自考英语综合二下册课文 lesson 8(在线收听

  [00:00.00]Lesson Eight
  [00:02.80]Text
  [00:05.43]How I Designed an A Bomb
  [00:09.59]in My Junior Year at Princeton John A . Phillips and David Michaelis
  [00:19.15]The first semester of my junior year at Princeton University is a disaster,
  [00:27.30]and my grades show it.
  [00:30.54]D's and F's predominate,and a note from the dean puts me on academic probation.
  [00:40.39]Flunk one more course,and I'm out.
  [00:44.83]Fortunately, as the new semester gets under way,
  [00:50.47]my courses begin to interest me.
  [00:55.01]Three hours a week,
  [00:58.17]I attend one called Nuclear Weapons Strategy and Arms Control.
  [01:04.63]One morning,Freeman Dyson,
  [01:09.20]an eminent physicist assisting Hal Feiveson in the course,
  [01:16.04]opens a discussion on the atomic bomb:
  [01:20.72]"Let me describe what occurs when a 20-kiloton bomb is exploded,
  [01:28.27]similar to the two dropped on Hiroshima and Nagasaki
  [01:34.64]First, the sky becomes illuminated by a brilliant white light.
  [01:41.59]Temperatures are so high around the point of explosion
  [01:47.26]that the atmosphere is actually made incandescent.
  [01:52.72]To an observer standing six miles away
  [01:57.68]the ball of fire appears brighter than a hundred suns.
  [02:03.53]"As the fireball begins to spread up and out into a mushroom shaped cloud,
  [02:10.66]temperatures spontaneously ignite all flammable materials for miles around.
  [02:19.02]Wood frame houses catch fire.
  [02:23.28]Clothing bursts into flame,
  [02:27.44]and people suffer intense third degree lash burns over their exposed flesh.
  [02:35.01]The very high temperatures also produce a shock wave
  [02:40.94]and a variety of nuclear radiation capable of penetrating 20 inches of concrete.
  [02:49.59]Silence falls over the roomas the titanic proportions of the destruction begin to sink in
  [02:57.53]"It takes only 15 pounds of plutonium to fabricate a crude atomic bomb,
  [03:05.68]"adds Hal Feiveson. "
  [03:09.20]If breeder reactors come into widespread use,
  [03:14.48]there will be sufficient plutonium shipped around the country each year
  [03:19.60]to fashion thousands of bombs.
  [03:24.15]Much of it could be vulnerable to theft or hijacking.
  [03:30.81]"The class discusses the possibility of terrorists
  [03:36.08] using a homemade atomic bomb to push their extravagant political demands.
  [03:43.22]"That's impossible," a student objects.
  [03:48.26]"Terrorists don't have the know how to build a bomb.
  [03:53.61]Besides, they don't have access to the knowledge.
  [03:58.58]"Impossible? Or is it?The question begins to haunt me.
  [04:06.52]I turn to reference books and find,according to a famous nuclear physicist,
  [04:13.78]that a terrorist group could easily steal plutonium
  [04:19.42]or uranium from a nuclear reactor
  [04:24.41]and then design a workable atomic bomb
  [04:29.27]with information available to the general public
  [04:34.23]are legally available at hardware stores and chemical supply houses.
  [04:41.68]Suddenly,an idea comes to mind.
  [04:45.94]Suppose an average or below average in my case physics student
  [04:53.20]could design a workable atomic bomb on paper?
  [04:58.76]If I could design a bomb, almost any intelligent person could.
  [05:05.53]But I would have to do it in less than three months
  [05:10.36]to turn it inas my junior independent project.
  [05:15.19]I decide to ask Freeman Dyson to be my adviser.
  [05:20.84]"You understand," said Dyson, "
  [05:25.20]my government security clearance will prevent me from giving you any more information
  [05:31.76]than that which can be found in physics libraries.
  [05:37.03]And that the law of'no comment' governing scientists
  [05:42.78] who have clearance to atomic research requires that,
  [05:48.13]if asked a question about the design of a bomb,
  [05:52.89]I can answer neither yes nor no?"
  [05:58.64]"Yes, sir," I reply."I understand.""Okay, then.
  [06:05.40]I'll give you a list of textbooks outlining the general principles
  [06:11.57]and I wish you luck."
  [06:14.80]A few days later,Dyson hands me a short list of books on nuclear reactor technology
  [06:23.45]general nuclear physics and current atomic theory.

  [06:29.51]"That's all?" I ask incredulously, having expected a bit more direction.
  [06:38.29]At subsequent meetings Dyson explains only the basic principles of nuclear physics
  [06:46.15]If I ask about a particular design or figure,
  [06:51.19]he will glance over what I've done and change the subject.
  [06:56.37]At first, I think this is his way of telling me I am correct.
  [07:02.11]To make sure, I hand him an incorrect figure.
  [07:07.39]He reads it and changes the subject.
  [07:11.83]Over spring vacation,I go to Washington,D.C
  [07:17.71]to search for records of the Los Alamos Project
  [07:23.35]that were declassified between 1954 and 1964.
  [07:30.22]I discover a copy of the literature given to scientists
  [07:36.07]who joined the project in the spring of 1943.
  [07:41.95]This text carefully outlines all the details of atomic fissioning
  [07:49.11]known to the world's most advanced scientists in the early '40s.
  [07:55.77]A whole batch of copies costs me about $ 25.
  [08:01.83]I gather them together and go over to the bureaucrat at the front desk.
  [08:08.49]She looks at the titles and then looks up at me.
  [08:13.17]"Oh, you want to build a bomb, too?" she asks matter-of-factly.
  [08:20.90]I can't believe it.
  [08:24.06]Do people go in there for bomb-building information every day?
  [08:30.41]When I show the documents to Dyson, he is visibly shaken.
  [08:36.05]His reaction indicates to me that I actually stand a chance of coming up with a workable design
  [08:44.88]The material necessary to explode my bomb is plutonium-239.
  [08:52.35]Visualize an atomic bomb as a marble inside a grape fruit
  [08:58.88]inside a basketball inside a beach ball.
  [09:04.52]At the center of the bomb is the initiator,
  [09:09.38]a marble-size piece of metal.
  [09:13.43]Around the initiator is a grapefruit-size ball of plutonium-239.
  [09:21.08]Wrapped around the plutonium
  [09:24.64]is a threeinch reflector shield made of beryllium.
  [09:30.70]High explosives are placed symmetrically around the beryllium shield.
  [09:36.94]When these detonate,an imploding shock wave is set off,
  [09:44.41]compressing the grapefruit-size ball of plutonium to the size of a plum.
  [09:51.67]At this moment, the process of atoms fissioning or splitting apart begins.
  [09:59.72]There are many subtleties involved in the explosion of an atomic bomb
  [10:06.09]Most of them center on the actual detonation
  [10:10.95]of the explosives surrounding the beryllium shield.
  [10:15.92]The grouping of these explosives
  [10:19.76]is one of the most highly classified aspects of the atomic bomb,
  [10:25.21]As the next three weeks go by,
  [10:29.29]I stop going to classes altogether and work day and night.
  [10:35.74]I develop a terrible case of bloodshot eyes.
  [10:40.89]Sleep comes rarely.
  [10:44.44]I approach every problem from a terrorist's point of view.
  [10:50.50]The bomb must be inexpensive to construct,
  [10:55.26]simple in design and small enough to sit unnoticed in the trunk of a car.
  [11:03.01]As the days and nights flow by,
  [11:07.06]I scan government documents for gaps
  [11:11.63] indicating an area of knowledge that is still classified.
  [11:17.20]Essentially, I am putting together a huge jigsaw puzzle.
  [11:23.08]The edge pieces are in place and various areas are getting filled in,
  [11:29.42]but pieces are missing.
  [11:32.79]Whenever the outline of one shows up,
  [11:36.92]I sit down to devise the solution that will fill the gap.
  [11:42.67]With only two weeks left, the puzzle is nearly complete,
  [11:48.73]but two pieces are still missing:
  [11:52.80]which explosives to use,and how to arrange them around the plutonium.
  [11:59.65]Seven days before the design is due,
  [12:04.09]I'm still deadlocked I realize something drastic must be done,
  [12:11.45]and I start all over at the beginning.
  [12:15.82]Occasionally I find errors in my old calculations,and I correct them.
  [12:23.47]I lose sense of time.
  [12:26.81]With less than 24 hours to go,
  [12:30.97]I run through a series of new calculations,
  [12:36.22]mathematically figuring the arrangement of the explosives around the plutonium
  [12:42.75]If my equations are correct,

  [12:46.82]my bomb might be just as effective as the Hiroshima and Nagasaki bombs.
  [12:54.27]But I can't be sure until I know the exact nature of the explosives I will use
  [13:01.64]Next morning, with my paper due at 5 p.m.,
  [13:07.20]I call the Du Pont Company from a pay phone
  [13:12.55]and ask for the head of the chemical explosives division,
  [13:18.30]a man I'll call Mr.Graves."Hello, Mr. Graves.
  [13:25.56]My name is John Phillips,a student doing work on a physics project.
  [13:32.83]I'd like to get some advice, if that's possible."
  [13:37.79]"What can I do for you?"
  [13:40.95]"Well," I stammer,"
  [13:44.48]I'm doing research on the shaping of explosive products
  [13:49.94]that create a very high density in a spherically shaped metal.
  [13:57.20]Can you suggest a Du Pont product that would fit in this category?"
  [14:03.68]"Of course." he says,in a helpful manner.
  [14:08.85]"We sell the names of the product
  [14:13.39]to do the job in similar density problem situations
  [14:20.06]to the one you're talking about.
  [14:23.82]"Mr. Graves has given me just the information I need.
  [14:29.49]Now,if my calculations are correct with respect to the new information,
  [14:36.85]all I have to do is complete my paper by five.
  [14:42.31]Five minutes to five,I race over to the physics building and bound up the stairs
  [14:50.36]Inside the office,everybody stops talking and stares at me.
  [14:57.12]"I came to hand in my project," I explain.
  [15:02.19]A week later, I return to the office to pick up my project.
  [15:08.43]My paper is not there.
  [15:12.27]"Aren't you the boy who designed the atomic bomb?"
  [15:16.95]The secretary looks up, then freezes.
  [15:21.21]"Yes," I reply.She takes a deep breath.
  [15:27.16]"The question has been raised
  [15:31.00]by the department whether your paper should be classified by the U. S. government
  [15:37.98]"What! Classified?"She takes my limp hand shaking it vigorously.
  [15:46.94]"Congratulations," she says, all smiles.
  [15:52.19]"You've got one of the only A's in the department.
  [15:57.15]"For a second I don't say anything.
  [16:01.38]Here I have put on paper the plan for a device
  [16:06.71]capable of killing thousands of people,
  [16:11.57]and all I was worrying about was flunking out.

 

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