National Aeronautics and Space Administration Age of the Universe: Size of the Universe: Infinite 300,000 Light Years Cosmic1919 Times MT. WILSON ASTRONOMER ESTIMATES SUN’S GRAVITY BENDS STARLIGHT MILKY WAY TEN TIMES BIGGER THAN THOUGHT Einstein’s Theory Triumphs But Disputes Suggestions that Spiral Nebulae are Other “Island Universes” “One of the greatest—perhaps the great- actly as arranged, but out of the 16 plates taken, The Milky Way is a “discoidal” (disc-shaped) Dr. Shapley has concluded that “our galactic est—of achievements in the history of human only two showed as many as five stars each. galaxy of stars 10 times bigger than astronomers universe appears as a single, enormous, all-com- thought” was what Sir Joseph Thomson, Presi- Prof. Eddington was also unable to stay several had previously conceived, according to Mt. Wil- prehending unit, the extent and form of which dent of the Royal Society of London, called Dr. more months to take check-photographs of the son astronomer, Dr. Harlow Shapley. Moreover, seem to be indicated through the dimensions of Albert Einstein’s prediction, which was appar- star field. he claims, the Sun exists nearer to its edge than the widely extended assemblage of globular clus- ently verified during the total eclipse of the Sun Sir Frank explained in detail the apparatus to its center. But he disputes the hypotheses of ters.” The center of our discoidal sidereal system May 29 last. both expeditions had employed, the way the other astronomers that scores of spiral nebulae “is distant from the Earth some twenty thousand Sir Joseph made his pronouncement during photographic plates were measured back at the seen in the starry heavens are other galaxies, parsecs”—more than 60,000 light-years—“in the a discussion of the results from observations of Greenwich Observatory, the corrections that had or “island universes”, that resemble the Milky direction of the constellation Sagittarius,” Dr. the solar eclipse at a joint meeting of the Roy- to be made for various disturbing factors, and the Way. Shapley continued. al Society and the Royal Astronomical Society methods by which comparison between the the- In his tour-de-force series of papers through- His conclusions fly in the face of generally ac- in London on Thursday evening, November 6, oretical and observed positions had been made. out 1918 and 1919, the prolific Dr. Shapley ex- cepted astronomical wisdom. “Until the last year before a large attendance of astronomers and He convinced the meeting that the results were amines other recent astronomical work in aston- or so, most students of stellar problems believed physicists. The excitement in the air was almost definite and conclusive, and that deflection did ishing detail, as well as presenting the results of rather vaguely that the Sun was not far from the palpable as it seemed generally accepted that take place. He also asserted that the measure- his own astronomical photography using the 60- center of the universe, and that the radius of the the observations were decisive in verifying the ments showed that the extent of the deflection inch reflector of the Mount Wilson Observatory galactic system was of the order of 1,000 par- prediction of Dr. Einstein, Professor of Physics was in close accord with the theoretical amount in southern California. His particular subject of secs,” he said (1,000 parsecs is more than 3,000 at the University of Berlin and Director of the predicted by Dr. Einstein, as opposed to half of interest is globular star clusters—nearly spheri- light-years). Some astronomers thought the Kaiser Wilhelm Physical Institute. that amount, the amount that would follow if the cal clusters of hundreds of stars that have long galactic system might be as large as 10,000 to principles of Newton were correct. puzzled astronomers because of their peculiar 20,000 light-years across. But according to Dr. The prediction “After a careful study of the plates I am pre- positions in only certain parts of the sky. When Shapley, the positions of globular clusters in the According to the gravitational principles pared to say that there can be no doubt that they Dr. Shapley began his study in 1914, 69 globular arrangement of sidereal objects suggest “that the enunciated by Sir Isaac Newton in his classic confirm Einstein’s prediction,” Sir Frank de- clusters were known; by the time he completed actual diameter of the galactic system is of the work Optics some two centuries ago, a ray of clared. “A very definite result has been obtained his work in 1918, he had added another 17 to the order of 100,000 parsecs”, This is a staggering light from a distant star just grazing across the that light is deflected in accordance with Ein- list. distance, larger than 300,000 light-years across, edge of a massive object should be bent by an stein’s law of gravitation.” In addition to pinpointing the exact position more than 10 times larger than any other astron- amount that depends on the object’s mass and “For the full effect that has been obtained, of each globular cluster in the sky, he also spread omer had hypothesized. thus its gravitational field. Newton thought of we must assume that gravity obeys the new law out their light into spectra to determine their mo- “This newer conception greatly embarrasses the gravity as a force that pulls things toward an ob- proposed by Einstein,” added Prof. Eddington. tions, specifically whether they were approach- interpretation of spirals as stellar organizations of a ject: the bigger the object, the stronger the pull. “This is one of the most crucial tests between ing the Sun or receding from it. From these data, size comparable to that of the Galaxy,” Dr. Shapley The most massive object in the vicinity of Newton’s law and the proposed new law.” Dr. Shapley sought to calculate the gravitation- said, because such a size would imply that the spi- the Earth is the Sun. So according to Newtonian al forces on the clusters, to learn whether they rals were inconceivable distances away in space. principles, a light ray from a distant star graz- WHY A TOTAL SOLAR ECLIPSE? were revolving around a common center, and if “For example,” he pointed out, “if any bright spiral so, the location of that center. He also sought to of 10 minutes of arc in angular measure has an ac- ing the edge of the Sun should be attracted or Herr Einstein in Berlin bent by the Sun’s gravity by an amount equal According to predictions by both Sir Isaac determine the distances of the globular clusters tual diameter directly comparable with that of the to 0.87 seconds of arc. To be sure, that angle is the Sun and the stars to be photographed at the Newton and Dr. Albert Einstein, a ray of light from the Sun using the novel method of Cepheid galactic system, its distance must be greater than a very small, about equivalent to a human hair at same time. from a star nearly behind the Sun (as seen from variables pioneered by Miss Henrietta Leavitt hundred million light-years.”. Similarly, the aver- 75 feet; but it is actually measurable on today’s Prof. Eddington himself decided to lead an Earth) will be deflected—bent toward the Sun— of Harvard Observatory. He also looked at ir- age proper motions suggested by the careful ob- astronomical photographic plates if adequate care expedition to the island of Principe, in the Gulf as it passes by the limb (edge) of the Sun. Such a regularly-shaped clusters of stars, the so-called servational measurements of several astronomers is taken. of Guinea close to the coast of West Africa, deflection would make the star look slightly far- “open clusters”, as well as other individual stars “would indicate appalling velocities in space.” Dr. Einstein’s general theory of relativity, near the end of the path of totality (see map). ther away from the edge of the Sun than it really and types of objects. In short, Dr. Shapley concludes, many observa- however, conceives of gravitation as indistinguish- He also convinced the Astronomer Royal—Sir is. After four years of diligent study, often assisted by tions “all seem definitely to oppose the “island uni- able from inertia. The “force” of gravity one feels Frank Dyson, Director of the Royal Observato- Dr. Einstein’s theory of relativity, however, his wife Martha B. Shapley, Dr. Shapley has pub- verse” hypothesis of the spiral nebulae.” pressing one down into a chair is the same as the ry, Greenwich—to send another expedition else- predicts that the amount of the deflection should lished a number of astonishing conclusions. “force” one feels when pulled forward in an auto- where, to minimize the chances of clouds inter- be double that predicted by Newtonian mechan- mobile when the driver brakes. fering with the observations. Led by Dr. Andrew ics. The maximum shift, for a star whose ray of According to Dr. Einstein, gravity, like in- Crommelin from the Royal Observatory, it set light just grazes the limb of the Sun, would be 1.75 ertia, doesn’t pull. Instead, a mass warps or up instruments at Sobral in northern Brazil, near seconds of arc, twice the amount Newton predicted EXPANDING OR CONTRACTING? curves space and time surrounding the object. the beginning of the path of totality. (0.87 arcsecond). The apparent positions of stars Einstein’s Theory Predicts Universe Must be Doing One or the Other The amount of curvature is proportional to the At each of these places, if the weather were pro- closer to the Sun’s limb would be shifted more than amount of mass.