4 Scientists Agree a Missile Could Be Rigged to Spread Death Over the Earth
RADIOACTIVITY THE KILLER
Experts Put Cost of Dispersing Cities and Other Safeguards at Untold Billions
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By WILLIAM L. LAURENCE. (New York Times, March 20, 1950).
The hydrogen bomb, if developed, could be rigged in such a way as to exterminate the entire world's population or most of it, four leading atomic scientists warned yesterday.
This could be done simply by incorporating common substances in the hydrogen bomb, they declared. When detonated, the explosion would release tremendous quantities of neutrons, the most penetrating particles in nature. These, in turn, would enter into the nuclei of the incorporated element and make them intensely radioactive.
If an element such as cobalt were chosen, they pointed out, it would be transmuted into a radioactive element about 320 times as powerful in its radioactivity as radium. The deadly radioactive cobalt would be scattered into the atmosphere and carried by the westerly winds all over the surface of the earth. Any living thing inhaling it, or even touched by it, would be doomed to certain death.
Other New Facts Brought Out
This hitherto unknown
information about the potential horrors in store for humanity in the event
of the development and use in warfare of the hydrogen bomb, as well as several
other facts so far not fully realized by the public, were brought out at the
University of Chicago Round Table Conference broadcast over the National Broadcasting
Company's network. New York and
vicinity will not hear this program until next week.
The participants in the discussion were Prof. Hans A. Bethe of Cornell University, Prof. Frederick Seitz of the University of Illinois, Prof. Leo Szilard and Dr. Harrison Brown of the University of Chicago. All four played major roles in the development of the wartime atomic bomb. Professor Szilard was a key figure in starting the Government project.
The element best suited for the hydrogen bomb, they brought out, is deuterium, the double-weight isotope (twin) of simple hydrogen, which constitutes one part in 5,000 of all waters on earth. The nuclei of deuterium, known as deuterons, are composed of one proton (positively charged elementary particle) and one neutron (neutral particle of about the same mass as the proton).
In a hydrogen bomb, two deuterons would be made to fuse by the intense temperatures developed by the detonation of an orthodox uranium-plutonium fission bomb, which would be used as the trigger for setting off the hydrogen bomb. In the fusing process one out of every four deuterons would set free its neutron. This means that one-eighth of the total mass of heavy hydrogen exploded would be released as neutrons.
Neutrons Enter Air's Nitrogen
If allowed to go free into the air, these neutrons would enter the nitrogen in the atmosphere and transmute it into a radioactive form of carbon of atomic mass fourteen. The radioactive carbon, it was pointed out, loses half its radioactivity in 5,100 years. This is a rather weak type of radioactivity and would not be fatal unless a great many hydrogen bombs were exploded.
On the other hand, Professor Szilard and his colleagues pointed out, it would be possible to add to the contents of the bomb a substance that, when made radioactive by neutrons, has a very short lifetime, and is thus much more powerfully radioactive. A substance with a half-life of only five years, for example, such as cobalt, would be 1,000 times more deadly in its radioactivity than carbon 14.
"Assuming that we
have a radioactive element that will last for five years,'' Professor Szilard
said, ''we just let it go into the air. During the following years it will
gradually settle out and cover the whole earth with dust. I have asked myself:
"How many neutrons, or how much heavy hydrogen, do we have to detonate
to kill everybody on earth by this particular method?"
Well, I come out with about fifty tons of neutrons being needed to kill everybody, Which means about
500 tons of heavy hydrogen.
Who would want to kill
everybody on earth? Suppose we have a war, and suppose we are at the point
of winning the war against Russia maybe after a struggle which lasts ten years.
Russia's rulers then can say. 'You come no further, you don't
invade Europe, and you don't drop ordinary bombs outside or else we detonate
our bombs and kill everybody.' Facing such a threat; I don't think we can
go forward."
"Do you think" Dr. Brown asked "that any nation would really be willing to kill all the people on earth rather than face defeat"? Would we be willing to do it for example?
"I do not know if
we would be willing to do it", Professor Szilard replied, "and I
don't know if Russia would be willing to do it, but I think that we might
threaten to do it and who will take the risk not to take that threat seriously?"
The discussion brought out that at our present state of knowledge, it is not
likely that a substance of short-lived radioactivity
could be developed so that it would be possible for one nation to exterminate
another and spare itself.
"We are faced with
the possible ironical conclusion," Dr. Brown said in summing up this
view, "that in this respect it becomes
easier to kill all the people in the world than just a part of them."
This, Professor Szilard assented, "is definitely so."
If we should build the hydrogen bomb, the scientists agreed, it would not entail just the cost of the bomb itself, but the expense of the defense measures we would be forced to take. These measures, the scientists said, would include the dispersal of the population of all our coastal cities involving the transportation of thirty to sixty million persons.
Tremendous cost seen
Our general defense measures, Dr. Szilard estimated, would reach $25,000,000,000 a year, while the dispersal proper would cost about $l5,000,000,000 a year. The dispersal of the coastal cities would take about ten years, Dr. Szilard said.
Dr. Bethe thought it would also be necessary to disperse our inland cities since they too might be attacked by planes or maybe by guided missiles.
To disperse all of our cities, Professor Szilard said, "we would probably have to spend something like $25,000,000,000 a year for ten years
"It certainly would mean a planned movement," he added. "It would mean controls much stricter than we ever had during the war time. It would be not a New Deal, but a Super-Super New Deal."
The dispersal, however, the four scientists agreed, would be of use only against the blast and flash burn effects of the hydrogen bomb. "The dispersal would be of no help at all against the effects of the radioactivity," they stressed, since that would go everywhere.
The size of the bomb,
Professor Bethe said, would depend only on how much heavy hydrogen could be
carried in a plane or in any other device that might be used to deliver the
bomb. A bomb of 1,000 times the power of the present atomic bomb would destroy
an area 100 times greater, he said, adding: "If a bomb were exploded
somewhere, then ten miles away from it there would be almost complete destruction,
and that would mean that a city as big as New York, that is, the biggest
cities on earth, would be destroyed by one single bomb.
Professor Seitz added that whereas the flash burn effect of the Hiroshima bomb extended only half a mile, the flash effect of the hydrogen bomb would be at least thirty times greater. This meant, he said, that people would suffer flash burns at least twenty miles away from the center of the detonation.
Professor Bethe said that by talking about the hydrogen bomb, "we unnecessarily gave the Russians the information that we consider it feasible, and the information that we are making it, which more or less forces them to do the same."
"We cannot predict whether the bomb can be made or not," Professor Bethe added. On the other hand, from the decision which has been made, we must conclude that our experts believe that it is probable that we can make it. Even so, I think we must be prepared that it will take several years before the bomb has been completed."
He explained later that
his best guess was that a minimum of three years would be required to complete
the first model of the hydrogen bomb.
Reference
New York Times. March 20, 1950.