TELETYPEWRITERS CAN NOW BE USED IN HOME
On the cover of this issue of the Science News Letter is shown a portion of the mechanism of the teletypewriter, a hybrid medium of communication. The new teletypewriter service is a telegraph system with telephone methods and typewriting thrown in for luck. It is now possible to use teletypewriters, formerly restricted to specialized fields, in either the home or the office after the manner of a telephone. A nationwide hook-up of teletypewriter stations is responsible.
Teletypewriters transmit typewritten messages electrically so that whatever is typed at one end of the circuit is typed simultaneously at the distant end. The hub of the teletypewriter service, recently inaugurated by the American Telephone and Telegraph Company, is the familiar switchboard operator, who, however, has a typewriter before her instead of a telephone set.
EINSTEIN AND DE SITTER RETURN TO EUCLIDEAN IDEA OF COSMOS
Prof. Albert Einstein, father of relativity, says that space may be and probably is the sort of uncurved, three-dimensional space that Euclid imagined and countless generations of schoolboys have learned. Although Prof. Einstein in a sense scraps the less familiar and more complicated brands of space-time that he has been using, this does not affect the validity of relativity, which has been at the foundation of so much scientific thinking for the past two decades.
Prof. Willem de Sitter, Dutch astronomer, who had built his own shape of universe on Einsteinian foundations, joins with Prof. Einstein in espousing space which is on the average Euclidean. These two eminent astrophysicists conceived the new kind of universe when working together recently at Mt. Wilson Observatory and their joint announcement was made to the world through the medium of the Proceedings of the National Academy of Sciences just issued. Prof. Einstein is now en route to his home in Germany while Prof. de Sitter is traveling in South America.
This joint announcement, which is sure to cause a furor in the world of science, means that the universe around us may be not only unbounded but also infinite, instead of finite and unbounded as Einstein and his followers have previously believed.
In the Euclidean universe now re-enthroned, light travels in straight lines and goes on and on forever and ever. A ray of light would not traverse the circuit of the universe and come back to where it started as it would in the superseded Einstein and other varieties of space. Curvature of space is on the average banished from the universe.
“We must conclude that at the present time it is possible to represent the facts without assuming a curvature of three-dimensional space,” Profs. Einstein and de Sitter say in their report.
Two important developments made Einstein and de Sitter change their universes. One of these was the piling up of evidence at Mt. Wilson Observatory at Pasadena, Calif., by Dr. Edwin P. Hubble and others that the shift toward the red of spectrum lines in light from far distant nebulae is evidence that the universe is expanding at a terrific rate, as high as 15,000 miles per second and that the farther away the nebula the faster the recession.
The other factor was the demonstration by Dr. Otto Heckmann, privat-dozent in astronomy at the University of Göttingen, Germany, that an expanding universe can have matter throughout it and still be Euclidean. When Einstein built his first universe he did not dream of an expanding space. He thought it static and constant in size and found himself forced to make space curved to fit this idea. This gave his famous finite but unbounded universe which, upon Dr. Heckmann’s suggestion, he and de Sitter now revise.
Into the equations of Einstein relativity which have stood the test of time, Profs. Einstein and de Sitter, following Heckmann’s lead, have inserted both Euclidean space and the recessional velocity of the nebulae indicated by the expanding universe idea and the Mt. Wilson measurements of redshift in light from the nebulae. The scientists were then able to compute the density of matter in the universe and found that it compares favorably with the ideas that are current as to how matter is spread throughout space on the average.
It is almost impossible to imagine how thinly spread on the average is the matter in the universe. One pound of matter spread throughout a sphere 16 times the diameter of Earth would give this extremely small density of matter. And as the universe is expanding at a super-terrific rate at extreme distances outward, always getting larger as it were, the density of the matter in the universe must be getting less and less.
Profs. Einstein and de Sitter observe, however, that as more astronomical data are gathered it will undoubtedly be possible to determine with more precision the density of matter in the universe. If it should turn out that there is more matter per unit volume of space, then it will be necessary to learn to live in a space of average negative curvature, such as Lobatschewski, the Russian scientist, dreamed of a century ago. In this strange space an infinite number of lines parallel to a given straight line can be drawn through any point.
The revision of the geometry of the universe by Profs. Einstein and de Sitter does not appreciably alter the geometry of the galaxy of stars in which we live. Consequently it leaves unaltered the theoretical predictions originally made by Einstein which so triumphantly vindicated his theory. These are: The wriggling of the orbit of the planet Mercury, the redshift of the spectral lines in the sun and companion of Sirius, and the bending of light rays about the sun which is merely the Euclidean interpretation of a Riemann straight line. A straight line in Riemann curved space is curved when interpreted in Euclidean space. The geometry of an Einstein universe is based on the assumption that light travels in straight lines.
CANNOT KNOW UNIVERSE’S SHAPE WITHOUT MORE OBSERVATIONS
Commentary by Prof. Richard C. Tolman, California Institute of Technology
The article of Einstein and de Sitter in the Proceedings of the National Academy of Sciences shows, if we assume a uniform distribution of material in the universe and assume the cosmological constant to be zero, that our present knowledge as to the density and velocity of recession of matter can be accounted for, if we ascribe the value zero to the spatial curvature of the universe. Our present observational data are thus shown to be insufficient to distinguish the three theoretically possible cases of positive, negative, or zero curvature, and hence we cannot now say whether the universe is closed, hyperbolic, or flat. It is possible that sufficient data to throw more light on such questions will be available in the not too distant future.
The article deals, of course, with the spatial curvature of the universe as a whole when looked at from a large scale point of view and does not affect views as to the curvature of space in the neighborhood of individual gravitating bodies.
ENTIRE UNIVERSE STILL YOUNG, LITTLE OLDER THAN EARTH ITSELF
The far-flung universe of stars, nebulae and stardust is not much older than the solar system and the earth itself.
This startling conclusion was presented by Dr. Ernst J. Opik of Tartu University Observatory, Estonia, now serving as lecturer in astrophysics at Harvard, who closed a symposium on the time scale held during the dedication of the new Harvard Observatory astrophotographic building.
Facts gathered by Dr. Opik indicate that the age of our universe is not very much more than 3,000 million years. The probable length of known geologic time is something like 1,800 million years.
This reduction in the time that the universe could have existed may have far-reaching effects on astronomical theory and conceptions. It deals a severe blow to the idea that the universe of stars and nebulae is an outgrowth of a process of relatively slow evolution.
“We infer that not much more than 3,000 million years have elapsed since the spiral nebulae, the stars, and the stardust, or meteors, were born out of the original parent system, which we call chaos because we do not know much about it,” Dr. Opik said.
Most impressive was evidence of the universe’s youth brought to Earth by meteorites, or “falling stars.” Dr Opik reported that Prof. Fritz Paneth, chemist at the University of Königsberg, Germany, has determined the age of a number of meteorites by analyzing their relative contents of helium and radium. He found values ranging from 100 million to 2,900 million years. Pultusk stone meteorites which were seen to fall in 1868 gave a preliminary age of 500 million years, which due to loss of helium in space and in museums during 60 years is probably a minimum age. Astronomers are confident that these meteorites came from interstellar space. These chemical determinations of age suggested to Dr. Opik a low age for the stellar universe.
Double stars also shine evidence that the universe is young. Dr. Opik found that statistics of the distribution of distances and relative magnitudes in double stars indicate that since their origin the masses of the stars could not have decreased appreciably. The drop in luminosity of an average dwarf star since its origin cannot have been more than half a magnitude, Dr. Opik found as another indication of the universe’s youth.
“Stars of different spectral classes cannot have evolved from one another,” he said. “They must have been created simultaneously and their age is too short for any appreciable evolution.”
The terrific rushing away of the nebulae as signaled in the reddening of their light, which is considered evidence of an expanding universe, indicates in Dr. Opik’s opinion, a possible age of the extragalactic universe of only a few thousand million years.
Ten years ago the universe was thought to be 10 million million years old. Now Prof. Opik divides these old estimates by a million or so and makes the universe about the same age as Earth, about 3,000 million years.
NEW LONG-TIME CLOCK IS ROTATION OF MILKY WAY
A new clock for measuring long periods of time may prove the rotation of the great galaxy of stars in which the solar system is located, Prof. Robert H. Baker, director of the University of Illinois Observatory, suggested in an address during the dedication of the new building housing the great Harvard collection of 400 thousand astronomical photographs.
The revolution of the Milky Way, which occurs about once in 400 million years, would supplement the rotation of Earth, which measures the day, and the swing of Earth around the sun, which measures the year.
When the dinosaurs existed, some 200 million years ago, Prof. Harlow Shapley, director of the Harvard College Observatory, said in commenting, the solar system was on the other side of the galaxy.
The age of Earth is not less than 1,800 million years, and probably about 2,000 million years, as measured by the radioactive clock, Prof. Arthur Holmes of Durham College, England, told the astronomers. Accurate determinations of the amount of helium in rocks give the geologist information on their age, because helium is given off at a known rate by the disintegration of radioactive uranium and thorium elements in the rocks.
The oldest known rocks exist in North America. Up until a few weeks ago uraninite from the Black Hills, S.D., held the record with 1,460 million years of age, but radium-bearing rock from the radium bonanza at Bear Lake in northern Canada has shown nearly the same age, and rock from Manitoba assays an age of 1,800 million years. As these rocks were molten when laid down and injected into existing rocks, the rocks around them must be older.
With increasing age Earth is not getting any feebler in energy, Prof. Holmes observed. In fact, in the Tertiary age, which led up to the appearance of man, Earth seems to have been more active than in earlier ages.
New estimates of the age of Earth have disturbed the astronomer’s confidence in the stability of the solar system. Prof. E.W. Brown of Yale declared. Although he feels no concern about the immediate safety of Earth, he cannot tell just what it was doing 2,000 million years ago when its crust was formed. Prof. P.W. Bridgman of Harvard warned that it was unsafe to theorize as to what had happened thousands of millions of years in the past and what would happen far in the future because we have only a few hundred years on which to base ideas.