STATE OF SCIENCE—COMPTON 403 
Now we jump to the fateful time, just 10 years ago, when the 
discovery of nuclear fission opened the way to the atomic bomb and 
atomic energy. In early January, 1939, two Germans, Hahn and 
Strassmann, found that an isotope of barium is produced when 
uranium is bombarded by neutroms. This news promptly reached 
Copenhagen, where it was given the true explanation as being a 
hitherto unsuspected phenomenon, nuclear fission, by two refugee 
scientists, Frisch and Lise Meitner, who had fled Germany to work 
with the great Danish physicist, Niels Bohr. 
On January 19, Bohr arrived in the United States to deliver some 
lectures, and brought with him the news of this discovery of nuclear 
fission. By January 26 this discovery had been confirmed in four 
United States laboratories, in Copenhagen, and in France, and there 
had been a scientific conference on the subject in Washington. All 
this had happened within the short space of less than one month. By 
the end of a year more than 100 scientific articles on nuclear fission 
had been published. 
Then, in 1940, the clouds of war shrouded the further developments 
in a degree of secrecy never before imposed in the field of science. 
This secrecy was at first entirely self-imposed by the scientists them- 
selves, who conceived of the military applications of nuclear energy 
before either officialdom or industry even knew of the existence of this 
new phenomenon. The project barely survived the skepticism with 
which it was initially received by many of the nonnuclear scientists 
and engineers who became concerned with it, but by the end of 1942 
its potentialities had become well established and the great Manhattan 
Project was undertaken, with close cooperation between the carefully 
selected scientific groups from the United States, the United Kingdom, 
and Canada. 
The rest of the story is now written into the history of the dramatic 
ending of World War II with Hiroshima and Nagasaki; of the efforts 
to turn atomic energy into an instrument, through international con- 
trol, for the maintenance of permanent peace; and of the current work 
under our Atomic Energy Commission to develop peacetime uses of 
atomic energy and radioactivity which are already beginning to influ- 
ence the processes of industrial production and medical practice, and 
to open entirely new fields of exploration in chemistry, geology, 
metallurgy, physiology, botany, and agriculture. On the horizon 
still uncertainly loom the possibilities of useful production of power 
for ship or aircraft propulsion and other special applications of heat 
and power. 
In this story we see the sudden merging of the results of many lines 
of investigation which had previously proceeded almost independently: 
50 years of research on radioactivity; 20 years’ development of high- 
voltage machines; the equivalence of mass and energy announced by 
