Fate of UNIVERSE May Be Told in Cosmic Ray Origin (Jul, 1932)
Fate of UNIVERSE May Be Told in Cosmic Ray Origin
by JAY EARLE MILLER
Where in the universe does the mysterious cosmic ray originate? Science is now conducting extensive research to solve that mystery, for the answer may disclose the destiny of the earth we live on.
ON MOUNTAIN tops in Hawaii, Alaska, Peru and at other isolated points around the worldâ€”eighteen stations in allâ€”an answer is being sought this summer to the most perplexing question in modern science â€”what is a cosmic ray?
First discovered nearly thirty years ago, and made famous in 1925 when Dr. Millikan of California Tech confirmed their existence, and, much to his embarrassment, the press named them “Millikan’s rays,” the cosmic emanation continues to be the baffling enigma on which scientists throughout the world are divided.
No one knows what they are, where they come from, or how they came into being, though all at last, as a result of Millikan’s patient investigation, have agreed that they do exist.
Here is a ray, hundreds, probably thousands of times more powerful than the strongest X-rays or radium rays known. While a thin sheet of lead foil will protect the body or a photographic plate from X-rays, and a couple of inches of lead are sufficient protection against the penetration of the largest concentration of radium, the cosmic ray passes with ease through as much as eighteen feet of lead.
They are found hundreds of feet down beneath the surface in snow fed mountain lakes. Instruments sealed in a cake of ice in the middle of Lake Ontario have detected them. Instruments flown more than ten miles into the air attached to sounding balloons have brought back similar records. There seems to be no place within reach in the known world where they are notâ€”and yet all the scientific brains of the world have been unable to find their source or tell exactly what they are.
Professor Arthur Holly Compton, of the University of Chicago, noted winner of the Nobel prize for physics in 1927, is now on a tour of mountain tops in Hawaii, Alaska and the Andes repeating and checking the previous experiments of Dr. Millikan.
Other scientists in Europe are making similar tests to assist him, and when the results are compiled they may at least settle the first great argument between the followers of Kolhorster and Hoffman, in Germany, who maintain that the rays come from the particular portion of the heavens, and the Millikan school, which declares they do not.
Nature of Rays Hotly Disputed
Even the nature of the rays is in dispute. Millikan maintains they are “hard” fast rays of the gamma sort given off in the disintegration of radiumâ€”their penetrating power being due to their “hardness”â€”super X-rays, in other words.
Bothe and Kolhorster, two of the greatest German investigators, on the other hand, claim they are fast corpuscles like electrons. Professor Compton, advancing a third view, suggests they may be protons or bullets of light.
The great argument goes back to the early days of the century, when the newly discovered radium was the marvel of the world. Radium, in breaking down, gives off alpha, beta and gamma rays, and it was discovered they have the extraordinary property of ionizing or electrifying the air.
It followed then that the air must be electrified by all the radium bearing rock in the world, and, up until about 1911 physicists were satisfied that this could account for all the hitherto unexplained atmospheric electricityâ€”that portion of it that was already known to be distinct from the purely static charge of thunderstorms and other natural phenomena.
Rays Increase With Height
But if that were true, then the gamma rays of radium should be absorbed by the atmosphere, and the charge should decrease with altitude. But a Jesuit priest, Father Wulff, went up to the top of Eiffel tower and found that, while the effect was less than on the ground, it was not so much less as should be expected. And Prof. Gockel, a Swiss investigator, sent up sounding balloons with recording instruments, and discovered that, while the rays decreased at first, as the instruments went higher the rays increased again!
There was only one conclusion, after repeated trials had proven the report was correct: somewhere in outer space there was a cosmic ray producer constantly supplying the world with a new bombardment.
The theory did not fit in with known facts, and science, as a whole, remained unconvinced. One of the most unconvinced ones was Professor Millikan. He started an independent investigation aimed to clear up the point. From Kelly Field, Texas, he sent balloons ten miles high. He carried instruments and lead shields to the top of Pikes Peak, to the top of Mount Whitney, had records taken in the Hudson Bay country and far down near the magnetic south pole. He sent instruments to the bottom of Lake Arrowhead and Muir Lake, the latter 11,800 feet above sea level. And, in 1925, he announced that the rays were coming from outer space.
That had hardly been settled when Kol-horster hollowed out a laboratory in the glacial ice of the Jungfraujoch in the Alps and returned with word that the rays were coming from the neighborhood of the spiral nebulae in Andromeda and that they fluctuated slightly in a regular cycle.
Millikan, Compton, Prof. Regener, of Stuttgart, and others made new investigations. As a result most of them denied the directional claim. They found rays present in about equal amounts in every direction. The point, however, remains unsettled.
As this is being written Dr. W. F. G. Swann, director of the laboratory of the Bartol Research Foundation at Franklin Institute, is preparing to take a new measuring device to Pikes Peak to settle it. He has built two steel spheres, filled with nitrogen gas, with a lead cylinder for shield between them.
The conductivity of the nitrogen gas increases with radiation from the cosmic rays, allowing more electricity to pass to the recording instruments. But, if the rays come from one direction, and one sphere is pointed there, it will cut off a portion of the rays reaching the other sphere behind it, and the difference can be measured.
In other words he has a telescope which measures not what reaches it, as the optical telescope does, but what does not reach it.
But, getting back to the argument over the origin of the cosmic radiation, where does it come from? The Abbe Lemaitre, at the last meeting of the British Association for the Advancement of Science, advanced the theory that the rays were the odds and ends left over where star atmospheres were born, tens of millions of years ago.
The stars, he explained, must have been born without atmosphere, and, when the cosmic rays escaped through the star crust, the atmosphere was created. “Cosmic rays,” he explained, “would be glimpses of the primeval fireworks of the formation of a star from an atom, coming to us after their long journey through space.” That would fix the source as those stars so far distant that rays leaving them millions of years ago are only just now arriving.
Millikan agrees in part, at least, that the rays are the product of new matter in creation. Sir James Jeans, the well-known British astronomer, takes the other extreme, and suggests they are the death rattle of matter committing suicide. Add to those two the view of the Abbe Lemaitre and other followers of Einstein, that the rays are the ghosts out of the remote past, and you can have your choice.
Millikan’s evidence that the rays are really very short waves, like waves of light, or like the gamma rays of radium, and not fast electrons, like the beta rays, as Professors Bothe and Kolhorster believe, seems to have the best of the argument. For, if the German scientists are correct, then the electrons, when entering the earth’s atmosphere, should spiral closely around the earth’s lines of magnetic force, with the result that they would fall more abundantly near the poles than at other places. But tests so far made on Hudson Bay and near the south magnetic pole show that is not true.
On the other hand Kolhorster’s claim that the rays originated from one portion of the sky may be easily explained if the rays are, as Millikan asserts, waves of short length. For it would naturally follow that more would arrive from directly overhead than from points near the horizon, just as the sun apparently is brighter at noon at the zenith than at dawn or dusk, when its rays must penetrate a far greater layer of earth’s atmosphere to reach the observer.
One clue was offered recently when Prof. Bothe and Dr. H. Becker produced cosmic rays experimentally at the University of Giessen by bombarding beryllium metal with the alpha particles from polonium, a radio-active element.
Linking that experiment with known facts about matter and the views of Millikan and Comp-ton are considerably strengthened. The 92 elements of the known world have been arranged for convenience in an atomic table, starting with the lightest of all, hydrogen, which was numbered one.
Helium was given the number four, indicating that four hydrogen atoms should make one helium atom. But as a matter of fact it takes only 3.97 hydrogen atoms to make a helium atom, and the mystery of the other three one-hundredths of an atom has been a disturbing mystery ever since the table was compiled. Throughout its length there are other similar mysteries.
Einstein says to look for energy, that the missing portion was used up as power during the change. The .03 of an atom should be converted into radiation, much of it of a penetrating power equivalent to cosmic rays, and that, says Millikan and Comp-ton, is undoubtedly how cosmic rays are born.
Out in space, Millikan believes, electrons and protons are floating about seeking to find mates. When these two separate bodies meet, after their long search through space, they combine and form the more simple atoms, such as hydrogen and helium. The collision, however, compels the electrons to give over some of their energy, which is liberated into space in the form of cosmic rays. This mass production of atoms in space is followed by the formation of molecules of gas which in time collect into huge gaseous masses. From energy acquired from the outside, this gaseous swirl begins to oscillate at great speeds, giving rise to extremely high temperatures. Thus the vaporous agglomeration becomes incandescent, condenses and forms a series of suns.
In time planets are born of this sun by a process upon which scientists are still in dispute. The entire cycle, from the consolidation of the atom to the creation of suns and planets, however, goes on for ever. Thus the universe is promised immortal life.
Opposing theories of Eddington and Jeans dispute this view of Millikan and Compton, holding that the universe is running down, and that it is doomed to ultimate extinction. The stars, particularly our sun, are slowly dissipating themselves in the form of light and heat. This attrition cannot go on forever, and hence in remote ages to come the sun and stars will grow cold and eventually shrink into nothingness.
Millikan applies the second law of thermodynamics to the universe, which states that energy in the form of light and heat runs down hill. This light has its starting point in the hot interior of the stars. In the sun, scientists estimate, the temperature runs up to 41,000,000 degrees Centigrade. Amidst this intense heat molecules are rushing to and fro at tremendous speeds, colliding with great violence and breaking up into electrons and protons. Out of these violent smash-ups vast amounts of energy are being liberated in the form of cosmic rays.
As the heat from the sun passes through the substance of the sun, considerable heat is lost, until the radiation arrives at the sun’s surface, where it is greatly diffused, but somewhat reduced in energy, being of the order of 6,000 degrees Absolute.
Further dissipation of the energy of radiation occurs when the cosmic rays traverse space, warming it slightly, but not enough to sustain life. With matter constantly being annihilated in the sun’s boiling interior, the mass of the sun also decreases, losing, scientists estimate, approximately 360 billion tons per day.
Jeans believes that this light energy which has its inception in the sun’s interior is constantly being dissipated, passing from a higher to a lower form, that is, degenerating from intense concentrated light, to diffused heat, so that the universe will eventually come to an end in a mild “heat death.”
As an illustration in point, consider the case of the formation of coal. Light energy, such of it as is left after its passage through space, creates coal on the earth, absorbing comparatively small heat, together with a large quantity of light. In the burning process, however, small light with a comparatively greater quantity of heat is given off, so that the process, illustrative of the entire cycle of energy transformation, passes from higher to lower form, ending in the wide diffusion of heat and ultimate dissipation of light. The two views can only be put to the test by measuring cosmic rays more accurately than has yet been done, and that is what the Compton expedition and its associated workers will attempt to do this summer.
If Millikan is proven right, then the birthplace of the rays is in outer space, and not in any particular locality, but in all outer space. While some of his views conflict with the Einstein theory, this one rests largely on Einstein’s equation for the relation between energy and mass.
If the correct answer is found, the solution of another old problem, the nature of the northern lights, should come with it. In fact as far back as 1919 W. F. G. Swann suggested that the origin of the penetrating rays might be in the X-rays produced by the electrons from the sun, which Birkeland supposed responsible for the aurora.
Birkeland assigned to these rays a velocity only slightly less than that of light, which would give them energies of about one billion volts. That would be more voltage than would be required for the purpose, so that the softer rays, which would be too soft to correspond to the aurora except at very high altitudes, would be left over as cosmic rays.