Sunday, March 25, 2012

The Uranium Bomb: The Beginning


E=MC2 is the most famous equation in the modern day world.  According to Albert Einstein’s grand equation mass could be converted to energy, and energy could be converted to mass.   This very equation gave atomic physicists hope that their theoretical work on the uranium and plutonium could produce a bomb.  The bomb would create a blast so powerful that it would be equivalent to 20,000 pounds of TNT or dynamite, and effectively end World War Two.  The journey to the culmination of this grand project of creating these world changing weapons of mass destruction did not come without its problems and painstaking questions that for some time boggled the minds of even the brightest scientists and engineers.  Not only was purifying the stock piles of uranium and creating the new metal plutonium a daunting task, but creating a bomb that would explode in the most effective and deadly manner was of the utmost importance.  Because of the hard work and dedication of the thousands of scientists, engineers, management officials, and other workers, the bomb was made, and effectively changed the world as we knew it. 

            This grand equation Einstein discovered during his many years of laboring brought to life a new kind of physics to the world of science.  His theory of energy and mass gave physicists across the globe the background work into the realm of nuclear or atomic physics.  Otto Hahn and Fritz Strassman were the two scientists who were able to make a breakthrough on nuclear fission in December of 1938.  Their work in a broad prospective stated that when one bombards the nucleus of a uranium atom with neutrons, it causes the atom to fission or split releasing pure energy.  The problem facing scientists during the production of the bomb was this: Uranium consisted of 99 percent Uranium-238 which was a much more stable mass than the Uranium-235 isotope that made up less than 1 percent of the entire element.  “ A more humdrum way of remembering the difference between the two types of Uranium is by focusing on the nature of the even and off numbers.  Since U238 had 238 particles in its nucleus, everything was paired off; but since U235 has an odd number of particles in its nucleus, that means there are 46 pairs of protons and 71 pairs of neutrons- and one extra neutron.”(Bodanis, 281)  When a slow moving neutron from the outside world or from a controlled environment reaches the nucleus of the uranium atom, the neutron causes the nucleus to oscillate or vibrate leading to the splitting of the atom, which can cause a reaction when neutrons from each affected atom cause a chain reaction culminating in the release of pure energy in the form of gamma rays.  This theory and application that took decades to understand and use in real life circumstances came at the most opportune time.  The Manhattan Project brought together the work of thousands of people to produce a sufficient amount of uranium to use to build a bomb of such destructive force to subsequently end the war, but how in the world could a bomb be made that could unleash such devastating amounts of energy. 

            In Los Alamos, New Mexico, after sufficient amounts of uranium-235 was produced in the nuclear reactors in Tennessee, the job of Oppenheimer and his crew was to devise a plan on how the bomb was going to work.  For an extended period of time, scientists and engineers quarreled over concepts on how to detonate the bomb.  The final decision was implosion, and this decision was complimented by the mathematic computations of the world’s greatest mathematician, John von Neumann of Hungary.  So exactly how was the bomb going to work you may ask?  When the bomb was dropped, there were two small holes around the middle where wires had been tugged out of it as it dropped away, which was the first arming system.  When the bomb reached 7,000 feet above the ground, a barometric switch was turned, priming the second arming system.  The bomb was just ten feet long and two and a half feet wide, but what was inside this small speck in the sky was the power of the sun.  Radio waves bounce off the ground detailing how far from the ground the bomb was.  At just under 2,000 feet Neumann calculated that this was the ideal height at which to detonate the uranium bomb.  “ An electric impulse lit cordite sacs, producing a conventional artillery blast.  A small part of the purified uranium was now pushed forward down a gun barrel that was actually inside the bomb.”(Bodanis,164)  The gun was a scaled-down model of the U.S. Navy weapon which was just one-fifth the weight of the conventional weapon.  The first uranium segment traveled about four feet within the gun barrel, and then impacted the remaining bulk of uranium.  There were a number of stray neutrons loose inside it, which helped induce the beginning of the chain reaction.  Because neutrons have no charge, they were not affected by the electrons of the outer casing of the atoms, and were able to freely enter the nucleus of the uranium atom.  “The nucleus normally blocked outside particles from entering, for it was seething with positively charged protons.  But since neutrons have no electric charge their invisible to the protons as well.  The arriving neutrons pushed into the nucleus, overbalancing it; causing it to oscillate and subsequently split.”(Bodanis, 165)  This reaction broke what we called the nucleus force.  Gluons which hold together the nucleus of an atom is ripped apart, causing a chain reaction in which mass was disappearing and being replaced by pure energy.  The entire chain reaction sequence was over within a few millionths of a second.  The bomb took 43 seconds to descend from 31,000 feet to 1,900, but the reaction triggered by nuclear fission took all but a fraction of a second.  “The chain reaction went through 80 “generations” of doubling before it ended.  By the last few moments of this, the segments of broken uranium nuclei were so abundant, and moving so fast, that they started heating up the metal around them.”(Bodanis,166)  Once there was no more matter to be converted over to energy, this energy was being transformed into heat energy because the speed of the uranium nuclei were moving at speeds close to the speed of light and were rubbing against resting metal.  This heat energy reaches temperatures equivalent to that of the sun.  As the heat moves up and goes through the steel around the uranium, as well the several thousand pound casing of the bomb, but then it pauses.  The energy of the explosion must be released, so x-rays push themselves outwards in all directions.  As the energy is used, and the fragments try to cool themselves, and the x-ray bombardment is over, the heat ball resumes its outward spread. This is now a site to see, as normal photons fill the sky, seeming as though a new star has been created just above the surface of the earth, and the bomb burns for a fraction of a second, taking a few more to empty itself out.  This new destructive force kills tens of thousands of Japanese citizens instantaneously.  “And when that great mushroom cloud appeared, E=MC2’s first work on planet Earth was done.”(Bodanis,169) 

            After the destructive force of the bomb was unleashed on Hiroshima on that sunny, 80 degree day, the world was changed forever.  The work of many scientists, engineers, and explosive experts was put to use to end the war, but the moral character of each person involved was questioned.  The bomb that they’ve created has now killed nearly 100,000 people most of whom died almost instantly.  The theory of mass and energy conversion and its first use in nuclear fission was born on this Earth, and has led the world into the Nuclear Age.  The idea of nuclear fallout lies in the back of every intelligent being on this Earth, for man now has the power of the sun, the power to kill hundreds of thousands and even millions of innocent people within a fraction of a second. 

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