Responding to a solicitation, I wrote a short essay (about 800 words)
entitled "Nuclear fission, discovery of" for Salem Press. They will
probably publish the essay in the book entitled "The Thirties in
America." Unfortunately, I am not allowed to share the draft at this
time. What I would like to do instead is to compose a longer essay
entitled "Fission versus fusion," or something like this. Here are
some initial observations.
1) Nuclear fission, discovered in 1938, was quickly confirmed in
several laboratories. Hahn and Strassmann's paper was published in
January of 1939; the mechanism of the reaction was understood weeks
later (by Lise Meitner, who coined the name "fission" and predicted
about 200 MeV of energy by event). This was at once confirmed
experimentally (by Frish in Denmark, by Joloit Curie in France, and by
Fermi in the US). The preexisting-accepted theory of Niels Bohr (the
liquid drop model) was at once used to explain why fission is possible
in the most massive nuclei, such as uranium (high values of Z^2/A).
The discoveries of secondary neutrons, first by Joliot Curie and then
by Fermi, were also made in January of 1939. The discovery that
fission induced by slow neutrons takes place only in U-235 was also
made in 1939 (Fermi and his collaborators). That important American
discovery opened the path to well-known applications, first military
(atom bomb) and then civilian (nuclear electricity). Spontaneous
fission was discovered in 1940, by Petrzhak in USSR. Note that these
discoveries were made at universities, years before government-
sponsored programs were created.
2) Basic nuclear physics facts behind hot fusion (exothermic nature of
reactions, their cross sections etc.) have also been known for very
long time, mostly from research conducted with low energy
accelerators. The preexisting-accepted theory was able to explain the
energy dependence of cross sections. Progress from knowing and
understanding to the first practical application (hydrogen bomb) took
about five years. But progress toward civilian practical applications
(hot fusion reactors) continues to be very slow.
3) Discovery of excess heat, attributed to a nuclear reaction, took
place twenty years ago. A large number of other CMNS discoveries (*),
such as emission of nuclear particles and transmutation, were
announced since that time. But the world is still waiting for a
protocol yielding a "reproducible on demand" demonstration of a strong
nuclear effect due to a chemical effect. (The word "strong" is
important; the probability of capture electrons--a form of beta decay--
does sometimes depend, to some extend, on chemical composition.)
4) Reproducibility on demand is essential; how else can a proposed
CMNS theory be validated? A theory is expected to make specific
verifiable predictions. How can predictions be verified without
phenomena being reproducible? How can a phenomenon be used in a
practical application without being reproducible?
(*) WHAT USED TO BE CALLED "COLD FUSION" IS NOW CALLED "CONDENSED
MATTER NUCLEAR SCIENCE" (CMNS). OTHER NAMES ARE LENR (LOW ENERGY
NUCLEAR REACTION), CANR (CHEMICALLY ASSISTED NUCLEAR REACTION), ETC.
Comments, as always, will be highly appreciated.
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Ludwik Kowalski, a retired physics teacher and an amateur journalist.
Updated links to selected publications and reviews are at: