It just occurred to me that there is a parallel between the nuclear fission and communicable disease.
- When an atom of Uranium 235 breaks up into two smaller atoms, it also emits several neutrons. Absorbing a new neutron causes an atom of Uranium 235 to break up into two smaller atoms. There are three possibilities according to the amount of Uranium 235 present and its configuration: a. on average each atom that breaks up causes less than one new atom to break up as happens in nature; b. on average, each atom that breaks up causes exactly one other atom to break up, as happens in a nuclear reactor; c. on average, each atom that breaks up causes more than one other atom to break up and since the break up of a Uranium 235 atom emits considerable energy, BOOM.
- When someone becomes sick with Ebola that person may infect one or more other persons. There are three possibilities according to the average number of others that each sick person infects: a. on average, each ill person infects fewer than one other person, and the outbreak is quickly contained; b. on average, each ill person infects exactly one other person, and the disease become endemic; 5. on average, each ill person infects more than one other person, and an epidemic occurs.
In the case of nuclear fission, the problem is to arrange the fissile material in such a way as to produce a safe nuclear reactor or a nuclear bomb (according to the purpose); in the case of an Ebola epidemic, the problem is to isolate the infective persons in such a way as to prevent or stop an epidemic.