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From the 1946 book, Dawn Over Zero.
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THE Atomic Age began at exactly 5.30 mountain war time on the morning of July 16, 1945, on a stretch of semi-desert land about fifty air-line miles from Alamogordo, New Mexico, just a few minutes before the dawn of a new day on that part of the earth.
At that great moment in history, ranking with the moment when man first put fire to work for him, the vast energy locked within the heart of the atoms of matter was released for the first time in a burst of flame such as had never before been seen on this planet, illuminating earth and sky, for a brief span that seemed eternal, with the light of many super-suns.
The elemental flame, first fire ever made on earth that did not have its origin in the sun, came from the explosion of the first atomic bomb. It was a full-dress rehearsal preparatory to dropping the bomb over Hiroshima and Nagasaki—and other Japanese military targets, had Japan refused to accept the Potsdam Declaration for her surrender.
The rehearsal marked the climax in the penultimate act of one of the greatest dramas in our history and the history of civilized man—a drama in which our scientists, under the direction of the Army Corps of Engineers, were working against time to create an atomic bomb ahead of our German enemy.
The collapse of Germany marked the end of the first act of this drama. The successful completion of our task, in the greatest challenge by man to nature so far, brought down the curtain on the second act. The grand finale came three weeks afterward in the skies over Japan, with a swift descent of the curtain on the greatest war in history.
The atomic flash in New Mexico came as a great affirmation to the prodigious labors of our scientists during the past four years. It came as the affirmative answer to the until then unanswered question: “Will it work?”
With the flash came a delayed roll of mighty thunder, heard, just as the flash was seen, for hundreds of miles. The roar echoed and reverberated from the distant hills and the Sierra Oscuro range near by, sounding as though it came from some supramundane source as well as from the bowels of the earth.
The hills said yes and the mountains chimed in yes. It was as if the earth had spoken and the suddenly iridescent clouds and sky had joined in one affirmative answer.
Atomic energy—yes. It was like the grand finale of a mighty symphony of the elements, fascinating and terrifying, uplifting and crushing, ominous, devastating, full of great promise and great forebodings.
I watched the birth of the era of atomic power from the slope of a hill in the desert land of New Mexico, on the northwestern corner of the Alamogordo Air Base, about 125 miles southeast of Albuquerque. The hill, named Compania Hill for the occasion, was twenty miles to the northwest of Zero, the code name given to the spot chosen for the atomic bomb test.
The area embracing Zero and Compania Hill, twenty-four miles long and eighteen miles wide, had the code name Trinity.
I joined a caravan of three busses, three automobiles, and a truck carrying radio equipment at 11 p.m. on Sunday, July 15, at Albuquerque. There were about ninety of us in that strange caravan, traveling silently and in the utmost secrecy through the night on probably as unusual an adventure as any in our day.
With the exception of myself the caravan consisted of scientists from the highly secret atomic bomb research and development center in the mesas and canyons of New Mexico, twenty-five miles northwest of Santa Fe, where we solved the secret of translating the fabulous energy of the atom into the mightiest weapon ever made by man. It was from there that the caravan set out at 5.30 that Sunday afternoon for its destination, 212 miles to the south.
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|Two days previous, the atomic bomb was delivered to the test site.|
The caravan wound its way slowly over the tortuous roads overlooking the precipitous canyons of northern New Mexico, passing through Espagnola, Santa Fe, and Bernalillo, arriving at Albuquerque at about 10 p.m.
At Albuquerque the caravan was joined by:
• Sir James Chadwick, who won the Nobel Prize and knighthood for his discovery of the neutron, the key that unlocks the atom;
• Professor Ernest O. Lawrence of the University of California, master atom-smasher, who won the Nobel Prize for his discovery of the cyclotron;
• Professor Edwin M. McMillan, also of the University of California, one of the discoverers of plutonium, the new atomic energy element; and
• several others from the atomic bomb center, who, like me, had arrived during the afternoon.
The night was dark with black clouds, and not a star could be seen. Occasionally a bolt of lightning would rend the sky and reveal for an instant the flat semi desert landscape, rich with historic lore of past adventure.
We rolled along on U. S. Highway 85, running between Albuquerque and El Paso, through sleeping ancient Spanish-American towns, their windows dark, their streets deserted—towns with music in their names, Los Lunas, Belen, Bernardo, Alamillo, Socorro, San Antonio.
At San Antonio we turned east and crossed “the bridge on the Rio Grande with the detour in the middle of it.” From there we traveled ten and one half miles eastward on U. S. Highway 380, and then turned south on a specially built dirt road, running for twenty-five miles to the base camp at Trinity.
The end of our trail was reached after we had covered about five and one fifth miles on the dirt road. Here we saw the first signs of life since leaving Albuquerque about three hours earlier, a line of silent men dressed in helmets. A little farther on, a detachment of military police examined our special credentials.
We got out of the busses and looked around us. The night was still pitch-black save for an occasional flash of lightning in the eastern sky, outlining for a brief instant the Sierra Oscuro Range directly ahead of us.
We were in the middle of the New Mexico desert, miles away from nowhere, with hardly a sign of life, not even a blinking light on the distant horizon. This was to be our caravansary until the zero hour.
From a distance to the southeast the beam of a searchlight probed the clouds. This gave us our first sense of orientation. The bomb-test site, "Zero," was a little to the left of the searchlight beam, twenty miles away. With the darkness and the waiting in the chill of the desert the tension became almost unendurable.
We gathered in a circle to listen to directions on what we were to do at the time of the test, directions read aloud by the light of a flashlight:
At a short signal of the siren at minus five minutes to zero, “all personnel whose duties did not specifically require otherwise” were to prepare “a suitable place to lie down on.”
At a long signal of the siren at minus two minutes to zero, “all personnel whose duties did not specifically require otherwise” were to “lie prone on the ground immediately, the face and eyes directed toward the ground and with the head away from Zero.
Do not watch for the flash directly,” the directions read, “but turn over after it has occurred and watch the cloud.
Stay on the ground until the blast wave has passed (two minutes). At two short blasts of the siren, indicating the passing of all hazard from light and blast, all personnel will prepare to leave as soon as possible.
“The hazard from blast is reduced by lying down on the ground in such a manner that flying rocks, glass and other objects do not intervene between the source of blast and the individual. Open all car windows.
“The hazard from light injury to eyes is reduced by shielding the closed eyes with the bended arms and lying face down on the ground. If the first flash is viewed a ‘blind spot’ may prevent your seeing the rest of the show.
“The hazard from ultraviolet light injuries to the skin is best overcome by wearing long trousers and shirts with long sleeves.”
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David Dow, assistant to the scientific director of the Atomic Bomb Development Center, handed each of us a flat piece of colored glass such as is used by arc welders to shield their eyes. Dr. Edward Teller of George Washington University cautioned us against sunburn.
Someone produced sunburn lotion and passed it around. It was an eerie sight to see a number of our highest ranking scientists seriously rubbing sunburn lotion on their faces and hands in the pitch-blackness of the night, twenty miles away from the expected flash. These were the men who, more than anybody else, knew the potentialities of atomic energy on the loose. It gave one an inkling of their confidence in their handiwork.
The bomb was set on a structural steel tower one hundred feet high. Ten miles away to the southwest was the base camp. This was G.H.Q. for the scientific high command, of which Professor Kenneth T. Bainbridge of Harvard University was field commander. Here were erected barracks to serve as living-quarters for the scientists, a mess hall, a commissary, a post exchange, and other buildings.
Here the vanguard of the atomists, headed by Professor J. R. Oppenheimer of the University of California, scientific director of the Atomic Bomb Project, lived like soldiers at the front, supervising the enormously complicated details involved in the epoch-making tests.
Here early that Sunday afternoon gathered:
• Major General Leslie R. Groves, commander in chief of the Atomic Bomb Project;
• Brigadier General T. F. Farrell, hero of World War I, General Groves’s deputy;
• Professor Enrico Fermi, Nobel prize winner and one of the leaders in the project;
• President James Bryant Conant of Harvard;
• Dr. Vannevar Bush, director of the Office of Scientific Research and Development;
• Dean Richard C. Tolman of the California Institute of Technology;
• Professor R. F. Bacher of Cornell;
• Colonel Stafford L. Warren, University of Rochester radiologist; and
• about a hundred and fifty other leaders in the atomic bomb program.
At the Base Camp was a dry, abandoned reservoir, about five hundred feet square, surrounded by a mound of earth about eight feet high. Within this mound bulldozers dug a series of slit trenches, each about three feet deep, seven feet wide, and twenty-five feet long.
At a command over the radio at zero minus one minute all observers at Base Camp, lay down in their assigned trenches, “face and eyes directed toward the ground and with the head away from Zero.” But most of us on Compania Hill remained on our feet.
Three other posts had been established, south, north, and west of Zero, each at a distance of 10,000 yards (5.7 miles). These were known, respectively, as South-10,000, North-10,000, and West-10,000, or S-10, N-10, and W-10. Here the shelters were much more elaborate wooden structures, their walls reinforced by cement, buried under a massive layer of earth.
S-10 was the control center. Here Professor Oppenheimer, as scientific commander in chief, and his field commander, Professor Bainbridge, issued orders and synchronized the activities of the other sites.
Here the signal was given and a complex of mechanisms was set in motion that resulted in the greatest burst of energy ever released by man on earth up to that time.
No switch was pulled, no button pressed, to light this first cosmic fire on this planet.
At forty-five seconds to zero, set for 5.30 o’clock, young Dr. Joseph L. McKibben of the University of California, at a signal from Professor Bainbridge, activated a master robot that set off a series of other robots, until, at last, strategically spaced electrons moved to the proper place at the proper split second.
Forty-five seconds passed and the moment was zero.
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|The first atomic bomb being hoisted up the 100 foot tower at Trinity.|
Meanwhile at our observation post on Compania Hill the atmosphere had grown tenser as the zero hour approached. We had spent the first part of our stay eating an early morning picnic breakfast that we had taken along with us. It had grown cold in the desert, and many of us, lightly clad, shivered.
Occasionally a drizzle came down, and the intermittent flashes of lightning made us turn apprehensive glances toward Zero. We had had some disturbing reports that the test might be called off because of the weather. The radio we had brought with us for communication with Base Camp kept going out of order, and when we had finally repaired it some blatant band would drown out the news we wanted to hear.
We knew there were two specially equipped B-29 Superfortresses high over head to make observations and recordings in the upper atmosphere, but we could neither see nor hear them. We kept gazing through the blackness.
Suddenly, at 5.29.50, as we stood huddled around our radio, we heard a voice ringing through the darkness, sounding as though it had come from above the clouds:
“Zero minus ten seconds!” A green flare flashed out through the clouds, descended slowly, opened, grew dim, and vanished into the darkness.
The voice from the clouds boomed out again: “Zero minus three seconds!” Another green flare came down. Silence reigned over the desert. We kept moving in small groups in the direction of Zero. From the east came the first faint signs of dawn.
And just at that instant there rose from the bowels of the earth a light not of this world, the light of many suns in one. It was a sunrise such as the world had never seen, a great green super-sun climbing in a fraction of a second to a height of more than eight thousand feet, rising ever higher until it touched the clouds, lighting up earth and sky all around with a dazzling luminosity.
Up it went, a great ball of fire about a mile in diameter, changing colors as it kept shooting upward, from deep purple to orange, expanding, growing bigger, rising as it expanded, an elemental force freed from its bonds after being chained for billions of years.
For a fleeting instant the color was unearthly green, such as one sees only in the corona of the sun during a total eclipse. It was as though the earth had opened and the skies had split. One felt as though one were present at the moment of creation when God said: “Let there be light.”
To another observer, Professor George B. Kistiakowsky of Harvard, the spectacle was “the nearest thing to doomsday that one could possibly imagine. I am sure,” he said, “that at the end of the world—in the last millisecond of the earth’s existence—the last man will see what we have just seen!”
A great cloud rose from the ground and followed the trail of the great sun. At first it was a giant column, which soon took the shape of a supramundane mushroom. For a fleeting instant it took the form of the Statue of Liberty magnified many times.
Up it went, higher, higher, a giant mountain born in a few seconds instead of millions of years, quivering convulsively. It touched the multicolored clouds, pushed its summit through them, kept rising until it reached a height of 41,000 feet, 12,000 feet higher than the earth’s highest mountain.
All through this very short but extremely long time interval not a sound was heard. I could see the silhouettes of human forms motionless in little groups, like desert plants in the dark. The newborn mountain in the distance, a giant among the pygmies of the Sierra Oscuro Range, stood leaning at an angle against the clouds, a vibrant volcano spouting fire to the sky.
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Then out of the great silence came a mighty thunder. For a brief interval the phenomena we had seen as light repeated themselves in terms of sound. It was the blast from thousands of blockbusters going off simultaneously at one spot. The thunder reverberated all through the desert, bounced back and forth from the Sierra Oscuro, echo upon echo.
The ground trembled under our feet as in an earthquake.
A wave of hot wind was felt by many of us just before the blast and warned us of its coming.
The big boom came about one hundred seconds after the great flash—the first cry of a newborn world. It brought the silent, motionless silhouettes to life, gave them a voice. A loud cry filled the air.
The little groups that had hitherto stood rooted to the earth like desert plants broke into a dance—the rhythm of primitive man dancing at one of his fire festivals at the coming of spring. They clapped their hands as they leaped from the ground—earthbound man symbolizing the birth of a new force that for the first time gives man means to free himself from the gravitational pull of the earth that holds him down.
The dance of the primitive man lasted but a few seconds, during which an evolutionary period of about 10,000 years had been telescoped. Primitive man was metamorphosed into modern man—shaking hands, slapping his fellow on the back, all laughing like happy children.
The sun was just rising above the horizon as our caravan started on its way back to Albuquerque and Los Alamos. We looked at it through our dark lenses to compare it with what we had seen.
“The sun can’t hold a candle to it!” one of us remarked.
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|Dawn Over Zero: Stages in test explosion.|
Atoms vs. Prometheus
IN that infinitesimal fraction of time, inconceivable and immeasurable, during which the first atomic bomb converted a small part of its matter into the greatest burst of energy released on earth up to that time, Prometheus had broken his bonds and brought a new fire down to earth, a fire three million times more powerful than the original fire he snatched from the gods for the benefit of man some five hundred thousand years ago.
Civilization as we know it has thrived until now on that original spark kindled by Prometheus. That fire, no matter in what form it is used, has its original source in the sun:
• When we burn wood, we use solar energy bottled up by the tree during the process of its growth.
• When we eat plants to get the energy for living, we utilize the sun’s energy trapped by the plant.
• When we burn coal or oil to produce heat or power, whether mechanical or electrical, we again take advantage of solar energy stored up in plants millions of years ago, for both coal and oil are but petrified vegetable matter that gathered up the sunlight of long ago, before man made his appearance on earth.
• The power of wind and of water is the direct result of solar heat, for water would freeze and the air would not circulate were it not for the sun.
But there is another type of energy known on earth that does not have its origin in the sun. This is the energy emanating from substances such as radium, uranium, and similar heavy elements, known as radioactivity. It is the discovery of these elements about fifty years ago that led step by step to the development of the atomic bomb.
The discovery of these radioactive elements brought about a complete revolution in our concepts of the two fundamental entities of our cosmos—matter and energy.
Every schoolboy had been taught, and is still being taught, as eternal verities, that matter can be neither created nor destroyed, but only altered in form, and similarly that energy can be neither created nor destroyed, but only altered in form.
These are known, respectively, as the law of the conservation of mass and the law of the conservation of energy.
The explosion of the atomic bomb in New Mexico demonstrated on a large scale what the discovery of the radioactive substances had already done on a small scale: namely, that matter and energy are but two manifestations of a single principle, and that matter and energy can be both created and destroyed in the sense that each can be converted into the other.
When the atomic bombs exploded over New Mexico and Japan, a sizable amount of what we call matter definitely disappeared from the cosmos and transformed itself into pure energy. There was less matter in the world after these explosions.
The law of conservation of mass and the law of conservation of energy were, in a sense, blown up by the atomic bomb as were the steel tower in New Mexico and the cities of Hiroshima and Nagasaki.
It is still true, of course, that neither matter nor energy can be destroyed in the sense of being completely annihilated. But since we know that matter can be transformed into energy, and vice versa, it is no longer true that matter always remains matter, and energy always remains energy.
We must, moreover, change our concepts of matter and energy even in their ordinary manifestations. For example, it is still commonly believed that when we burn a piece of coal, the weight of the ashes and the gaseous products evolved would be exactly the same as that of the original piece of coal.
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For all practical purposes this is still true, but only because the actual amount of matter in the coal that is converted into energy, in the form of heat and light, is so infinitesimal that we have no means for determining it.
By comparing the amount of heat liberated with the much greater amounts of heat liberated from radium, for example, we know exactly how much of the coal substance has been converted into energy, since Einstein, in his theory of relativity, has provided us with a formula for the amount of energy equivalent to a given amount of matter.
But so far we have not been able to demonstrate experimentally the actual loss of matter in ordinary types of combustion, in which only molecular energy is liberated.
Through the Einstein formula, the correctness of which has been proved again and again by measuring the energy emanating from radioactive substances and comparing it with the corresponding loss of mass in these substances, as well as by other methods, we now know that one gram of matter, four tenths the weight of a dime, if converted entirely into energy, would yield 25 million kilowatt-hours, about three billion times the energy that is liberated in the burning of an equal amount of coal.
The burning of one gram of coal would therefore entail the loss of one third of a billionth of a gram, an amount too small to be measured by present means at our disposal.
What accounts for this vast difference between the energy contained in matter and its actual yield in ordinary processes of combustion, such as the burning of coal or oil? The answer is to be found in the fundamental structure of matter.
The material universe, until the advent of the atomic bomb, consisted of ninety-two natural elements, such as hydrogen, carbon, nitrogen, oxygen, iron, copper, silver, gold, platinum, mercury, and many other common, or relatively rare, natural substances.
The smallest unit of any of these ninety-two elements—that is, the unit beyond which it can not be further divided without losing its identity—is known as the atom of that particular element.
Two or more atoms of the same element, or two or more atoms of different elements, held together by chemical forces, are known as molecules. For example, two atoms of hydrogen and one atom of oxygen unite chemically to form one molecule of water. One atom of sodium and two atoms of chlorine unite chemically to form one molecule of table salt.
The atoms in their turn are not the simple solid substances they were thought to be less than fifty years ago. They are now conceived of as extremely minute solar systems, with a heavy central core, or nucleus, surrounded by much lighter particles that revolve about the central nucleus as the planets revolve around the sun. The central nucleus is from two thousand to five thousand times heavier than its surrounding “planets.”
99.98 per cent of the matter of our cosmos is concentrated in the central nucleus of the atoms of the ninety-two basic elements.
Since matter is equivalent to energy, it can be readily seen that nearly all the energy in the universe is concentrated within the atomic nucleus.
Now, the nucleus is nature’s most formidable citadel. It is surrounded by a barrier of such inconceivable magnitude that no force at man’s disposal, until the atomic bomb, was sufficient to make any appreciable dent in it. As Sir Arthur Eddington said in 1930, it was, the “cosmic cupboard,” the key to which nature had successfully bidden from man.
All the energy at his disposal, that which he obtained through the bounty of the sun, in the combustion of fuels, in ordinary explosions, and through other chemical processes, could come only from the energy liberated when atoms share between themselves the “planets” that form the outer portion of an atom’s structure, which contain no more than two hundredths of one per cent of the total energy within the atom. In fact, he could get only a small fraction of that two hundredths of one per cent, since only the outermost “planets,” those few in the outside orbits farthest away from the nucleus, are involved in ordinary chemical reactions.
The nucleus of the atom is in no way affected by these processes.
The “planets” surrounding the nuclei of the atoms are known as electrons, exceedingly minute fundamental particles of matter, carrying a basic unit of negative electricity. Since their discovery in 1897 by J. J. Thomson they have brought about the modern age of electronics. They have made possible radio, television, talking motion pictures, the transatlantic telephone, thousands of automatic industrial processes.
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|Simple hydrogen atom. Proton with electron "planet" surrounding it.|
Long before the electron’s identity was even suspected—in fact, since the beginning of time—they have made possible man’s existence on earth, for all life is a chemical process and all chemical processes, as we have seen, are carried on by the outermost electrons in the planetary orbits around the nuclei of the atoms.
When Prometheus taught man the use of fire he was, without knowing it, teaching man how to liberate the molecular energy bound up in the electrons.
Of all the atoms, the simplest is the hydrogen atom. It has only one electron, which revolves planet-like around the nucleus. This nucleus consists of one proton, another fundamental atomic particle, 1,836 times heavier than the electron.
The proton carries a fundamental unit of positive electricity of exactly the same magnitude as the electron, so that the two balance each other electrically, making the atom electrically neutral.
Nature built up her ninety-two elements with beautiful simplicity, in the manner of a child placing one block on top of another. All she did was to add one proton to the nucleus of hydrogen and, presto, there was the next element, helium. She added one proton to helium and there was her third element, lithium.
Step by step, one proton at a time, she thus built up her elements until she stopped at element No. 92, uranium, which, until the advent of the atomic bomb, was the heaviest element in nature.
The number of protons in the nucleus determines the number of electrons in the various planet-like orbits in the relatively vast outer spaces of the atoms; and the outermost electrons, in their turn, determine the chemical properties of the atoms.
Since each proton has one definite unit of electric charge, the nature of each element depends on the number of these units.
The number of positive electric charges in the nucleus—namely, the number of protons—is known as the atomic number. Thus hydrogen stands at atomic No. 1 in the periodic table of elements. Helium, with two protons in its nucleus, stands at No. 2; lithium at No. 3. Carbon, with six protons in its nucleus, stands at No. 6, nitrogen at No. 7, oxygen at No. 8, and so on through the entire list of natural elements, up to uranium, which stands at atomic No. 92, meaning that its nucleus contains ninety-two fundamental units of positive electricity—in other words, ninety-two protons.
This enables us to understand why the alchemists failed in their efforts to transmute the elements. The only way this could be done would be to change the atomic number of an element by adding to or subtracting from the fixed number of its protons. This, as explained earlier, requires forces great enough to overcome the tremendous electrical barrier surrounding the nucleus, forces that had not been available to man until now.
Gold has the atomic number 79, as its nucleus contains seventy-nine protons. Mercury has the atomic number 80. Thus if one could knock one proton out of the nucleus of mercury one would realize the alchemist’s dream. While this has been done on a very small scale, we still do not know of a practical way of doing it.
There is a third fundamental building block of nature, which, from the point of view of the atomic bomb and atomic power in general, is the most important. It was discovered in 1932 by Professor Chadwick, of Cambridge University, and caused one of the greatest revolutions in man’s history, with implications so vast that it will take many years, possibly several generations, to assess its full significance.
This particle was named the neutron. As its name implies, it is electrically neutral. It has a mass almost the same as that of the proton. It possesses tremendous energy. Its habitat is inside the nucleus of the atoms.
The total number of protons and neutrons in the nucleus determines the atomic mass, as distinguished from the atomic number. Thus carbon stands at atomic number 6 on the periodic table of the elements, but has an atomic mass of 12. This means that, in addition to six protons, it also contains six neutrons. By subtracting the atomic number (that is, the number of protons) from the atomic mass, the number of neutrons in the nucleus of each element can be determined.
Elements that have the same atomic number but different atomic masses are known as isotopes. For example, hydrogen has three isotopes of atomic masses 1, 2, and 3, respectively. They all contain one proton in the nucleus. But the first contains no neutrons (the only element of its kind), the second contains one neutron, and the third, two.
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|Three isotopes of hydrogen. "It is again the neutron that served as the trigger in the atomic bomb."|
Elements that have the same atomic mass but different atomic numbers are known as isobars. For example, there is a rare form of helium of atomic mass 3. It thus has the same mass as hydrogen 3, but whereas the nucleus of the latter contains one proton and two neutrons, that of the former contains two protons and one neutron.
It is the neutron that provided us with the key to the cosmic store of power in the nucleus of uranium, nature’s heaviest atom, and holds out the promise of tapping the energy in the nuclei of other atoms.
It is again the neutron that served as the trigger in the atomic bomb. It is the long-sought philosophers’ stone, with which man has created many new elements more precious than gold. With it, more concentrated power has been liberated than ever before in history, but even that is only a trickle compared with the promise of things to come.
Used properly, it gives man the means for realizing the dream of the ages. With it he can shatter his world to bits “and then remould it nearer to the Heart’s Desire.” Or he can just shatter it to bits.
The neutron possesses this power just because it is electrically neutral, which makes possible its use as a projectile into the nuclei of atoms. All other atomic particles available for such purposes, such as protons and electrons, are stopped from penetrating into the nucleus of atoms by the tremendous electrical wall surrounding it. The neutron, possessing no electrical charge, can slip right through that barrier.
Penetrating the nucleus! That was the key science bad been looking for, the key that nature had hidden from man since the beginning of time. For to tap the vast cosmic storehouse of power within the nucleus man needed a cosmic bullet with which to split it open. All other atomic bullets he had until then bounced right back off the electrical wall.
The neutron bounced right in. It was the sword with which to open the cosmic oyster.
Atomic energy, harnessed for the first time by our scientists for use in atomic bombs, is the practically inexhaustible source of power that enables our sun to supply us with heat, light, and other forms of radiant energy, without which life on earth would not be possible.
It is the same energy, stored in the nuclei of the atoms of the material universe, that keeps the stars, bodies much larger than our sun, radiating their enormous quantities of light and heat for billions of years instead of burning themselves out in periods measured only in thousands of years.
The existence of atomic energy was first discovered by Einstein about forty years ago on purely theoretical grounds, as an outgrowth of his famous theory of relativity, according to which a body in motion has a greater mass than the same body at rest, this increase in mass bearing a direct relationship to the velocity of light.
This meant that the energy of motion imparts an actual increase in mass.
From the formula for the relationship of this increase of mass to the velocity of light Einstein derived his famous mathematical equation that revealed for the first time an equivalence between mass and energy, one of the most revolutionary concepts in the intellectual history of mankind. The mass-energy equation showed that any given quantity of mass is the equivalent of a specific amount of energy, and vice versa.
Specifically this equation revealed the fact, incredible at that time, that very small amounts of matter contain tremendous amounts of energy. A piece of coal the size of a pea, the equation proved, contains enough energy to drive the largest ocean liner across the Atlantic and back.
No one, however, least of all Einstein himself, believed at that time that any means could ever be found to tap this cosmic source of elemental energy.
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|Hiroshima. "Einstein himself, believed at that time that any means could ever be found to tap this cosmic source of elemental energy."|
In the mass-energy theorem Einstein showed the existence of a definite relationship between the cosmic trinity of matter, energy, and the velocity of light. The relationship is so simple that, once arrived at, a grammar-school student could work it out.
In this formula the letter"
• m stands for mass in terms of grams;
• E represents energy in terms of ergs (a small unit of energy or work);
• c stands for the velocity of light in terms of centimeters per second.
The energy content of any given quantity of any substance, the formula states, is equal to the mass of the substance (in terms of grams) multiplied by the square of the velocity of light (in terms of centimeters per second). The velocity of light (in round numbers) is 300,000 kilometers, or 30 billion centimeters, per second.
Take one gram of any substance. According to the Einstein formula, the amount of energy (E) in ergs in this mass is equal to 1 (the mass of the substance in grams) multiplied by 30 billion squared. In other words, the energy content of one gram of matter equals 900 billion billion ergs.
Translated into terms of pounds and kilowatt-hours, this means that one pound of matter contains the energy equivalent of 10 billion kilowatt-hours.
If this energy could be fully utilized:
• It would take only twenty-two pounds of matter to supply all the electrical power requirements of the United States for a year.
• One third of a gram of water would yield enough heat to turn 12,000 tons of water into steam.
• One gram of water would raise a load of a million tons to the top of a mountain six miles high.
• A breath of air would operate a powerful airplane continuously for a year.
• A handful of snow would heat a large apartment house for a year.
• The pasteboard in a small railroad ticket would run a heavy passenger train several times around the world.
• A cup of water would supply the power of a great generating station of 100,000-kilowatt capacity for six years.
One pound of any substance, if its atomic-energy content could be utilized one hundred per cent, is equivalent in power content to 3 billion pounds of coal, or 1.5 million tons.
The energy we are now able to utilize in the atomic bombs, at maximum efficiency, constitutes only one tenth of one per cent of the total energy present in the material. But even one hundredth of one per cent would still be by far the most destructive force on this earth.
Atomic energy, released through the splitting of atoms, differs radically from ordinary types of energy hitherto available to man in that it involves a fundamental change in the nature of the atom, a change in which an appreciable amount of matter is converted into energy.
This is materially different from obtaining power by the use of a water wheel, for example, or by the burning of coal or oil.
In the case of the water wheel, the water molecules taking part remain entirely unchanged. They simply lose potential energy as they pass from the dam to the tailrace.
In the case of burning coal or oil a more intense process takes place, as the atoms of carbon, hydrogen, and oxygen (of which the coal and oil molecules are composed) are regrouped by combustion into new molecules forming new substances. The atoms themselves, however, still remain unchanged—they still are carbon, hydrogen, and oxygen. None of them, so far as can be measured, loses any part of its mass.
In the case of atomic energy, however, the atom itself completely changes its identity, and in this process of change it loses part of its mass, which is converted into energy. The amount of energy liberated in this process is directly proportional to the amount of atomic mass destroyed.
The sun, for example, obtains its energy through the partial destruction of its hydrogen, through a complex process in which the hydrogen is converted into helium. In this process four hydrogen atoms, each with an atomic mass of 1.008 (four hydrogen atoms equal 4.032 atomic mass units) combine to form one helium atom, which has an atomic mass of 4.003.
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|"The sun, for example, obtains its energy through the partial destruction of its hydrogen . . ." (Solar eclipse pictured.)|
This represents a loss of mass in the four hydrogen atoms (in addition to a loss of two positive electrons) of 0.029 atomic mass units, which is converted into pure energy. The amount of energy liberated in this process by the enormous quantities of hydrogen in the sun represents an actual loss of the sun’s mass at the rate of 4 million tons per second, a mere speck of dust in relation to the sun’s total mass of two billion billion billion tons.
If the sun, however, were a mass of coal weighing the same amount, it would have to burn three billion times the mass it is burning now to produce the same amount of energy. If that were the case, it would have used up the entire store of molecular energy contained in its body of coal in the course of 5,750 years. In other words, it would have burned out long before the earth was born.
By the use of atomic energy the sun has been able to give off its enormous amounts of radiation for a period estimated at 10 billion years, and its mass, at the present rate of burning, is enough to last 15,000 billion years more, although, of course, the amount of its radiation would be greatly reduced long before that in proportion to the decrease of its mass.
Radiations in amounts sufficient to support life on earth are estimated to continue for some ten billion to a hundred billion years longer.
Since the very existence of atomic energy was first discovered through the theory of relativity, the development of the atomic bomb constitutes the most dramatic proof so far offered for the correctness of the theory, and also marks the first time it has been put to practical use in mundane affairs.
It is one of the great ironies of history that the German war lords, who drove Einstein into exile, were forced to rely on the theory of relativity in their efforts to develop an atomic bomb to save them from defeat.
The United States, of which Einstein is now an honored citizen, succeeded where the Nazis failed. When the bombs fell over Hiroshima and Nagasaki, they represented the fruition of what had been originally a pure mathematical concept.
Had that concept not come when it did, the development of the atomic bomb might also have had to wait. This might have meant a prolongation of the war.
Thousands of young Americans thus may owe their lives to the theory of relativity—which is another way of saying that pure science, no matter how impractical it may appear, pays high dividends in the end.
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