The fundamental point in fabricating a chain reacting machine is of course to see to it that each fission produces a certain number of neutrons and some of these neutrons will again produce fission.
Enrico FermiExperimental confirmation of a prediction is merely a measurement. An experiment disproving a prediction is a discovery.
Enrico FermiWhatever Nature has in store for mankind, unpleasant as it may be, men must accept, for ignorance is never better than knowledge.
Enrico Fermi