Best Answer - Chosen by Asker I am afraid that there will be an attack and that an atomic bomb of the size and yield of that exploded over Hiroshima may be detonated in the near future in London .Let me explain. I read Physics , amongst other subjects , at Cambridge University and am an MA and Senate member of that body , and a Mensa member . To prove my qualifications I have put my University website email address in my profile . Since the 1970's I have researched the following - If a nuclear chain reaction is sustained by just the neutrons released , it is true that a fantastically expensive 'Critical Mass ' of Plutonium or Uranium 235 is required . However , a massive amount of high energy Gamma Radiation is also released during fission and if the PROCESS and Geometry are understood , this may be incorporated in sustaining the chain reaction using the technique of "Photodisintegration" and , to cut a very long story short , Isotope separation is not needed and naturally occurring Uranium may be used . Thus a functional , Hiroshima size atomic weapon and neutron device may be built for about 500 pounds sterling out of openly available material in the UK in a matter of weeks , putting atomic weapons within the grasp of every third world country , revolutionary army and criminal or terrorist group . We are on the edge of the Abyss . The following