Slashdot Mirror
When Scientific Publishing was Withheld
karvind writes "Article in Physical Review Focus reveals the silence practiced by Physical Review during WWII to delay publishing results related to fission, the splitting of an atom's nucleus accompanied by a prodigious release of energy. From the article: Because of fears that Germany would use American research to pursue an atomic weapon, the Physical Review agreed to withhold reports of significant advances. It was not until several months after an atomic bomb exploded over Nagasaki, Japan, that Phys. Rev. published the paper announcing the discovery of plutonium, the material used in that bomb. Physicist Abraham Pais later called the journal's silence on the subject 'the most important nonevent in the history of the Physical Review.'"
For people who like this subject matter and want to read more about the history of the development of atomic bombs (including the history of early 20th century atomic physics), I can recommend The Making of the Atomic Bomb by Richard Rhodes. Solid history _and_ good writing.
I bought it after it was recommended in some other Slashdot post, and loved it.
I believe posters are recognized by their sig. So I made one.
"A Soviet scientist deduced from the Americans' silence on the topic that they were pursuing an atomic bomb. The Soviets soon followed suit."
"what really made it easy for the Soviets to build their own bomb was knowing that it would work. It wasn't even certain whether the research would take anywhere, whether an atomic bomb was possible at all."
To anyone who is interested in the history of the project and its continuation in hydrogen bomb effort, I strongly recommend Gregg Herken's "Brotherhood of the Bomb: The Tangled Lives and Loyalties of Robert Oppenheimer, Ernest Lawrence, and Edward Teller".
The focus of this detailed book is on personal politics of the project in US but the important developments in USSR are mentioned also. Using declassified documents from KGB and FBI archives, Herken shows that Kurchatov had a complete scoop on MAUD report (British effort) and then on Manhattan project. By espionage, they got everything US had known until 1946. The first russian nuclear reactor was based on Hanford reactors. The first russian nuke was exact replica of Fat Man. That much for uncertainity.
What realy changed in Russia after Hiroshima was not the attitude of scientists but the priorities of the political leadership. Beria the Terrible ("He is our Himmler", Stalin introduced him playfuly to Churchil) became the boss of the russian program. Money was no problem. The expenditures was fantastic while russians were dying of starvation and lack of medical care.
I doubt that we will ever figure out - and I suspect that even if we did figure out we couldn't do much about it
According to a theorem usually attributed to Cybenko, any continuous nonlinear function can be represented by a linear combination of sigmoid functions of a linear combination of your parameters. In neural nets terms, a single hidden layer net with 2n+1 neurons in your hidden layer can represent _any_ continuous function.
That doesn't mean the usual neural net training algorithms are able to achieve that representation, but it's still a strong result, and it mostly justifies neural nets being increasingly looked at seriously at nonparametric (without individual input effect parameters as an usual OLS model would yield) statistics.
All in all, I do have a lot of faith in the future of nonparametric methods. They might be no substitute of empirical experiment (and that's what the parametric statistical methods that comprise econometrics strive for), but the sheer success of neural nets in spite of their lukewarm academic reception shows they can be quite useful.
"economics is not a science"
is astronomy? is paleotology? is geography?
How do you do experiments in paleobiology?
Granted, much of econ. is layered with preconceptions; much of it IS covet , unconscious, politics.
There are two problems with this argument:
There's no point in questioning authority if you aren't going to listen to the answers.
Not really.
Plutonium was being produced in the Oklo natural nuclear reactor that was running in Gabon 2 billion years ago. It had decayed away by the time we showed up on the scene. See this, for example.
We learned of it by making it, but nature had done it long before us.
Cybenko's result was more of a reality check for the NN community than anything else. If NNs didn't have this property, there wouldn't be much use in studying them. The Weierstrass Approximation theorem, which you can find in a good real analysis book, shows that plain old vanilla polynomials of the form sum(i=1,n) a_i x^i have the same property.
Barron had a paper giving rate-of-approximation results for a certain class of functions. This starts to answer the question "how big should n be?" I'm not sure what new work has appeared along these lines. I've been out of touch with the NN community for a few years. That said, a lot of the learning people seem to be more excited about support vector machines and kernel methods these days. I guess some people group these techniques along with neural networks, but they lie on a much more solid foundation of statistics.
cheers, Rick
From Here.
---
the pen is mightier than the sword, the sword is mightier than the court, the court is mightier than the pen.