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The Atomic Age was born.
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There is no denying that since that moment, the shadow of the atom bomb has been across all our lives.
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All men of goodwill earnestly hope that a realistic control of atomic weapons can and will be achieved.
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Meanwhile, good sense requires that all of us prepare for any eventuality.
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But wisdom demands, too, that we take time to understand this force.
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Because, here, in fact, is the answer to a dream as old as man himself. A giant of limitless power at man's command.
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And where was it science found that giant?
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In the atom, a particle so infinitely small that it takes over 100 billion billion atoms to make up the head of a pin.
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Just as other millions and quadrillions of atoms are the tiny building blocks,
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which make up everything in the world: ships and shoes and sealing wax and cabbages and kings.
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Although no one has ever seen an atom, scientists have learned a great deal about how they behave,
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and there are widely accepted theories as to what they are like.
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Let's start by meeting a leading authority on the subject, Dr. Atom.
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Now, observing the professor himself, we can see that his structure resembles, in many ways, something almost as vast as the atom is small: the solar system.
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And there are certain similarities. This is the center with electrons in surrounding orbits.
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But whereas the planets movement [inaudible], electrons is slightly different.
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There are other differences, too.
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Hey, hold it! Thank you.
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Now, the solar system [inaudible] is electrical.
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The electrons, which are negative, are attracted by the protons, which are positive, and vice versa.
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But here in the nucleus are other particles with no electrical charge called neutrons, very important characters too, as we shall see.
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And equally important when it comes to atomic energy is what scientists call the atom's binding force. It's a kind of cosmic glue holding the nucleus together.
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This then is a single atom, but certainly not all atoms are alike.
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There are in nature more than 90 basic elements, which is science's term for families of atoms.
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To scientists, the atoms of the individual atom families, or elements, are identified by number, that is, the number of protons or positive charges in their nucleus.
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And they vary all the way from hydrogen, which has just one proton,
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to oxygen with eight protons,
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to gold —he's rich with 79—,
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finally on to the heaviest of all natural elements: uranium with 92 protons.
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Now, within each element, or family of atoms, there can be different members, each one having the same number of protons, but differing in the number of neutrons.
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The total of an atom's protons and neutrons is its atomic weight.
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Thus, in natural uranium, we have U-234, U-235, and U-238.
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These different members of the same element or atom family, science calls isotopes.
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Some elements, tin for instance, have a great many isotopes.
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Others, like aluminum, are lone wolves with just one.
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Now, most atoms of most elements are content with their lot in life. We speak of them as being stable.
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But others are busy day and night being what science calls radioactive.
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Like radium, throwing off powerful rays along with some of its neutrons and protons, until it actually alters its own nuclear structure
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and changes to another family, and then to another, until it does become stable at last.
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This spontaneous changing of elements is called natural transmutation. Its discovery gave men of science an idea.
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If an atom could change itself, why couldn't man change an atom?
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Using as bullets the very particles which radium threw off, a noted British scientist bombarded nitrogen and converted it to oxygen.
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In terms of individual atoms, this is what happened.
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The radium nucleus threw off an alpha particle consisting of two protons and two neutrons.
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One of the protons was absorbed into the nitrogen nucleus, turning it to oxygen.
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This was artificial transmutation, man changing the elements.
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From that first experiment, others by the thousands followed as scientists devised ever more powerful particle accelerators, commonly called atom-smashers,
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to transmute more and more kinds of atoms, all scientifically important but hardly world-shaking.
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Then in 1939, some scientists were experimenting with transmutation of uranium.
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What would happen, they wondered, if they fired a neutron at a uranium nucleus, already the heaviest in nature? Why not try?
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So they tried, and the result: nuclear fission. Instead of a minor change, the atom split in two! Truly a discovery to change the world.
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For what had happened when the uranium atom split was a kind of double miracle of science.
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Half of the miracle concerned that binding force we spoke of before, that kind of cosmic glue which holds the atom's nucleus together.
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We still don't know all about that binding force yet, but we do know it is equivalent to mass. Therefore, we may speak of it as having a kind of weight of its own.
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Now, the two atoms into which a uranium atom splits also have binding force, but for some reason it takes less of that glue to hold them together,
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and in the process of fission, a tiny fraction is left over.
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What happens to it? It explodes as energy, proving Einstein's theory that mass and energy are really the same.
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But we spoke of a double miracle. To understand the second one, let's slow down that fission a million or so times.
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A single particle starts the reaction, splitting the uranium atom.
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Here now is the release of energy as heat and blast. Here are powerful rays being given off, similar to X-rays.
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But here, here are free neutrons driven out with tremendous speed.
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And provided there is sufficient U-235 present, what science calls a critical mass, those neutrons bombard other uranium atoms, causing them to split and split still others.
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The result: a chain reaction, over a million, billion, billion atoms exploding within two seconds.
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And the force? It would take Yankee Stadium full of dynamite to equal the energy released in the complete fission of an amount of U-235 the size of a baseball.
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With this discovery at the time the free world faced a war for survival, it was little wonder the first thought was a weapon.
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But how to obtain enough material for even a single bomb?
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Only a small fraction of natural uranium is the U-235 isotope which will fission in a chain reaction,
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and to separate enough U-235 quickly enough seemed all but impossible.
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But the impossible became reality as industry, labor, science, and the military combined their efforts to build Oak Ridge,
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where enough U-235 was separated to build the first atomic bomb.
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At Hanford, Washington, another impossible project proved possible when a huge plant was built for the mass production of the artificial element plutonium.
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This process involves what may be called the furnace of atomic energy: the reactor pile.
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Here is a structure or pile of graphite blocks. In the reactor are placed rods of natural uranium containing both U-235 and U-238.
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As U-235 begins to fission, the graphite slows down the free neutrons and some of them hit other U-235 atoms, keeping the chain reaction going.
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But others of those slowed-down neutrons hit U-238 atoms, and here's what happens.
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Remember, we said that U-238 wouldn't support a chain reaction.
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However, it will capture neutrons from U-235 fission and start a process which converts the U-238, first to neptunium, then to plutonium.
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And plutonium will fission in chain reaction. Thus, the reactor itself is a source of atomic fuel.
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Besides producing plutonium, the nuclear reactor makes possible two very important peacetime uses of atomic energy.
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Remember that the chain reaction process in the reactor creates tremendous heat, which scientists have learned how to control.
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Thus, a reactor may be substituted in many industrial applications, where heat is now provided by coal or petroleum. But such uses in the foreseeable future are limited.
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For one thing, a reactor pile must be shielded to protect the workers around it from dangerous radiation, and this shielding adds tremendous weight.
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However, an atomic energy power plant has already proved feasible.
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The future supplying of electric power to entire cities is far from impossible,
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while nuclear power in locomotives, submarines, ships, and even very large airplanes,
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may all but revolutionize future transportation on land, sea and air.
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But perhaps the most valuable by-product of the nation's reactor piles is radioactive isotopes.
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Research has revealed that many elements not naturally radioactive, became so when placed in a nuclear reactor.
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And these isotopes, working as tracers with such measuring devices as a Geiger counter, became invisible detectives, aiding the cause of science in many different fields.
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In agriculture, isotopes are now used to test such things as the effect of fertilizers on plant growth
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and the proper timing for their use, helping to assure bigger and better yields from tomorrow's farms.
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In industry, isotopes have found literally hundreds of new uses, such as the automatic thickness control of sheet aluminum,
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saving hundreds of man hours of labor and assuring accuracy never before possible.
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In the fields of medicine and biochemistry, isotopes are performing near miracles of diagnosis and discovery.
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With radioactive sodium, doctors are solving more of the seeming mysteries of heart disease and circulatory disturbances.
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Radioactive phosphorous has been used to locate tumors in the brain and greatly simplify operations for their removal.
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Iodine-131 finds one of many uses in revealing conditions of the thyroid. And there are many more.
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New ways of using isotopes are being discovered constantly through the tireless work of modern pioneers in such fields as chemistry, metallurgy, medicine, and biology.
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Truly the superpower which man has released from within the atom's heart is not one, but many giants.
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One is the warrior, the destroyer. Another is the engineer seeking to provide vast quantities of energy to run the world's machines.
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Another is the farmer, helping to better feed tomorrow's world.
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Still another is the healer, helping to diagnose and cure the sick.
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And the last is the research worker, working on in the fields of pure science to reveal more of the mysteries of the universe.
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But all are within man's power, subject to his command.
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On man's wisdom, on his firmness in the use of that power, depends now the future of his children and his children's children,
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in the new world of the Atomic Age.
