Evening star., 1952-12-02
'eors Of Atomic Research
BY Enrico Fermi
NueIsor Physicist

NueIsor Physicist
It has been 10 years since man
first achieved a self-sustaining
atomic reaction.
Many people link this event
only with the development of the
atomic bomb and the subsequent
efforts to develop the hydrogen
bomb, to which reference has
been made in the last few days
by the Atomic Energy Commis-
sion.
The history Of the first self
sustaining nuclear chain reaction.
like that of all scientific achieve
mentS, begins with mans first
philosophical speculations about
the nature of the universe. Its
ultimate consequences are still
unpredictable.
The sequence Of discoveries
leading to the atomic chain reac-
ton was part of the search of
science for a fuller explanation
of nature and the world around
us. No one had any idea or intent
in the beginning of contributing
to a major industrial or military
development.
A partial list of the main
stepping stones to this develop
ment indicates that many coun-
tries contributed to it.
The story begins in Paris in
1896 when Antoine Henri Bee
ouerel discovered the existence of
radioactive elements: that is, ele-
ments which spontaneously emit
invisible. penetrating rays. Two
years later, also in Paris. Pierre
and Marie Curie discovered ra-
dium, for many yearse the best
known of the radioactive elements.
In 1905 in Zurich. Switzerland.
Albert Einstein announced his
belief that mass was equivalent to
energy. This led to speculation
that one could be transformed
into the other.
A most important discovery
came in 1912 when Ernest Ruth
erford discovered the minute but
heavy nucleus which forms the
core of the atom. In ordinary
elements this core is stable; in
radioactive elements it is un-
stable.
Shortly after the First World
War. the same Rutherford
achieved for the first time the
artificial disintegration of the
nucleus at.the center of the nitro
gen atom.
3 Great Discoveries in 1882.
During the next decade, re-
search progressed steadily, if un-
spectacularly. Then. in 1882,
came a series of three discoveries
by scientists working in three
different countries which led to
the next great advance.
Bottle in Germany and Joliot-
Curie in Paris prepared the
groundwork that led James Chad
Wich of England to the discovery
of the neutron. The neutron is
an electrically neutral building
block of the nuclear structure.
The other building block is the
positively charged proton.
The next step was taken in
Rome in 1884. In experiments
in which I was concerned it was
shown that these neutrons could
disintegrate many atoms includ-
ing those of uranium. This dis
coVery was to be directly applied
in the first atomic chain reaction
eight years later.
The final stepping stone was
put in place in Berlin when Otto
Hahn, working with Fritz Strass-
man. discovered f1ssion or split
ting of the uranium atom. When
Hahn achieved fisSion, it oc-
Cured to many scientists that
this fact opened the possibility
OF a form of nuclear (atomic)
energy.
The year was 1899. A world
war was about to start. The new
possibilities appeared likely to
be important not only for peace
but also for war.
A group of physicists in the
United States including Leo
Szilard, Walter Zinn, now direc-
tor of Argonne National Labora-
tory; Herbert Anderson and my
self-agreed privately to delay
further publication of findings in
this field. We were afraid that
these findings might be of help
to the NaZis. Our action, of
course, represented a break with
scientific tradition and was not
taken lightly. Subsequently when
the Government became inter-
ested in the atom bomb project,
secrecy. of course. became COM.
pulsory.
Chain Reaction Defined.
Here it may be we'll to define
what is meant by the Chain re-
action which was to constitute
our next objective in the search