首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
The History of the Atomic Bomb On August 2, 1939, just before the beginning of World War II, Albert Einstein wrote to then
The History of the Atomic Bomb On August 2, 1939, just before the beginning of World War II, Albert Einstein wrote to then
admin
2014-09-18
70
问题
The History of the Atomic Bomb
On August 2, 1939, just before the beginning of World War II, Albert Einstein wrote to then President Franklin D. Roosevelt. Einstein and several other scientists told Roosevelt of efforts in Nazi Germany to purify uranium-235, which could be used to build an atomic bomb. It was shortly thereafter that the United States Government began the serious undertaking known then only as "The Manhattan Project". Simply put, the Manhattan Project was committed to expediting research that would produce a viable atomic bomb.
The most complicated issue to be addressed in making of an atomic bomb was the production of ample amounts of "enriched" uranium to sustain a chain reaction. At the time, uranium-235 was very hard to extract. In fact, the ratio of conversion from uranium ore to uranium metal is 500:1. Compounding this, the one part of uranium that is finally refined from the ore is over 99% uranium-238, which is practically useless for an atomic bomb. To make the task even more difficult, the useful U-235 and nearly uselessU-238 are isotopes(同位素), nearly identical in their chemical makeup. No ordinary chemical extraction method could separate them; only mechanical methods could work.
A massive enrichment laboratory/plant was constructed at Oak Ridge, Tennessee. Harold C. Urey and his colleagues at Columbia University devised an extraction system that worked on the principle of gaseous diffusion, and Ernest O. Lawrence (inventor of the Cyclotron) at the University of California in Berkeley implemented a process involving magnetic separation of the two isotopes.
Next, a gas centrifuge was used to further separate the lighter U-235 from the heavier, non-fissionable U-238. Once all of these procedures had been completed, all that needed to be done was to put to the test the entire concept behind atomic fission ("splitting the atom", in layman’s terms).
Over the course of six years, from 1939 to 1945, more than $2 billion was spent during the history of the Manhattan Project. The formulas for refining uranium and putting together a working atomic bomb were created and seen to their logical ends by some of the greatest minds of our time. Chief among the people who unleashed the power of the atom was J. Robert Oppenheimer, who oversaw the project from conception to completion.
Finally, the day came when all at Los Alamos would find out if "The Gadget" (code-named as such during its development) was going to be the colossal dud of the century or perhaps an end to the war. It all came down to a fateful morning in midsummer, 1945.
Who has been working at the making of the atomic bomb from beginning to end’?
选项
A、Albert Einstein.
B、Harold C. Urey.
C、Ernest O. Lawrence.
D、J. Robert Oppenheimer.
答案
D
解析
根据提问,查看有关的段落,是J.Robert Oppenheimer who oversaw the project from conception to completion。
转载请注明原文地址:https://kaotiyun.com/show/GaTK777K
0
专业英语四级
相关试题推荐
Individualsportsarerunbyover370independentgovernmentbodieswhosefunctionsusuallyinclude______rules,holdingevents
Withtheintroductionofthecomputer,librariestodayarequitedifferentfrom______theywereinthepast.
Foralongtime,newspapershavebeenthechiefmeansbywhichpeoplegetthemselves(1)______.Thenewspapers,daily,evening,a
Foralongtime,newspapershavebeenthechiefmeansbywhichpeoplegetthemselves(1)______.Thenewspapers,daily,evening,a
TherearemanytheoriesaboutthebeginningofdramainancientGreece.Theonemost(1)______acceptedtodayisbasedontheass
TherearemanytheoriesaboutthebeginningofdramainancientGreece.Theonemost(1)______acceptedtodayisbasedontheass
Althoughinteriordesignhasexistedsincethebeginningofarchitecture,itsdevelopmentintoaspecializedfieldisreallyqui
Overthepastcentury,thecompositionofthehumangenepool______appreciably.
Shortlybeforehediedoflymphoma(淋巴瘤),thegreatwriterandphysicianLewisThomas,whosebooksturnedscienceintoawayofa
Alargepartofhumanactivity,particularlyinrelationtotheenvironment,is______conditionsorevents.
随机试题
动圈式弧焊变压器焊接电流细调是通过改变一次绕组和二次绕组的距离实现的,距离越大则电流越大。()
A.“铅管”征B.“鹅卵石”征C.“鸟嘴”征D.“杯口”征E.充盈缺损肠套叠的典型X线征象是
一个慢性肾炎尿毒症期患者,近1个月来厌食、皮肤瘙痒。前日起呕吐。体检:血压23/16kPa(172/120mmHg),神清,贫血貌,心、肺检查无异常。Hb50g/L,尿蛋白(+),比重1.010,血肌酐795μmol/L,血钾4.0mmol/L。该患者
测绘类专业大学本科学历取得注册测绘师资格业务条件应具备:从事测绘业务工作满()。
长距离输电线路中心桩测定后,一般采用()或平行基线法进行控制。
Canadians’motherlanguageor"mandarin"is______.
欧洲中世纪大学主要有三大专业,即法学、医学和________。
Somepessimisticexpertsfeelthattheautomobileisboundtofallintodisuse.Theyseeadayinthenot-mo-distantfuturewhen
基于数据库pdtmng建立如图3-7所示顶层表单应用,表单文件名为myform.scx,表单控件名为goods,表单标题为“商品”。①表单内含一表格控件Gridl(默认控件名),当表单运行时,该控件将按用户的选择(单击菜单)来显示products
HowtoTakeLectureNotes1.Whatiseffectivenote-taking?To【T1】______thematerialandwritedownkeyelements2.Takenotes
最新回复
(
0
)