Back Page on Nuclear Weapons Gets it Right
I want to commend the excellent Back Page article by Raymond Jeanloz [APS News, April 2009] regarding the Washington home for the nuclear weapons program. Jeanloz argues persuasively against putting the program in the Department of Defense.
I spent the better part of fifty years in nuclear weapons R&D at Los Alamos and am a former leader of the program. In addition, I spent almost forty years as an advisor to the government on arms control and proliferation. In 1976 I was on the study team that recommended against putting the nuclear weapons program in the DoD for just the reasons cited in the article.
I wholeheartedly endorse professor Jeanloz’s rationale and conclusions.
John C. Hopkins
Los Alamos, NM
Sunday Explosion Supports Back Page Estimate
Many (~25) years ago I participated in a series of atmospheric nuclear simulation tests that used high explosives to generate shock waves to study their effects on structures, military vehicles, etc. The most impressive test saw the assembly, at White Sands (New Mexico), of a fiberglass half sphere of 40 ft radius (80 foot diameter on the ground) which had a central ignition explosive charge and was filled with ammonium nitrate N2H4O3 pellets (~1.7 gm/cm3) wetted with diesel oil. This device was shot off one Sunday morning, after the Soviet spy satellites had passed. Later the test director announced that it was 20 kiloton equivalent explosion. Raymond Jeanloz’s Back Page article in the April APS News led me to estimate the mass of N2H4O3 to have been 5x106 kilograms. The Hiroshima (Little Boy, gun assembled enriched uranium, 14-18 kiloton air burst) and Nagasaki (Fat Man, internal spherical implosion of Pu, 20 KT air burst) bombs destroyed their cities. Both used about one kilogram of fissile material. Compared to the above half sphere test there is a ratio of 5 x 106. Ammonium nitrate has about half the energy density of TNT, while air shots see a doubling of shock wave strength due to the interaction between the reflected and incident shock waves (“Mach Y Stem”). My remembrance supports Jeanloz’s 106 ratio between nuclear and chemical energy storages. I use my “half sphere” experience to more graphically explain the difference between the two energy densities and the dangers of even 20 kiloton nuclear bombs, which can easily be transported. All these devices are beyond considering, along with other more powerful more modern nuclear weapons.
Ralph F. Wuerker
Westlake Village, CA
Science Overlaps with Most Religions
In your February issue, you did well in presenting some comments about Faith and Physics. And yes, we might all disagree about everything when it comes to such a subject. For that very reason, it is fine to include such comments from time to time. It would be wrong to never mention their “various relationships.”
Most religions are based upon an acceptance of a God, who exists within our reality, and who was involved with the creation of the earth, and placed man here upon the earth. So with some religions, there really are going to be some assumptions about certain events that are able to be addressed by science. Therefore, science really could place some religions into rankings as to how close or to how far apart each might be in terms of their “scientific acceptableness.” And science should do such things!
And in turn, religions can use science to tell how well they are doing as a religion, and how well science is doing. Thus, there really are some overlaps, and we should be willing to point out those areas that support both, or do not support both.
Gerald L. O'Barr
San Diego, CA
Anything Supernatural Must be FictionIn the April 2008 issue of APS News, Joseph R. Tatarczuk at Poestenkill, NY wrote “What caused the Big Bang? The standard answer is that a physicist cannot answer that question.” First of all, that’s not true since there are theories in physics such as eternal inflation and quantum cosmology that do answer that question. Second, even if we don’t know what caused it, we know what definitely did not cause it. We know it was definitely not caused by magic. If you watch a magician perform a trick, and you have absolutely no idea how he did it, you know for certain how he did not do it. You know for certain he didn’t do it using magic powers. If you read a book that does not contain magic, you might wonder whether it’s fiction or nonfiction. On the other hand, if you read a book that contains magic, you would know for certain that it’s fiction. It would be possible for someone to read “War and Peace” and mistake it for nonfiction. It would not be possible for someone to read “Lord of the Rings” and mistake it for nonfiction. The word “magic” is a synonym for “impossible,” and the “impossible” is defined as something that can exist only within fiction. Christians say an omnipotent supernatural being with infinite magic powers deliberately made the entire infinite universe using only its most inifinite magic powers. That's the most magic thing, meaning the most impossible thing, that anyone ever made up.
The Christians say its magic, so they say it’s impossible, so they admit they’re talking about a work of fiction.
Article Makes Blinking Mistake
“This Month in Physics History” [APS News, March, 2009] is about Clyde Tombaugh and his discovery of Pluto. It seems that his “blink comparator”–a classical astrometric device, has grown a suffix to become a “blinking comparator,” leaving some of us, indeed, blinking!
Peter D. Noerdlinger