 661pp  · 169,298 words

of disputations about such questions as just why Galileo was persecuted by the Roman Catholic Church or whether Einstein had the Michelson-Morley experiment in mind when he composed his special theory of relativity. Having tiptoed through more than a few of these minefields, I am full of admiration for scholars

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something close to the received word of God. Even today, when Newtonian dynamics is viewed as but a part of the broader canvas painted by Einstein’s relativity, most of us continue to think in Newtonian terms, and Newton’s laws still work well enough to guide spacecraft to the moon and

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way that Newton’s account of gravitation and inertia advanced physics to the point that it could embrace a moving Earth in a heliocentric solar system, Einstein’s relativity enabled physics to deal with the much higher velocities, greater distances and more furious energies encountered in the wider universe of the galaxies. If

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and mathematical time, of itself, and from its own nature, flows equably without relation to anything external.”1 Einstein determined that this assumption was both superfluous and misleading. The special theory of relativity revealed that the rate at which time flows and the length of distances gauged across space vary, according to

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leading scientists to take the Lorentz contraction seriously, came close to developing it into a form that was mathematically equivalent to Einstein’s theory; Poincaré spoke presciently of “a principle of relativity” that would prescribe that no object could exceed the velocity of light.6 But most researchers found it odd to

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: “Direct observation of facts,” he said, “has always had for me a kind of magical attraction.”5 The intellectual odyssey that led Einstein to the special theory of relativity—and from there to the general theory, which was to deliver theoretical cosmology from its infancy—began when he was no more than

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, Mach argued, is not a thing, but an expression of interrelationships among events. “All masses and all velocities, and consequently all forces, are relative,” he wrote.29 Einstein agreed, and was encouraged to attempt to write a theory that built space and time out of events alone, as Mach prescribed. He never

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, explaining that he did not own a watch. Yet here began the reformation of the concepts of space and time. With the special theory of relativity, Einstein had at last resolved the paradox that had occurred to him at age sixteen, that Maxwell’s equations failed if one could chase a beam

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of time they experienced as a result of their velocity in orbit. These and other implications of special relativity initially struck the lay public, and many scientists as well, as uncommonly strange.* But if Einstein’s approach was radical, his intention was essentially conservative. As is implied by the title of his

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, not just in a quiet laboratory in Zurich but in whirling dynamos and on moving worlds hurtling past one another at staggering speeds. The term relativity, coined not by Einstein but by Poincaré and applied to the theory by the physicist Max Planck, is somewhat misleading in this sense

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; Einstein, stressing, its conservative function, had preferred to call it Invariantentheorie—“invariance theory.” Relativity nonetheless cast its net wide, embracing the study not only of light and space and time, but of matter

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its being. To alter one’s conception of electromagnetism is, therefore, to reconsider the very nature of matter. Einstein caught sight of this connection only three months after the first account of special relativity had appeared, and published a paper titled, “Does the Inertia Content of a Body Depend Upon Its Energy

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to a deeper understanding of inertia and gravitation.”32 His inquiry set him on his way up the craggy road toward the general theory of relativity. Einstein’s first insight into the question came one day in 1907, in what he later called “the happiest thought of my life.” The memory of

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three-dimensional space; the passengers in the elevator in the New York skyscraper, after all, are not flying through space relative to the earth. The search for an answer required brought Einstein to consider the concept of a four-dimensional spacetime continuum. Within its framework, gravitation ts acceleration, the acceleration of objects

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on Lorentz. In 1908 Minkowski published a paper on Lorentz’s theory that cleared away much of the mathematical deadwood that had cluttered Einstein’s original formulation of special relativity. It demonstrated that time could be treated as a dimension in a four-dimensional universe. “Henceforth space by itself, and time by

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the two will preserve an independent reality,” Minkowski predicted.34 His words proved prophetic, and the special theory of relativity has been viewed in terms of a “spacetime continuum” ever since. Einstein initially dismissed Minkowski’s formulation as excessively pedantic, joking that he scarcely recognized his own theory once the mathematicians got

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’s play.”37 Nowhere in human history is there to be found a more sustained and heroic labor of the intellect than in Einstein’s trek toward general relativity, nor one that has produced a greater reward. He completed the theory in November 1915 and published it the following spring. Though its

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dialogue between the human mind and the conundrums of cosmological space. The theory was beautiful, but was it true? Einstein, having been to the mountaintop, felt supremely confident on this score. General relativity explained a precession in the orbit of the planet Mercury that had been left unaccounted for in Newtonian mechanics

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wider scientific community, however, awaited the verdict of experiment. There would be a total solar eclipse on May 29, 1919, at which time the sun would stand against the bright stars of the Hyades cluster. The English astronomer Arthur Stanley Eddington led an expedition to a cocoa plantation on Principe Island off west Equatorial Africa

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up out of the sun’s space well—and all these trials it has survived. Too modest to be immodest, Einstein had written when publishing his completed account of general relativity that “hardly anyone who has truly understood this theory will be able to resist being captivated by its magic.”44 But

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11 THE EXPANSION OF THE UNIVERSE Nature lives in motion. —James Hutton Eyesight should learn from reason. —Kepler When Einstein began to investigate the cosmological implications of the general theory of relativity, he found something strange and disturbing: The theory implied that the universe as a whole could not be static, but

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term had made an algebraic error, dividing by a quantity that could be zero. When Friedmann corrected the error, general relativity broke free of its fetters and the relativistic universe, to Einstein’s frustration, once again took on wings. Connoisseurs of irony’s serrated edge will appreciate that it was in 1917

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, the very year that Einstein besmirched his general theory of relativity by introducing the cosmological term, that the American astronomer Vesto Slipher published a paper containing the first observational evidence that the universe is

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distance relation, is what Hubble found for the galaxies. It was also, of course, just what the general theory of relativity had predicted, at least before being fettered by the lambda term. (Fumed Einstein, “If Hubble’s expansion had been discovered at the time of the creation of the general theory of

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area at the lower left represents the galaxies observed by Hubble when he discovered the law. As it happened, the man who put together Einstein’s relativity with the redshifts of the spirals was neither an eminent theorist nor a skilled observer, but an obscure Belgian priest and mathematician named Georges Lemaître

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, has recently come under the purview of the “electroweak” unified theory. Gravitation remains the odd man out. Its workings are still described by Einstein’s general theory of relativity, which is a classical theory, meaning that it does not incorporate the quantum principle. This does not cause problems under most conditions, but

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influenced by the gravitational force exerted by their colleagues that gravity can be ignored. Another reason is that gravitational interactions are interpreted, through Einstein’s general theory of relativity, as resulting from the geometry of space itself. The “gravitons” thought to convey gravitation must therefore dictate the very shape of space, and

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something of an ad hoc affair, like putting up a tent in a high wind; while one sets the pegs, the tent flaps free. Einstein’s relativity required abandoning classical conceptions of space and time; quantum mechanics required abridging classical causality. The odd thing about string theory was very odd indeed: It

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and their data tenderly garnered from trickles of ancient starlight; none will ever touch a star. Particle physicists, in contrast, are relatively gregarious—they have to be; not even an Einstein knows enough physics to do it all by himself—and physical: They are by tradition hands-on students of the here

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, rather than slowing down as had been expected, appears to be accelerating. Evidently there is something like antigravity after all—a prospect envisioned in Einstein’s general relativity theory, but not previously found in nature. This newly discovered antigravity field, often called dark energy, could be the same force that caused cosmic

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force is directly proportional to the mass of each object, and decreases by the square of the distance separating the objects involved. (3) In Einstein’s general relativity, gravity is viewed as a consequence of the curvature of space induced by the presence of a massive object. In quantum mechanics the gravitational

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rest of the mass and energy distributed throughout the universe. Though unproved and perhaps unprovable, Mach’s principle inspired Einstein, who sought with partial success to incorporate it into the general theory of relativity. Magellanic Clouds. Two galaxies that lie close to the Milky Way galaxy. They are visible in the southern

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mass, slowing of time, etc.—that must be taken into account by combining relativity with quantum theory if accurate predictions are to be made. Relativity, general theory of. Einstein’s theory of gravitational force. Relativity, special theory of. Einstein’s theory of the electrodynamics of moving systems. Renaissance. Generally, the period of cultural awakening in

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by the radioactive decay of minerals in rocks could be employed to measure the age of the earth. Time: 1905 Noteworthy Events: Albert Einstein publishes special theory of relativity, indicating that measurements of space and time are distorted at high velocity and implying that mass and energy are equivalent; in another paper

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of the atom. Time: 1916 Noteworthy Events: Albert Einstein publishes the general theory of relativity, portraying gravitation as an effect of curved space and delivering cosmology from the ancient dilemma of a finite versus an infinite universe. Time: 1916–1917 Noteworthy Events: Arthur Stanley Eddington demonstrates theoretically that stars are gaseous spheres; his work

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, p. 31. 44. In Holton and Elkana, 1982, p. 104. CHAPTER ELEVEN: THE EXPANSION OF THE UNIVERSE 1. Albert Einstein, “Cosmological Considerations on the General Theory of Relativity,” 1917, in Einstein, 1952, p. 188. 2. Einstein, 1923, p. 127. 3. In Smith, Robert, 1982, p. 173. 4. Hubble, 1985, p. 35. 5. Ibid. 6

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. Clayton, and D.N. Schramm, eds. Essays in Nuclear Astrophysics. London: Cambridge University Press, 1982. Barnett, Lincoln. The Universe and Dr. Einstein. New York: Sloane, 1948. Venerable popularization of relativity theory. Barrow, John D., and Frank Tipler. The Anthropic Cosmological Principle. London: Oxford University Press, 1986. Barut, Asim O., Alwyn van der

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. New York: Dover, 1964. Innovative popularization. Bonola, Roberto. Non-Euclidean Geometry. New York: Dover, 1955. On the origins of the geometries employed by Einstein’s general theory of relativity. Boodin, John. Cosmic Evolution. New York: Macmillan, 1925. Expansive extrapolation of the evolutionary hypothesis, influential in its day. Boorse, Henry A., and Lloyd

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. New York: Walker, 1971. Documents a decades-long debate over the philosophy of quantum physics, conducted in high spirits and with great mutual respect. —————. Einstein’s Theory of Relativity. New York: Dover, 1965, —————. My Life. New York: Scribner’s, 1978. —————. The Restless Universe, trans. Winifred M. Deans. New York: Dover, 1951. Illustrated

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, Paul. The Religion of Science. Chicago: Open Court, 1913. Caspar, Max. Kepler, trans. C. Doris Hellman. New York: Abelard-Schuman, 1959. Cassirer, Ernst. Einstein’s Theory of Relativity. New York: Dover, 1953. —————. The Individual and the Cosmos in Renaissance Philosophy, trans. Mario Domandi. New York: Harper & Row, 1963. —————. Kant’s Life and

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, Stephen W., and G.F.R. Ellis. The Large Scale Structure of Space-Time. London: Cambridge University Press, 1973. —————, and W. Israel, eds. General Relativity: An Einstein Centenary Survey. New York: Cambridge University Press, 1979. —————, and M. Rocek, eds. Superspace and Supergravity. London: Cambridge University Press, 1981. Proceedings of a 1980 Cambridge

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Research with the Space Telescope. Washington, D.C.: NASA, 1979. Papers presented at a colloquium on the Hubble Space Telescope. Lorentz, H.A. The Einstein Theory of Relativity. New York: Brentano’s, 1920. Losee, J. An Historical Introduction to the Philosophy of Science. London: Oxford University Press, 1972. Short survey, with an

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University Press, 1973. Emphasizes Bruno’s predecessors and influences. Michelmore, Peter. Einstein, Profile of the Man. New York: Dodd, Mead, 1962. Mihalas, Dimitri, and James Binney. Galactic Astronomy. San Francisco: Freeman, 1981. Textbook. Miller, Arthur. Albert Einstein’s Special Theory of Relativity. Reading, Mass.: Addison-Wesley, 1981. The development and early reception of the

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special theory; includes a new translation of Einstein’s 1905 paper. —————. Imagery in Scientific Thought. Boston: Birkhäuser, 1984. Study of contributors

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theories (GUTs), 327–328, 332–334 early-universe theory and, 345, 348 Gravitation, 293–298 contraction of the sun and, 247–248 Einstein’s conception of, 120 general theory of relativity and, 196–197 Kepler’s theories of, 94 Newton and, 103, 107–109, 113–118, 120–121, 177 stellar energy and

Strange New Worlds: The Search for Alien Planets and Life Beyond Our Solar System

by Ray Jayawardhana  · 3 Feb 2011  · 257pp  · 66,480 words

” came in 1867. Some two decades earlier, the Austrian physicist Christian Dop-pler had proposed that the observed frequency of a wave depends on the relative motion of the source and the observer. If a source is moving toward you, waves from it will be compressed, increasing their frequency and reducing

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.” For example, two unusual meteorites recovered during the 2006 expedition consist mostly of the mineral feldspar, which is common in lunar rocks. Since it is relatively lightweight, feldspar is thought to have foated to the top of the magma ocean on the young Moon, forming a concentrated layer, while denser material

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70 Ophiuchi as “probably among the most thoroughly studied dozen binaries in the heavens.” During the course of two centuries, many observers have recorded the relative motions of the pair. Starting with Herschel himself, a number of them suspected the presence of an unseen third body whose gravity tugs on the

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continued to publish in a German journal as well as in popular magazines, gaining fame even as he feuded with other scientists and attacked Einstein’s theory of relativity. The claims of a planet in the 70 Ophiuchi system reappeared in the 1940s. Dirk Reuyl and Erik Holmberg of the University of

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a big disadvantage, however. It can only determine the minimum mass of a companion, not its exact mass, without knowing the inclination of its orbit relative to the plane of the sky. If the companion’s orbit is aligned exactly edge-on from our vantage point, we will see the star

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at the American Astronomical Society meeting in Vancouver that June. The Associated Press report published in the New York Times carried the headline “Planets Outside Solar System Hinted,” refecting the excitement of the press conference. Other astronomers were much more skeptical. When Campbell, Walker, and Yang published their results in

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well beyond the planetary regime. After all, Doppler measurements only give us the minimum mass of a companion. Depending on the tilt of its orbit relative to the sky, the actual mass could be a lot higher than the minimum. Even a faint stellar companion would produce only small radial velocity

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Virginis. Besides, the radial velocity method by itself can only measure the minimum mass of a companion. That is because the tilt of the orbit relative to the sky is unknown. Even a fairly massive companion would cause only small shifts in the line-of-sight velocity of a star if

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a disk that spins in the same direction as its star. In a number of other cases, a planet’s orbit appears to be tilted relative to the star’s equator. Perhaps most surprisingly, Barbara McArthur of the University of Texas at Austin and her colleagues reported that the orbits of

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two massive planets around the star upsilon Andromedae are inclined sharply relative to each other, by nearly 30 degrees. In contrast, the eight major planets in our solar system orbit in nearly the same plane. All of this evidence, taken together, implies that planets move

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Both depend on fnding chance alignments of celestial objects through brightness changes of stars. The frst technique exploits a remarkable property of gravity that Albert Einstein discovered: its ability to bend light, thus to magnify the brightness of a distant star temporarily when a nearer star happens to cross our line

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four centuries. Every once in a while, we see Venus and Mercury cross the Sun, appearing as a little black dot against the bright solar disk. These mini-eclipses, called transits, occur when one of these inner two planets passes precisely between the Sun and the Earth. Similarly, if the orbit of

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that she, a Kiwi mother with no formal scientifc training, was treading on the legacy of Albert Einstein, possibly the most celebrated scientist of all time. In his general theory of relativity, completed in 1915, Einstein proposed a whole new theory of gravity. Instead of the Newtonian idea of gravity as an attractive

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in a straight line, takes a curved path in its vicinity. Einstein’s equations predicted by just how much the light’s path would bend. The stunning confrmation came four years later. A total solar eclipse was to take place on May 29, 1919. Conveniently, it would occur in front of a rich cluster

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of stars known as the Hyades, offering an excellent opportunity to measure any defection of starlight by the Sun’s gravity. Less conveniently, the total eclipse could only be seen

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from the tropics. So the English astrophysicist Arthur Eddington mounted an

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stars during the totality with those taken a few months earlier at night and measure any shifts in the stars’ positions relative to each other. Most of Eddington’s photographs during the eclipse turned out to be useless, because wispy clouds obscured the stars. But one good photograph allowed him to discern a

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a very different technique has proven best. Here, instead of a temporary magnifcation due to the chance alignment of two stars, astronomers look for mini-eclipses of a star due to a planet around it passing in front. Unlike microlensing events, these transits occur again and again, each time the planet

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brightness dips resembling planetary transits. Spectroscopic follow-up with telescopes in Arizona and Chile revealed most of them to be binary stars that undergo grazing eclipses or contain a faint stellar companion. But fve promising candidates remained. With more intensive spectroscopic observations at Keck in Hawaii, Sasselov’s team confrmed

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After processing the images, the team looked for tiny brightness dips characteristic of planet transits, taking care to eliminate others that were due to grazing eclipses among binary and triple star systems. Unfortunately, of the sixteen good candidates they announced in 2006, only two are around stars bright enough for measuring

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. When they analyzed the data later, the researchers noticed that the star had disappeared briefy from view fve times both before and after the planet eclipsed it. The reason, they deduced, was the presence of narrow rings around Uranus. If the star had dimmed only on one side of the

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main eclipse, a moon rather than a ring could have been responsible. So far, astronomers observing transiting exoplanets have not seen evidence of rings or big moons,

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star also slips behind the star for part of its orbit (except in very rare cases). Just before a planet goes into such a “secondary eclipse,” its dayside, fully illuminated by starlight like the full Moon is by the Sun, is facing us. Astronomers have exploited this fact to detect the

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heat—from several exoplanets directly. Like many other measurements in astronomy, this one is done in a relative sense: astronomers measure the light from the combined star and planet just before the secondary eclipse and then subtract from it the light from the star alone when the planet is hidden behind. What

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continued in its orbit, more of its dayside rotated into view, with the entire bright half visible just before the planet went into the secondary eclipse behind the star. As a result, the scientists were able to make a simple map of how temperature varies with longitude on an exoplanet for

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with ground-based telescopes. Bryce Croll, a graduate student working with me at the University of Toronto, is among those chasing secondary eclipses. So far, we have detected the eclipses of four of the hottest exoplanets, using the 3.6-meter Canada-France-Hawaii telescope on Mauna Kea. Ours are the most

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precise measurements yet of planetary eclipses from the ground. For two of the planets we observed, the temperatures appear to be similar on the permanent dayside and the nightside. “Since

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taught dance. As a boy, he devoured science fction books. So it was quite a thrill for him, at fourteen, to meet the legendary writer Arthur C. Clarke in Sri Lanka, where his father was on a Fulbright lectureship. (For a year Basri attended the same school as I did—Royal

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objects. One obvious clue is that brown dwarfs are common as isolated, free-foating objects both in young star clusters and in the feld, but relatively rare as companions to stars. For example, Doppler velocity surveys have revealed a “brown dwarf desert” within a few astronomical units of Sun-like stars

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hard not to imagine the disastrous result of accidentally dropping something heavy on it. One of Subaru’s strengths is its large feld of view relative to other telescopes of similar size. A single picture taken with its workhorse optical camera, mounted at the prime focus, covers a patch of the

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a deep imaging survey of a portion of the sigma Orionis star cluster, with the tender age of a few million years and located in relative proximity about 1,200 light-years from Earth. The researchers identifed eighteen objects so faint and so red, compared with previously known stars and brown

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common in a third region, the NGC 1333 cluster in Perseus. As we survey other regions, we hope to determine whether the number of planemos relative to more-massive brown dwarfs and stars depends on the birth environment—whether denser clusters harbor fewer of them, for instance. Once we fnd and

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had managed to take a spectrum of the candidate, which revealed absorption features due to water vapor in the object’s atmosphere and confrmed its relatively low temperature. The comparison of the spectra and the brightness at several wavelengths with those of theoretical models gave a mass estimate of about fve

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from Gemini to take pictures of the two targets at two other wavelengths frst; if the candidates’ colors turned out to be very red, implying relatively cool temperatures, we would also take their spectra. The follow-up images showed that one was bluish, thus likely a background star, but the other

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use of coronagraphs. Invented by the French astronomer Bernard Lyot in 1930 to observe the Sun’s outer realms without having to wait for a solar eclipse, a coronagraph at its simplest is an occulting mask placed inside a telescope (or instrument) to block the bright, central part of the Sun. Modern

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person.” Growing up in the French countryside east of Paris, he discovered astronomy at the age of ten, thanks to a book given by a relative. His parents bought him a telescope a few years later. “Maybe they regretted it, because I spent many school nights outside,” he told me

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years to perfect the technology.” His mission concept, called PECO (for Pupil-mapping Exoplanet Coronographic Observer), calls for a 1.4-meter telescope. Trauger’s Eclipse mission design is a bit larger, at 1.8 meters. “Such a telescope will give us a good shot at imaging super-Earths, but an

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. Interferometers accomplish this with a clever trick: when combining light from two telescopes, if the light path from one is offset by half a wavelength relative to the other for the star’s location, its light would be canceled, or nulled. However, light coming from a slightly different direction, say from

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be in tighter orbits around red dwarfs, thus increasing the likelihood that they will be seen in transit. Second, because red dwarfs are smaller, the relative dip in brightness when a planet passes in front would be bigger; thus a small rocky planet’s transit might be measurable even with a

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, tar-covered surfaces, and atmospheres rich in hydrocarbons and carbon monoxide. “Such planets are likely to be rare, because you need an overabundance of carbon relative to oxygen in the disk for them to form,” said Harvard’s Sasselov. Kuchner points out that carbon planets could form in much the same

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fnd is gravy, frosting on the cake.” One critical challenge is disentangling real planetary transits from unrelated brightness dips—like those due to eclipsing double stars whose eclipses appear small because of blended light from a third star—that can mimic a planet’s signal. Perhaps one hundred of these candidates would

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includes planning for future space missions, such as NASA’s Terrestrial Planet Finder and ESA’s Darwin (see chapter 7). Scientists need to evaluate the relative signifcance of various planetary biosignatures before agreeing on the most promising observing strategies. Using earthshine as a benchmark does have a severe drawback: it is

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Jupiter-like planet in a tight orbit that happens to be seen edge-on from Earth, we might see the host star undergo a total eclipse, Jura pointed out. What’s more, if the hypothetical system also included a second terrestrial planet, then its feeble refected light might peek through

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during the total eclipse. “That would give us a chance to measure its colors in order to look for signatures of life,” said Jura, who is well regarded among

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lower-mass stars. But it is possible that one of the many ongoing planet-transit searches around the world will turn up a near-total eclipse of a small star. For now, Jura guesses that perhaps only one out of every 10,000 low-mass stars would undergo a total

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, shielded by the Cascades, offers some respite from terrestrial radio interference but not from satellites overhead, which makes some frequencies unusable. The array is built relatively cheaply with mass-produced 6-meter dishes and incorporates state-of-the-art digital signal-processing technology. The latter is critical, because it will examine

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, 238 Dyson, Freeman, 152 earth, search for life on, 206–14 Earth-centric model of cosmos, 3 earthshine, 210–14, 231 eccentricity, 231 Eddington, Arthur, 96, 176 Eichhorn, Heinrich, 53 Einstein, Albert, 94 electromagnetic spectrum, 9–11 electron, 232 El Niño, 33 Enceladus, 215 Endeavor (ship), 106 enstatite chondrites, 193 epsilon Eridani, 36

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, 236 radio telescopes, 23 Rasio, Frederic, 75–76 Rebolo, Rafael, 132, 134 red dwarf, 52 red edge, 211–14 Redfeld, Seth, 117 Reipurth, Bo, 137 relativity, general theory of, 96 Reuyl, Dirk, 50 Rivera, Eugenio, 185 Roberge, Aki, 193 Roddier, François, 152 Rosenblatt, Frank, 174 Ruiz, Maria Teresa, 134–35 Sagan

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144, 146 silicates, 192 Sirius, and Doppler effect, 13 Sloan Digital Sky Survey, 135 Smith, Bradford, 32 sodium absorption, 116–17 Solander, Daniel, 106 solar mass, 237 solar-nebula model, 5–6 Space Interferometry Mission (SIM), 171 space shuttle Discovery, 29 Sparks, William, 223 spectral lines, 237 spectral resolution, 237 spectrograph, 55

The Last Stargazers: The Enduring Story of Astronomy's Vanishing Explorers

by Emily Levesque  · 3 Aug 2020

physics, thanks to Carl Sagan and Planetron, and I had a smattering of knowledge about gravity and how stars worked and even some factoids on relativity, but I certainly couldn’t have told you much about the math behind how a spring worked, or derived an equation to describe friction,

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they could guide the telescope during exposures. The platform itself could be raised, lowered, extended, and retracted, keeping the observer at a comfortable position relative to the tilting telescope. That said, the whole setup worked best when the instrument cage could be placed with the position of the telescope in

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Other animals are sheer delights, and most astronomers will be spotting them for the first time. In southern Arizona, coatimundi, a distant house cat–sized relative of the raccoon with a ringed tail and mischievous-looking upturned nose, will occasionally drop by observatories; a few have made it as far as

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wandering into the dome and leaving dusty footprints across a mirror. Chilean observatories are regularly visited by guanacos (close relatives of llamas) and owls. A few of the latter have figured out that observatories’ all-sky cameras, small towers with a fish-eye-lens

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with a door. • • • If astronomers as a community were asked to pick a favorite observatory animal, it would likely be the viscacha. Viscachas are relatives of chinchillas but resemble wise rabbit grandfathers with tall ears, long curled tails, sleepy eyes, and long, drooping whiskers. They frequent many Chilean observatories, and

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other astronomers, George Preston and Anneila Sargent, George asked how everyone’s previous night had gone. Jay, who had been observing on the mountain’s relatively small twenty-four-inch telescope, responded with “well…a little difficult, maybe.”14 When pressed, he explained that the secondary mirror had fallen out

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at close to the speed of light. At that breakneck speed, the very light emitted by these galaxies was getting distorted by the effects of relativity and producing a phenomenon known as redshift, the electromagnetic cousin of the Doppler effect. The Doppler effect is a classic one: if a car

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to use portable supplementary oxygen, and the on-site observatory building has oxygen piped in. Employees sleep at the Operations Support Facility, which has a relatively low altitude of about 9,500 feet. Still, impressive as it is, ALMA’s altitude is an excellent improvement over sea level but still

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1965, the Galileo I was a modified Convair 990 with additional windows mounted along the top of the aircraft. It was used to observe a solar eclipse and comet flyby in 1965, and NASA had hoped that Galileo I could be used as a multifaceted airborne science facility, studying astronomy as well

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on the continent until flights resume. It can be a long and trying stretch of time for anyone, and life is especially quirky at the relatively sparsely populated Amundsen-Scott Station (as opposed to McMurdo, the sprawling outpost closer to the coast). Roopesh Ojha, who has wintered over to work

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I discovered how thoroughly my fellow scientists defied this stereotype when I started talking to them about my eclipse plans. Like so many other people, I would be seeing my first ever total solar eclipse in August 2017, when the moon would perfectly block the sun for a huge swath of the United

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States. My colleagues and I were all fully conversant in the nuts and bolts of the eclipse: the date and time and place, the

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up its beauty. Observers who had seen eclipses before—either for research or for sheer love of the heavens—waxed on about the haunting quietude that settled over them at the moment of totality, the meditative calm of feeling at one with the solar system, the arresting sight of the white

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blaze of the solar corona, and how they really took the two and a half minutes of totality to drink in the exquisite beauty of the universe. My own reaction proved to be a bit less Zen. For the 2017 eclipse, I joined some colleagues in Wyoming

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of viewing devices sprouted up from the group: everyone was clutching a pair of dark-tinted eclipse glasses, but attendees were also busting out shielded binoculars, every possible stripe of digital camera, small telescopes with solar filters, and setups that could project images of the sun through pinholes and onto screens.

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Many attendees were eclipse veterans—I talked to someone who told me this was their twentieth eclipse—but my family and I were first-timers. My friend

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his family, and a variety of aunts and uncles and cousins) who were all as uncontrollably excited as I was about seeing their first total solar eclipse. Most of the family had traveled via plane or car or camper van from Massachusetts to join me at this particular spot, banking an entire

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the sun reemerged, a momentary diamond ring as the first brilliant hint of the solar surface started peeking out from between the moon’s mountains, I whooped and cheered again with the rest of the group, shouted “ECLIPSE GLASSES BACK ON!” (still at top volume) and then shot across the field

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breath like I’d just run a race and gasping that it had been “the fastest two and a half minutes of my life.” • • • Total solar eclipses can be some of the toughest but most rewarding events to observe in astronomy. They give us a unique opportunity to study everything from the

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out new information about planet atmospheres, asteroid shapes, and how our solar system works. The trick with all these—just like with the 2017 solar eclipse—is actually getting into position to catch them. Observing eclipses can be a herculean undertaking. Any eclipse-like event, whether it’s the moon passing in front of

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many people flocked to a narrow strip of the United States stretching from Oregon down to South Carolina in 2017 to catch the last total solar eclipse: the eclipse path marked the shadow cast by the moon on the earth as it passed between us and the sun. For astronomers who make a

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hard to pin down in its own right. Astronomers have a pretty good mathematical grip on the relative motion of the earth, moon, and sun and can predict the timing and shadow position of solar eclipses perfectly. However, the math gets messier and more uncertain when we’re dealing with, say, a

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filled entire books, including David Baron’s American Eclipse, recounting a worldwide Gilded Age scramble to study the solar eclipse that crossed North America in 1878. The most scientifically famous eclipse observation is undoubtedly Arthur Eddington’s expedition in 1919 to test Albert Einstein’s theory of general relativity. According to Einstein, the sun should “lens” background stars as

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all the other stars in the sky. An eclipse would solve this, handily blocking the sun and allowing Arthur Eddington to measure the position of nearby stars. He just needed to pack up the cutting-edge astronomical equipment of 1919 and get into the path of the eclipse. In 2017, many normally quiet corners of

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the United States found themselves overrun with astronomy enthusiasts as they crammed themselves, their cars, and their cameras into the path of the solar eclipse. Still, a traffic jam in Wyoming isn’t quite as rough as what Eddington

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’s 1919 trip entailed. More than two months before the May 29 eclipse, he sailed from England to Príncipe Island off the coast of western Africa

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torrential rain and thick clouds blocked out the sky all morning. Luckily, just before the eclipse, the skies cleared, and they were able to take a few precious photographs that confirmed Einstein’s theories. Not every historical observer got this lucky: wonky equipment or badly timed clouds can be all it

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phones make travel considerably easier, but solar astronomers still have to crisscross the planet every few years to put themselves into the paths of eclipses. Shadia Habbal, who uses eclipses as an opportunity to study the sun’s wind and magnetic fields, has led ten solar eclipse expeditions to locations all over the globe

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. By following the eclipses, she and her team get repeated opportunities to study the

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and the anticipated climate in the area, both meteorological and political, as Shadia discovered for a solar eclipse in 2006. The path of that eclipse arced through northern Africa and was ideally observable from southern Libya, which could have potentially posed a challenge. Luckily for the astronomers, in early 2004,

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of the country, even going as far as setting up a dish for internet at the research campsite in the middle of the desert. Another solar eclipse in 2015 passed over the Arctic Circle, and Shadia’s team chose Svalbard in northern Norway as the ideal site for the observations. With their

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someone was constantly keeping watch. Still, even fear of polar bears was able to take a back seat to what became an extraordinarily beautiful eclipse, with the solar corona illuminating the snow-blanketed valley walls all around them. The town where Shadia’s team was staying closed everything down fifteen minutes before

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totality so that every resident could go out and watch the eclipse. Shadia also recalled a similar local reaction from another expedition that otherwise couldn

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moment of totality is pretty much impossible to miss if you’re in the path of the eclipse, and the universal bond shared by everyone standing underneath the sun as it momentarily disappears is palpable. • • • Solar eclipses are dramatic and spectacular and well-studied events: thanks to orbital math and carefully measured distances

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, we can predict solar eclipse times and locations down to the second. However, as astronomers move to smaller events—say, a

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laid out depending on how well we think we know the distance, orbit, shape, and size of the asteroid. The stakes also go up accordingly. Solar eclipses happen somewhere on Earth about once every eighteen months on average, but the odds of any one particular asteroid crossing neatly in front of a

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even fairly routine equipment problems. At the same time, events like this can be met with the same level of cheer and enthusiasm that greets solar eclipses. Larry Wasserman recalled the commotion that ensued in Comodoro Rivadavia, a city of about 180,000 in southern Argentina, when the 2014 MU69 occultation teams

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glance at the science can quickly establish that the apparent motion of Mercury (“Mercury in retrograde” is a simple trick of perspective thanks to the relative orbital speeds of Mercury and Earth, which can create the illusion that Mercury is sometimes moving backward in the sky) or which constellation is

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all over the planet; and to a golf course in Wyoming where more than a dozen family members had come together to see their first solar eclipse. It may be chance and choice—the statistical wiggles of the universe combined with the wacky decisions of those of us who have decided to

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finished reemerging from behind the moon and chattered about what we had seen. Several people were already asking about April 2024, when the next total solar eclipse to hit the United States would be tracing out a path that arced over the eastern swath of North America from Mexico and Texas to

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’t been any clouds blocking our view. Perhaps most shocking was the eclipse itself. It’s easy to miss this fact, but Earth’s total solar eclipses are actually a stunning quirk of fate, a party trick of our solar system that likely sets us apart as a rarity even among the many

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friendly aliens, Earth’s solar eclipses would probably function as a planetary tourism draw in the same way that the Grand Canyon draws people to Arizona. There was also another layer of incredible serendipity thrumming under the surface on that August day during the eclipse, although only a relatively small handful of people knew

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about it at the time. It was the reason I’d pulled out my phone and started poking at the internet shortly after the eclipse had completed, admiring heaps of totality photos on

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million light-years away and throwing a handful of astronomers into a frantic and quiet chaos. CHAPTER TEN TEST MASS Four days before the 2017 solar eclipse, on the afternoon of August 17, Dave and I were waiting in line at a neighborhood ice cream shop. I was busy pondering the

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as well. Gravitational waves fall into that wonderful realm of physics where things exist simply because the math of the universe insists they should. Einstein’s famous general theory of relativity, which describes the relationship between gravity, space, and time, is described by a series of ten mathematical equations. In 1916

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, Einstein found that one consequence of these equations was the existence of gravitational waves. The challenge came from proving this (and, by extension, proving a

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, a decent fraction of these people were headed out to some of the most remote corners of the United States for the August 21 solar eclipse. Mansi Kasliwal, a team leader for one of the follow-up groups, had volunteered for a massive public

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timing, Oscar’s naked-eye observation was the first. Astronomers had been discovering supernovae for years, but they had all been much farther away in relatively distant galaxies. The last one visible from Earth with the naked eye had been a cool 383 years earlier, in 1604, several years before

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and art as very different pursuits, but Levesque writes about her colleagues’ love of music, their cartoons depicting life at observatories, their poetic descriptions of solar eclipses, and their appreciation for the beauty of the universe. Why do you think we see science and art as distinct? Has your opinion on this

The Star Builders: Nuclear Fusion and the Race to Power the Planet

by Arthur Turrell  · 2 Aug 2021  · 297pp  · 84,447 words

bring a little nearer to fulfilment our dream of controlling this latent power for the well-being of the human race, or for its suicide.” —Arthur Eddington, “The Internal Constitution of the Stars,” 19201 Who are the fusion pioneers aiming, like Prometheus, to steal the secret of fire from the heavens?

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only dig it out of the ground and set it on fire, no lasers or force fields required. In the past, the price was low relative to other energy sources. Fossil fuels are able to respond quickly to demand, in just a few seconds in some cases. They don’t

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production. Fusion’s cousin, nuclear fission, supplies around 4 percent. Biomass refers to biologically grown materials that can be burned for energy, including wood. Solar, wind, and other forms of renewables are barely large enough to feature except for a sizeable sliver attributable to hydroelectricity (6 percent). There is a

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carbon-free energy sources at a rate that is unprecedented.26 Star builders have been keen to tell me that massive adoption of renewable energy (solar power, wind power, tidal power, hydroelectricity, and so on) is part of the solution. Renewables have some fantastic advantages—the most obvious being that

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from renewables less certain. As the worldwide pattern of both weather and climate changes, it will create renewable energy winners and losers. The potential for solar power will likely rise in Europe and China but fall in the western USA, Saudi Arabia, and across Africa. Overall, the effects seem likely

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, conducted after the tragic meltdown at the Fukushima nuclear plant, found that fission had the lowest public support globally of any source of power, including solar, wind, hydro, gas, and coal. Some countries are phasing out fission power altogether. “Fission faces a great acceptance problem,” Sibylle Günter said.36 Nuclear

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. The greatest problem of energy production is climate change: fusion will produce no more carbon dioxide than fission. How much carbon dioxide is that? Solar photovoltaics have life-cycle emissions that are 50 percent higher than fission and wind. Everything else, including biomass and hydro, has emissions that are at

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capacity is comparatively tiny. Maybe there’s hope for fusion yet.44 And yet… nuclear fusion is qualitatively different. Even Charles Fritts’s first solar cell managed a net energy gain, harvesting 1 percent of the sunlight energy that fell on it. Ignoring the energy cost of creating the cell

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will one day learn to release it and use it for his service. The store is well-nigh inexhaustible, if only it could be tapped.” —Arthur Eddington, “The Internal Constitution of the Stars,” 19201 This book is about scientists’ attempts to unlock energy from within the atom, and the star builders owe

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and inconsequential, but it is the very reason why nuclear fusion works. The physicist and great popularizer of science Arthur Eddington was struck by this apparent mistake in the arithmetic of the universe. Eddington was a nuclear visionary, suggesting long before Rutherford’s fusion experiment that the power source of stars was subatomic

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mass of the end products was always the same as the mass of the reactants. Conservation of mass was a central tenet of physics. Eddington wondered whether a theory published by a brilliant physicist he greatly admired could shed light on the puzzle. It said that mass and energy were

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published this theory along with three others that challenged fundamental concepts in physics in 1905. His name was Albert Einstein.11 The Secrets of Atomic Energy The theory of Einstein’s that Eddington had in mind to explain the minute differences in mass of atoms said that the relationship between an object’s

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for millions, perhaps billions, of years: not only is it plentiful, we don’t need very much of it. But there’s a problem. Einstein’s equation can tell star builders how much energy they can expect to release, if the reaction happens. But how do they know what reactions

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get canceled out by an “antigravity.” These unusual properties are why it’s gravity that determines how the structure of the universe evolves, despite its relative weakness. Electromagnetism also has infinite range but comes in positive and negative versions that tend to cancel out on large scales. In contrast, the strong

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smashing way is like throwing darts blindfolded: you might know the rough direction, but you’re not going to get many bull’s-eyes. Einstein himself said that the “likelihood of transforming matter into energy is something akin to shooting birds in the dark in a country where there are

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of average speed at the atomic scale, so more heat means more movement, and more vibration. The molecules in liquid water are bound together by relatively weak forces. Put in a little heat, and the water molecules vibrate more. With enough heat, the energy of the vibrations is more than

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—the stars are not hot enough. The critics lay themselves open to an obvious retort; we tell them to go and find a hotter place.” —Arthur Eddington, 19271 Nature is good at fusion. Really, really good. It’s galling for the star builders. On Earth, they’re trying to build the

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plasma rose, until particles began to crash together with enough speed for nuclear fusion reactions to begin: light, energy, heat—all unleashed as the solar system came alive. Likewise, the universe’s Dark Ages ended as the tender young universe was flooded with light from fusion. That light swept through

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the road for fusion reactions. These stars gracefully retire as “white dwarfs”—smaller, brighter stars that gradually cool. They do have their surprises though; as Arthur Eddington put it, they’re so dense that a ton of their plasma could fit in a matchbox.9 Medium stars have similar masses to our

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less dense than in the Sun, even less dense than the air we breathe, but they do it by creating the hottest temperatures in the solar system, hotter than the Sun, and by using long energy confinement times. Inertial confinement fusion uses a different mix of temperature, density, and confinement.

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the runaway processes that ruin confinement. He had an alternative. The plasma in magnetic fusion conditions is like the solar corona, the outer, wispy part of the Sun that becomes visible during solar eclipses. Physicists still don’t properly understand it, and even then Teller knew that working with similar plasmas would present

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work is fiddly and hard, requiring saintlike patience. The satisfaction of having created something tangible that can help probe the most extreme conditions in the solar system is the reward. Following a Saturday spent building equipment, Rutherford once exclaimed to a colleague, “I am sorry for the poor fellows that

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house of cards stand up requires everything to work perfectly together: the laser, the hohlraum, the capsule, the human operators, and even the computer codes. “Relatively small things can make a big difference,” Mark Herrmann told me, when we talked about the painstaking precision that’s needed. A few percent error

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these magnets operate at is twenty degrees above absolute zero. The old “low-temperature” ones only worked at two degrees Kelvin, so it’s all relative. Magnetic resonance imaging, or MRI, machines in hospitals use superconducting technology and need to stay below around ten degrees Kelvin. They’re about the highest

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dropped on Nagasaki probably killed another 150,000 people. The destruction wrought by nuclear weapons is so effective at making entire cities vanish that, paraphrasing Arthur C. Clarke, it’s as if the technology were magic, albeit of the darkest and most terrible kind. Nuclear weapons are among the most

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,” Dr. Nick Hawker, CEO of First Light Fusion, told me. Besides, fissionable isotopes and their precursors are detectable in small quantities, so it’s relatively easy to check for them. Inspection equipment at a reactor would need only seconds or minutes to find out what was going on. And all

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mass than fossil fuels produce, but what is created is more problematic. Most of the one kilogram is low-level waste that becomes safe relatively quickly. The really dangerous part is the 3 percent of high-level waste so radioactive that it must be actively cooled for its first forty

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“Fission plants produce waste as an inherent part of their process,” Jonathan Carling told me. “The only waste that a fusion plant produces is relatively low-activation waste of the plant itself because it gets hit by neutrons.” In fission, the spent fuel and the reactor are radioactive; in fusion

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South Korea’s KSTAR, and the Joint European Torus (JET). The stellarator Wendelstein 7-X is not far behind them, achieving impressive feats for a relatively new machine based on a different technology.7 For now, it looks as though the private sector fusion firms are lagging behind—though some are

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account the negative externalities of air pollution and carbon dioxide. The other fossil fuels are relatively expensive. The really interesting comparisons are with renewables; concentrating solar thermal (using mirrors to heat a liquid) is $34 per gigajoule, industrial-scale solar photovoltaic (panels) is $16, offshore wind is $24, and onshore wind is $

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that rely on large areas of land are susceptible to environmental changes. Fission could be one solution. Star power is another: the fuels are (relatively) common—deuterium is found in all the world’s oceans while lithium is found on all the world’s inhabited continents—and in any case

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read almost every chapter of every single draft, and was indefatigable in providing critique and encouragement; both have been invaluable. ABOUT THE AUTHOR © ARTHUR TURRELL. PHOTOGRAPH: KAREN HATCH ARTHUR TURRELL has a PhD in plasma physics from Imperial College London and won the Rutherford Prize for the Public Understanding of Plasma Physics

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works as a deputy director at the Data Science Campus of the Office for National Statistics in the UK. SimonandSchuster.com www.SimonandSchuster.com/Authors/Arthur-Turrell @ScribnerBooks We hope you enjoyed reading this Simon & Schuster ebook. Get a FREE ebook when you join our mailing list. Plus, get updates

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(2018), https://www.seattletimes.com/business/billionaires-back-fusion-energy-projects-in-pursuit-of-a-spacex-moment/. Chapter 1: The Star Builders 1. A. S. Eddington, “The Internal Constitution of the Stars,” Observatory 43 (1920): 341–58. 2. I. T. Chapman, “Modelling the Stability of the N=1 Internal Kink

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UK Government, Electricity Generation Costs 2020 (Department of Business, Energy and Industrial Strategy, 2020). 28. L. M. Miller and D. W. Keith, “Corrigendum: Observation-Based Solar and Wind Power Capacity Factors and Power Densities,” Environmental Research Letters 14 (2019): 079501. 29. D. J. C. MacKay, Sustainable Energy—Without the Hot Air

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of Quantitative Projections,” Renewable and Sustainable Energy Reviews 116 (2019): 109415. 33. P. Denholm, M. O’Connell, G. Brinkman, and J. Jorgenson, Overgeneration from Solar Energy in California. A Field Guide to the Duck Chart (National Renewable Energy Lab [NREL], Golden, CO, 2015). 34. O. Edenhofer, R. Pichs-Madruga, Y

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A. Einstein, “Does the Inertia of a Body Depend on Its Energy Content?,” Annalen der Physik 323 (1905): 639–41; F. W. Dyson, A. S. Eddington, and C. Davidson, “A Determination of the Deflection of Light by the Sun’s Gravitational Field, from Observations Made at the Total Eclipse of May 29, 1919,” Philosophical

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); D. Clery, A Piece of the Sun: The Quest for Fusion Energy (New York: Abrams, 2014). Chapter 4: How the Universe Builds Stars 1. A. Eddington, Stars and Atoms (Oxford: Clarendon Press, 1927). 2. H. Johnston, Lives of the Stars Lectures: Star Birth (2016). 3. L. Koopmans et al., “The

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Differential Rotation in 13 Sun-like Stars,” Science 361 (2018): 1231–234. 6. “The Hidden Mechanics of Magnetic Field Reconnection, A Key Factor in Solar Storms and Fusion Energy Reactors,” Phys.org (2017), https://phys.org/news/2017-10-hidden-mechanics-magnetic-field-reconnection.html; NASA, “The Day the Sun

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Tramper et al., “Massive Stars on the Verge of Exploding: The Properties of Oxygen Sequence Wolf-Rayet Stars,” Astronomy & Astrophysics 581 (2015): A110. 9. A. Eddington, Stars and Atoms (Oxford: Clarendon Press, 1927). 10. K. P. Schröder and R. Connon Smith, “Distant Future of the Sun and Earth Revisited,” Monthly Notices

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165, 166 atomic energy, 53–61 deuterium-tritium fusion reactions and, 55–56, 58–59 difficulty of getting net energy from reactions in, 61–64 Einstein’s early research in, 57–59 four fundamental forces of nature affecting, 59–61, 96 Rutherford’s heavy hydrogen (deuterium) experiment and, 54–55 splitting

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186–87 net energy gain goal and, 192–93 Shenguang III megajoule laser in, 14, 193 tokamaks in, 14, 184, 193 Chittenden, Jerry, 99 Clarke, Arthur C., 165 climate change energy addiction and, 28–29 energy crisis related to, 33–34, 42 IPCC’s deadline for averting, 33–34, 36, 45

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Richard, 13, 144 Dyson, Freeman, 82–83, 214 Dyson spheres, 83 Eagle Nebula, 74 EAST tokamak, China, 14, 184, 193 Eddington, Arthur, 15, 49, 56–57, 71, 84 EDF Energy, 174 Einstein, Albert, 57–59, 62 electricity. See also energy generation Teller’s idea of using hydrogen bombs to generate, 115–16 electromagnetism

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of, 17 LIFE power plant prototype at, 199, 206 location of, 110–11 magnetic confinement device at, 97–98 NIF at. See National Ignition Facility solar energy used by, 111–12 Lawrenceville Plasma Physics. See LPP Fusion Lawson, John equations on conditions by, 109–10, 113, 129, 130, 132, 142,

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See National Ignition Facility Nuckolls, John, 67, 115–18, 120, 129 nuclear fission climate change solution using, 39–41, 216 deaths per exajoule for, 181 Einstein’s theory on, 58 problems using, 40–41 public support for using, 40 regulatory considerations for, 40–41 renewables used with, 41 nuclear fission reactors

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instability, in tokamaks, 103–4 Shenguang III megajoule laser, China, 14, 193 Siemens, Werner von, 133 Sierra supercomputer, 189 simulations, 10, 23, 185, 188 solar power. See also renewable energy carbon dioxide emissions and, 42 climate change solution using, 216 costs of, 47, 202, 207 deaths per exajoule for, 181

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Power Facility, 16 Scribner An Imprint of Simon & Schuster, Inc. 1230 Avenue of the Americas New York, NY 10020 www.SimonandSchuster.com Copyright © 2021 by Arthur Turrell All rights reserved, including the right to reproduce this book or portions thereof in any form whatsoever. For information, address Scribner Subsidiary Rights Department

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at www.simonspeakers.com. Jacket design by Jonathan Bush Library of Congress Cataloging-in-Publication Data Names: Turrell, Arthur, author. Title: The star builders : nuclear fusion and the race to power the planet / Arthur Turrell. Description: First Scribner hardcover edition. | New York : Scribner, 2021. | Includes bibliographical references and index. Identifiers: LCCN

When Einstein Walked With Gödel: Excursions to the Edge of Thought

by Jim Holt  · 14 May 2018  · 436pp  · 127,642 words

the last two decades. I selected them with three considerations in mind. First, the depth, power, and sheer beauty of the ideas they convey. Einstein’s theory of relativity (both special and general), quantum mechanics, group theory, infinity and the infinitesimal, Turing’s theory of computability and the “decision problem,” Gödel’s

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infinitely small—the infinitesimal—raises the question of whether reality is more like a barrel of molasses (continuous) or a heap of sand (discrete). Einstein’s relativity theory either challenges our notion of time or—if Gödel’s ingenious reasoning is to be credited—abolishes it altogether. Quantum entanglement calls the reality

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him as a peer, someone who, like him, had single-handedly launched a conceptual revolution. If Einstein had upended our everyday notions about the physical world with his theory of relativity, the younger man, Kurt Gödel, had had a similarly subversive effect on our understanding of the abstract world of mathematics.

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car, I would actually see its length contracted and you moving in slow motion inside.) So Einstein set about recasting the laws of physics accordingly. To make these laws absolute, he made distance and time relative. It was the sacrifice of absolute time that was most stunning. Isaac Newton believed that

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Prize in Physics, it was for his work on the photoelectric effect. The Swedish Academy forbade him to make any mention of relativity in his acceptance speech. As it happened, Einstein was unable to attend the ceremony in Stockholm. He gave his Nobel lecture in Gothenburg, with King Gustav V seated in

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the front row. The king wanted to learn about relativity, and Einstein obliged him. * * * In 1906, the year after Einstein’s annus mirabilis, Kurt Gödel was born in the city of Brno (now in the Czech Republic). Kurt was both an

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that are beyond the reach of a logical system. Gödel was twenty-four when he proved his incompleteness theorems (a bit younger than Einstein was when he created relativity theory). At the time, much to the disapproval of his strict Lutheran parents, he was courting an older Catholic divorcée by the name

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time that Gödel was studying the Constitution, he was also taking a close look at Einstein’s relativity theory. The key principle of relativity is that the laws of physics should be the same for all observers. When Einstein first formulated the principle in his revolutionary 1905 paper, he restricted “all observers” to

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truly objective description of nature, they ought to be valid for observers moving in any way relative to one another—spinning, accelerating, spiraling, whatever. It was thus that Einstein made the transition from his “special” theory of relativity of 1905 to his “general” theory, whose equations he worked out over the next decade

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they explained gravity, the force that governs the overall shape of the cosmos. Decades later, Gödel, walking with Einstein, had the privilege of picking up the subtleties of relativity theory from the master himself. Einstein had shown that the flow of time depended on motion and gravity and that the division of events

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way; for Jones, the Andromedan council of tyrants has not even decided whether to send the fleet. What Einstein had shown was that there is no universal “now.” Whether two events are simultaneous is relative to the observer. And once simultaneity goes by the board, the very division of moments into “past

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“flowing” from one event to another. As the mathematician Hermann Weyl memorably put it, “The objective world simply is; it does not happen.” Einstein, through his theory of relativity, furnished a scientific justification for a philosophical view of time that goes back to Spinoza, to Saint Augustine, even to Parmenides—one that

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not. Like Einstein himself, we are stubbornly in thrall to our temporal illusions. We cannot help feeling ourselves to be slaves to one part of the timescape (the past) and hostages to another part (the future). Nor can we help feeling that we are quite literally running out of time. Arthur Eddington, one

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of the first physicists to grasp Einstein’s relativity theory, declared that our intuitive sense of time’s passage is so powerful that it must correspond to something in the

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popularizations. What one seldom encounters in such books, however, is the rather different view that Russell expressed in his late eighties, when he dismissed his (relatively) youthful rhapsodizing as “largely nonsense.” Mathematics, the aged Russell wrote, “has ceased to seem to me non-human in its subject-matter. I have

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by coercion. But Galton’s goal, to breed the barbarism out of humanity, was not despicable. The new eugenics, by contrast, is based on a relatively sound (if still largely incomplete) science, and it is not coercive; it might be called “laissez-faire” eugenics, because decisions about the genetic endowment

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pure intellectual invention, unmotivated by the needs of contemporary science. Six decades later, his tensor calculus furnished precisely the apparatus that Einstein required to work out the general theory of relativity. But the immediate effect of Riemann’s revolution was to destroy the old notion of geometry as the science of physical

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the idea rendered disreputable by its association with mystics and charlatans; it also seemed devoid of testable consequences. Then, during World War I, Einstein framed his general theory of relativity. By uniting the three dimensions of space and the one dimension of time into a four-dimensional manifold, “space-time,” and then

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way of slicing up the four-dimensional space-time manifold into purely spatial and temporal dimensions.) When newspaper headlines announced the triumphant confirmation of general relativity in 1919, the idea that time was the fourth dimension entered the culture at large, and interest in higher spatial dimensions began to dry up—quite

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be more to our spatial world than meets the eye, dimensionally speaking. To understand why, consider that contemporary physics has two sets of laws: general relativity, which describes how things behave on a very massive scale (stars on up); and quantum theory, which describes how things behave on a very

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out of their lectures, hinting only at the “mystical beauty” of the mathematical world and the importance of bestowing names on its objects. But the relative permissiveness ended when Stalin came to power. Egorov was denounced as “a reactionary supporter of religious beliefs, a dangerous influence on students, and a

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elaborate (and untranslatable) pun about sodomy and higher mathematics, whereupon Kolmogorov struck him in the face. The Moscow school of mathematics flourished long after the eclipse of its mystically inclined founders. In the postwar era, only Paris rivaled the Russian capital as a center of mathematical talent. But the higher infinities

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was finally dispelled when, in his early teens, he met another boy who shared his passion for science. They became inseparable friends, exploring esoterica like Einstein’s relativity theory together. When, a year later, the boy died of tuberculosis, Turing seems to have been left with an ideal of romantic love that

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“exceptional creativity”—which they put at less than 1 percent of the population—were more likely to suffer from manic depression or to be near-relatives of manic-depressives. As for the psychological mechanisms behind creative genius, those remain pretty much a mystery. About the only point generally agreed on

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mathematics. He virtually created the modern field of topology, framing the “Poincaré conjecture” for future generations to grapple with, and he beat Einstein to the mathematics of special relativity. Unlike many geniuses, Poincaré was a man of great practical prowess; as a young engineer, he conducted on-the-spot diagnoses of mining

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in physics, as in the rest of life, beauty can be a slippery thing. The gold standard for beauty in physics is Albert Einstein’s general theory of relativity. What makes it beautiful? First, there is its simplicity. In a single equation, it explains the force of gravity as a curving

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Family, in which every figure on the canvas is perfectly placed and there is nothing you would have wanted the artist to do differently. Einstein’s general relativity was one of two revolutionary innovations in the early part of the twentieth century that inaugurated the modern era in physics. The other was

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quantum mechanics. Of the two, quantum mechanics was the more radical departure from the old Newtonian physics. Unlike general relativity, which dealt with well-defined objects existing in a smooth (albeit curved) space-time geometry, quantum mechanics described a random, choppy microworld where change

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behavior instantaneously across vast distances—even though all known methods of communication are, in accord with relativity, limited by the speed of light. Einstein’s conclusion in the EPR thought experiment was the same as in Einstein’s Boxes: such a link would be “spooky action at a distance.” Quantum entanglement can’

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’t be used for communication, quantum entanglement doesn’t give rise to the sorts of causal anomalies Einstein warned about—like being able to send a message backward in time. So quantum theory and relativity, though conceptually at odds with each other, can “peacefully coexist.” For John Bell, that wasn’t

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of contemporary theory,” he observed in a 1984 lecture. If our picture of physical reality is to be coherent, Bell believed, the tension between relativity theory and quantum mechanics must be confronted. In 2006, an impressive breakthrough along these lines was made by Roderich Tumulka, a German-born mathematician at

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out influences that are faster than light. (Indeed, physicists sometimes talk about hypothetical particles called tachyons that move faster than the speed of light.) What relativity does rule out is absolute time: a universal “now” that is valid for all observers. Entangled particles would seem to require such a universal

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how a certain speculative extension of quantum mechanics—known, for complicated reasons, as flashy GRW—could allow entangled particles to act in synchrony without violating relativity’s ban on absolute simultaneity. Although the mechanism behind this nonlocal “spooky action” remains obscure, Tumulka at least proved that it is logically consistent

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with relativity after all—a result that might well have surprised Einstein. However it works, nonlocality has subversive implications for our understanding of space. Its discovery suggests that we might live in a

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two scenarios would come to pass depended on one crucial thing: how much stuff there was in the universe. So, at least, said Einstein’s general theory of relativity. Stuff—matter and energy—creates gravity. And, as every undergraduate physics major will tell you, gravity sucks. It tends to draw things together

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the ages, all the devotion, all the inspiration, all the noonday brightness of human genius, are destined to extinction in the vast death of the solar system, and that the whole temple of Man’s achievement must inevitably be buried beneath the debris of a universe in ruins.” Yet a few

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render the two dimensions comparable. Here is where contemporary physics comes in handy. In trying to blend the theories that describe the very large (Einstein’s general relativity) and the very small (quantum mechanics), physicists have found that it is natural to regard space and time as being composed, on the tiniest

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genius for detecting the paradoxical in unexpected places. He looked into the axioms of mathematics and saw incompleteness. He looked into the equations of general relativity and saw “closed time-like loops.” And he looked into the Constitution of the United States and saw a logical loophole that could allow

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mechanics and optics could be deduced. Since then, the law of least action has, in its various guises, continued to be extraordinarily powerful. Einstein’s equations of relativity, which replaced Newtonian gravitation, can be derived from an action principle not unlike the one Maupertuis set forth. “The highest and most coveted aim

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began as a purely mechanical notion eventually came to encompass thermal, electric, magnetic, acoustic, and optical varieties of energy—all, fortunately, interconvertible. With Einstein’s theory of relativity, even matter came to be viewed as “frozen” energy. Sooner than give up energy conservation, Henri Poincaré once observed, we would invent new forms

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bit harsher than mine. In The Times Literary Supplement of February 9, 2001, for instance, the philosopher Stephen Neale described Smith’s analysis of the relative contributions of Kripke and Marcus as “confused” and “not worthy of discussion” and claimed that philosophically Smith was “out of his depth.” So the

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It Means for Black Holes, the Big Bang, and Theories of Everything (Scientific American / Farrar, Straus and Giroux, 2015). Tim Maudlin, Quantum Non-Locality and Relativity: Metaphysical Intimations of Modern Physics, 3rd ed. (Wiley-Blackwell, 2011). 20. HOW WILL THE UNIVERSE END? Steven Weinberg, The First Three Minutes: A Modern

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Presper École Nationale des Ponts et Chaussées École Normale Supérieure École Polytechnique Eddington, Arthur efficient market hypothesis Egorov, Dmitri Ehrenfest, Paul Eilenberg, Samuel Einstein, Albert; death of; Gödel’s walks with; at Institute for Advanced Study; Nobel Prize of; relativity theory of, see relativity; unified theory of physics pursued by; Witten compared to Eisenhower, Dwight

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, Steve Google Gorbachev, Mikhail Gott, J. Richard, III Göttingen, University of Gould, Stephen Jay Graham, Loren Grassmann, Hermann gravity; Newton’s laws of; in relativity theory; in string theory Greeks, ancient; see also Aristotle; Plato; Socrates; Zeno of Elea Greene, Brian Gresham, Thomas Grothendieck, Alexander group theory Guelph, University of

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Isidor Ramachandran, V. S. Rampal, Jean-Pierre Raphael rationalism Rawls, John Reagan, Ronald reference: new theory of; self– regression Reign of Terror Reimann surfaces relativism relativity; experiments confirming; Gödel on; publication of papers on; quantum physics and; space-time in; thought experiment on Renaissance Revue du Mois Rhodes, Colossus of Richard

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Thompson, Clive thought experiments time; absolute; dimensionality of; infinitesimal divisions of; infinity of; least, principle of; Planck; Platonic transcendence of space and; regression in; relativity of; in theories of names; travel through; unreality of; see also space-time Times Literary Supplement, The Times of London “Time Without End” (Dyson) Tipler

Day We Found the Universe

by Marcia Bartusiak  · 6 Apr 2009  · 412pp  · 122,952 words

the spirals' sizes and the brightness of their novae only made sense if they were milky ways at great distance. The highly respected English astrophysicist Arthur Eddington was captivated by the vast breadth of this idea; it engaged his theoretical fantasies. “If the spiral nebulae are within the stellar system [the

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of system beyond system … in which the great stellar system of hundreds of millions of stars (our galaxy)…would be an insignificant unit.” For Eddington, the heavens just seemed to make more sense viewed from this grander perspective. The epicenter of this resurgence was located right at the Lick Observatory

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nebulae in the major journals, and his cogent arguments in support of distant galaxies were already convincing the top astronomers who counted, such luminaries as Eddington at Cambridge University, in England, Campbell at Lick, and Hertzsprung, then at the Potsdam Observatory, in Germany. The swift velocities that Slipher was finding

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waning days of World War I, but Shapley couldn't wait that long to spread the news. On January 8, 1918, he wrote the noted Arthur Eddington in England that “now, with startling suddenness and definiteness, [the cluster studies] seem to have elucidated the whole sidereal structure”—in other words, the

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community like a lightning bolt. Praise for the work, from the most eminent corners of astronomy, was immediate. After reading Shapley's completed papers, Eddington wrote Shapley that “this marks an epoch in the history of astronomy, when the boundary of our knowledge of the universe is rolled back to

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Shapley's worries; the most ardent believers in external galaxies still held fast to their convictions—not only Curtis but also such major players as Arthur Eddington, W. W. Campbell, and V. M. Slipher. It was the undecideds who were most affected by Shapley's arguments and so remained huddled on

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be-observed inner planet. This wasn't just a vague prediction; the equations of general relativity accounted for Mercury's extra 43 arcseconds of shift per century with utmost precision. Arthur Eddington, for one, was immediately smitten by Einstein's groundbreaking opus. “Whether the theory ultimately proves to be correct or not, it claims

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attention as being one of the most beautiful examples of the power of general mathematical reasoning,” he wrote in his account of general relativity, the first book

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on the subject to appear in English. With Eddington acting as Einstein's translator and champion, the two were often linked in people's minds. An accomplished popularizer of science

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, Eddington said that Einstein had taken “Newton's plant, which had outgrown its pot, and transplanted it to a more open field.” Eddington was becoming so proficient at explaining relativity that “people seem to forget that I am an astronomer and that

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relativity is only a side issue,” he lamented after one wearying interview with reporters. Arthur Eddington

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(AIP Emilio Segrè Visual Archives) For Eddington to serve as a spokesman for a radical new theory was somewhat out of character for him. He was

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declared valuable to the “national interest” at his university post. As both an astronomer and a theorist, Eddington divined early on the revolutionary significance of Einstein's ideas: that the general theory of relativity was offering a means to comprehend the workings of the cosmos within a rational and mathematical framework. While

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deal with the immensity of space-time as a whole. And at the moment Eddington was beginning to work on a translation of general relativity for his colleagues, Einstein was already at work applying his revolutionary new theory to the universe at large. For Newton, space was eternally at rest, merely an

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track of general relativity's development as early as 1911 and was one of the first to recognize its deep significance to astronomy. After meeting with Einstein in Leiden on several occasions in 1916, discussions in fact that inspired Einstein to conceive his spherical universe, de Sitter soon corresponded with Eddington on the

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subject. Intrigued by de Sitter's insights, Eddington asked him to write up his impressions of general relativity for the Monthly Notices of the Royal Astronomical Society, which

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resulted in three long papers on the topic, the first articles to make Einstein's accomplishment widely known to scientists outside Germany. De

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matter dropped inside its space-time would immediately fly off. That was another possible reason for the red-shifts Slipher was noticing. Eddington liked to say that “Einstein's universe contains matter but no motion and de Sitter's contains motion but no matter.” Before the publication of his bizarre yet

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my grasp.” All of that changed, though, once the findings of a British solar-eclipse expedition in 1919 transformed the name of Einstein, the former Swiss patent clerk, into a synonym for genius. At the time Einstein was working on general relativity, he had early on suggested a specific test that astronomers could perform to confirm

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organize and carry out the intricate venture. On the evening before sailing, Eddington and his eclipse companion, E. T Cottingham, joined Dyson in his study. The discussion turned to the amount of deflection expected from classical Newtonian theory compared to Einstein's predicted value, which was twice as great. “What will it

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mean,” asked Cottingham playfully, “if we get double the Einstein deflection?” Dyson replied, “Then Eddington will go mad and you will have to come home alone!” The next day Eddington and his assistant began their journey to the tiny isle of Principe, situated 140 miles off

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Cottingham, too, took sixteen photographs, but most ultimately turned out useless because of the intervening clouds. For several days after the eclipse, Eddington spent the daytime hours taking a first stab at measuring the star images on the plates that did turn out well. Upon examining the

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go home alone.” He saw evidence that the streams of starlight had indeed bent around the darkened Sun according to Einstein's rules. At a dinner soon after his return to England, Eddington entertained some fellow astronomers with a poem in the style of the Rubáiyát. “One thing is certain, and

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images, the British team decided to downplay that instrument's results. Eddington admitted he was unscientifically rooting for Einstein, but his instincts to reject the astrographic telescope results turned out to be good in the end. Campbell headed up another solar-eclipse expedition in 1922, which arrived at similar results and further confirmed

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on the cosmos being empty, but the universe was undoubtedly chock-full of matter. In the ensuing discussion, Arthur Eddington casually wondered aloud why only two cosmological models—Einstein's and de Sitter's—had so far come out of general relativity to describe the universe. Were other solutions possible, ready for plucking within

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, Annales de la Société Scientifique de Bruxelles (Annals of the Brussels Scientific Society) rather than a publication on every astronomer's must-read list. Eddington had either put Lemaître's paper aside, never getting around to reading it, or simply didn't comprehend its importance at the time. In any

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problem we were discussing.” De Sitter as well grasped the brilliance of Lemaître's approach, calling it “ingenious” and immediately abandoning his own solution. Eddington soon arranged for Lemaître's paper to be translated and reprinted in the March 1931 issue of the Monthly Notices of the Royal Astronomical Society

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was ordained a priest in 1923. Becoming fascinated with the mathematical beauty of general relativity, he went to Cambridge University for postdoctoral studies to broaden his understanding of Einstein's equations under the guidance of the eminent Eddington, who soon noticed Lemaître's talents. With his dark hair combed straight back and

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off by a stiff white clerical collar. Others could find him just by pursuing the sound of his full, loud laugh, which was readily aroused. Eddington told Shapley that the young Belgian, then turning thirty, was “exceptionally brilliant… quite remarkable both for his insight into physical significance of problems, and

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was reported as breathtaking in its grandeur and terrifying in its implications. “The theory of the expanding universe is in some respects so preposterous,” said Eddington, “that we naturally hesitate before committing ourselves to it. It contains elements apparently so incredible that I feel almost an indignation that anyone should

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, with a speed that doubles its size every 1,400 million years… If Einstein's relativity cosmology is sound, the nebulae have no alternative—the properties of the space in which they exist compel them to scatter.” Eddington first devised this picture when he introduced his colleagues to Lemaître's solution in

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a bit, and a discussion would follow.” There was much to argue about. Those still skeptical of general relativity were offering other explanations for the outward march of the galaxies. British cosmologist E. Arthur Milne, for example, posited that the expansion of space-time was merely an illusion. Space was steady

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's Palomar Mountain] within a few years.” Maintaining his lawyerly ways, Hubble covered all the bases when making a public statement. Others, such as Eddington, were confounded by such equivocation. “I just don't understand this eagerness to find some other theory than the expanding universe,” he wrote in a

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Aside from perhaps receiving a Nobel Prize, there was no higher accolade in science at the time. A few weeks before Einstein roamed over the summit of Mount Wilson, Eddington delivered an address to the British Mathematical Association, where he called attention to the notorious elephant in the room, present ever

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and all of creation. Could you reach a “beginning of time,” he asked, when all matter and energy had the highest degree of organization possible? Eddington was horrified by this thought. The Cambridge theorist concluded that “philosophically, the notion of a beginning of the present order of Nature is repugnant to

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description on a 1949 BBC radio program, this time with an added adjective, which secured the scientific name—Big Bang—for the moment of creation). Eddington, though, preferred a commencement less abrupt and more restrained. “I picture…an even distribution of protons and electrons, extremely diffuse and filling all (spherical)

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and then gaining speed. Lemaître, however, was far bolder and had no hesitation at all in contemplating a more dramatic genesis. In response to Eddington's repulsion at an abrupt cosmic beginning, Lemaître submitted a short note to the journal Nature with the splendiferous title: “The Beginning of the World

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He was uncomfortable with Einstein's theory and participated in solar-eclipse tests hoping to prove general relativity wrong. In the 1930s he told Harlow Shapley that he wasn't keen on where the research on spiral nebulae was going: “I have so little confidence in the theories of Lemaître, Eddington, et al. in

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details were presented in both the Astrophysical Journal and Contributions from the Mount Wilson Observatory. 128 “now, with startling suddenness and definiteness”: HUA, Shapley to Eddington, January 8, 1918. 129 “You may have been completely prepared for the result”: Ibid. 129 “While I cannot pretend to have anticipated the view

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frequency of light-vibrations diminishes”: De Sitter (1917), p. 26. 143 “amongst the most distant objects we know”: Ibid., p. 27. 143 “Einstein's universe contains matter but no motion”: Eddington (1933), p. 46. 143 “does not make sense to me”: Kahn and Kahn (1975), p. 453. 144 “systematically”: De Sitter (

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Davidson (1920). 147 “LIGHTS ALL ASKEW IN THE HEAVENS”: New York Times, November 10, 1919, p. 17. 147 Eddington admitted he was unscientifically rooting for Einstein: Eddington (1920), p. 116. 148 “I hoped it would not be true”: Douglas (1957), p. 44. 148 “We met in quick succession Their Eminences”: LOA,

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solutions … that does not matter”: Ibid., p. 39. 240 “a concept outside their mental framework”: Kragh (2007), p. 139. 240 Lemaître soon read the remarks Eddington made: Eisenstaedt (1993), p. 361; McVittie (1967), p. 295. 241 “This seems a complete answer to the problem we were discussing”: Smith (1982), p.

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devised this picture: Eddington (1930), p. 669. 246 “embedded in the surface of a balloon”: Ibid. 247 “About every two weeks some of the men from Mount Wilson and Cal Tech came to the house”: HUB, Box 7, Grace's memoir. 247 British cosmologist E. Arthur Milne, for example, posited that

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to hunt for the sole twelve men in the world: “Relativity” (1930), p. A4. 250 “This reminds me of a Punch and Judy show”: “Einstein Battles ‘Wolves’” (1930), p. 1. 250 “his face … as smooth as a girl's”: Ibid., p. 2. 250 Arthur Fleming … first extended the invitation: Sutton (1930), p.

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): x. Doig, P. 1924. “The Spiral Nebulae.” Journal of the British Astronomical Association 35 (December): 99-105. Douglas, A. V. 1957. The Life of Arthur Stanley Eddington. London: Thomas Nelson and Sons Ltd. Dreiser, T, and F. Booth. 1916. A Hoosier Holiday. New York: John Lane. Dunaway, D. K. 1989. Huxley

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256: 9-20. Dyson, F. W. 1917. “On the Opportunity Afforded by the Eclipse of 1919 May 29 of Verifying Einstein's Theory of Gravitation.” Monthly Notices of the Royal Astronomical Society 77: 445-47. Dyson, F. W., A. S. Eddington, and C. Davidson. 1920. “A Determination of the Deflection of Light by the

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Sun's Gravitational Field, from Observations Made at the Total Eclipse of May 29, 1919.” Philosophical Transactions of the Royal Society of London 220: 291-333. Eddington, A. S. 1916. “The Nature of Globular Clusters.” Observatory 39: 513-14. ——. 1920. Space, Time, and Gravitation.

Big Bang

by Simon Singh  · 1 Jan 2004  · 492pp  · 149,259 words

the size of the Sun is obvious, because it is a well-established fact that the Moon fits almost perfectly over the Sun during a solar eclipse. Therefore, the ratio of the Sun’s diameter to the Sun’s distance from the Earth must be the same as the ratio of the

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to estimate the size of the Sun, once we know its distance. One approach is to use a total solar eclipse and our knowledge of the Moon’s distance and diameter. A total solar eclipse is visible only from a small patch on the Earth’s surface at any given time, because the Sun

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and the Moon appear almost the same size when viewed from the Earth. This diagram (not to scale) shows how an eclipse observer on the Earth is

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the Sun, Earth and Moon form a right angle at half Moon, and the observation that the Moon fits perfectly over the Sun during a solar eclipse. Throw in some assumptions, such as moonlight being nothing more than reflected sunlight, and a framework of scientific logic takes shape. This architecture of

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unmoved; that the Earth is borne around the Sun on the circumference of a circle.’ Yet philosophers completely abandoned this largely accurate vision of the Solar System, and the idea of a Sun-centred world disappeared for the next fifteen hundred years. The ancient Greeks were supposed to be smart,

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common sense, declaring it to be ‘the collection of prejudices acquired by age eighteen’. Another reason why the Greeks rejected Aristarchus’ Solar System was its apparent failure to stand up to scientific scrutiny. Aristarchus had built a model of the universe that was supposed to match reality

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the Sun — indeed, everything on Earth should fall towards the Sun. Today we have a clearer understanding of gravity, which makes a Sun-centred Solar System much more sensible. The modern theory of gravity describes how objects close to the massive Earth are attracted to the Earth, and in turn

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be irregular. In particular, the retrograde motions exhibited by Mars, Saturn and Jupiter are easy to explain. Figure 8(a) shows a stripped-down Solar System containing just the Sun, Earth and Mars. Earth orbits the Sun more quickly than Mars, and as we catch up to Mars and pass

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AD. Figure 8 Planets such as Mars, Jupiter and Saturn exhibit so-called retrograde motion when viewed from Earth. Diagram (a) shows a stripped-down Solar System with just the Earth and Mars orbiting (anticlockwise) around the Sun. From position 1, we would see Mars move increasingly ahead of us,

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data. Gradually an unbiased model of the universe began to emerge. Sure enough, Kepler’s new equations for the orbits matched the observations, and the Solar System took shape at last. Kepler exposed Copernicus’s errors, and showed that: 1. the planets move in ellipses, not perfect circles, 2. the

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: ‘O, Almighty God, I am thinking Thy thoughts after Thee.’ In fact, the second and third points in Kepler’s new model of the Solar System emerge out of the first, which states that planetary orbits are elliptical. A quick guide to ellipses and how they are constructed reveals why

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diagram shows a highly exaggerated planetary orbit. The height of the ellipse is roughly 75% of its width, whereas for most planetary orbits in the Solar System this proportion is typically between 99% and 100%. Similarly, the focus occupied by the Sun is far off-centre, whereas it is only

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speed so it covers a smaller section of the circumference in the same time. Kepler’s ellipses provided a complete and accurate vision of our Solar System. His conclusions were a triumph for science and the scientific method, the result of combining observation, theory and mathematics. He first published his

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me who had to go through with at least seventy repetitions of it, at a very great loss of time.’ Kepler’s model of the Solar System was simple, elegant and undoubtedly accurate in terms of predicting the paths of the planets, yet almost nobody believed that it represented reality.

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such as magnetism. The power of this formula is that it encapsulates everything that Copernicus, Kepler and Galileo had been trying to explain about the Solar System. For example, the fact that an apple falls towards the ground is not because it wants to get to the centre of the

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to its original orbital orientation. Astronomers had assumed that Mercury’s peculiar behaviour was caused by the gravitational tug of the other planets in the Solar System pulling at its orbit, but when Le Verrier used Newton’s formula for gravity he found that the combined effect of the other

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measurement. Whereas Einstein was a theoretical physicist, Freundlich was an accomplished astronomer and therefore in a better position to say how one might go about making the observations that would discern the optical warping predicted by general relativity. Initially, they wondered whether Jupiter, the most massive planet in the Solar System, might

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be big enough to bend the light from a distant star, as shown in Figure 25. But when Einstein performed the relevant calculation using his formula, it was

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to Freundlich suggesting that they look for stellar shifts during a total solar eclipse. Figure 26 Einstein hoped that the bending of starlight by the Sun could be used to prove his general theory of relativity. The line of sight between the Earth and the distant star is blocked by the Sun, but

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rather a star whose light has been warped so that it appears to be a fraction of a degree outside the solar disc. Einstein hoped that Freundlich could examine photographs of past eclipses to find the changes in position that he needed in order to prove that his gravity formula was correct, but

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up to scratch. There was only one option. Freundlich would have to mount a special expedition to photograph the next solar eclipse, which would be observable from the Crimea on 21 August 1914. Einstein’s reputation depended on this observation, so he was prepared to fund the mission if necessary. He became so

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of relativity which later led to an understanding of black holes. On 24 February 1916, Einstein presented the paper to the Prussian Academy. Just four months later, Schwarzschild was dead. He had contracted a fatal disease on the Eastern front. While Schwarzschild volunteered to fight, his counterpart at the Cambridge Observatory, Arthur Eddington,

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My world had been so shaken that I experienced something very like a nervous breakdown.’ Figure 27 Eddington’s results from the 1919 eclipse expedition were confirmed in 1922 by a team of astronomers who observed a solar eclipse from Australia. This chart shows the actual positions of fifteen stars around the Sun (the dots

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the general theory of relativity had predicted. In a wonderful demonstration of mock hubris, Einstein answered: ‘Then I would feel sorry for the Good Lord. The theory is correct anyway.’ Figure 28 Albert Einstein, who developed the theoretical framework of general relativity, and Sir Arthur Eddington, who proved it by observing the 1919 eclipse. This photograph was

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taken in 1930, when Einstein visited Cambridge to collect an

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honorary degree. Einstein’s Universe Newton’s theory of gravity is still widely used

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properties and interactions of the entire universe. When Copernicus, Kepler and Galileo formulated their vision of the universe, they effectively focused their attention on the Solar System, but Einstein was truly interested in the whole universe, as far as any telescope could see and beyond. Soon after publishing this paper

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but in practice the tiniest disturbance in the gravitational equilibrium would upset this balance and end in catastrophe. For example, a comet passing through the Solar System would momentarily increase the mass density of each part of space through which it passed, attracting more material towards those regions and thus initiating

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were two ways of arriving at the truth’, he said. ‘I decided to follow them both.’ After ordination, Lemaître spent a year in Cambridge with Arthur Eddington, who described him as ‘a very brilliant student, wonderfully quick and clear-sighted, and of great mathematical ability’. The following year he went to

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comet, until it became clear that the object did not possess a tail, and was in fact a new planet, a momentous addition to the Solar System. For thousands of years astronomers had known only of the five other planets (Mercury, Venus, Mars, Jupiter and Saturn) visible to the naked

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mind that it is one of the closest stars to the Earth. To put this into perspective, if the universe were miniaturised so that our Solar System, everything from the Sun to the outer reaches of Pluto’s orbit, could be squeezed inside a house, then our neighbouring stars would

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to the Sun. However, the first generation of scientists, including Eratosthenes and Anaxagoras, invented techniques that allowed them to span the globe and the Solar System. Then Herschel and Bessel used brightness and parallax to measure the size of the Milky Way and the distance to the stars. Now it

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well-connected Yorkshire family, and was a gentleman astronomer of the first order. A close friend of William Herschel, Pigott made careful observations of two solar eclipses and the 1769 transit of Venus. He also constructed one of only three private observatories that existed in England in the late 1700s. Consequently, his

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but physicists at the start of the nineteenth century noticed that specific wavelengths were missing. These wavelengths revealed themselves as fine black lines in the solar spectrum. It was not long before somebody realised that the missing wavelengths had been absorbed by atoms in the Sun’s atmosphere. Indeed, the

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, except real measurements may be much less distinct. In reality, detailed studies of sunlight showed that there were hundreds of missing wavelengths in the solar spectrum. These wavelengths had been absorbed by various atoms in the Sun’s atmosphere, and by measuring the wavelengths of these dark absorption lines it

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’t let us sleep,’ wrote Bunsen. ‘Kirchhoff has made a wonderful, entirely unexpected discovery in finding the cause of the dark lines in the solar spectrum…thus a means has been found to determine the composition of the Sun and fixed stars with the same accuracy as we determine sulphuric

…

proper motion has given only a limited insight into stellar velocities. Figure 57 Barnard’s Star (circled) is the second nearest star to our Solar System and the one with the greatest proper motion. It moves across the sky at 10 arcseconds each year. These pictures were taken almost half

…

the Big Bang camp, Arthur Eddington summarised what he thought was wrong with Zwicky’s theory: ‘Light is a queer thing—queerer than we imagined twenty years ago—but I should be surprised if it is as queer as all that.’ In other words, Einstein’s theory of relativity had transformed our understanding

…

studying the stars, returning home early in the morning. Fred’s early fascination with astronomy was reinforced at the age of twelve when he read Arthur Eddington’s Stars and Atoms. Eventually Hoyle was persuaded to give the British education system a chance. He settled down at Bingley Grammar School and

…

heavier elements were not created in the moments immediately after the Big Bang, then the problem was clear: where and when were they created? Arthur Eddington had already put forward one possible theory about nucleosynthesis: ‘I think the stars are the crucibles in which lighter atoms are compounded into more complex

…

Those who have contributed to the history of cosmology have financially supported their research in a variety of ways. Copernicus found time to study the Solar System in between his duties as physician to the Bishop of Ermland, while Kepler benefited from the patronage of Herr Wackher von Wackenfels. The

…

realised that if the mysterious radio hiss peaked once each sidereal day, then its source had to be something far beyond the Earth and the Solar System. The sidereal day implied a cosmic radio source. Indeed, when Jansky tried to establish the direction of the radio signal, he discovered that

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few millimetres or centimetres. It is usually regarded as a subdivision of radio waves. Milky Way A name given to the galaxy in which our Solar System resides. The Milky Way is a spiral galaxy containing around 200 billion stars, and the Sun is located in one of its spiral

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, On Giants’ Shoulders (Sceptre, 1999) Twelve of history’s greatest scientists are profiled, including several who played a role in the development of cosmology. Arthur Eddington, The Expanding Universe (CUP, 1988) This entertaining and popular essay about the expanding universe hypothesis was written in 1933, when the concept of the Big

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, 20, 71,132-3, 135, 138-40, 141 Eddington, Arthur 134-41, 144,157, 338,476; expanding universe theory 270,280-3; and Lemaître 268-9,280; The Mathematical Theory of Relativity 135; nucleosynthesis theory 385; on rebounding universe 491; solar eclipse observations 135,137-41,143; Space, Time and Gravitation 138; on tired

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light theory 280 Ehrenfest, Paul 123 Egyptians 18-19,28 Einstein, Albert 24,105-7, 108, 144,191, 198; and

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Air and Space Museum 437, 439 Smoot, George 450-4, 456,459-62 Sochocky, Sabin von 286 sodium 232, 234,235, 235, 236,237 Solar System 22-5,54,57-8,118-19, 145 Solvay Conferences 160,307, 312, 384 Sombrero Galaxy 247—8 sound 92,93,243-4,406

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16-17, 17, 18, 20,38,Table 1; nuclear reactions 300-1,303-5, 304, 310; radio emissions 410, 411; solar eclipse 17,20, 71,132-3,135,138-40, 141; solar spectrum 236, 236,237 Sun-centred universe 65—72, 66, 75,124, 367,Table 2,3; Aristarchus’ model 22-7, 23

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always there during times of crisis, and I cannot imagine there are many literary agents who would accompany their authors to Zambia to witness a solar eclipse. In short, Patrick has been the best friend that any author could wish for. Simon Singh London June 2004 About the Author Simon Singh

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